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  • 1.
    Brändström, Helge
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Anestesiologi och intensivvård.
    Grip, Helena
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Hallberg, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Ängquist, Karl-Axel
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Kirurgi.
    Giesbrecht, Gordon G
    Hand cold recovery responses before and after 15 months of military training in a cold climate2008Ingår i: Aviation, Space and Environmental Medicine, ISSN 0095-6562, E-ISSN 1943-4448, Vol. 79, nr 9, s. 904-908Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    INTRODUCTION: The ability of fingers to rapidly rewarm following cold exposure is a possible indicator of cold injury protection. We categorized the post-cooling hand-rewarming responses of men before and after participation in 15 mo of military training in a cold environment in northern Sweden to determine: 1) if the initial rewarming category was related to the occurrence of local cold injury during training; and 2) if cold training affected subsequent hand-rewarming responses. METHODS: Immersion of the dominant hand in 10 degrees C water for 10 min was performed pre-training on 77 men. Of those, 45 were available for successful post-training retests. Infrared thermography monitored the dorsal hand during 30 min of recovery. Rewarming was categorized as normal, moderate, or slow based on mean fingertip temperature at the end of 30 min of recovery (TFinger,30) and the percentage of time that fingertips were vasodilated (%VD). RESULTS: Cold injury occurrence during training was disproportionately higher in the slow rewarmers (four of the five injuries). Post-training, baseline fingertip temperatures and cold recovery variables increased significantly in moderate and slow rewarmers: TFinger30 increased from 21.9 +/- 4 to 30.4 +/- 6 degrees C (Moderate), and from 17.4 +/- 0 to 22.3 +/- 7 degrees C (Slow); %VD increased from 27.5 +/- 16 to 65.9 +/- 34% (Moderate), and from 0.7 +/- 2 to 31.7 +/- 44% (Slow). CONCLUSIONS: Results of the cold recovery test were related to the occurrence of local cold injury during long-term cold-weather training. Cold training itself improved baseline and cold recovery in moderate and slow rewarmers.

  • 2. Gerdle, Björn
    et al.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Karlsson, Stefan J
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Holtermann, Andreas
    Roeleveld, Karin
    Altered neuromuscular control mechanisms of the trapezius muscle in fibromyalgia.2010Ingår i: BMC Musculoskeletal Disorders, ISSN 1471-2474, E-ISSN 1471-2474, Vol. 11, s. 42-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND: fibromyalgia is a relatively common condition with widespread pain and pressure allodynia, but unknown aetiology. For decades, the association between motor control strategies and chronic pain has been a topic for debate. One long held functional neuromuscular control mechanism is differential activation between regions within a single muscle. The aim of this study was to investigate differences in neuromuscular control, i.e. differential activation, between myalgic trapezius in fibromyalgia patients and healthy controls. METHODS: 27 fibromyalgia patients and 30 healthy controls performed 3 minutes bilateral shoulder elevations with different loads (0-4 Kg) with a high-density surface electromyographical (EMG) grid placed above the upper trapezius. Differential activation was quantified by the power spectral median frequency of the difference in EMG amplitude between the cranial and caudal parts of the upper trapezius. The average duration of the differential activation was described by the inverse of the median frequency of the differential activations. RESULTS: the median frequency of the differential activations was significantly lower, and the average duration of the differential activations significantly longer in fibromyalgia compared with controls at the two lowest load levels (0-1 Kg) (p < 0.04), but not at the two highest load levels (2 and 4 Kg). CONCLUSION: these findings illustrate a different neuromuscular control between fibromyalgia patients and healthy controls during a low load functional task, either sustaining or resulting from the chronic painful condition. The findings may have clinical relevance for rehabilitation strategies for fibromyalgia.

  • 3. Gerdle, Björn
    et al.
    Östlund, Nils
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Roeleveld, Karin
    Karlsson, Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Firing rate and conduction velocity of single motor units in the trapezius muscle in fibromyalgia patients and healthy controls.2008Ingår i: Journal of Electromyography & Kinesiology, ISSN 1050-6411, E-ISSN 1873-5711, Vol. 18, nr 5, s. 707-716Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fibromyalgia is a common chronic pain condition in the population (2-4%), which often is associated with prominent negative consequences with respect to participation in daily activities. There are several reports in the literature concerning the effects of acute experimental pain on motor control. However, a more heterogeneous picture exists in the literature with respect to whether chronic pain conditions affect motor control. This study compares firing rate and conduction velocity (CV) of single motor units (MUs) in the trapezius muscle of fibromyalgia patients (FM) and healthy controls (CON). Multi-channel surface electromyography was used to estimate both MU firing rate and CV because this technique allows simultaneous estimation of both these variables and the measurements are easy and non-invasive. In this study, 29 FM and 30 CON subjects participated and performed isometric shoulder elevations using weights up to 4 kg. No significant differences in the firing rate of MUs in the trapezius muscle were found between the FM and CON groups (95% confidence interval was -1.9 and 1.3 pulses per second). There were no significant differences in CV between the groups at 1 and 2 kg load. However, the FM group had significantly higher CV in contractions without external load (p=0.004). We were unable to confirm the pain-adaptation model since no differences in firing rate between the two groups were found. CV was significantly higher in FM than in healthy controls; this might be due to alterations in histopathology and microcirculation.

  • 4.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Spatio-temporal processing of surface electromyographic signals: information on neuromuscular function and control2006Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    During muscle contraction, electrical signals are generated by the muscle cells. The analysis of those signals is called electromyography (EMG). The EMG signal is mainly determined by physiological factors including so called central factors (central nervous system origin) and peripheral factors (muscle tissue origin). In addition, during the acquisition of EMG signals, technical factors are introduced (measurement equipment origin). The aim of this dissertation was to develop and evaluate methods to estimate physiological properties of the muscles using multichannel surface EMG (MCsEMG) signals.

    In order to obtain accurate physiological estimates, a method for automatic signal quality estimation was developed. The method’s performance was evaluated using visually classified signals, and the results demonstrated high classification accuracy.

    A method for estimation of the muscle fibre conduction velocity (MFCV) and the muscle fibre orientation (MFO) was developed. The method was evaluated with synthetic signals and demonstrated high estimation precision at low contraction levels.

    In order to discriminate between the estimates of MFCV and MFO belonging to single or populations of motor units (MUs), density regions of so called spatial distributions were examined. This method was applied in a study of the trapezius muscle and demonstrated spatial separation of MFCV (as well as MFO) even at high contraction levels.

    In addition, a method for quantification of MU synchronisation was developed. The performance on synthetic sEMG signals showed high sensitivity on MU synchronisation and robustness to changes in MFCV. The method was applied in a study of the biceps brachii muscle and the relation to force tremor during fatigue. The results showed that MU synchronisation accounted for about 40 % of the force tremor.

    In conclusion, new sEMG methods were developed to study muscle function and motor control in terms of muscle architecture, muscle fibre characteristics, and processes within the central nervous system.

  • 5.
    Grönlund, Christer
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Albano, Amanda
    Gustavsson, Sandra
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Wiklund, Urban
    Henein, Michael Y
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Lindqvist, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi.
    Significant beat-to-beat variability of E/e’ irrespective of respiration2013Ingår i: International cardiovascular forum, ISSN 2409-3424, Vol. 1, nr 2, s. 88-89Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The E/e’ ratio is commonly used in Doppler echocardiographic examinations to estimate the pulmonary capillary wedge pressure. The rationale of using this ratio is to combine left ventricular (LV) filling (E) and relaxation (e’) velocities to indirectly assess left atrial pressure. However, the accuracy of this index has recently been questioned, particularly in patients with controlled heart failure. Likewise, the potential beat-to-beat variability of such measurements remains undetermined. The cardiovascular system is subject to several oscillations with the potential of influencing LV function and its intra-cavitary pressures, hence measurements of its filling and relaxation velocities. The aim of this pilot study was to assess the beat-to-beat variability of the E/e’ ratio in one minute long examination in healthy subjects, and patients with various severity of amyloid heart disease. The results show that despite critical application of the standard echocardiographic recording recommendations, E/e’ beat-to-beat variability was 36 % (22 to 50%) in healthy subjects and 17 % (11-26%) in patients, and where the most severe amyloid heart disease had the least variability. Thus, clinical use of a single or few cardiac beats might not necessarily reflect an accurate ratio between the two velocities, and hence casts doubt over their diagnostic value.

  • 6.
    Grönlund, Christer
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Claesson, Kenji
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    D'hooge, Jan
    Department of Cardiovascular sciences, Leuven, Belgium.
    Henein, Michael Y.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi. Umeå Heart Centre.
    Lindqvist, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi. Umeå Heart Centre.
    Simultaneous quantification of myocardial and blood flow velocities based on duplex mode ultrasound imaging2013Ingår i: Biomedical engineering online, ISSN 1475-925X, E-ISSN 1475-925X, Vol. 12, artikel-id 107Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND: Ultrasound imaging of the heart is a commonly used clinical tool to assess cardiac function. The basis for this analysis is the quantification of cardiac blood flow and myocardial velocities. These are typically measured using different imaging modes and on different cardiac cycles. However, due to beat-to-beat variations such as irregular heart rhythm and transient events, simultaneous acquisition is preferred. There exists specialized ultrasound systems for this purpose; however, it would be beneficial if this could be achieved using conventional ultrasound systems due to their wide availability. The conventional Duplex mode ultrasound allows simultaneous acquisition, however at a highly reduced spatial and temporal resolution.

    METHODS: The aim of this work was to present and evaluate the performance of a novel method to recover myocardial tissue velocity using conventional Duplex ultrasound imaging, and to demonstrate its feasibility for the assessment of simultaneous blood flow and myocardial velocity in-vivo. The essence of the method was the estimation of the axial phase shift of robust echogenic structures between subsequent image frames. The performance of the method was evaluated on synthetic tissue mimicking B-mode image sequences at different frame rates (20--60 Hz) and tissue velocities (peak velocities 5-15cm/s), using cardiac deformation and displacement characteristics. The performance was also compared to a standard 2-D speckle tracking technique.

    RESULTS: The method had an overall high performance at frame rates above 25 Hz, with less than 15% error of the peak diastolic velocity, and less than 10 ms peak timing error. The method showed superior performance compared to the 2-D tracking technique at frame rates below 50 Hz. The in-vivo quantification of simultaneous blood flow and myocardial tissue velocities verified the echocardiographic patterns and features of healthy subjects and the specific patient group.

    CONCLUSIONS: A novel myocardial velocity quantification method was presented and high performance at frame rates above 25Hz was shown. In-vivo quantification of simultaneous myocardial and blood flow velocities was feasible using the proposed method and conventional Duplex mode imaging. We propose that the methodology is suitable for retrospective as well as prospective studies on the mechanics and hemodynamics of the heart.

  • 7.
    Grönlund, Christer
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Claesson, Kenji
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Holtermannz, Andreas
    Imaging two-dimensional mechanical waves of skeletal muscle contraction2013Ingår i: Ultrasound in Medicine and Biology, ISSN 0301-5629, E-ISSN 1879-291X, Vol. 39, nr 2, s. 360-369Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Skeletal muscle contraction is related to rapid mechanical shortening and thickening. Recently, specialized ultrasound systems have been applied to demonstrate and quantify transient tissue velocities and one-dimensional (1-D) propagation of mechanical waves during muscle contraction. Such waves could potentially provide novel information on musculoskeletal characteristics, function and disorders. In this work, we demonstrate two-dimensional (2-D) mechanical wave imaging following the skeletal muscle contraction. B-mode image acquisition during multiple consecutive electrostimulations, speckle-tracking and a time-stamp sorting protocol were used to obtain 1.4 kHz frame rate 2-D tissue velocity imaging of the biceps brachii muscle contraction. The results present novel information on tissue velocity profiles and mechanical wave propagation. In particular, counter-propagating compressional and shear waves in the longitudinal direction were observed in the contracting tissue (speed 2.8-4.4 m/s) and a compressional wave in the transverse direction of the non-contracting muscle tissue (1.2-1.9 m/s). In conclusion, analysing transient 2-D tissue velocity allows simultaneous assessment of both active and passive muscle tissue properties. (E-mail: christer.gronlund@vll.se) (C) 2013 World Federation for Ultrasound in Medicine & Biology.

  • 8.
    Grönlund, Christer
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Holtermann, A
    Roeleveld, K
    Karlsson, J Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Quantification of motor unit synchronization from surface EMG signals with minimized dependency on muscle fibre conduction velocityManuskript (preprint) (Övrigt vetenskapligt)
  • 9.
    Grönlund, Christer
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Holtermann, Andreas
    Roeleveld, Karin
    Karlsson, J Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Motor unit synchronization during fatigue: a novel quantification method.2009Ingår i: Journal of Electromyography & Kinesiology, ISSN 1050-6411, E-ISSN 1873-5711, Vol. 19, nr 2, s. 242-251Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Motor unit (MU) synchronization is the result of commonality in the pre-synaptic input to MUs. Previously proposed techniques to estimate MU synchronization based on invasive and surface electromyography (sEMG) recordings have been, respectively, limited by the analyzed MU population size and influence of changes in muscle fibre conduction velocities (MFCVs). The aim of this paper was to evaluate a novel descriptor of MU synchronization on a large MU population, and to minimize its dependency on MFCV. The method is based on the asymmetry of MU action potentials, causing synchronized MU action potentials to skew the monopolar sEMG signal distribution. The descriptor was the skewness statistic used on sub-band filtered monopolar sEMG signals (sub-band skewness). The method was evaluated using simulated signals and its performance was evaluated in terms of bias and sensitivity of the sub-band skewness quantifying the MU synchronization level. The best sensitivity was obtained using sub-band filtering at scale 5 (Mexican hat wavelet). The sensitivity was in general about 0.1units per 5% MU synchronization level. Changes in MFCV had a minimal influence, and caused at most a 5% deviant MU synchronization quantification level. A halved recruitment level had higher bias and a 20% lower sensitivity. Increased firing rate (14-34Hz) reduced the sensitivity about 50%. The sensitivity of the descriptor was robust to noise, and different volume conduction properties. It should be noted that the sub-band skewness comprises a subject-dependent component implying that only changes in MU synchronization level can be quantified.

  • 10.
    Grönlund, Christer
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Roeleveld, Karin
    Holtermann, Andreas
    Karlsson, J Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    On-line signal quality estimation of multichannel surface electromyograms2005Ingår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 43, nr 3, s. 357-364Artikel i tidskrift (Refereegranskat)
  • 11.
    Grönlund, Christer
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Östlund, Nils
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Lindh, Jack
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Onkologi.
    Bergström, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Onkologi.
    Karlsson, Stefan J
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Spatio-temporal processing of surface EMG signals from the sternocleidomastoideus muscle to assess effects of radiotherapy on motor unit conduction velocity and firing rate: a pilot study2008Ingår i: Biomedical Signal Processing and Control, ISSN 1746-8094, Vol. 3, nr 2, s. 163-168Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Radiation therapy causes both muscle and nerve tissue damage. However, the evolution and mechanisms of these damages are not fully understood. Information on the state of active muscle fibres and motoneurons can be obtained by measuring sEMG signals and calculating the conduction velocity (CV) and firing rate of individual motor units, respectively. The aim of this pilot study was to evaluate if the multi-channel surface EMG (sEMG) technique could be applied to the sternocleidomastoideus muscle (SCM) of radiotherapy patients, and to assess if the CV and firing rate are altered as a consequence of the radiation.

    Surface EMG signals were recorded from the radiated and healthy SCM muscles of 10 subjects, while subjects performed isometric rotation of the head. CV and firing rate were calculated using two recently proposed methods based on spatio-temporal processing of the sEMG signals. The multi-channel sEMG technique was successfully applied to the SCM muscle and CV and firing rates were obtained. The measurements were fast and simple and comfortable for the patients. Sufficient data quality was obtained from both sides of seven and four subjects for the CV and firing rate analysis, respectively. No differences in CV or firing rate were found between the radiated and non-radiated sides (p = 0.13 and p = 0.20, respectively). Firing rate and CV were also obtained from a myokymic discharge pattern. It was found that the CV decreased significantly (p = 0.01) during the bursts.

  • 12.
    Grönlund, Christer
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Östlund, Nils
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Roeleveld, Karin
    Karlsson, J Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Simultaneous estimation of muscle fibre conduction velocity and muscle fibre orientation using 2D multichannel surface electromyogram2005Ingår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 43, nr 1, s. 63-70Artikel i tidskrift (Refereegranskat)
  • 13.
    Gustafsson, Sandra
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Granåsen, Gabriel
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Wiklund, Urban
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Suhr, Ole B.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
    Lindqvist, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi.
    Discriminating hereditary transthyretin cardiomyopathy from hypertrophic cardiomyopathy using an echocardiographic and ECG based classification tree2014Ingår i: European Heart Journal, ISSN 0195-668X, E-ISSN 1522-9645, Vol. 35, nr Supplement 1, Meeting abstract P5254, s. 929-929Artikel i tidskrift (Övrigt vetenskapligt)
  • 14.
    Gustafsson, Sandra
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi. Umeå Heart Centre.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Mörner, Stellan
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi. Umeå Heart Centre.
    Suhr, Ole
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
    Lindqvist, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi. Umeå Heart Centre.
    Can echocardiography differentiate hereditary transthyretin amyloidosis from hypertrophic cardiomyopathy?2013Ingår i: European Heart Journal, ISSN 0195-668X, E-ISSN 1522-9645, Vol. 34, nr Supplement: 1, s. 213-213Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Purpose: Hereditary transthyretin amyloidosis (ATTR) andhypertrophic cardiomyopathy (HCM) have many phenotypic similarities when examined by echocardiography. As the two conditions have different treatment strategies it is of importance to accurately diagnose these patients early in the disease. This study aimed to identify the most accurate echocardiographic method in differentiating these two conditions by using traditional and speckle tracking echocardiographyas well as myocardial texture analysis.

    Methods: We investigated 40 healthy controls, 33 patients with biopsy proven ATTR and 20 with HCM. All patients had septal thickness >12 mm. We measured left ventricular (LV) global strain as intrinsic systolic function and LV E/e' to estimate filling pressures. We also tested septal cyclic integrated backscatter (cIBS) and septal entropy as both being measures for myocardial highly reflection pattern whereas cIBS showing motion of highly reflective echoes and entropy the distribution of highly reflective echoes.

    Results: LV global strain, cIBS and E/e' were not useful in differentiating ATTR from HCM. However, septal entropy was found to be significantly different and showed an area under the curve from ROC analysis of 0.66 separating ATTR from HCM.

    Conclusion: After using detailed analysis of different aspects of LV morphology and function we found that myocardial texture behavior from entropy analysis was the only method useful in differentiating patients with ATTR fromHCM.

  • 15.
    Gustavsson, Sandra
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Granåsen, Gabriel
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Wiklund, Urban
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Mörner, Stellan
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Henein, Michael
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Suhr, Ole B
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
    Lindqvist, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Can echocardiography and ECG discriminate hereditary transthyretin V30M amyloidosis from hypertrophic cardiomyopathy?2015Ingår i: Amyloid: Journal of Protein Folding Disorders, ISSN 1350-6129, E-ISSN 1744-2818, Vol. 22, nr 3, s. 163-170Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Objective: Hereditary transthyretin (ATTR) amyloidosis with increased left ventricular wall thickness could easily be misdiagnosed by echocardiography as hypertrophic cardiomyopathy (HCM). Our aim was to create a diagnostic tool based on echocardiography and ECG that could optimise identification of ATTR amyloidosis. Methods: Data were analysed from 33 patients with biopsy proven ATTR amyloidosis and 30 patients with diagnosed HCM. Conventional features from ECG were acquired as well as two dimensional and Doppler echocardiography, speckle tracking derived strain and tissue characterisation analysis. Classification trees were used to select the most important variables for differentiation between ATTR amyloidosis and HCM. Results: The best classification was obtained using both ECG and echocardiographic features, where a QRS voltage >30 mm was diagnostic for HCM, whereas in patients with QRS voltage <30 mm, an interventricular septal/posterior wall thickness ratio (IVSt/PWt) >1.6 was consistent with HCM and a ratio <1.6 supported the diagnosis of ATTR amyloidosis. This classification presented both high sensitivity (0.939) and specificity (0.833). Conclusion: Our study proposes an easily interpretable classification method for the differentiation between HCM and increased left ventricular myocardial thickness due to ATTR amyloidosis. Our combined echocardiographic and ECG model could increase the ability to identify ATTR cardiac amyloidosis in clinical practice.

  • 16.
    Henein, Mark
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Tossavainen, Erik
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Söderberg, Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Gonzalez, Manuel
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Lindqvist, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
    Left atrial strain rate estimates PCWP2013Ingår i: International cardiovascular forum, ISSN 2409-3424, nr 1, s. 25-30Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    OBJECTIVE: Raised left atrial (LA) pressure is a common pathway for many pathologies and is known for its complications. It has a direct effect on LA cavity size and potentially also its function. We hypothesized that raised LA pressure, as shown by pulmonary capillary wedge pressure (PCWP), correlates with severity of global LA deformation abnormalities during atrial systole (LASRa). DESIGN AND PATIENTS: We prospectively studied 46 consecutive patients, mean age 61 ±13 years, 17 males, of various etiologies who underwent right heart catheterization and simultaneous Doppler echocardiography using spectral, tissue Doppler and speckle tracking echocardiography techniques for assessing LA structure and function. RESULTS: PCWP correlated with direct measurements of LA structure and function: LA volume (r= 0.43, p<0.01) and LASRa (r=0.79, p<0.001). PCWP correlated also with other indirect measures of LA pressure such as E/A (r=0.65, p<0.001), E wave deceleration time (r=0.54, p<0.001), E/e’ (r=0.49, p<0.001) and LA systolic filling fraction (r=0.52, p<0.001). However, LASRa together with LA systolic filling fraction, had the highest areas under the curve (0.83 and 0.87, respectively) for identifying patients with PCWP > 15 mmHg. CONCLUSION: PCWP correlates with LA deformation rate during atrial systole and to a higher extent than conventional Doppler measures of raised LA pressures. These findings should have significant clinical implications in correctly identifying breathless patients due to raised LA pressure.

  • 17.
    Henein, Michael Y
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Tossavainen, Erik
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Söderberg, Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Gonzalez, Manuel
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för medicin.
    Lindqvist, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi.
    Right and left heart dysfunction predict mortality in pulmonary hypertension2017Ingår i: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 37, nr 1, s. 45-51Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In pulmonary hypertension (PH), the right heart dysfunction is a strong predictor of adverse clinical outcome, while the role of the left heart is not fully determined. The aim of this study was to identify predictors of mortality in precapillary PH including measures of both right and left heart function. We studied 34 patients (mean age 64 ± 13, range 31-82 years, 24 females) with precapillary PH, all of whom underwent detailed Doppler echocardiographic examination of the right and left heart function using conventional and speckle-tracking echocardiography. Patients were followed up for up to 8 years (mean 4·2 ± 1·9 years). At follow-up, 16 patients survived. Left ventricular (LV) filling time (P = 0·007), pulmonary artery acceleration time (P = 0·009), right atrial pressure (RAP) (P<0·001) and tricuspid regurgitation (TR) severity (P = 0·007) were worse in the deceased group. RV global longitudinal strain (GLS) (P = 0·001), RAP (P≤0·001), LV filling time (P<0·001) and TR severity (P<0·001) were the most accurate predictors, having the largest AUC (>0·65) and carried the highest risk for mortality (P<0·001 for all). The strongest predictors of mortality in precapillary PH indirectly reflect both left and right heart dysfunction including atrial structure and function disturbances. While an interaction pattern is observed, it needs to be confirmed in a larger cohort.

  • 18.
    Holtermann, A
    et al.
    Human Movement Sciences Programme, Norwegian University of Science and Technology, Trondheim, Norway.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Ingebrigtsen, J
    Human Movement Sciences Programme, Norwegian University of Science and Technology, Trondheim, Norway.
    Karlsson, J Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Roeleveld, K
    Human Movement Sciences Programme, Norwegian University of Science and Technology, Trondheim, Norway.
    Duration of differential activations is functionally related to fatigue prevention during low-level contractions.2010Ingår i: Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology, ISSN 1873-5711, Vol. 20, nr 2, s. 241-245Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this study was to investigate the importance of duration of differential activations between the heads of the biceps brachii on local fatigue during prolonged low-level contractions. Fifteen subjects carried out isometric elbow flexion at 5% of maximal voluntary contraction (MVC) for 30 min. MVCs were performed before and at the end of the prolonged contraction. Surface electromyographic (EMG) signals were recorded from both heads of the biceps brachii. Differential activation was analysed based on the difference in EMG amplitude (activation) between electrodes situated at the two heads. Differential activations were quantified by the power spectral median frequency of the difference in activation between the heads throughout the contraction. The inverse of the median frequency was used to describe the average duration of the differential activations. The relation between average duration of the differential activations and the fatigue-induced reduction in maximal force was explored by linear regression analysis. The main finding was that the average duration of differential activation was positively associated to relative maximal force at the end of the 30 min contraction (R(2)=0.5, P<0.01). The findings of this study highlight the importance of duration of differential activations for local fatigue, and support the hypothesis that long term differential activations prevent fatigue during prolonged low-level contractions.

  • 19. Holtermann, A.
    et al.
    Grönlund, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Karlsson, J. Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Roeleveld, Karin
    Differential activation of regions within the biceps brachii muscle during fatigue2008Ingår i: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 192, nr 4, s. 559-567Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aim: To examine the occurrence of repeated differential activation between the heads of the biceps brachii muscle and its relation to fatigue prevention during a submaximal contraction.

    Methods: Thirty‐nine subjects carried out an isometric contraction of elbow flexion at 25% of maximal voluntary contraction (MVC) until exhaustion. A grid of 13 by 10 electrodes was used to record surface electromyographic signals from both heads of the biceps brachii. The root‐mean‐square of signals recorded from electrodes located medially and laterally was used to analyse activation differences. Differential activation was defined as periods of 33% different activation level between the two heads of the biceps brachii muscle.

    Results: Differential muscle activation was demonstrated in 30 of 33 subjects with appropriate data quality. The frequency of differential activation increased from 4.9 to 6.6 min−1 at the end of the contractions with no change in duration of the differential activations (about 1.4 s). Moreover, the frequency of differential activation was, in general, negatively correlated with time to exhaustion.

    Conclusion: The observed differential activation between the heads of the biceps brachii can be explained by an uneven distribution of synaptic input to the motor neurone pool. The findings of this study indicate that differential activation of regions within a muscle does not prevent fatigue at a contraction level of 25% of MVC.

  • 20. Holtermann, Andreas
    et al.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Karlsson, J Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Roeleveld, Karin
    Motor unit synchronization during fatigue: described with a novel sEMG method based on large motor unit samples.2009Ingår i: Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology, ISSN 1873-5711, Vol. 19, nr 2, s. 232-241Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The amount of documented increase in motor unit (MU) synchronization with fatigue and its possible relation with force tremor varies largely, possibly due to inhomogeneous muscle activation and methodological discrepancies and limitations. The aim of this study was to apply a novel surface electromyographical (EMG) descriptor for MU synchronization based on large MU populations to examine changes in MU synchronization with fatigue at different sites of a muscle and its relation to tremor. Twenty-four subjects performed an isometric elbow flexion at 25% of maximal voluntary contraction until exhaustion. Monopolar EMG signals were recorded using a grid of 130 electrodes above the biceps brachii. Changes in MU synchronization were estimated based on the sub-band skewness of EMG signals and tremor by the coefficient of variation in force. The synchronization descriptor was dependent on recording site and increased with fatigue together with tremor. There was a general association between these two parameters, but not between their fluctuations. These results are in agreement with other surface EMG studies and indicate that the novel descriptor can be used to attain information of synchronization between large MU populations during fatigue that cannot be retrieved with intra-muscular EMG.

  • 21. Holtermann, Andreas
    et al.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Karlsson, Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Roeleveld, Karin
    Spatial distribution of active muscle fibre characteristics in the upper trapezius muscle and its dependency on contraction level and duration.2008Ingår i: Journal of Electromyography & Kinesiology, ISSN 1050-6411, E-ISSN 1873-5711, Vol. 18, nr 3, s. 372-381Artikel i tidskrift (Refereegranskat)
  • 22. Holtermann, Andreas
    et al.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Roeleveld, Karin
    Gerdle, Björn
    The relation between neuromuscular control and pain intensity in fibromyalgia2011Ingår i: Journal of Electromyography & Kinesiology, ISSN 1050-6411, E-ISSN 1873-5711, Vol. 21, nr 3, s. 519-524Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fibromyalgia patients are shown to have a different neuromuscular control (differential activation) than healthy persons. Before clinical trials can be initiated, the relation between differential activations and pain intensity among fibromyalgia patients needs to be investigated. Twenty-seven fibromyalgia patients performed 3 min bilateral shoulder elevations with different loads (0-4 kg) with a high-density surface electromyographical (EMG) grid placed on the upper trapezius. Differential activation was quantified by the power spectral median frequency of the difference in EMG amplitude between the cranial and caudal parts of the upper trapezius. The average duration of the differential activation was described by the inverse of the median frequency of the differential activations. The relation between frequency and duration of differential activations as an average of the 4 loads and pain intensity the same day prior to the experiment was explored by Pearson's correlation coefficients. A strong negative relation between frequency of differential activations and pain intensity (R=-0.67, p<0.001) and a strong positive association between duration of differential activations and pain intensity (R=0.66, p<0.001) were found. The significant association between frequency and duration of differential activations and pain intensity among the fibromyalgia patients indicates a relation between this neuromuscular control pattern and pain intensity. This finding support initiation of clinical trials for investigating effects on pain intensity of modifying differential activations among fibromyalgia patients.

  • 23. Holtermann, Andreas
    et al.
    Roeleveld, Karin
    Mork, Paul Jarle
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Karlsson, J Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Andersen, Lars L
    Olsen Baare, Henrik
    Zebis Kreutzfeldt, Mette
    Sjøgaard, Gisela
    Søgaard, Karen
    Selective activation of neuromuscular compartments within the human trapezius muscle.2009Ingår i: Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology, ISSN 1873-5711, Vol. 19, nr 5, s. 896-902Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Task-dependent differences in relative activity between "functional" subdivisions within human muscles are well documented. Contrary, independent voluntary control of anatomical subdivisions, termed neuromuscular compartments is not observed in human muscles. Therefore, the main aim of this study was to investigate whether subdivisions within the human trapezius can be independently activated by voluntary command using biofeedback guidance. Bipolar electromyographical electrodes were situated on four subdivisions of the trapezius muscle. The threshold for "active" and "rest" for each subdivision was set to >12% and <1.5% of the maximal electromyographical amplitude recorded during a maximal voluntary contraction. After 1h with biofeedback from each of the four trapezius subdivisions, 11 of 15 subjects learned selective activation of at least one of the four anatomical subdivisions of the trapezius muscle. All subjects managed to voluntarily activate the lower subdivisions independently from the upper subdivisions. Half of the subjects succeeded to voluntarily activate both upper subdivisions independently from the two lower subdivisions. These findings show that anatomical subdivisions of the human trapezius muscle can be independently activated by voluntary command, indicating neuromuscular compartmentalization of the trapezius muscle. The independent activation of the upper and lower subdivisions of the trapezius is in accordance with the selective innervation by the fine cranial and main branch of the accessory nerve to the upper and lower subdivisions. These findings provide new insight into motor control characteristics, learning possibilities, and function of the clinically relevant human trapezius muscle.

  • 24.
    Ibrahimi, Pranvera
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Jashari, Fisnik
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Johansson, Elias
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin. Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Bajraktari, Gani
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Wester, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
    Henein, Michael Y.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Common carotid intima-media features determine distal disease phenotype and vulnerability in asymptomatic patients2015Ingår i: International Journal of Cardiology, ISSN 0167-5273, E-ISSN 1874-1754, Vol. 196, s. 22-28Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Objectives: There is a growing awareness of the importance of carotid plaque features evaluation in stroke prediction. Carotid intima-media thickness (IMT) and recently its echogenicity were used for stroke prediction, although their clinical relevance was not well determined. The aim of this study was to assess the relationship between common carotid artery (CCA) ultrasound markers of atherosclerosis and distal, bifurcation and internal carotid artery (ICA), plaque features. Methods: We analyzed 137 carotid arteries in 87 asymptomatic patients with known carotid disease (mean age 69 +/- 6 year, 34.5% females). Intima media thickness (IMT) and its gray scale median (IM-GSM) were measured at the CCA. Plaque textural features including gray scale median (GSM), juxtaluminal black area (JBA-mm(2)) without a visible cap, and plaque coarseness, at bifurcation and ICA were also determined. CCA measurements were correlated with those of the distal plaques. Results: An increased IMT in CCA correlated with plaque irregularities in the bifurcation and ICA (r = 0.53, p < 0.001), while IM-GSM was closely related to plaque echogenicity (GSM) (r = 0.76, p < 0.001), and other textural plaque features. Both, IMT and IM-GSM correlated weakly with stenosis severity (r = 0.27, p = 0.001 and r = -0.18, p = 0.026) respectively. Conclusion: In asymptomatic patients, measurements of CCA reflect distal, bifurcation and ICA disease, with IMT reflecting plaque irregularities and IM-GSM as markers of textural plaque abnormalities. Integrating measurements of both IMT and IM-GSM in a model could be used as a better marker of disease vulnerability over and above each measure individually. 

  • 25.
    Ibrahimi, Pranvera
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Jashari, Fisnik
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Johansson, Elias
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap. Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Bajraktari, Gani
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Wester, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
    Henein, Michael Y
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Vulnerable plaques in the contralateral carotid arteries in symptomatic patients: a detailed ultrasound analysis2014Ingår i: Atherosclerosis, ISSN 0021-9150, E-ISSN 1879-1484, Vol. 235, nr 2, s. 526-531Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND AND AIM: Carotid plaques may represent a generalized atherosclerotic syndrome or a localized disease. The aim of this study was to assess the morphological and textural features of carotid plaques located contralateral to the symptomatic side and compare them with the symptomatic side and with plaques from asymptomatic patients. METHODS: We studied 66 arteries in 39 patients (mean age 70 ± 7 year, 33% females). Arterial plaques were classified as either symptomatic (n = 30), contralateral to symptomatic (n = 25) or asymptomatic (n = 11). We compared several plaque features between these groups including the mean values of the grey scale median (GSM), entropy, juxtaluminal black area (JBA) without visible echogenic cap, GSM of the JBA and surface irregularity. RESULTS: The plaques contralateral to symptomatic arteries had similar morphological and textural features to those in the symptomatic arteries. In contrast, they had more vulnerable morphological and textural features than those in asymptomatic arteries: less smooth plaques (12% vs. 55%) and instead more often mildly irregular (60% vs 36%) or markedly irregular (28% vs. 9%; p = 0.03), lower GSM (26.2 ± 8 vs. 49.4 ± 14, p < 0.001) and lower GSM of the JBA (5.0 ± 3.6 vs. 11.4 ± 2.1, p = 0.008). The frequency of entropy and plaque calcification was similar in all groups. CONCLUSION: Symptomatic patients with carotid artery disease seem to have similar morphological and textural features of vulnerability in the symptomatic and the contralateral carotid arteries, which are profound compared with asymptomatic carotid arteries. These findings support the concept of generalized carotid atherosclerotic pathology rather than incidental unilateral disease, and also emphasize a need for aggressive measures for plaque stabilization, particularly in symptomatic patients.

  • 26.
    Ibrahimi, Pranvera
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Jashari, Fisnik
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Johansson, Elias
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Wester, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
    Henein, Michael Y.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Common carotid intima-media measurements determine distal disease structure and vulnerability in asymptomatic patients2015Ingår i: Atherosclerosis, ISSN 0021-9150, E-ISSN 1879-1484, Vol. 241, nr 1, s. E164-E164Artikel i tidskrift (Övrigt vetenskapligt)
  • 27.
    Jashari, Fisnik
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Ibrahimi, Pranvera
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Bajraktari, Gani
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Wester, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för medicin. Department of Clinical Sciences, Danderyds Hospital, Karolinska Institute, Stockholm, Sweden.
    Henein, Michael Y
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Carotid plaque echogenicity predicts cerebrovascular symptoms: a systematic review and meta-analysis2016Ingår i: European Journal of Neurology, ISSN 1351-5101, E-ISSN 1468-1331, Vol. 23, nr 7, s. 1241-1247Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background and purpose: Many reports have shown an association between hypoechoic (echolucent) carotid atherosclerotic plaques and unstable features. In this meta-analysis our aim was to determine the role of carotid plaque echogenicity in predicting future cerebrovascular (CV) symptoms.

    Methods: Electronic databases (PubMed, MEDLINE, EMBASE and Cochrane Center Register) up to September 2015 were systematically searched. Studies with ultrasound-based characterization of carotid artery plaque echogenicity and its association with focal neurological symptoms of vascular origin were eligible for analysis. In the meta-analysis, heterogeneity was measured usingI2 statistics and publication bias was evaluated using the Begg–Mazumdar test. In addition several comparisons between subgroups were performed.

    Results: Of 1387 identified reports, eight studies with asymptomatic patients and three studies with symptomatic patients were meta-analyzed. Pooled analysis showed an association between echolucent carotid plaques and future CV events in asymptomatic patients [relative risk 2.72 (95% confidence interval 1.86–3.96)] and recurrent symptoms in symptomatic patients [relative risk 2.97 (95% confidence interval 1.85–4.78)]. The association was preserved for all stenosis degrees in asymptomatic patients, whilst patients with echolucent plaques and severe stenosis were at higher risk of future events. Also, computer-assisted methods for assessment of carotid plaque echogenicity and studies analyzing ultrasound data collected after the year 2000 showed better prediction.

    Conclusions: In asymptomatic and symptomatic patients, analysis of carotid plaque echogenicity could identify those at high risk of CV events.

  • 28.
    Jashari, Fisnik
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap. Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Ibrahimi, Pranvera
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för medicin.
    Johansson, Elias
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för medicin.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Wester, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för medicin. Department of Clinical Sciences, Danderyds Hospital, Karolinska Institute, Stockholm, Sweden.
    Henein, Michael Y.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Carotid IM-GSM is better than IMT for identifying patients with multiple arterial disease2018Ingår i: Scandinavian Cardiovascular Journal, ISSN 1401-7431, E-ISSN 1651-2006, Vol. 52, nr 2, s. 93-99Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Objective. Atherosclerosis is a systemic inflammatory disease that can affect more than one arterial bed simultaneously. The aim of this study was to determine the relationship between ultrasound markers of atherosclerosis and multiple arterial disease. Design. We have included 87 currently asymptomatic carotid disease patients (mean age 69 +/- 6 year, 34% females) in this study. Intima media thickness (IMT) and intima media-grey scale median (IM-GSM) were measured in the common carotid artery (CCA), and correlated with previous and/or current atherosclerotic vascular disease in the coronary, carotid and lower extremities. Patients were divided into three groups: (1) asymptomatic, (2) previous symptoms in one arterial territory and (3) previous symptoms in multiple arterial territories. Results. Patients with previous disease in the coronary arteries had higher IMT (p=.034) and lower IM-GSM (p<.001), and those with prior stroke had lower IM-GSM (p=.007). Neither IMT nor IM-GSM was different between patients with and without previous lower extremity vascular disease. IM-GSM was significantly different between groups, it decreased significantly with increasing number of arterial territories affected (37.7 +/- 15.4 vs. 29.3 +/- 16.4 vs. 20.7 +/- 12.9) p<.001, for asymptomatic, symptoms in one and in multiple arterial systems, respectively. Conventional IMT was not significantly different between groups p=.49. Conclusion. Carotid IMT was higher and IM-GSM lower in patients with symptomatic nearby arterial territories but not in those with peripheral disease. In contrast to conventional IMT, IM-GSM can differentiate between numbers of arterial territories affected by atherosclerosis, suggesting that it is a better surrogate for monitoring multiple arterial territory disease.

  • 29.
    Jashari, Fisnik
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Ibrahimi, Pranvera
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Johansson, Elias
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Wester, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
    Henein, Michael Y.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Carotid im-gsm is related to multisite atherosclerosis disease2015Ingår i: Atherosclerosis, ISSN 0021-9150, E-ISSN 1879-1484, Vol. 241, nr 1, s. E164-E164Artikel i tidskrift (Övrigt vetenskapligt)
  • 30.
    Karlsson, J Stefan
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Roeleveld, Karin
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Holtermann, Andreas
    Östlund, Nils
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Signal processing of the surface electromyogram to gain insight into neuromuscular physiology.2009Ingår i: Philosophical Transactions. Series A: Mathematical, physical, and engineering science, ISSN 1364-503X, E-ISSN 1471-2962, Vol. 367, nr 1887, s. 337-356Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A surface electromyogram (sEMG) contains information about physiological and morphological characteristics of the active muscle and its neural strategies. Because the electrodes are situated on the skin above the muscle, the sEMG is an easily obtainable source of information. However, different combinations of physiological and morphological characteristics can lead to similar sEMG signals and sEMG recordings contain noise and other artefacts. Therefore, many sEMG signal processing methods have been developed and applied to allow insight into neuromuscular physiology. This paper gives an overview of important advances in the development and applications of sEMG signal processing methods, including spectral estimation, higher order statistics and spatio-temporal processing. These methods provide information about muscle activation dynamics and muscle fatigue, as well as characteristics and control of single motor units (conduction velocity, firing rate, amplitude distribution and synchronization).

  • 31. Khangure, Simon R.
    et al.
    Benhabib, Hadas
    Machnowska, Matylda
    Fox, Allan J.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Herod, Wendy
    Maggisano, Robert
    Sjöberg, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Wester, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för medicin. Department of Clinical Sciences, Karolinska Institutet Danderyds Hospital, Stockholm, Sweden.
    Hojjat, Seyed-Parsa
    Hopyan, Julia
    Aviv, Richard I.
    Johansson, Elias
    Carotid near-occlusion frequently has high peak systolic velocity on Doppler ultrasound2018Ingår i: Neuroradiology, ISSN 0028-3940, E-ISSN 1432-1920, Vol. 60, nr 1, s. 17-25Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose: Carotid near-occlusion is a tight atherosclerotic stenosis of the internal carotid artery (ICA) resulting in decrease in diameter of the vessel lumen distal to the stenosis. Near-occlusions can be classified as with or without full collapse, and may have high peak systolic velocity (PSV) across the stenosis, mimicking conventional > 50% carotid artery stenosis. We aimed to determine how frequently near-occlusions have high PSV in the stenosis and determine how accurately carotid Doppler ultrasound can distinguish high-velocity near-occlusion from conventional stenosis.

    Methods: Included patients had near-occlusion or conventional stenosis with carotid ultrasound and CT angiogram (CTA) performed within 30 days of each other. CTA examinations were analyzed by two blinded expert readers. Velocities in the internal and common carotid arteries were recorded. Mean velocity, pulsatility index, and ratios were calculated, giving 12 Doppler parameters for analysis.

    Results: Of 136 patients, 82 had conventional stenosis and 54 had near-occlusion on CTA. Of near-occlusions, 40 (74%) had high PSV (≥ 125 cm/s) across the stenosis. Ten Doppler parameters significantly differed between conventional stenosis and high-velocity near-occlusion groups. However, no parameter was highly sensitive and specific to separate the groups.

    Conclusion: Near-occlusions frequently have high PSV across the stenosis, particularly those without full collapse. Carotid Doppler ultrasound does not seem able to distinguish conventional stenosis from high-velocity near-occlusion. These findings question the use of ultrasound alone for preoperative imaging evaluation.

  • 32. Lindberg, F
    et al.
    Öhberg, Fredrik
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Brodin, LA
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Assessment of intramuscular activation patterns using ultrasound M-mode strain2013Ingår i: Journal of Electromyography & Kinesiology, ISSN 1050-6411, E-ISSN 1873-5711, Vol. 23, nr 4, s. 879-885Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The intramuscular activation pattern can be connected to the motor unit recruitment strategy of force generation and fatigue resistance. Electromyography has earlier been used in several studies to quantify the spatial inhomogeneity of the muscle activation. We applied ultrasound M-mode strain to study the activation pattern through the tissue deformation. Correlation values of the strain at different force levels were used to quantify the spatial changes in the activation. The assessment was done including the biceps brachii muscle of 8 healthy subjects performing isometric elbow flexion contractions ranging from 0% to 80% of maximum voluntary contraction. The obtained results were repeatable and demonstrated consistent changes of the correlation values during force regulation, in agreement with previously presented EMG-results. Both intra-subject and inter-subject activation patterns of strain were considered along and transverse the fiber direction. The results suggest that ultrasound M-mode strain can be used as a complementary method to study intramuscular activation patterns with high spatial resolution.

    (C) 2013 Elsevier Ltd. All rights reserved.

  • 33. Lindberg, Frida
    et al.
    Mårtensson, Mattias
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Brodin, Lars-Åke
    Evaluation of ultrasound Tissue Velocity Imaging: a phantom study of velocity estimation in skeletal muscle low-level contractions2013Ingår i: BMC Medical Imaging, ISSN 1471-2342, E-ISSN 1471-2342, Vol. 13, nr 16Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: Tissue Velocity Imaging (TVI) is an ultrasound based technique used for quantitative analysis of the cardiac function and has earlier been evaluated according to myocardial velocities. Recent years several studies have reported applying TVI in the analysis of skeletal muscles. Skeletal tissue velocities can be very low. In particular, when performing isometric contractions or contractions of low force level the velocities may be much lower compared to the myocardial tissue velocities. Methods: In this study TVI was evaluated for estimation of tissue velocities below the typical myocardial velocities. An in-house phantom was used to see how different PRF-settings affected the accuracy of the velocity estimations. Results: With phantom peak velocity at 0.03 cm/s the error ranged from 31% up to 313% with the different PRF-settings in this study. For the peak velocities at 0.17 cm/s and 0.26 cm/s there was no difference in error with tested PFR settings, it is kept approximately around 20%. Conclusions: The results from the present study showed that the PRF setting did not seem to affect the accuracy of the velocity estimation at tissue velocities above 0.17 cm/s. However at lower velocities (0.03 cm/s) the setting was crucial for the accuracy. The PRF should therefore preferable be reduced when the method is applied in low-level muscle contraction.

  • 34. Lindberg, Frida
    et al.
    Öhberg, Fredrik
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Granåsen, Gabriel
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Brodin, Lars-Åke
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Pennation angle dependency in skeletal muscle tissue doppler strain in dynamic contractions2011Ingår i: Ultrasound in Medicine and Biology, ISSN 0301-5629, E-ISSN 1879-291X, Vol. 37, nr 7, s. 1151-1160Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Tissue velocity imaging (TVI) is a Doppler based ultrasound technique that can be used to study regional deformation in skeletal muscle tissue. The aim of this study was to develop a biomechanical model to describe the TVI strain's dependency on the pennation angle. We demonstrate its impact as the subsequent strain measurement error using dynamic elbow contractions from the medial and the lateral part of biceps brachii at two different loadings; 5% and 25% of maximum voluntary contraction (MVC). The estimated pennation angles were on average about 4° in extended position and increased to a maximal of 13° in flexed elbow position. The corresponding relative angular error spread from around 7% up to around 40%. To accurately apply TVI on skeletal muscles, the error due to angle changes should be compensated for. As a suggestion, this could be done according to the presented model.

  • 35.
    Lindkvist, Markus
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Granåsen, Gabriel
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Coherent Derivation of Equations for Differential Spectroscopy and Spatially Resolved Spectroscopy: An undergraduate tutorial2013Ingår i: Spectroscopy Letters, ISSN 0038-7010, E-ISSN 1532-2289, Vol. 46, nr 4, s. 243-249Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Near-infrared spectroscopy (NIRS) is a spectroscopic method that is frequently used in health care and sports medicine to monitor oxygenation parameters in biological tissue. This tutorial provides a coherent derivation of equations for differential spectroscopy and spatially resolved spectroscopy, from basic theories to implementable equations. The basic theories are applicable to any kind of tissue oximeter but mainly focus on continuous-wave instruments. 

  • 36.
    Lindkvist, Markus
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Granåsen, Gabriel
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Medicinska fakulteten, Institutionen för epidemiologi och global hälsa.
    Precontractile optical response during excitation-contraction in human muscle revealed by non-invasive high-speed spatiotemporal NIR measurement2018Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, artikel-id 213Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    During muscle contraction the excitation-contraction process mediates the neural input and mechanical output. Proper muscle function and body locomotion depends on the status of the elements in the same process. However, non-invasive and in-vivo methods to study this are not available. Here we show the existence of an optical response occurring during the excitation-contraction process in human biceps brachii muscle. We developed a non-invasive instrument from a photodiode array and light emitting diodes to detect spatially propagating (similar to 5 m/s) and precontractile (similar to 6 ms onset) optical signals closely related to the action potential during electrostimulation. Although this phenomenon was observed 60 years ago on isolated frog muscle cells in the lab, it has not been shown in-vivo before now. We anticipate our results to be a starting point for a new category in-vivo studies, characterising alterations in the excitation-contraction process in patients with neuromuscular disease and to monitor effects of therapy.

  • 37.
    Lindkvist, Markus
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Absolute quantifications of oxy- and deoxyhemoglobin concentrations by combination of differentially resolved spectroscopy and spatially resolved spectroscopy2015Ingår i: Spectroscopy Letters, ISSN 0038-7010, E-ISSN 1532-2289, Vol. 48, nr 3, s. 170-172Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This letter proposes a theoretical framework to calculate absolute concentrations of oxy- and deoxyhemoglobin using continuous-wave near-infrared spectroscopy. While previous methods on this topic require assumptions on constant blood volume, the proposed method does not. Equations for the absolute concentrations were derived from a combination of the modified Beer-Lambert equation and the theory of diffusion of photons in turbid media. The method has an advantage over and is theoretically consistent with previous methods. It needs yet to be evaluated in an experimental study.

  • 38. Lindqvist, G
    et al.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Söderberg, Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Gonzalez, Manuel
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Henein, Michael Y
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Tossavainen, Erik
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Biventricular dysfunction and their consequences predict mortality in pulmonary arterial hypertension2014Ingår i: European Heart Journal, ISSN 0195-668X, E-ISSN 1522-9645, Vol. 35, nr Supplement 1, Meeting abstract P492, s. 78-78Artikel i tidskrift (Övrigt vetenskapligt)
  • 39.
    Nyman, Emma
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Vanoli, Davide
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi.
    Lindqvist, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi.
    Näslund, Ulf
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Carotid artery plaque assessment within the Västerbotten intervention programme: VIPVIZA2015Ingår i: Atherosclerosis, ISSN 0021-9150, E-ISSN 1879-1484, Vol. 241, nr 1, s. E159-E159Artikel i tidskrift (Övrigt vetenskapligt)
  • 40.
    Nyman, Emma
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Lindqvist, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Näslund, Ulf
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Risk marker variability in subclinical carotid plaques based on ultrasound is influenced by cardiac phase, echogenicity and size2018Ingår i: Ultrasound in Medicine and Biology, ISSN 0301-5629, E-ISSN 1879-291X, Vol. 44, nr 8, s. 1742-1750Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Identification of risk markers based on quantitative ultrasound texture analysis of carotid plaques has the ability to define vulnerable components that correlate with increased cardiovascular risk. However, data describing factors with the potential to influence the measurement variability of risk markers are limited. The aim of this study was to evaluate the influence of electrocardiogram-guided image selection, plaque echogenicity and area on carotid plaque risk markers and their variability in asymptomatic carotid plaques. Plaque risk markers were measured in 57 plaques during three consecutive heartbeats at two cardiac cycle time instants corresponding to the electrocardiogram R-wave (end diastole) and end of T-wave (end systole), resulting in six measurements for each plaque. Risk marker variability was quantified by computing the coefficient of variation (CV) across the three heartbeats. The CV was significantly higher for small plaques (area <15 mm2, 10%) than for large plaques (area >15 mm2, 6%) (p <0.001) in measurements of area, and the CV for measurements of gray-scale median were higher for echolucent plaques (<40, 15%) than for echogenic plaques (>40, 9%) (p <0.001). No significant differences were found between systole and diastole for the mean of any risk marker or the corresponding CV value. However, in a sub-analysis, the echolucent plaques were found to have a higher CV during systole compared with diastole. The variability also caused plaque type reclassification in 16% to 25% of the plaques depending on cutoff value. The results of this study indicate that echolucent and small plaques each contribute to increased risk marker variability. Based on these results, we recommend that measurements in diastole arc preferred to reduce variation, although we found that it may not be possible to characterize small plaques accurately using contemporary applied risk markers. 

  • 41.
    Nyman, Emma
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi.
    Vanoli, Davide
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Näslund, Ulf
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Lindqvist, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi.
    Area measurement of carotid plaque comparing B-MODE, Doppler color and contrast-enhanced ultrasound imaging2016Ingår i: Atherosclerosis, ISSN 0021-9150, E-ISSN 1879-1484, Vol. 252, s. E191-E191Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Objectives: Carotid plaque characteristic analysis are suggested to improve risk stratification. Plaque area and echolucent plaques have shown to correlate with increased risk for cardiovascular diseases. A limitation with B-mode imaging is the uncertainty that the whole plaque area is identified, primarily on echolucent plaques. Contrast-enhanced ultrasound (CEUS) is used to improve carotid imaging including better plaque area measurement. Aim: Evaluate if CEUS could improve accurate plaque area measurement compared with B-mode and Doppler color flow imaging. Methods: The study included 28 participants (50% females, mean age 58 years) with identified asymptomatic carotid plaques. We performed B-mode, Doppler color and CEUS ultrasound imaging whereas the plaque area was manually outdrawn by a single operator. Plaques were also subjectively classified as 1 echogenic, 2 echolucent, or 3 mixed plaques. Results: We did not find a significant difference in plaque area measurements between different ultrasound image modalities having all plaque types included. In the group of echolucent plaques (n= 11) we found a significant different between B-mode and CEUS (p=0.049) and also between B-mode and Doppler color imaging (p=0.039) (Illustrated in Fig 1). Conclusions: Echolucent plaque can be underestimated with B-mode imaging. Use of contrast-enhanced ultrasound should be considered in carotid plaque imaging on echolucent plaques when plaque outline is difficult to identify.

  • 42.
    Nyman, Emma
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin.
    Vanoli, Davide
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin.
    Näslund, Ulf
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Inter-sonographer reproducibility of carotid ultrasound plaque detection using Mannheim consensus in subclinical atherosclerosis2019Ingår i: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097XArtikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aims: To determine the inter-sonographer reproducibility of carotid ultrasound plaque detection using Mannheim consensus in a subclinical population and evaluate associations related to the reproducibility.

    Methods and results: Bilateral ultrasound screening for carotid plaques defined by Mannheim consensus was performed on 106 subclinical participants. Two different sonographers scanned the same participant, and reproducibility of plaque detection was measured by Cohens kappa. Associations with reproducibility were evaluated by comparing wall, and plaque characteristics between subjects with plaques identified in one and both scans. In general, the inter-sonographer reproducibility of plaque detection was substantial with a kappa value of 0 center dot 70 (95% CI 0 center dot 60-0 center dot 80). Plaques detected in only one scan had significantly lower plaque area and plaque thickness (6 center dot 82 mm(2) and 1 center dot 45 mm) as compared to plaques detected in both scans (11 center dot 65 mm(2) and 1 center dot 96 mm, P<0 center dot 001).

    Conclusion: Minor carotid plaques contribute to decreased reproducibility as compared to large plaques when screening for subclinical atherosclerosis using Mannheim consensus. Using an alternative plaque definition based on plaque thickness >1.5 mm and plaque area >10 mm(2) could increase the reproducibility of plaque detection in subclinical atherosclerosis.

  • 43.
    Näslund, Ulf
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin.
    Ng, Nawi
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Epidemiologi och global hälsa.
    Lundgren, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Epidemiologi och global hälsa.
    Fhärm, Eva
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Allmänmedicin.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin.
    Johansson, Helene
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Epidemiologi och global hälsa.
    Lindahl, Bernt
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Lindahl, Bertil
    Lindvall, Kristina
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Epidemiologi och global hälsa.
    Nilsson, Stefan K.
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap, Fysiologisk kemi.
    Nordin, Maria
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi.
    Nordin, Steven
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi.
    Nyman, Emma
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin.
    Rocklöv, Joacim
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Vanoli, Davide
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin.
    Weinehall, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Epidemiologi och global hälsa.
    Wennberg, Patrik
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Allmänmedicin.
    Wester, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
    Norberg, Margareta
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Epidemiologi och global hälsa.
    Visualization of asymptomatic atherosclerotic disease for optimum cardiovascular prevention (VIPVIZA): a pragmatic, open-label, randomised controlled trial2019Ingår i: The Lancet, ISSN 0140-6736, E-ISSN 1474-547X, Vol. 393, nr 10167, s. 133-142Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND: Primary prevention of cardiovascular disease often fails because of poor adherence among practitioners and individuals to prevention guidelines. We aimed to investigate whether ultrasound-based pictorial information about subclinical carotid atherosclerosis, targeting both primary care physicians and individuals, improves prevention.

    METHODS: Visualization of asymptomatic atherosclerotic disease for optimum cardiovascular prevention (VIPVIZA) is a pragmatic, open-label, randomised controlled trial that was integrated within the Västerbotten Intervention Programme, an ongoing population-based cardiovascular disease prevention programme in northern Sweden. Individuals aged 40, 50, or 60 years with one or more conventional risk factors were eligible to participate. Participants underwent clinical examination, blood sampling, and ultrasound assessment of carotid intima media wall thickness and plaque formation. Participants were randomly assigned 1:1 with a computer-generated randomisation list to an intervention group (pictorial representation of carotid ultrasound plus a nurse phone call to confirm understanding) or a control group (not informed). The primary outcomes, Framingham risk score (FRS) and European systematic coronary risk evaluation (SCORE), were assessed after 1 year among participants who were followed up. This study is registered with ClinicalTrials.gov, number NCT01849575.

    FINDINGS: 3532 individuals were enrolled between April 29, 2013, and June 7, 2016, of which 1783 were randomly assigned to the control group and 1749 were assigned to the intervention group. 3175 participants completed the 1-year follow-up. At the 1-year follow-up, FRS and SCORE differed significantly between groups (FRS 1·07 [95% CI 0·11 to 2·03, p=0·0017] and SCORE 0·16 [0·02 to 0·30, p=0·0010]). FRS decreased from baseline to the 1-year follow-up in the intervention group and increased in the control group (-0·58 [95% CI -0·86 to -0·30] vs 0·35 [0·08 to 0·63]). SCORE increased in both groups (0·13 [95% CI 0·09 to 0·18] vs 0·27 [0·23 to 0·30]).

    INTERPRETATION: This study provides evidence of the contributory role of pictorial presentation of silent atherosclerosis for prevention of cardiovascular disease. It supports further development of methods to reduce the major problem of low adherence to medication and lifestyle modification.

  • 44.
    Tossavainen, Erik
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Henein, Michael Y
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Lindqvist, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi.
    Left Atrial Intrinsic Strain Rate Correcting for Pulmonary Wedge Pressure Is Accurate in Estimating Pulmonary Vascular Resistance in Breathless Patients2016Ingår i: Echocardiography, ISSN 0742-2822, E-ISSN 1540-8175, Vol. 33, nr 8, s. 1156-1165Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    OBJECTIVES: We hypothesized that left atrial deformation during atrial systole (LASRa) correlates with pulmonary capillary wedge pressure (PCWP), thus enabling echo-derived pulmonary vascular resistance (PVR) estimation in a wide range of different subsets of patients.

    BACKGROUND: Various etiologies of pulmonary hypertension (PH) have different mechanisms and treatments for breathlessness. Irrespective of the location of the underlying pulmonary vascular pathology, pre- or postcapillary, the resulting PH is fairly easy to assess by Doppler echocardiography, but PVR remains a challenge.

    METHODS: We prospectively included 46 patients (mean age 61 ± 13 years) in sinus rhythm, who underwent right heart catheterization because of dyspnea. According to the NICE guidelines classification, 22 belonged to group 1 pulmonary artery hypertension (PAH), 19 belonged to group 2 congestive heart failure (CHF), 1 belonged to group 4 chronic thromboembolic pulmonary hypertension (CTEPH), and 4 had normal hemodynamics. Simultaneous Doppler echocardiography using spectral, tissue Doppler, and speckle tracking echocardiography techniques for assessing LA structure and function was performed.

    RESULTS: PCWPrhc correlated with LASRa (r(2) = 0.65, P < 0.001). PCWPecho was calculated using the equation (PCWPecho = 26.12 - 11.09 × LASRa), and the resulting PVR echo strongly correlated with the respective catheter-based measurements PVRrhc (r(2) = 0.69. P < 0.001) with a sensitivity of 85% and specificity of 74% identifying a PVR ≥ 3 WU.

    CONCLUSIONS: Left atrial strain rate during atrial systole correlates closely with pulmonary capillary wedge pressure and consequently the calculated pulmonary vascular resistance, irrespective of the etiology of PH.

  • 45.
    Tossavainen, Erik
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Söderberg, Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Gonzalez, Manuel
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Henein, Michael Y
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Lindqvist, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi. Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi.
    Pulmonary artery acceleration time in identifying pulmonary hypertension patients with raised pulmonary vascular resistance2013Ingår i: European Heart Journal Cardiovascular Imaging, ISSN 2047-2404, E-ISSN 2047-2412, Vol. 14, nr 9, s. 890-897Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND: In patients with pulmonary hypertension (PH), ascertaining raised vascular resistance as a cause is a clinical objective, for which various Doppler-based measurements have been proposed, but with modest accuracy. We hypothesize that pulmonary acceleration time (PAcT) and the ratio of PAcT/peak pulmonary artery systolic pressure (PASP) reflect better the extent of the vascular resistance, compared with other available methods, and can differentiate accurately between pre- and post-capillary PH.

    METHODS AND RESULTS: We investigated 56 patients (mean age 61 ± 13 years, 23 males) in a simultaneous echocardiography and right heart catheterization (RHC) study. Based on the RHC, pulmonary vascular resistance (PVR), and pulmonary capillary wedge pressure (PCWP), patients were divided into four groups: Group 1 = normal PVR [<3 WU (Wood units)] and PCWP (<12 mmHg), Group 2 = raised PVR but normal PCWP, Group 3 = raised PVR and PCWP; and Group 4 = normal PVR but raised PCWP. We used spectral Doppler to measure PAcT (corrected for heart rate) and to estimate PASP (peak tricuspid regurgitation pressure drop + estimated right atrial pressure of 7 mmHg). We also tested other available methods for assessing PVR. There were small age differences between patient groups but no age difference between Groups 2 and 4. PAcT and PAcT/PASP were both significantly (P = 0.008) reduced in Groups 2 and 3 compared with Groups 1 and 4. PAcT ≤90 had an 84% sensitivity and an 85% specificity in identifying patients with PVR ≥3 WU with a positive and a negative predictive value of 88% and 81%, respectively. The non-linear relationship between PVR and PAcT gave a quadratic r = 0.61, P < 0.001. ROC curve analysis showed PAcT having the best accuracy (83%) in detecting a PVR ≥3 WU.

    CONCLUSION: PAcT <90 ms can serve as a strong non-invasive predictor of PVR >3 WU, which could differentiate patients with pre- and post-capillary PH.

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