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Dunås, T., Wahlin, A., Ambarki, K., Zarrinkoob, L., Birgander, R., Malm, J. & Eklund, A. (2016). Automatic labeling of cerebral arteries in magnetic resonance angiography. Magnetic Resonance Materials in Physics, Biology and Medicine, 29(1), 39-47.
Open this publication in new window or tab >>Automatic labeling of cerebral arteries in magnetic resonance angiography
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2016 (English)In: Magnetic Resonance Materials in Physics, Biology and Medicine, ISSN 0968-5243, E-ISSN 1352-8661, Vol. 29, no 1, 39-47 p.Article in journal (Refereed) Published
Abstract [en]

In order to introduce 4D flow magnetic resonance imaging (MRI) as a standard clinical instrument for studying the cerebrovascular system, new and faster postprocessing tools are necessary. The objective of this study was to construct and evaluate a method for automatic identification of individual cerebral arteries in a 4D flow MRI angiogram. Forty-six elderly individuals were investigated with 4D flow MRI. Fourteen main cerebral arteries were manually labeled and used to create a probabilistic atlas. An automatic atlas-based artery identification method (AAIM) was developed based on vascular-branch extraction and the atlas was used for identification. The method was evaluated by comparing automatic with manual identification in 4D flow MRI angiograms from 67 additional elderly individuals. Overall accuracy was 93 %, and internal carotid artery and middle cerebral artery labeling was 100 % accurate. Smaller and more distal arteries had lower accuracy; for posterior communicating arteries and vertebral arteries, accuracy was 70 and 89 %, respectively. The AAIM enabled fast and fully automatic labeling of the main cerebral arteries. AAIM functionality provides the basis for creating an automatic and powerful method to analyze arterial cerebral blood flow in clinical routine.

Keyword
Magnetic resonance angiography, Cerebral angiography, Circle of Willis, Atlases as topic, Automatic data processing
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-117830 (URN)10.1007/s10334-015-0512-5 (DOI)000370159800005 ()
Available from: 2016-04-05 Created: 2016-03-04 Last updated: 2017-11-30Bibliographically approved
Marshall-Goebel, K., Ambarki, K., Eklund, A., Malm, J., Mulder, E., Gerlach, D., . . . Rittweger, J. (2016). Effects of short-term exposure to head-down tilt on cerebral hemodynamics: a prospective evaluation of a spaceflight analog using phase-contrast MRI. Journal of applied physiology, 120(12), 1466-1473.
Open this publication in new window or tab >>Effects of short-term exposure to head-down tilt on cerebral hemodynamics: a prospective evaluation of a spaceflight analog using phase-contrast MRI
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2016 (English)In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 120, no 12, 1466-1473 p.Article in journal (Refereed) Published
Abstract [en]

Alterations in cerebral hemodynamics in microgravity are hypothesized to occur during spaceflight and could be linked to the Visual Impairment and Intracranial Pressure syndrome. Head-down tilt (HDT) is frequently used as a ground-based analog to simulate cephalad fluid shifts in microgravity; however, its effects on cerebral hemodynamics have not been well studied with MRI techniques. Here, we evaluate the effects of 1) various HDT angles on cerebral arterial and venous hemodynamics; and 2) exposure to 1% CO2 during an intermediate HDT angle (-12 degrees) as an additional space-related environmental factor. Blood flow, cross-sectional area (CSA), and blood flow velocity were measured with phase-contrast MRI in the internal jugular veins, as well as the vertebral and internal carotid arteries. Nine healthy male subjects were measured at baseline (supine, 0 degrees) and after 4.5 h of HDT at -6 degrees, -12 degrees (with and without 1% CO2), and -18 degrees. We found a decrease in total arterial blood flow from baseline during all angles of HDT. On the venous side, CSA increased with HDT, and outflow decreased during -12 degrees HDT (P = 0.039). Moreover, the addition of 1% CO2 to -12 degrees HDT caused an increase in total arterial blood flow (P = 0.016) and jugular venous outflow (P = 0.001) compared with -12 degrees HDT with ambient atmosphere. Overall, the results indicate decreased cerebral blood flow during HDT, which may have implications for microgravity-induced cerebral hemodynamic changes.

Keyword
visual impairment and intracranial pressure, microgravity, cerebral blood flow, head-down tilt, MRI
National Category
Neurology
Identifiers
urn:nbn:se:umu:diva-124145 (URN)10.1152/japplphysiol.00841.2015 (DOI)000378054800011 ()27013606 (PubMedID)
Available from: 2016-08-05 Created: 2016-07-21 Last updated: 2017-05-10Bibliographically approved
Fordell, H., Bodin, K., Eklund, A. & Malm, J. (2016). RehAtt – scanning training for neglect enhanced by multi-sensory stimulation in Virtual Reality. Topics in Stroke Rehabilitation, 23(3), 191-199.
Open this publication in new window or tab >>RehAtt – scanning training for neglect enhanced by multi-sensory stimulation in Virtual Reality
2016 (English)In: Topics in Stroke Rehabilitation, ISSN 1074-9357, E-ISSN 1945-5119, Vol. 23, no 3, 191-199 p.Article in journal (Refereed) Published
Abstract [en]

Background: There is a lack of effective treatment for neglect. We have developed a new training method, RehAtt (TM). The objective of this study was to determine whether RehAtt (TM) improves spatial attention in chronic neglect after stroke. Methods: RehAtt (TM) consists of a computer with monitor, 3D glasses, and a force feedback interface (Robotic pen) giving sensory motor activation to the contra-lesional arm. The software combines visual scanning training with multi-sensory stimulation in 3D virtual reality (VR) game environment. Fifteen stroke patients with chronic neglect (duration > 6 month) had repeated baseline evaluations to confirm stability of symptoms. There were no test-retest effects for any of the tests. Thereafter, all patients trained 15 h in RehAtt (TM) (3 x 1 h for 5 weeks). A neglect test battery and Catherine Bergego Scale, CBS, were used to assess behavioral outcome after intervention. CBS was also used at a 6-month follow-up. Results: Using repeated measurement analysis improvements due to the training were found for Star cancellation test (p = 0.006), Baking tray task (p < 0.001), and Extinction test (p = 0.05). In the Posner task improvements were seen fewer missed targets (p = 0.024). CBS showed improvements in activities of daily life immediately after training (p < 0.01). After 6 months the patients still reported improvement in CBS. Conclusion: RehAtt (TM) is a new concept for rehabilitation of neglect. Training with the VR-method improved spatial attention and showed transfer to improved spatial attention in activities of daily living in chronic neglect. Our results are promising and merit further studies.

Place, publisher, year, edition, pages
Taylor & Francis Group, 2016
Keyword
Spatial neglect, Cognitive rehabilitation, Attention, treatment, virtual reality, stroke
National Category
Neurology
Identifiers
urn:nbn:se:umu:diva-121621 (URN)10.1080/10749357.2016.1138670 (DOI)000375149700007 ()27077985 (PubMedID)
Available from: 2016-06-20 Created: 2016-06-03 Last updated: 2017-11-15Bibliographically approved
Israelsson, H., Allard, P., Eklund, A. & Malm, J. (2016). Symptoms of Depression are Common in Patients With Idiopathic Normal Pressure Hydrocephalus: The INPH-CRasH Study. Neurosurgery, 78(2), 161-168.
Open this publication in new window or tab >>Symptoms of Depression are Common in Patients With Idiopathic Normal Pressure Hydrocephalus: The INPH-CRasH Study
2016 (English)In: Neurosurgery, ISSN 0148-396X, E-ISSN 1524-4040, Vol. 78, no 2, 161-168 p.Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: If patients with idiopathic normal pressure hydrocephalus (INPH) also have depression, this could have important clinical ramifications in assessment and management of their cognitive function and response to shunting. In many dementias, depression is overrepresented, but the prevalence of depression in shunted patients with INPH is unknown.

OBJECTIVE: The objective of this case-control study was to assess the prevalence of symptoms of depression in shunted INPH patients compared with population-based controls.

METHODS: INPH patients consecutively shunted from 2008 to 2010 in Sweden were analyzed. Patients remaining after inclusion (within 60-85 years and not having dementia, ie, mini-mental state examination >=23) had a standardized visit to their healthcare provider and answered an extensive questionnaire. Age- and sex-matched population-based controls underwent the same procedure. Symptoms of depression were assessed using the Geriatric Depression Scale 15 (suspected depression defined as >=5 points, suspected severe depression as >=12 points). This study is part of the INPH-CRasH study.

RESULTS: One hundred seventy-six INPH patients and 368 controls participated. After adjustment for age, sex, cerebrovascular disease, and systolic and diastolic blood pressure, patients had a higher mean depression score (patients: 4.9 ± 3.7 SD, controls: 1.9 ± 2.3 SD; OR 1.4, 95% CI 1.3-1.6, P < .001), more patients had suspected depression (46% vs 13%, OR 6.4, 95% CI 3.8-10.9, P < .001), and more patients had suspected severe depression (7.3% vs 0.6%, OR 14.4, 95% CI 3.0-68.6, P < .005).

CONCLUSION: Symptoms of depression are overrepresented in INPH patients compared with the population, despite treatment with a shunt. Screening for depression should be done in the evaluation of INPH patients in order to find and treat a coexisting depression.

Keyword
Case-control studies, Dementia, Depression, Depressive disorder, Follow-up studies, GDS 15, drocephalus, Normal pressure
National Category
Psychiatry Geriatrics
Identifiers
urn:nbn:se:umu:diva-116731 (URN)10.1227/NEU.0000000000001093 (DOI)000368585600001 ()26528670 (PubMedID)
Available from: 2016-02-19 Created: 2016-02-11 Last updated: 2017-11-30Bibliographically approved
Ambarki, K., Wåhlin, A., Zarrinkoob, L., Wirestam, R., Petr, J., Malm, J. & Eklund, A. (2015). Accuracy of Parenchymal Cerebral Blood Flow Measurements Using Pseudocontinuous Arterial Spin-Labeling in Healthy Volunteers. American Journal of Neuroradiology, 36(10), 1816-1821.
Open this publication in new window or tab >>Accuracy of Parenchymal Cerebral Blood Flow Measurements Using Pseudocontinuous Arterial Spin-Labeling in Healthy Volunteers
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2015 (English)In: American Journal of Neuroradiology, ISSN 0195-6108, E-ISSN 1936-959X, Vol. 36, no 10, 1816-1821 p.Article in journal (Refereed) Published
Abstract [en]

BACKGROUND AND PURPOSE: The arterial spin-labeling method for CBF assessment is widely available, but its accuracy is not fully established. We investigated the accuracy of a whole-brain arterial spin-labeling technique for assessing the mean parenchymal CBF and the effect of aging in healthy volunteers. Phase-contrast MR imaging was used as the reference method. MATERIALS AND METHODS: Ninety-two healthy volunteers were included: 49 young (age range, 20-30 years) and 43 elderly (age range, 65-80 years). Arterial spin-labeling parenchymal CBF values were averaged over the whole brain to quantify the mean pCBF(ASL) value. Total. CBF was assessed with phase-contrast MR imaging as the sum of flows in the internal carotid and vertebral arteries, and subsequent division by brain volume returned the pCBF(PCMRI) value. Accuracy was considered as good as that of the reference method if the systematic difference was less than 5 mL/min/100 g of brain tissue and if the 95% confidence intervals were equal to or better than +/- 10 mL/min/100 g. RESULTS: pCBF(ASL) correlated to pCBF(PCMRI) (r = 0.73; P < .001). Significant differences were observed between the pCBF(ASL) and pCBF(PCMRI) values in the young (P = .001) and the elderly (P < .001) volunteers. The systematic differences (mean 2 standard deviations) were -4 +/- 14 mL/min/100 g in the young subjects and 6 +/- 12 mL/min/100 g in the elderly subjects. Young subjects showed higher values than the elderly subjects for pCBF(PCMRI) (young, 57 +/- 8 mL/min/100 g; elderly, 54 +/- 7 mL/min/100 g; P = .05) and pCBF(ASL) (young, 61 +/- 10 mL/min/100 g; elderly, 48 +/- 10 mL/min/100 g; P < .001). CONCLUSIONS: The limits of agreement were too wide for the arterial spin-labeling method to be considered satisfactorily accurate, whereas the systematic overestimation in the young subjects and underestimation in the elderly subjects were close to acceptable. The age-related decrease in parenchymal CBF was augmented in arterial spin-labeling compared with phase-contrast MR imaging.

National Category
Neurosciences
Identifiers
urn:nbn:se:umu:diva-111006 (URN)10.3174/ajnr.A4367 (DOI)000362700900006 ()26251434 (PubMedID)
Available from: 2015-11-04 Created: 2015-11-02 Last updated: 2018-01-10Bibliographically approved
Zarrinkoob, L., Ambarki, K., Wahlin, A., Birgander, R., Eklund, A. & Malm, J. (2015). Blood flow distribution in cerebral arteries. Journal of Cerebral Blood Flow and Metabolism, 35(4), 648-654.
Open this publication in new window or tab >>Blood flow distribution in cerebral arteries
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2015 (English)In: Journal of Cerebral Blood Flow and Metabolism, ISSN 0271-678X, E-ISSN 1559-7016, Vol. 35, no 4, 648-654 p.Article in journal (Refereed) Published
Abstract [en]

High-resolution phase-contrast magnetic resonance imaging can now assess flow in proximal and distal cerebral arteries. The aim of this study was to describe how total cerebral blood flow (tCBF) is distributed into the vascular tree with regard to age, sex and anatomic variations. Forty-nine healthy young (mean 25 years) and 45 elderly (mean 71 years) individuals were included. Blood flow rate (BFR) in 21 intra-and extracerebral arteries was measured. Total cerebral blood flow was defined as BFR in the internal carotid plus vertebral arteries and mean cerebral perfusion as tCBF/brain volume. Carotid/vertebral distribution was 72%/28% and was not related to age, sex, or brain volume. Total cerebral blood flow (717 +/- 123 mL/min) was distributed to each side as follows: middle cerebral artery (MCA), 21%; distal MCA, 6%; anterior cerebral artery (ACA), 12%, distal ACA, 4%; ophthalmic artery, 2%; posterior cerebral artery (PCA), 8%; and 20% to basilar artery. Deviating distributions were observed in subjects with 'fetal' PCA. Blood flow rate in cerebral arteries decreased with increasing age (P < 0.05) but not in extracerebral arteries. Mean cerebral perfusion was higher in women (women: 61 +/- 8; men: 55 +/- 6 mL/min/100 mL, P < 0.001). The study describes a new method to outline the flow profile of the cerebral vascular tree, including reference values, and should be used for grading the collateral flow system.

Keyword
aging, cerebral blood flow, circle of Willis, cognitive impairment, phase-contrast MRI, stroke
National Category
Clinical Medicine
Identifiers
urn:nbn:se:umu:diva-103545 (URN)10.1038/jcbfm.2014.241 (DOI)000352027900015 ()25564234 (PubMedID)
Available from: 2015-05-25 Created: 2015-05-21 Last updated: 2017-12-04Bibliographically approved
Schrauben, E., Wåhlin, A., Ambarki, K., Spaak, E., Malm, J., Wieben, O. & Eklund, A. (2015). Fast 4D flow MRI intracranial segmentation and quantification in tortuous arteries. Journal of Magnetic Resonance Imaging, 42(5), 1458-1464.
Open this publication in new window or tab >>Fast 4D flow MRI intracranial segmentation and quantification in tortuous arteries
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2015 (English)In: Journal of Magnetic Resonance Imaging, ISSN 1053-1807, E-ISSN 1522-2586, Vol. 42, no 5, 1458-1464 p.Article in journal (Refereed) Published
Abstract [en]

PurposeTo describe, validate, and implement a centerline processing scheme (CPS) for semiautomated segmentation and quantification in carotid siphons of healthy subjects. 4D flow MRI enables blood flow measurement in all major cerebral arteries with one scan. Clinical translational hurdles are time demanding postprocessing and user-dependence induced variability during analysis. Materials and MethodsA CPS for 4D flow data was developed to automatically separate cerebral artery trees. Flow parameters were quantified at planes along the centerline oriented perpendicular to the vessel path. At 3T, validation against 2D phase-contrast (PC) magnetic resonance imaging (MRI) and 4D flow manual processing was performed on an intracranial flow phantom for constant flow, while pulsatile flow validation was performed in the internal carotid artery (ICA) of 10 healthy volunteers. The CPS and 4D manual processing times were measured and compared. Flow and area measurements were also demonstrated along the length of the ICA siphon. ResultsPhantom measurements for area and flow were highly correlated between the CPS and 2D measurements (area: R=0.95, flow: R=0.94), while in vivo waveforms were highly correlated (R=0.93). Processing time was reduced by a factor of 4.6 compared with manual processing. Whole ICA measurements revealed a significantly decreased area in the most distal segment of the carotid siphon (P=0.0017), with flow unchanged (P=0.84). ConclusionThis study exhibits fast semiautomated analysis of intracranial 4D flow MRI. Internal consistency was shown through flow conservation along the tortuous ICA siphon, which is typically difficult to assess. J. Magn. Reson. Imaging 2015;42:1458-1464.

Place, publisher, year, edition, pages
John Wiley & Sons, 2015
Keyword
4D flow MRI, vascular, segmentation, automated processing
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-111468 (URN)10.1002/jmri.24900 (DOI)000363280300033 ()25847621 (PubMedID)
Available from: 2015-12-09 Created: 2015-11-13 Last updated: 2017-12-01Bibliographically approved
Malm, J. (2015). Improving research and care for patients with idiopathic NPH. Lancet Neurology, 14(6), 561-563.
Open this publication in new window or tab >>Improving research and care for patients with idiopathic NPH
2015 (English)In: Lancet Neurology, ISSN 1474-4422, E-ISSN 1474-4465, Vol. 14, no 6, 561-563 p.Article in journal, Editorial material (Other academic) Published
National Category
Neurology
Identifiers
urn:nbn:se:umu:diva-106123 (URN)10.1016/S1474-4422(15)00055-1 (DOI)000354829900003 ()25934243 (PubMedID)
Available from: 2015-07-14 Created: 2015-07-09 Last updated: 2017-12-04Bibliographically approved
Farahmand, D., Qvarlander, S., Malm, J., Wikkelsö, C., Eklund, A. & Tisell, M. (2015). Intracranial pressure in hydrocephalus: impact of shunt adjustments and body positions. Journal of Neurology, Neurosurgery and Psychiatry, 86(2), 222-228.
Open this publication in new window or tab >>Intracranial pressure in hydrocephalus: impact of shunt adjustments and body positions
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2015 (English)In: Journal of Neurology, Neurosurgery and Psychiatry, ISSN 0022-3050, E-ISSN 1468-330X, Vol. 86, no 2, 222-228 p.Article in journal (Refereed) Published
Abstract [en]

Background The association between intracranial pressure (ICP) and different shunt valve opening pressures in relation to body positions is fundamental for understanding the physiological function of the shunt.

Objective To analyse the ICP and ICP wave amplitude (AMP) at different shunt settings and body positions in patients with hydrocephalus.

Methods In this prospective study 15 patients with communicating hydrocephalus were implanted with a ligated adjustable ventriculoperitoneal shunt. They also received a portable intraparenchymatous ICP-monitoring device. Postoperative ICP and AMP were recorded with the patients in three different body positions (supine, sitting and walking) and with the shunt ligated and open at high, medium and low valve settings. In each patient 12 10 min segments were coded, blinded and analysed for mean ICP and mean AMP using an automated computer algorithm.

Results Mean ICP and mean AMP were lower at all three valve settings compared with the ligated shunt state (p<0.001). Overall, when compared with the supine position, mean ICP was 11.5 +/- 1.1 (mean +/- SD) mm Hg lower when sitting and 10.5 +/- 1.1 mm Hg lower when walking (p<0.001). Mean ICP was overall 1.1 mm Hg higher (p=0.042) when walking compared with sitting. The maximal adjustability difference (highest vs lowest valve setting) was 4.4 mm Hg.

Conclusions Changing from a supine to an upright position reduced ICP while AMP only increased at trend level. Lowering of the shunt valve opening pressure decreased ICP and AMP but the difference in mean ICP in vivo between the highest and lowest opening pressures was less than half that previously observed in vitro.

National Category
Surgery Neurology Other Medical Engineering
Identifiers
urn:nbn:se:umu:diva-101344 (URN)10.1136/jnnp-2014-307873 (DOI)000349720700018 ()24963125 (PubMedID)
Available from: 2015-03-27 Created: 2015-03-27 Last updated: 2017-12-04Bibliographically approved
Ambarki, K., Petr, J., Wahlin, A., Wirestam, R., Zarrinkoob, L., Malm, J. & Eklund, A. (2015). Partial Volume Correction of Cerebral Perfusion Estimates Obtained by Arterial Spin Labeling. In: 16th Nordic-Baltic Conference on Biomedical Engineering: 16. NBC & 10. MTD 2014 joint conferences. October 14-16, 2014, Gothenburg, Sweden. Paper presented at 16th Nordic-Baltic Conference on Biomedical Engineering, October 14-16, 2014, Gothenburg, Sweden (pp. 17-19). , 48.
Open this publication in new window or tab >>Partial Volume Correction of Cerebral Perfusion Estimates Obtained by Arterial Spin Labeling
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2015 (English)In: 16th Nordic-Baltic Conference on Biomedical Engineering: 16. NBC & 10. MTD 2014 joint conferences. October 14-16, 2014, Gothenburg, Sweden, 2015, Vol. 48, 17-19 p.Conference paper, Published paper (Refereed)
Abstract [en]

Arterial Spin labeling (ASL) is a fully non-invasive MRI method capable to quantify cerebral perfusion. However, gray (GM) and white matter (WM) ASL perfusions are difficult to assess separately due to limited spatial resolution increasing the partial volume effects (PVE). In the present study, ASL PVE correction was implemented based on a regression algorithm in 22 healthy young men. PVE corrected perfusion of GM and WM were compared to previous studies. PVE-corrected GM perfusion was in agreement with literature values. In general, WM perfusion was higher despite the use of PVE correction.

Series
IFMBE Proceedings, ISSN 1680-0737 ; 48
Keyword
MRI, cerebral perfusion, gray and white matter, arterial spin labeling and healthy
National Category
Neurosciences
Identifiers
urn:nbn:se:umu:diva-100142 (URN)10.1007/978-3-319-12967-9_5 (DOI)000347893000005 ()978-3-319-12966-2 (ISBN)978-3-319-12967-9 (ISBN)
Conference
16th Nordic-Baltic Conference on Biomedical Engineering, October 14-16, 2014, Gothenburg, Sweden
Available from: 2015-02-26 Created: 2015-02-24 Last updated: 2018-01-11Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6451-1940

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