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Cerebral blood flow and intracranial pulsatility studied with MRI: measurement, physiological and pathophysiological aspects
Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
2012 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

During each cardiac cycle pulsatile arterial blood inflates the vascular bed of the brain, forcing cerebrospinal fluid (CSF) and venous blood out of the cranium. Excessive arterial pulsatility may be part of a harmful mechanism causing cognitive decline among elderly. Additionally, restricted venous flow from the brain is suggested as the cause of multiple sclerosis. Addressing hypotheses derived from these observations requires accurate and reliable investigational methods. This work focused on assessing the pulsatile waveform of cerebral arterial, venous and CSF flows. The overall aim of this dissertation was to explore cerebral blood flow and intracranial pulsatility using MRI, with respect to measurement, physiological and pathophysiological aspects.

Two-dimensional phase contrast magnetic resonance imaging (2D PCMRI) was used to assess the pulsatile waveforms of cerebral arterial, venous and CSF flow. The repeatability was assessed in healthy young subjects. The 2D PCMRI measurements of cerebral arterial, venous and CSF pulsatility were generally repeatable but the pulsatility decreased systematically during the investigation.

A method combining 2D PCMRI measurements with invasive CSF infusion tests to determine the magnitude and distribution of compliance within the craniospinal system was developed and applied in a group of healthy elderly. The intracranial space contained approximately two thirds of the total craniospinal compliance. The magnitude of craniospinal compliance was less than suggested in previous studies.

The vascular hypothesis for multiple sclerosis was tested. Venous drainage in the internal jugular veins was compared between healthy controls and multiple sclerosis patients using 2D PCMRI. For both groups, a great variability in the internal jugular flow was observed but no pattern specific to multiple sclerosis could be found.

Relationships between regional brain volumes and potential biomarkers of intracranial cardiac-related pulsatile stress were assessed in healthy elderly. The biomarkers were extracted from invasive CSF pressure measurements as well as 2D PCMRI acquisitions. The volumes of temporal cortex, frontal cortex and hippocampus were negatively related to the magnitude of cardiac-related intracranial pulsatility.

Finally, a potentially improved workflow to assess the volume of arterial pulsatility using time resolved, four-dimensional phase contrast MRI measurements (4D PCMRI) was evaluated. The measurements showed good agreement with 2D PCMRI acquisitions.

In conclusion, this work showed that 2D PCMRI is a feasible tool to study the pulsatile waveforms of cerebral blood and CSF flow. Conventional views regarding the magnitude and distribution of craniospinal compliance was challenged, with important implications regarding the understanding of how intracranial vascular pulsatility is absorbed. A first counterpoint to previous near-uniform observations of obstructions in the internal jugular veins in multiple sclerosis was provided. It was demonstrated that large cardiac- related intracranial pulsatility were related to smaller volumes of brain regions that are important in neurodegenerative diseases among elderly. This represents a strong rationale to further investigate the role of excessive intracranial pulsatility in cognitive impairment and dementia. For that work, 4D PCMRI will facilitate an effective analysis of cerebral blood flow and pulsatility. 

Ort, förlag, år, upplaga, sidor
Umeå: Umeå universitet , 2012. , s. 72
Serie
Umeå University medical dissertations, ISSN 0346-6612 ; 1505
Nyckelord [en]
Arterial Pulsatility, cerebrospinal fluid, cerebral blood flow, venous flow, intracranial pressure, pulse pressure, dementia, hippocampus, multiple sclerosis, magnetic resonance imaging
Nationell ämneskategori
Medicinteknik
Forskningsämne
radiofysik
Identifikatorer
URN: urn:nbn:se:umu:diva-55424ISBN: 978-91-7459-428-7 (tryckt)OAI: oai:DiVA.org:umu-55424DiVA, id: diva2:526678
Disputation
2012-06-08, Bergasalen, by 27, Norrlands universitetssjukhus, Umeå, 13:00 (Engelska)
Opponent
Handledare
Forskningsfinansiär
Vetenskapsrådet, 621-2011-5216Tillgänglig från: 2012-05-16 Skapad: 2012-05-14 Senast uppdaterad: 2018-06-08Bibliografiskt granskad
Delarbeten
1. Phase contrast MRI quantification of pulsatile volumes of brain arteries, veins, and cerebrospinal fluids compartments: repeatability and physiological interactions
Öppna denna publikation i ny flik eller fönster >>Phase contrast MRI quantification of pulsatile volumes of brain arteries, veins, and cerebrospinal fluids compartments: repeatability and physiological interactions
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2012 (Engelska)Ingår i: Journal of Magnetic Resonance Imaging, ISSN 1053-1807, E-ISSN 1522-2586, Vol. 35, nr 5, s. 1055-1062Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

PURPOSE: To study measurement repeatability and physiological determinants on measurement stability for phase contrast MRI (PC-MRI) measurements of cyclic volume changes (ΔV) of brain arteries, veins, and cerebrospinal fluid (CSF) compartments.

MATERIALS AND METHODS: Total cerebral blood flow (tCBF), total internal jugular flow (tJBF) and spinal CSF flow at C2-C3 level and CSF in the aqueduct was measured using five repetitions in 20 healthy subjects. After subtracting net flow, waveforms were integrated to calculate ΔV of arterial, venous, and cerebrospinal fluid compartments. The intraclass correlation coefficient (ICC) was used to measure repeatability. Systematic errors were investigated by a series of phantom measurements.

RESULTS: For ΔV calculated from tCBF, tJBF and both CSF waveforms, the ICC was ≥0.85. ΔV from the tCBF waveform decreased linearly between repetitions (P = 0.012). Summed CSF and venous volume being shifted out from the cranium was correlated with ΔV calculated from the tCBF waveform (r = 0.75; P < 0.001). Systematic errors increased at resolutions <4 pixels per diameter.

CONCLUSION: Repeatability of ΔV calculated from tCBF, tJBF, and CSF waveforms allows useful interpretations. The subject's time in the MR system and imaging resolution should be considered when interpreting volume changes. Summed CSF and venous volume changes was associated with arterial volume changes.

J. Magn. Reson. Imaging 2011;. © 2011 Wiley Periodicals, Inc.

Ort, förlag, år, upplaga, sidor
John Wiley & Sons, 2012
Nyckelord
brain, blood, cerebrospinal fluid, flow, volume changes, repeatability
Nationell ämneskategori
Medicinsk bildbehandling Radiologi och bildbehandling
Identifikatorer
urn:nbn:se:umu:diva-50992 (URN)10.1002/jmri.23527 (DOI)000302721800007 ()22170792 (PubMedID)
Anmärkning
Kompletteras 2012-09Tillgänglig från: 2012-01-04 Skapad: 2012-01-04 Senast uppdaterad: 2018-06-08Bibliografiskt granskad
2. Assessment of craniospinal pressure-volume indices
Öppna denna publikation i ny flik eller fönster >>Assessment of craniospinal pressure-volume indices
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2010 (Engelska)Ingår i: American Journal of Neuroradiology, ISSN 0195-6108, E-ISSN 1936-959X, Vol. 31, nr 9, s. 1645-1650Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

BACKGROUND AND PURPOSE: The PVI(CC) of the craniospinal compartment defines the shape of the pressure-volume curve and determines the damping of cyclic arterial pulsations. Despite no reports of direct measurements of the PVI(CC) among healthy elderly, it is believed that a change away from adequate accommodation of cardiac-related pulsations may be a pathophysiologic mechanism seen in neurodegenerative disorders such as Alzheimer disease and idiopathic normal pressure hydrocephalus. In this study, blood and CSF flow measurements are combined with lumbar CSF infusion measurements to assess the craniospinal PVI(CC) and its distribution of cranial and spinal compartments in healthy elderly.

MATERIALS AND METHODS: Thirty-seven healthy elderly were included (60-82 years of age). The cyclic arterial volume change and the resulting shift of CSF to the spinal compartment were quantified by PC-MR imaging. In addition, each subject underwent a lumbar CSF infusion test in which the magnitude of cardiac-related pulsations in intracranial pressure was quantified. Finally, the PVI was calculated by using a mathematic model.

RESULTS: After excluding 2 extreme values, the craniospinal PVI(CC) was calculated to a mean of 9.8 ± 2.7 mL and the estimated average 95% confidence interval of individual measurements was ± 9%. The average intracranial and spinal contributions to the overall compliance were 65% and 35% respectively (n = 35).

CONCLUSIONS: Combining lumbar CSF infusion and PC-MR imaging proved feasible and robust for assessment of the craniospinal PVI(CC). This study produced normative values and showed that the major compensatory contribution was located intracranially.

Identifikatorer
urn:nbn:se:umu:diva-36883 (URN)10.3174/ajnr.A2166 (DOI)000283011300019 ()20595369 (PubMedID)
Tillgänglig från: 2010-10-13 Skapad: 2010-10-13 Senast uppdaterad: 2018-06-08Bibliografiskt granskad
3. Venous and cerebrospinal fluid flow in multiple sclerosis. A case-control study.
Öppna denna publikation i ny flik eller fönster >>Venous and cerebrospinal fluid flow in multiple sclerosis. A case-control study.
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2010 (Engelska)Ingår i: Annals of Neurology, ISSN 0364-5134, E-ISSN 1531-8249, Vol. 68, nr 2, s. 255-259Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The prevailing view on multiple sclerosis etiopathogenesis has been challenged by the suggested new entity chronic cerebrospinal venous insufficiency. To test this hypothesis, we studied 21 relapsing-remitting multiple sclerosis cases and 20 healthy controls with phase-contrast magnetic resonance imaging. In addition, in multiple sclerosis cases we performed contrast-enhanced magnetic resonance angiography. We found no differences regarding internal jugular venous outflow, aqueductal cerebrospinal fluid flow, or the presence of internal jugular blood reflux. Three of 21 cases had internal jugular vein stenoses. In conclusion, we found no evidence confirming the suggested vascular multiple sclerosis hypothesis.

Ort, förlag, år, upplaga, sidor
Wiley, 2010
Nationell ämneskategori
Neurologi
Forskningsämne
neurologi
Identifikatorer
urn:nbn:se:umu:diva-35616 (URN)10.1002/ana.22132 (DOI)000280721500020 ()20695018 (PubMedID)
Tillgänglig från: 2010-08-26 Skapad: 2010-08-26 Senast uppdaterad: 2018-06-08Bibliografiskt granskad
4. In healthy elderly the volumes of several brain regions are related to pulsatility in cerebral arteries and cerebrospinal fluid
Öppna denna publikation i ny flik eller fönster >>In healthy elderly the volumes of several brain regions are related to pulsatility in cerebral arteries and cerebrospinal fluid
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(Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
Nationell ämneskategori
Neurologi
Identifikatorer
urn:nbn:se:umu:diva-55475 (URN)
Tillgänglig från: 2012-05-16 Skapad: 2012-05-16 Senast uppdaterad: 2018-06-08Bibliografiskt granskad
5. Measuring pulsatile flow in cerebral arteries using 4D phase-contrast magnetic resonance imaging
Öppna denna publikation i ny flik eller fönster >>Measuring pulsatile flow in cerebral arteries using 4D phase-contrast magnetic resonance imaging
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2013 (Engelska)Ingår i: American Journal of Neuroradiology, ISSN 0195-6108, E-ISSN 1936-959X, Vol. 34, nr 9, s. 1740-1745Artikel i tidskrift (Övrigt vetenskapligt) Published
Abstract [en]

BACKGROUND AND PURPOSE: 4D PCMRI can be used to quantify pulsatile hemodynamics in multiple cerebral arteries. The aim of this study was to compare 4D PCMRI and 2D PCMRI for assessments of pulsatile hemodynamics in major cerebral arteries. MATERIALS AND METHODS: We scanned the internal carotid artery, the anterior cerebral artery, the basilar artery, and the middle cerebral artery in 10 subjects with a single 4D and multiple 2D PCMRI acquisitions by use of a 3T system and a 32-channel head coil. We assessed the agreement regarding net flow and the volume of arterial pulsatility (V) for all vessels. RESULTS: 2D and 4D PCMRI produced highly correlated results, with r = 0.86 and r = 0.95 for V and net flow, respectively (n = 69 vessels). These values increased to r = 0.93 and r = 0.97, respectively, during investigation of a subset of measurements with <5% variation in heart rate between the 4D and 2D acquisition (n = 31 vessels). Significant differences were found for ICA and MCA net flow (P = .004 and P < .001, respectively) and MCA V (P = .006). However, these differences were attenuated and no longer significant when the subset with stable heart rate (n = 31 vessels) was analyzed. CONCLUSIONS: 4D PCMRI provides a powerful methodology to measure pulsatility of the larger cerebral arteries from a single acquisition. A large part of differences between measurements was attributed to physiologic variations. The results were consistent with 2D PCMRI.

Nationell ämneskategori
Neurologi
Identifikatorer
urn:nbn:se:umu:diva-55477 (URN)10.3174/ajnr.A3442 (DOI)000329848800020 ()
Tillgänglig från: 2012-05-16 Skapad: 2012-05-16 Senast uppdaterad: 2018-06-08Bibliografiskt granskad

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