scholarly journals Cerebral Blood Volume Changes during Brain Activation

2012 ◽  
Vol 32 (8) ◽  
pp. 1618-1631 ◽  
Author(s):  
Steffen Norbert Krieger ◽  
Markus Nikolar Streicher ◽  
Robert Trampel ◽  
Robert Turner
Keyword(s):  
Blood Volume ◽  
Cerebral Blood Volume ◽  
Axial Flow ◽  
Brain Activation ◽  
Approximate Solutions ◽  
Theory Model ◽  
Surrounding Tissue ◽  
Apparent Paradox ◽  
Positron Emission ◽  
Capillary Membranes

Cerebral blood volume (CBV) changes significantly with brain activation, whether measured using positron emission tomography, functional magnetic resonance imaging (fMRI), or optical microscopy. If cerebral vessels are considered to be impermeable, the contents of the skull incompressible, and the skull itself inextensible, task- and hypercapnia-related changes of CBV could produce intolerable changes of intracranial pressure. Because it is becoming clear that CBV may be useful as a well-localized marker of neural activity changes, a resolution of this apparent paradox is needed. We have explored the idea that much of the change in CBV is facilitated by exchange of water between capillaries and surrounding tissue. To this end, we developed a novel hemodynamic boundary-value model and found approximate solutions using a numerical algorithm. We also constructed a macroscopic experimental model of a single capillary to provide biophysical insight. Both experiment and theory model capillary membranes as elastic and permeable. For a realistic change of input pressure, a relative pipe volume change of 21±5% was observed when using the experimental setup, compared with the value of approximately 17±1% when this quantity was calculated from the mathematical model. Volume, axial flow, and pressure changes are in the expected range.

scholarly journals Effects of Acetazolamide on Cerebral Blood Flow, Blood Volume, and Oxygen Metabolism: A Positron Emission Tomography Study with Healthy Volunteers

2001 ◽  
Vol 21 (12) ◽  
pp. 1472-1479 ◽  
Author(s):  
Hidehiko Okazawa ◽  
Hiroshi Yamauchi ◽  
Kanji Sugimoto ◽  
Hiroshi Toyoda ◽  
Yoshihiko Kishibe ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Metabolic Rate ◽  
Blood Volume ◽  
Cerebral Blood Volume ◽  
Capillary Blood ◽  
Emission Tomography ◽  
Positron Emission ◽  
Capillary Blood Volume

To evaluate changes in cerebral hemodynamics and metabolism induced by acetazolamide in healthy subjects, positron emission tomography studies for measurement of cerebral perfusion and oxygen consumption were performed. Sixteen healthy volunteers underwent positron emission tomography studies with15O-gas and water before and after intravenous administration of acetazolamide. Dynamic positron emission tomography data were acquired after bolus injection of H215O and bolus inhalation of15O2. Cerebral blood flow, metabolic rate of oxygen, and arterial-to-capillary blood volume images were calculated using the three-weighted integral method. The images of cerebral blood volume were calculated using the bolus inhalation technique of C15O. The scans for cerebral blood flow and volume and metabolic rate of oxygen after acetazolamide challenge were performed at 10, 20, and 30 minutes after drug injection. The parametric images obtained under the two conditions at baseline and after acetazolamide administration were compared. The global and regional values for cerebral blood flow and volume and arterial-to-capillary blood volume increased significantly after acetazolamide administration compared with the baseline condition, whereas no difference in metabolic rate of oxygen was observed. Acetazolamide-induced increases in both blood flow and volume in the normal brain occurred as a vasodilatory reaction of functioning vessels. The increase in arterial-to-capillary blood volume made the major contribution to the cerebral blood volume increase, indicating that the raise in cerebral blood flow during the acetazolamide challenge is closely related to arterial-to-capillary vasomotor responsiveness.

Evidence that cerebral blood volume can provide brain activation maps with better spatial resolution than deoxygenated hemoglobin

NeuroImage ◽  
2005 ◽  
Vol 27 (4) ◽  
pp. 947-959 ◽  
Author(s):  
Joseph P. Culver ◽  
Andrew M. Siegel ◽  
Maria Angela Franceschini ◽  
Joseph B. Mandeville ◽  
David A. Boas
Keyword(s):  
Blood Volume ◽  
Spatial Resolution ◽  
Cerebral Blood Volume ◽  
Brain Activation ◽  
Deoxygenated Hemoglobin

scholarly journals In vivo Measurement of Regional Cerebral Haematocrit Using Positron Emission Tomography

1984 ◽  
Vol 4 (3) ◽  
pp. 317-322 ◽  
Author(s):  
Adriaan A. Lammertsma ◽  
David J. Brooks ◽  
Ronald P. Beaney ◽  
David R. Turton ◽  
Malcolm J. Kensett ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Blood Volume ◽  
Cerebral Blood Volume ◽  
Mean Value ◽  
Emission Tomography ◽  
Regional Cerebral Blood ◽  
In Vivo Measurement ◽  
Positron Emission ◽  
Regional Cerebral Blood Volume

A method is described for measuring the regional cerebral-to-large vessel haematocrit ratio using inhalation of carbon-11-labelled carbon monoxide and the intravenous injection of carbon-11-labelled methyl-albumin in combination with positron emission tomography. The mean value in a series of nine subjects was 0.69. This is ∼20% lower than the value of 0.85 previously reported. It is concluded that previous measurements of regional cerebral blood volume using a haematocrit ratio of 0.85 will have underestimated the value of regional cerebral blood volume by 20%.

scholarly journals Validation of VASO cerebral blood volume measurement with positron emission tomography

2010 ◽  
Vol 65 (3) ◽  
pp. 744-749 ◽  
Author(s):  
Jinsoo Uh ◽  
Ai-Ling Lin ◽  
Kihak Lee ◽  
Peiying Liu ◽  
Peter Fox ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Blood Volume ◽  
Cerebral Blood Volume ◽  
Volume Measurement ◽  
Emission Tomography ◽  
Positron Emission ◽  
Blood Volume Measurement

scholarly journals Changes in the Arterial Fraction of Human Cerebral Blood Volume during Hypercapnia and Hypocapnia Measured by Positron Emission Tomography

2005 ◽  
Vol 25 (7) ◽  
pp. 852-857 ◽  
Author(s):  
Hiroshi Ito ◽  
Masanobu Ibaraki ◽  
Iwao Kanno ◽  
Hiroshi Fukuda ◽  
Shuichi Miura
Keyword(s):  
Positron Emission Tomography ◽  
Blood Volume ◽  
Cerebral Blood Volume ◽  
Venous Blood ◽  
Capillary Blood ◽  
Emission Tomography ◽  
Arterial Blood ◽  
Positron Emission ◽  
Capillary Blood Volume ◽  
Arterial Blood Volume

Hypercapnia induces cerebral vasodilation and increases cerebral blood volume (CBV), and hypocapnia induces cerebral vasoconstriction and decreases CBV. Cerebral blood volume measured by positron emission tomography (PET) is the sum of three components, that is, arterial, capillary, and venous blood volumes. Changes in arterial blood volume ( Va) and CBV during hypercapnia and hypocapnia were investigated in humans using PET with H215O and 11CO. Arterial blood volume was determined from H215O PET data by means of a two-compartment model that takes Va into account. Baseline CBV and values during hypercapnia and hypocapnia in the cerebral cortex were 0.034 ± 0.003, 0.038 ± 0.003, and 0.031 ± 0.003 mL/mL (mean ± s.d.), respectively. Baseline Va and values during hypercapnia and hypocapnia were 0.015 ± 0.003, 0.025 ± 0.011, and 0.007 ± 0.003 mL/mL, respectively. Cerebral blood volume changed significantly owing to changes in PaCO2, and Va changed significantly in the direction of CBV changes. However, no significant change was observed in venous plus capillary blood volume (= CBV- Va). This indicates that changes in CBV during hypercapnia and hypocapnia are caused by changes in arterial blood volume without changes in venous and capillary blood volume.

scholarly journals Changes in Human Regional Cerebral Blood Flow and Cerebral Blood Volume during Visual Stimulation Measured by Positron Emission Tomography

2001 ◽  
Vol 21 (5) ◽  
pp. 608-612 ◽  
Author(s):  
Hiroshi Ito ◽  
Kazuhiro Takahashi ◽  
Jun Hatazawa ◽  
Seong-Gi Kim ◽  
Iwao Kanno
Keyword(s):  
Positron Emission Tomography ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Blood Volume ◽  
Cerebral Blood Volume ◽  
Visual Stimulation ◽  
Emission Tomography ◽  
Neural Activation ◽  
Positron Emission ◽  
Stimulation Of

The hemodynamic mechanism of increase in cerebral blood flow (CBF) during neural activation has not been elucidated in humans. In the current study, changes in both regional CBF and cerebral blood volume (CBV) during visual stimulation in humans were investigated. Cerebral blood flow and CBV were measured by positron emission tomography using H215O and 11CO, respectively, at rest and during 2-Hz and 8-Hz photic flicker stimulation in each of 10 subjects. Changes in CBF in the primary visual cortex were 16% ± 16% and 68% ± 20% for the visual stimulation of 2 Hz and 8 Hz, respectively. The changes in CBV were 10% ± 13% and 21% ± 5% for 2-Hz and 8-Hz stimulation, respectively. Significant differences between changes in CBF and CBV were observed for visual stimulation of 8 Hz. The relation between CBF and CBV values during rest and visual stimulation was CBV = 0.88CBF0.30. This indicates that when the increase in CBF during neural activation is great, that increase is caused primarily by the increase in vascular blood velocity rather than by the increase in CBV. This observation is consistent with reported findings obtained during hypercapnia.

Arterial fraction of cerebral blood volume in humans measured by positron emission tomography

2001 ◽  
Vol 15 (2) ◽  
pp. 111-116 ◽  
Author(s):  
Hiroshi Ito ◽  
Iwao Kanno ◽  
Hidehiro Iida ◽  
Jun Hatazawa ◽  
Eku Shimosegawa ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Blood Volume ◽  
Cerebral Blood Volume ◽  
Emission Tomography ◽  
Positron Emission

scholarly journals Regional Asymmetries of Cerebral Blood Flow, Blood Volume, and Oxygen Utilization and Extraction in Normal Subjects

1987 ◽  
Vol 7 (1) ◽  
pp. 64-67 ◽  
Author(s):  
Joel S. Perlmutter ◽  
William J. Powers ◽  
Peter Herscovitch ◽  
Peter T. Fox ◽  
Marcus E. Raichle
Keyword(s):  
Blood Volume ◽  
Cerebral Blood Volume ◽  
Normal Subjects ◽  
Anterior Cingulate ◽  
Oxygen Extraction ◽  
Oxygen Utilization ◽  
Positron Emission ◽  
Sensorimotor Area ◽  
Left And Right ◽  
Subcortical Regions

Positron emission tomography (PET) and 15O-labeled radiotracers were used to measure regional CBF, cerebral blood volume (CBV), CMRO2, and oxygen extraction in 32 right-handed subjects at rest. Mean left hemispheric CBF (46.2 ± 6.8 ml/100 g/min) and CMRO2 (2.60 ± 0.59 ml/100 g/min) were significantly lower than right hemispheric values (47.4 ± 7.2 and 2.66 ± 0.61 ml/100 g/min, respectively; p < 0.0001 for both), whereas left and right hemispheric CBV and oxygen extraction were not significantly different. We further investigated these asymmetries by comparing left- and right-sided values for specific cortical and subcortical regions. We found that left-sided CBF and CMRO2 were significantly lower than right-sided values for sensorimotor, occipital, and superior temporal regions, whereas only left-sided CBF values were lower for anterior cingulum. CBV was asymmetric for the anterior cingulate and midfrontal regions, and oxygen extraction was asymmetric for the sensorimotor area. No asymmetries were observed in inferior parietal cortex, thalamus, putamen, or pallidum. Knowledge of these normal physiological asymmetries is essential for proper interpretation of PET studies of physiology and pathology. Furthermore, the ability to detect asymmetries with PET may lead to a better understanding of the lateralization of specific functions in the human brain.

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