Cerebral Blood Flow Measurement Using fMRI and PET: A Cross-Validation Study

An important aspect of functional magnetic resonance imaging (fMRI) is the study of brain hemodynamics, and MR arterial spin labeling (ASL) perfusion imaging has gained wide acceptance as a robust and noninvasive technique. However, the cerebral blood flow (CBF) measurements obtained with ASL fMRI have not been fully validated, particularly during global CBF modulations. We present a comparison of cerebral blood flow changes (ΔCBF) measured using a flow-sensitive alternating inversion recovery (FAIR) ASL perfusion method to those obtained usingH2O15PET, which is the current gold standard for in vivo imaging of CBF. To study regional and global CBF changes, a group of 10 healthy volunteers were imaged under identical experimental conditions during presentation of 5 levels of visual stimulation and one level of hypercapnia. The CBF changes were compared using 3 types of region-of-interest (ROI) masks. FAIR measurements of CBF changes were found to be slightly lower than those measured with PET (averageΔCBF of21.5±8.2% for FAIR versus28.2±12.8% for PET at maximum stimulation intensity). Nonetheless, there was a strong correlation between measurements of the two modalities. Finally, at-test comparison of the slopes of the linear fits of PET versus ASLΔCBF for all 3 ROI types indicated no significant difference from unity (P>.05).

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Dietary nitrate facilitates an acetazolamide-induced increase in cerebral blood flow during visual stimulation

Journal of Applied Physiology ◽

10.1152/japplphysiol.00797.2013 ◽

2014 ◽

Vol 116 (3) ◽

pp. 267-273 ◽

Cited By ~ 6

Author(s):

Rasmus Aamand ◽

Yi-Ching Lynn Ho ◽

Thomas Dalsgaard ◽

Andreas Roepstorff ◽

Torben E. Lund

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Dietary Intake ◽

Vascular Function ◽

Visual Stimulation ◽

No Production ◽

Positive Interaction ◽

Healthy Human ◽

Cerebrovascular System

The carbonic anhydrase (CA) inhibitor acetazolamide (AZ) is used routinely to estimate cerebrovascular reserve capacity in patients, as it reliably increases cerebral blood flow (CBF). However, the mechanism by which AZ accomplishes this CBF increase is not entirely understood. We recently discovered that CA can produce nitric oxide (NO) from nitrite, and that AZ enhances this NO production in vitro. In fact, this interaction between AZ and CA accounted for a large part of AZ's vasodilatory action, which fits well with the known vasodilatory potency of NO. The present study aimed to assess whether AZ acts similarly in vivo in the human cerebrovascular system. Hence, we increased or minimized the dietary intake of nitrate in 20 healthy male participants, showed them a full-field flickering dartboard, and measured their CBF response to this visual stimulus with arterial spin labeling. Doing so, we found a significant positive interaction between the dietary intake of nitrate and the CBF modulation afforded by AZ during visual stimulation. In addition, but contrary to studies conducted in elderly participants, we report no effect of nitrate intake on resting CBF in healthy human participants. The present study provides in vivo support for an enhancing effect of AZ on the NO production from nitrite catalyzed by CA in the cerebrovascular system. Furthermore, our results, in combination with the results of other groups, indicate that nitrate may have significant importance to vascular function when the cerebrovascular system is challenged by age or disease.

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A Spatiotemporal Profile of In Vivo Cerebral Blood Flow Changes Following Intranasal Oxytocin in Humans

Biological Psychiatry ◽

10.1016/j.biopsych.2014.10.005 ◽

2016 ◽

Vol 79 (8) ◽

pp. 693-705 ◽

Cited By ~ 95

Author(s):

Yannis Paloyelis ◽

Orla M. Doyle ◽

Fernando O. Zelaya ◽

Stefanos Maltezos ◽

Steven C. Williams ◽

...

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Flow Changes

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Relationship between cerebral blood flow changes during visual stimulation and baseline flow levels investigated with functional MRI

Neuroreport ◽

10.1097/00001756-199906030-00023 ◽

1999 ◽

Vol 10 (8) ◽

pp. 1751-1756 ◽

Cited By ~ 15

Author(s):

Andreas Kastrup ◽

Tie-Qiang Li ◽

Gunnar Krüger ◽

Gary H. Glover ◽

Michael E. Moseley

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Functional Mri ◽

Visual Stimulation ◽

Flow Changes ◽

Baseline Flow

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Cerebral blood flow predicts differential neurotransmitter activity

10.1101/207407 ◽

2017 ◽

Author(s):

Juergen Dukart ◽

Štefan Holiga ◽

Christopher Chatham ◽

Peter Hawkins ◽

Anna Forsyth ◽

...

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Mechanisms Of Action ◽

Resonance Imaging ◽

Neurotransmitter Receptor ◽

Neurotransmitter Systems ◽

Neurotransmitter Activity ◽

Flow Changes ◽

Unknown Link

AbstractApplication of metabolic magnetic resonance imaging measures such as cerebral blood flow in translational medicine is limited by the unknown link of observed alterations to specific neurophysiological processes. In particular, the sensitivity of cerebral blood flow to activity changes in specific neurotransmitter systems remains unclear. We address this question by probing cerebral blood flow in healthy volunteers using seven established drugs with known dopaminergic, serotonergic, glutamatergic and GABAergic mechanisms of action. We use a novel framework aimed at disentangling the observed effects to contribution from underlying neurotransmitter systems. We find for all evaluated compounds a reliable spatial link of respective cerebral blood flow changes with underlying neurotransmitter receptor densities corresponding to their primary mechanisms of action. The strength of these associations with receptor density is mediated by respective drug affinities. These findings suggest that cerebral blood flow is a sensitive brain-wide in-vivo assay of metabolic demands across a variety of neurotransmitter systems in humans.

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Interdependence of Regional and Global Cerebral Blood Flow during Visual Stimulation: An O-15-Butanol Positron Emission Tomography Study

Journal of Cerebral Blood Flow & Metabolism ◽

10.1097/00004647-200106000-00004 ◽

2001 ◽

Vol 21 (6) ◽

pp. 664-670 ◽

Cited By ~ 27

Author(s):

Lars J. Kemna ◽

Stefan Posse ◽

Lutz Tellmann ◽

Thomas Schmitz ◽

Hans Herzog

Keyword(s):

Positron Emission Tomography ◽

Blood Flow ◽

Cerebral Blood Flow ◽

Visual Stimulation ◽

Emission Tomography ◽

Global Flow ◽

Positron Emission ◽

Global Cerebral Blood Flow ◽

Flow Changes ◽

O 15

The authors investigated the influence of variations in global cerebral blood flow (gCBF) on regional flow changes during visual stimulation. Global flow was varied using different end-expiratory CO2 values (Petco2) between 20 and 70 mm Hg. Visual stimulation was performed with a red LED-array flashing at 8 Hz. Blood flow was measured with O-15-butanol, continuous arterial blood sampling, and positron emission tomography (PET). Global flow changes surpassed the published values of O-15-H2O studies, better fitting the results of the inert gas technique (gCBF at 20, 40, and 70 mm Hg Petco2 ± SD was 31 ± 4, 48 ± 13, and 160 ± 50 mL 100 g−1 min−1, respectively). The relation between Petco2 and CBF in the current study was best described by an exponential rather than a linear function. At low Petco2, the activation-induced flow changes are moderately damped, whereas at high Petco2, they are nearly lost (ΔCBF (±SD): 52% ± 25%, 68% ± 22%, 16% ± 25% at Petco2 = 20, 40, 70 mm Hg, respectively).

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