Document Detail


A theoretical framework for estimating cerebral oxygen metabolism changes using the calibrated-BOLD method: modeling the effects of blood volume distribution, hematocrit, oxygen extraction fraction, and tissue signal properties on the BOLD signal.
MedLine Citation:
PMID:  21669292     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Calibrated blood oxygenation level dependent (BOLD) imaging, a technique used to measure changes in cerebral O(2) metabolism, depends on an accurate model of how the BOLD signal is affected by the mismatch between changes in cerebral blood flow (CBF) and cerebral metabolic rate of O(2) (CMRO(2)). However, other factors such as the cerebral blood volume (CBV) distribution at rest and with activation also affect the BOLD signal. The Davis model originally proposed for calibrated BOLD studies (Davis et al., 1998) is widely used because of its simplicity, but it assumes CBV changes are uniformly distributed across vascular compartments, neglects intravascular signal changes, and ignores blood-tissue signal exchange effects as CBV increases and supplants tissue volume. More recent studies suggest that venous CBV changes are smaller than arterial changes, and that intravascular signal changes and CBV exchange effects can bias estimated CMRO(2). In this paper, recent experimental results for the relationship between deoxyhemoglobin and BOLD signal changes are integrated in order to simulate the BOLD signal in detail by expanding a previous model to include a tissue compartment and three blood compartments rather than only the venous blood compartment. The simulated data were then used to test the accuracy of the Davis model of calibrated BOLD, demonstrating that the errors in estimated CMRO(2) responses across the typical CBF-CMRO(2) coupling range are modest despite the simplicity of the assumptions underlying the original derivation of the model. Nevertheless, the accuracy of the model can be improved by abandoning the original physical meaning of the two parameters α and β and treating them as adjustable parameters that capture several physical effects. For a 3Tesla field and a dominant arterial volume change with activation, the accuracy of the Davis model is improved with new values of α=0.14 and β=0.91.
Authors:
Valerie E M Griffeth; Richard B Buxton
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2011-06-06
Journal Detail:
Title:  NeuroImage     Volume:  58     ISSN:  1095-9572     ISO Abbreviation:  Neuroimage     Publication Date:  2011 Sep 
Date Detail:
Created Date:  2011-07-26     Completed Date:  2011-11-23     Revised Date:  2014-09-20    
Medline Journal Info:
Nlm Unique ID:  9215515     Medline TA:  Neuroimage     Country:  United States    
Other Details:
Languages:  eng     Pagination:  198-212     Citation Subset:  IM    
Copyright Information:
Copyright © 2011 Elsevier Inc. All rights reserved.
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MeSH Terms
Descriptor/Qualifier:
Algorithms
Blood Volume / physiology*
Calibration
Cerebrovascular Circulation / physiology
Computer Simulation
Hematocrit / methods
Hemoglobins / metabolism
Humans
Hypercapnia / physiopathology
Kinetics
Magnetic Resonance Imaging
Models, Neurological
Models, Statistical
Oxygen / blood*
Oxygen Consumption / physiology*
Signal Processing, Computer-Assisted
Grant Support
ID/Acronym/Agency:
EB-9380/EB/NIBIB NIH HHS; GM7198/GM/NIGMS NIH HHS; HL-7089/HL/NHLBI NIH HHS; NS-36722/NS/NINDS NIH HHS; R01 NS036722/NS/NINDS NIH HHS; R01 NS036722-13/NS/NINDS NIH HHS
Chemical
Reg. No./Substance:
0/Hemoglobins; 9008-02-0/deoxyhemoglobin; S88TT14065/Oxygen
Comments/Corrections

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