2002
DOI: 10.1002/mrm.10317
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Transient relationships among BOLD, CBV, and CBF changes in rat brain as detected by functional MRI

Abstract: The transient relationship between arterial cerebral blood flow (CBF A ) and total cerebral blood volume (CBV T ) was determined in the rat brain. Five rats anesthetized with urethane (1.2 g/kg) were examined under graded hypercapnia conditions (7.5% and 10% CO 2 ventilation). The blood oxygenation level-dependent (BOLD) contrast was determined by a gradient-echo echo-planar imaging (GE-EPI) pulse sequence, and CBV T changes were determined after injection of a monocrystalline iron oxide nanocolloid (MION) con… Show more

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Cited by 61 publications
(66 citation statements)
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References 30 publications
(57 reference statements)
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“…It was found that changes in capillary red blood cell velocities occurred mainly in the larger and medium capillaries, whereas volume changes were observed mainly in the small capillaries. Spatial heterogeneity of the exponent a has been shown for hypercapnia and hypocapnia (Wu et al, 2002;Rostrup et al, 2005). The dissociations in our results go further to show that spatial dependence of the volume-flow relationship is influenced by the nature of the conditionsareas around sizeable arteries show different volume-flow relationships during neurogenic and nonneurogenic conditions, unlike areas with mainly tissue.…”
Section: Vascular Reactions During Functional Challengessupporting
confidence: 78%
“…It was found that changes in capillary red blood cell velocities occurred mainly in the larger and medium capillaries, whereas volume changes were observed mainly in the small capillaries. Spatial heterogeneity of the exponent a has been shown for hypercapnia and hypocapnia (Wu et al, 2002;Rostrup et al, 2005). The dissociations in our results go further to show that spatial dependence of the volume-flow relationship is influenced by the nature of the conditionsareas around sizeable arteries show different volume-flow relationships during neurogenic and nonneurogenic conditions, unlike areas with mainly tissue.…”
Section: Vascular Reactions During Functional Challengessupporting
confidence: 78%
“…All these parameters and other physiological quantities are lumped into the constant M which can be measured on a pixel-by-pixel basis. A modified CMRO 2 model has been proposed to take into account the arterial-venous blood volume contributions and includes a non-steady state determination of CMRO 2 (Wu et al, 2002). While Hoge et al (1999), Mandeville et al (1999), and others have reproduced and extended Davis' findings.…”
Section: Introductionmentioning
confidence: 91%
“…Of note, in an fMRI study performed at 4.7 T, Spenger et al (2000) also report highly variable activations outside the somatosensory pathway (with no changes in MABP and HR) during forepaw stimulation in rats under α-chloralose anesthesia previously optimized to eliminate pain response to electrical stimulation. Second, isoflurane also depresses cerebrovascular reactivity to CO 2 relative to awake conditions (Sicard et al, 2003) which may explain the stronger hypercapnic challenges required to derive M. In animal studies, 5% and 10% CO 2 challenges are commonly used with other anesthetics (Luo et al, 2003;Wu et al, 2002), and the former is frequently used in human studies (Davis et al, 1998;Hoge et al, 1999). Third, isoflurane is a cerebrovasodilator which increases basal CBF (Hendrich et al, 2001;Matta et al, 1999), thus potentially reducing the head room for forepaw stimulation-or hypercapnia-evoked CBF and/or BOLD increases.…”
Section: Potential Drawbacks Of the Isoflurane-anesthetized Forepaw-smentioning
confidence: 99%
“…This equation has since been used extensively in fMRI signal modeling, and the power-law coefficient of 0.38 has been widely assumed when estimating the oxygen metabolism change (DCMRo 2 ) using calibrated BOLD (1,4,5). The general validity of Grubb's power-law relationship has been supported by data from other imaging modalities in animal and human studies (6)(7)(8)(9), but as much as it is widely assumed, the value of a has remained a subject of investigation and debate. Using MRI at 9.4 T, Lee et al (7) found the relationship between the relative CBF (rCBF) and total relative CBV (rCBV) during hypercapnia to be rCBV(total) ¼ rCBF 0.…”
Section: Introductionmentioning
confidence: 94%