Measurement of regional cerebral blood volume by emission tomography

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Summary: A new "mean regional" method for calcu lating global hemispheric values of blood flow, blood volume, and metabolism with positron emission tomog raphy is presented. It is based on a standardized set of regions defined according to coordinates in a stereotactic atlas of the brain, Region locations in each individual scan were determined by a localization technique that is in dependent of the appearance of the physiological images.

Section: Methodsmentioning

confidence: 99%

Standardized Mean Regional Method for Calculating Global Positron Emission Tomographic Measurements

Perlmutter

Herscovitch

Fox

et al. 1985

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“…The regional CBF and OEF were obtained by calculating the values with lookup tables created from the arterial whole blood and plasma radioactivity curves, and then correcting them for delay and dispersion (Iida et al, 1986). The CBV was measured by a 3-min inhalation of C 15 O with blood sampling (Grubb et al, 1978). The OEF was corrected for the effect of the regional CBV (Lammertsma and Jones, 1983;Mintun et al, 1984).…”

Section: O Gasesmentioning

confidence: 99%

Quantitative Evaluation of Cerebral Hemodynamics in Patients with Moyamoya Disease by Dynamic Susceptibility Contrast Magnetic Resonance Imaging—Comparison with Positron Emission Tomography

Tanaka

Nariai

Nagaoka

et al. 2006

We examined whether the degree of hemodynamic stress in patients with chronic occlusive cerebral vascular disease can be quantitatively evaluated with the use of perfusion-weighted magnetic resonance imaging (PWI). Thirty-six patients with moyamoya disease (mean age, 26.8 years; range, 18 to 59) underwent PWI and positron emission tomography (PET) within a month's interval. The PWI data were calculated by three different analytic methods. The cerebral blood flow (CBF) ratio, cerebral blood volume (CBV) ratio, and mean transit time (MTT) of the anterior circulation were calculated using the cerebellum as a control region and compared with PET data on the same three parameters and oxygen extraction fraction (OEF). Parametric maps of PWI attained a higher resolution than the PET maps and revealed focal perfusion failure on a gyrus-bygyrus level. The relative CBV and MTT obtained with PWI showed significant linear correlations with the corresponding PET values (CBV, R 2 ¼ 0.47 to 0.58; MTT, R 2 ¼ 0.32 to 0.68). We also found that we could detect regions with abnormally elevated OEF and CBV based on the delay of PWI-measured MTT relative to the control region by defining a 2.0-sec delay as a threshold. The sensitivity and specificity were 92.3% and 100% in detecting regions with abnormally elevated OEF, and 20.0% and 100% in detecting regions with abnormally elevated CBV, respectively. Among the parameters obtained with PWI, our results suggested that the relative CBV value and delay of MTT might be quantitatively manipulated to assist in clinical decision-making for patients with moyamoya disease.

“…Cerebral vascular mean transit time (MTT) relates to cerebral blood flow (CBF) and cerebral blood volume (CBV) according to the following: MTT = CBV/CBF (Meier and Zierler, 1954) and is a sensitive index of decline in perfusion pressure (Gibbs et al, 1984;Sette et al, 1989). By PET, CBF can be measured with 15 O-labeled water (H 2 15 O) as a diffusible tracer, which is regarded as the gold standard (Raichle et al, 1983;Kanno et al, 1987;Iida et al, 1989), and CBV can be measured with 15 O-labeled or 11 C-labeled carbon monoxide (C 15 O or 11 CO) (Martin et al, 1987;Grubb et al, 1978;Phelps et al, 1979).…”

Section: Introductionmentioning

confidence: 99%

Cerebral Vascular Mean Transit Time in Healthy Humans: A Comparative Study with PET and Dynamic Susceptibility Contrast-Enhanced MRI

Ibaraki

Ito²,

Shimosegawa

et al. 2006

Cerebral vascular mean transit time (MTT), defined as the ratio of cerebral blood volume to cerebral blood flow (CBV/CBF), is a valuable indicator of the cerebral circulation. Positron emission tomography (PET) and dynamic susceptibility contrast-enhanced magnetic resonance imaging (DSC-MRI) are useful for the quantitative determination of MTT in the clinical setting. The aim of this study was to establish a normal value set of MTT as determined by PET and by DSC-MRI and to identify differences between these methods. Seven healthy volunteers were studied with 15 O-PET (H 2 15 O and C 15 O) and gradient-echo echo-planar DSC-MRI at 1.5 T. In the DSC-MRI study with bolus injection of contrast agent, deconvolution analysis was performed. Comparison of gray-to-white matter ratios showed fairly good agreement between PET and DSC-MRI for all parameters (relative CBV, relative CBF, and relative MTT), confirming the validity of relative measurements with DSC-MRI. However, quantitative MTT measured by DSC-MRI was significantly shorter than that measured by PET in cerebral cortical regions (2.8 to 3.0 secs for DSC-MRI versus 3.9 to 4.3 secs for PET) and the centrum semiovale (3.5 secs for DSC-MRI versus 4.8 secs for PET). These discrepancies may be because of the differences in the intrinsic sensitivity of each imaging modality to vascular components; whereas PET measurement of CBV is equally sensitive to all vascular components, measurement with DSC-MRI originates from the microvasculature in the vicinity of the brain parenchyma. This underlying difference may influence interpretation of MTT determined by PET or by DSC-MRI for patients with cerebrovascular disease.