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To evaluate a new simplified bolus method for measurement of cerebral perfusion and metabolism, the parametric images with that method were compared with those obtained from the conventional steady-state method with 15 O-gas. The new method also provided images of arterial blood volume (V 0 ), which is a different parameter from cerebral blood volume (CBV) obtained using a C 15 O technique. Seven healthy volunteers and 10 patients with occlusive cerebrovascular diseases underwent positron emission tomography (PET) scans with both methods. Three-weighted integration was applied to calculate regional cerebral blood flow (rCBF) and regional cerebral metabolic rate of oxygen (rCMRO 2 ) in the bolus method. Global and regional CBF and CMRO 2 in volunteers were compared between the two methods and used as control data. Regional values in patients also were evaluated to observe differences between the bilateral hemispheres. Both rCBF and rCMRO 2 were linearly well correlated between the two methods, although global difference in CMRO 2 was significant. The difference in each parametric image except for V 0 was significant between the bilateral hemispheres in patients. The bolus method can simplify oxygen metabolism studies and yield parametric images comparable with those with the steady-state method, and can allow for evaluation of V 0 simultaneously. Increase in CBV without a change in V 0 suggested the increase might mainly be caused by venous dilatation in the ischemic regions.
Okazawa et al. (Sun,) studied this question.