Simplified quantitative determination of cerebral perfusion reserve with (H2OPET)-O-15 and acetazolamide

The measurement of regional cerebral blood flow (rCBF) and perfusion reserv e (PR) with (H2O)-O-15 positron emission tomography (PET) and acetazolamide challenge is of importance in evaluating patients with cerebrovascular dis ease and is thought to be useful in selecting patients for possible vascula r surgery. Full quantitative assessment of I CBF with PET requires arterial blood sampling, which is inconvenient in a clinical setting. In this work, we present a simple non-invasive method with which to quantitatively evalu ate PR in one PET session lasting no more than 30 min. In ten patients with cerebrovascular disease, rCBF was measured with (H2O)-O-15 PET under the b aseline condition and after administration of 1 acetazolamide using a stand ard technique involving arterial blood sampling, The activity accumulated o ver 60 s was normalized to injected activity per kilogram body weight (nAA) and compared with rCBF in eight different brain regions. A high linear cor relation was found for PR based on nAA (PR,,) and rCBF (PRrCBF) (PRnAA = 0. 843 PRrCBF + 0.092, r=0.83, Pearson's correlation coefficient). Bland-Altma n analyses further confirmed that PR,A, reflects PR in a quantitative manne r. These results demonstrate that the method based on normalized counts all ows the quantitative assessment of PR without blood sampling.