Optimal timing for measuring cerebral blood flow after acetazolamide administration to detect preexisting cerebral hemodynamics and metabolism in patients with bilateral major cerebral artery steno-occlusive diseases: 15O positron emission tomography studies.

The present study determined the optimal timing of scanning for measurement of cerebral blood flow (CBF) after acetazolamide (ACZ) administration for detection of preexisting cerebral hemodynamics and metabolism in bilateral major cerebral artery steno-occlusive diseases. Thirty three patients underwent 15O gas positron emission tomography (PET) and each parameter was obtained in the bilateral middle cerebral artery (MCA) territories. CBF was also obtained using H2 15O PET scanning performed at baseline and at 5, 15, and 30 min after ACZ administration. Relative CBF at each time point after ACZ administration to baseline CBF was calculated. For MCA territories with normal cerebral blood volume (CBV) and cerebral metabolic rate of oxygen (CMRO2), CBF continued increasing until 15 min after ACZ administration. For MCA territories with abnormally increased CBV, CBF decreased 5 min after ACZ administration. After that, CBF continued increasing until 30 min after ACZ administration. For MCA territories with abnormally decreased CMRO2, CBF did not change 5 min after ACZ administration. Ten min later, CBF increased. The accuracy to detect abnormally increased CBV was significantly greater for relative CBF5 than for relative CBF15. The accuracy to detect abnormally decreased CMRO2 was significantly greater for relative CBF5 or CBF15 than for relative CBF30. For detecting abnormally increased oxygen extraction fraction, the accuracy did not differ among each relative CBF. These findings suggested that CBF measurement at 5 min after ACZ administration is the optimal timing for detection of preexisting cerebral hemodynamics and metabolism in bilateral major cerebral artery steno-occlusive diseases. AJNMMI