[A time-saving approach for quantifying regional cerebral blood flow and application to split-dose method with 123I-IMP SPECT using a single-head rotating gamma-camera].

: We have proposed a modified early method, which can shorten the total time required for the quantitative regional cerebral blood flow (rCBF) measurement with N-isopropyl-p(-)[123I]iodoamphetamine (123I-IMP) using single-head rotating gamma-camera and the continuous arterial sampling method. Between 7 to 25 minutes after the intravenous injection of 123I-IMP, brain activity increases linearly, the SPECT data acquisition is being performed, and during which detector is rotating continuously. Then the rCBF values based on the microsphere model were calculated using the planar images obtained before and after the above acquisition and 5 min after the injection, and input counts obtained by the continuous arterial sampling. A good correlation (r = 0.951) was observed between the rCBF values obtained by this method and the traditional method, in which the SPECT data acquisition started about 30 min after injection. Applying this method to the quantitative rCBF measurements at rest and during stress with Diamox by the split dose method of 123I-IMP, we could evaluate the rCBF at rest and cerebral perfusion reserve in the same day. We conclude that this method can shorten the total time required for the standard normal microsphere method and can be applied to the split dose method, and this method provide the rCBF values not so much affected by washout of the tracer from the brain.