A NEW METHOD OF REGIONAL CEREBRAL BLOOD-FLOW MEASUREMENT USING ONE-POINT ARTERIAL SAMPLING BASED ON THE MICROSPHERE MODEL WITH N-ISOPROPYL-P-[I-123]-IODOAMPHETAMINE SPECT

We developed a new method for quantitative measurement of regional cer ebral blood flow (rCBF) using one-point arterial sampling with N-isopr opyl-p-[I-123]-iodoamphetamine (I-123-IMP) and single photon emission computed tomography (SPECT) based on the microsphere model. Although t he conventional microsphere method requires both the continuous withdr awal of arterial blood (integral of Ca(t)) and treatment of the blood with octanol to obtain the fraction of true tracer activity in the int egral of Ca(t) (N), the new method does not require these two procedur es. We examined 14 patients to analyse the correlation between the int egral of Ca(t)N and a small arterial sample obtained at one time point [one-point Ca(t)] after the injection of I-123-IMp Without octanol tr eatment. The integral of Ca(t)N was calculated from one point Ca(t) us ing the regression line of the correlation. An error of 8.1% in the ca lculated value compared to the actual value of the integral of Ca(t)N, could be inferred from one-point Ca(t) obtained at 6 min after the in jection. Then regional cerebral blood flow was measured by the method and a significant correlation was obtained with rCBF measured using th e Xe-133 inhalation method (r = 0.773). The one-point Ca(t) method pro vides fast, easy, accurate and non-invasive measurement of rCBF withou t inserting catheters and without treatment of arterial blood with oct anol.