[Regional cerebral blood flow measurements at pre- and post-Diamox test using split dose 99mTc-ECD SPECT: comparison with 133Xe inhalation method and linearization correction].

A new method for quantitative measurement of regional cerebral blood flow (rCBF) before and after acetazolamide (Diamox) administration was developed using 99mTc labeled ethyl cysteinate dimer (ECD) and consecutive SPECT with continuous arterial blood sampling. Moreover, the correction was proposed for underestimation of rCBF due to the inherent low first pass extraction of ECD in high blood flow regions. The rCBF values obtained by the microsphere model in 5 patients correlated well with those obtained by 133Xe gas inhalation method. The slope of the regression line, however, was 0.576 due to the underestimation of high CBF values. The reproducibility of two resting rCBF obtained by the microsphere model proposed here was confirmed in another 5 patients with the mean values of 41.8 +/- 5.6 ml/100 g/min and 38.9 +/- 5.3 ml/100 g/min for the 1st and 2nd measurement, respectively. The correction of rCBF obtained with ECD and the proposed microsphere model was performed using the permeability-surface area product model described by Crone. In 14 patients with cerebrovascular diseases, the corrected rCBFs correlated well with those by 133Xe gas inhalation method with the improvement of the slope of regression line (0.427 to 0.865), although the correlation coefficient did not change significantly (0.697 to 0.699). The results indicated that the proposed correction method could reflect precisely the increase in rCBF elicited after Diamox administration, so that the cerebral perfusion reserve could be evaluated more exactly than the methods which have ever been utilized in the routine clinical measurements.