A MULTICENTER VALIDATION OF REGIONAL CEREBRAL BLOOD-FLOW QUANTITATIONUSING [I-123] IODOAMPHETAMINE AND SINGLE-PHOTON EMISSION COMPUTED-TOMOGRAPHY

Recently, two methods have been proposed for regional cerebral blood f low (rCBF) quantitation using [I-123]iodoamphetamine (IMP) and single- photon emission computed tomography (SPECT). The table look-up (TLU) m ethod has been shown to provide both rCBF and volume of distribution, V-d, images from two SPECT scans, while a single-scan autoradiographic (ARG) technique provided rCBF using a fixed and assumed V-d. In both methods, a single blood sample was referred to calibrate the previousl y determined standard input function The present multicenter project w as designed to evaluate the accuracy of both methods for use as clinic al investigative tools. Ten independent institutions performed [I-123] IMP-SPECT studies according to both methods in 76 subjects (10 normal volunteers, 32 patients with cerebrovascular disease, and 34 patients with other diseases). Calculated rCBF values were compared with those obtained by the following reference methods available in the participa ting institutions; [O-15] H2O positron emission tomography (PET) (five institutions), [Xe-133]SPECT (four institutions), and the [I-123]IMP microsphere method (three institutions). Both ARG and TLU methods prov ided rCBF values that were significantly correlated with those measure d by the [O-15] H2O PET technique (p < 0.001 for all subjects; overall regression equation, y = 15.14 + 0.54x) and those measured by the [I- 123]IMP-microsphere method (p < 0.001 for all subjects; y = 2.0 + 0.80 x). Significant correlation (p < 0.05) was observed in 18 of 24 subjec ts studied with the [Xe-133] SPECT reference technique (overall regres sion equation, y = 15.0 + 0.55x). Mean cortical gray matter rCBF in a group of normal subject was 43.9 +/- 3.3 and 33.4 +/- 2.0 ml/min/100 g for the ARG and TLU methods, respectively. Regional V-d of [I-123]IMP estimated by the TLU method was 45 ml/ml +/- 20% in the normal cortic al region, Close agreement between ARG and TLU rCBF values was observe d (y = -3.21 + 1.07x, r = 0.97), confirming the validity of assuming a fixed V-d in the ARG method. Results of this study demonstrate that b oth the ARG and TLU methods accurately and reliably estimate rCBF in a variety of clinical settings.