Recently, two methods have been proposed for regional cerebral blood flow (rCBF) quantitation using [123I]iodoamphetamine (IMP) and single-photon emission computed tomography (SPECT). The table look-up (TLU) method has been shown to provide both rCBF and volume of distribution, Vd, images from two SPECT scans, while a single-scan autoradiographic (ARG) technique provided rCBF using a fixed and assumed Vd. In both methods, a single blood sample was referred to calibrate the previously determined standard input function. The present multicenter project was designed to evaluate the accuracy of both methods for use as clinical investigative tools. Ten independent institutions performed [123I]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 participating institutions; [15O] H2O positron emission tomography (PET) (five institutions), [133Xe]SPECT (four institutions), and the [123I]IMP microsphere method (three institutions). Both ARG and TLU methods provided rCBF values that were significantly correlated with those measured by the [15O] H2O PET technique (p < 0.001 for all subjects; overall regression equation, y = 15.14 + 0.54x) and those measured by the [123I]IMP-microsphere method (p < 0.001 for all subjects: y = 2.0 + 0.80x). Significant correlation (p < 0.05) was observed in 18 of 24 subjects studied with the [133Xe] SPECT reference technique (overall regression equation, y = 15.0 + 0.55x). Mean cortical gray matter rCBF in a group of normal subject was 43.9 +/- 3.3 and 43.4 +/- 2.0 ml/min/100 g for the ARG and TLU methods, respectively. Regional Vd of [123I]IMP estimated by the TLU method was 45 ml/ml +/- 20% in the normal cortical region. Close agreement between ARG and TLU rCBF values was observed (y = -3.21 + 1.07x, r = 0.97), confirming the validity of assuming a fixed Vd in the ARG method. Results of this study demonstrate that both the ARG and TLU methods accurately and reliably estimate rCBF in a variety of clinical settings.

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Relative regional cerebral blood flow was measured with single photon emission computed tomography (SPECT) using 99mTc-hexamethylpropyleneamine oxime (99mTc-HMPAO) in 16 patients with major depression while they were in the depressed state as well as in remission. All patients were closely matched with regard to medication status. In the depressed state, significant reductions in tracer uptake were found in the left superior frontal, bilateral parietal and right lateral temporal cortex. During remission, significant increases in uptake were found in the left superior frontal, right parietal and right lateral temporal cortex. There were no significant differences in tracer uptake between patients in remission and controls. These findings suggest that the regional decreases in tracer uptake observed in the depressed state might be a state-related abnormality.

IT has been proposed that iodine-123 15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid (123I-BMIPP) is an agent for myocardial fatty acid metabolism in animal models. The aim of the present study was to determine whether alterations in fatty acid uptake and/or utilization in patients with hypertrophic cardiomyopathy (HCM) could be detected by 123I-BMIPP. Myocardial imaging with 123I-BMIPP and thallium-201 (201Tl) was performed in 14 fasted patients. A dose of 111 MBq of 123I-BMIPP was administered intravenously at rest, and myocardial emission computed tomography was obtained 20 min and 3 h after injection. The 201Tl imaging was also performed within 1 week after the 123I-BMIPP study. The regional myocardial uptake and clearance of 123I-BMIPP and 201Tl were assessed quantitatively. The myocardial distribution of 123I-BMIPP was more heterogeneous than that of 201Tl in patients with HCM. The myocardial uptake of 123I-BMIPP was lower in the anteroseptal region of the left ventricle than in the posterolateral region (74% vs. 85%, P less than 0.001). The anteroseptal wall showed a faster clearance of 123I-BMIPP than the posterolateral wall (33% vs. 27%, P less than 0.01). Both a decreased uptake and rapid clearance of 123I-BMIPP were observed in the hypertrophied myocardium of the anteroseptal wall, where 201Tl uptake was normal or even increased. Myocardial segments with a markedly increased thickness showed a lower uptake and faster clearance of 123I-BMIPP than those with mild hypertrophy (uptake 73% vs. 82%, P less than 0.05; clearance 30% vs. 25%, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)