PURPOSE: To compare the accuracy with which electron beam tomography (EBT) and 99m Tc-MIBI scanning measure myocardial perfusion valve. MATERIALS AND METHODS: Twenty-two subjects [normal volunteers (n = 6), patients in whom ischemic heart disease was diagnosed (n = 5), and those in whom ischemic heart disease was suspected but who were found to be normal (n = 11)] were involved in this study. EBT was performed after bolus injection of contrast media (50 ml of Iopamiro 370 or Optiray 350, 3 ml/sec). The myocardium was divided into 16 segments according to the classification devised by the American Society of Echocardiography, and each myocardial perfusion value was calculated by post-image processing. A pharmacologic stress test was performed in all subjects except four patients with acute myocardial infarction, and myocardial perfusion reserve ratios were assessed. Single photon emission computed tomography (SPECT) was performed after the injection of 20 mCi of 99m Tc-MIBI. Any segments with moderate to severe photon defect on visual analysis of SPECT were identified and perfusion values determined by EBT in normal and ischemic segments were compared. RESULTS: No difference in myocardial perfusion was found between volunteers and the suspected group. Their perfusion values were 0.71 +/-0.14 ml/g/min in the resting state and 1.16 +/-0.24 ml/g/min on the stress test and the myocardial perfusion reserve ratio was, therefore, 1:1.68 +/-0.38. In ischemic patients, 99m Tc-MIBI scanning revealed a perfusion defect in 28 segments, and on EBT the measurement obtained was 0.54 +/-0.19 ml/g/min. The remaining 324 perfusion segments shown by SPECT to be normal showed a perfusion value of 0.79 +/-0.22 ml/g/min on EBT. CONCLUSION: Compared with 99mTc-MIBI scanning, the measurement of myocardial perfusion by EBT provides absolute quantification of perfusion value and more detailed anatomic information.