Clinical Performance of the Discovery NM530c in Japanese Patients

The Discovery NM530 is a new generation of SPECT cameras equipped with semiconductor cadmium-zinctelluride (CZT) detector technology. It provides a shorter scan time and reduces the patient’s radiation exposure wthout loss of image quality compared with the conventional Anger camera. Combined supine and prone imaging with the Discovery NM530c is useful for reducing the false-positive rate in the infero-posterior or inferolateral segment associated with supine imaging. As studied by multicenter registry, 74% sensitivity, 85% specificity, and 81% accuracy for left anterior descending coronary artery stenosis, 76% sensitivity, 89% specificity, and 85% accuracy for left circumflex coronary artery stenosis, and 72% sensitivity, 86% specificity, and 82% accuracy for right coronary artery stenosis were observed in detecting an angiographic diameter narrowing of ≥75% on visual estimation. Using a low-dose technetium-99m (185/370 MBq) 1-day protocol with an effective dose of ≤5 mSv, CZT SPECT demonstrated an acceptable diagnostic yield in detecting a significant coronary stenosis as assessed by fractional flow reserve (FFR). As for limiting to 92 coronary lesions in which FFR was measured, stress SPECT showed 77% sensitivity, 91% specificity, and 84% accuracy, whereas the diagnostic value decreased to 52% sensitivity, 68% specificity, and 58% accuracy based only on visual estimation of ≥ 75% diameter narrowing. In addition, the quantification of myocardial perfusion reserve derived by dynamic SPECT imaging using the Discovery NM530c may help identify balanced ischemia in patients with left main or 3-vessel disease.