Single-photon emission tomography studies of rubidium-81 in the detection of ischaemic heart disease, using a stress-reinjection protocol

Abstract

The present study was designed to determine the feasibility of using single-photon emission tomography (SPET) imaging with rubidium-81 (T1/2 = 4.54 h) to detect ischaemic heart disease, using a stress-reinjection protocol and a specially constructed 511-keV hexagonal hole collimator for a standard gamma camera. The diagnostic performance of 81Rb SPET in detecting coronary artery disease (CAD) was investigated in 52 patients with a high prevalence of CAD. Coronary arteriography was performed in 34 patients, 25 of whom were classified as having significant stenosis (> or = 50%). At peak exercise (Cornell protocol), 111-222 MBq 81Rb was injected i.v. for stress imaging, and after 3 h of rest, 74-111 MBq was reinjected for rest imaging. The displayed short- and long-axis slices and the polar map images were interpreted qualitatively. In comparison to coronary arteriography, which served as the gold standard, the performance of 81Rb SPET revealed a sensitivity of 95% for the detection of CAD. Images of diagnostic quality were obtained in all patients, these being comparable to thallium-201 SPET images. In conclusion, these results indicate that the described method can be routinely used for the positron emitter 81Rb with a conventional gamma camera and special shielding. 81Rb has the well-known advantages of a potassium analogue and 81Rb SPET permits better visualization, particularly of the posterior wall of the myocardium, due to the higher photon energy. Considering the typical dose of 201Tl used for SPET (74-148 MBq), a 81Rb SPET scan imposes a significantly lower radiation burden on the patient.