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 (T _1/2 = 4.54 h) to detect ischaernic 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 (≥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.