Uptake of Myocardial Imaging Agents by Rejecting and Nonrejecting Cardiac Transplants. A Comparative Clinical Study of Thallium-201, Technetium-99m, and Gallium-67

To study the scintigraphic detectability of cardiac rejection, we performed 135 planar myocardial scans (({sup 99m}Tc)pyrophosphate, 85; {sup 201}Tl, 36; {sup 67}Ga, 14) together with endomyocardial biopsies in ten patients for a (mean) 17-mo postoperative period. Specificity of each agent exceeded 89%. Technetium-99m pyrophosphate showed results that significantly correlated with the severity of rejection (p = 0.03), as shown by biopsy, but neither {sup 201}Tl nor 67Ga did so (p = 0.63 and 0.81, respectively). Technetium-99m pyrophosphate showed better diagnostic accuracy (85%) than {sup 201}Tl (69%) and {sup 67}Ga (64%). Technetium-99m pyrophosphate also showed higher negative predictive value (91%) than thallium (76%) and gallium (69%). Thus, a normal {sup 99m}Tc pyrophosphate scan was usually associated with absence of cardiac rejection. However, all three agents showed unacceptably poor sensitivity (0% to 30%) and thus were not useful as a screening test for cardiac rejection, even when the same agent was used serially in imaging a given patient.