Indium-111 platelet scintigraphy in carotid disease

Forty-five patients (35 men, 10 women) undergoing carotid surgery had Indium-111 platelet scintigraphy as part of their preoperative work-up. Imaging was performed within three hours after injection of the Indium-111. A second series of views was obtained 24 hours later and repeated at 24 hour intervals for two days. Of 54 scintigrams, 22 were positive and 32 negative. Positive results were defined as a twofold or more increase in local activity on a visualized carotid after 24 hours. The sensitivity of the method was 41%, intraoperatively, and the specificity, 100%. The low sensitivity places this method behind sonography and duplex-scanning for screening patients for surgery. We believe that indications for platelet scintigraphy are limited to: 1. Repeated transient ischemic attacks in the same territory with minimal lesions on arteriography and non-homogeneous plaque on duplex scan; 2. Symptomatic patients being treated medically as a possible argument for surgery; 3. Determining therapeutic policy for patients having experienced a transient ischemic attack with a coexisting intracardiac thrombus.