CLINICAL SCIENCES

The fibrinogen uptake test using 1-125 fibrinogen is widely accepted as a useful, accurate method for the detection of deep-vein thrombosis (1—3). If either I-i 31 or I- 123 is used to label fibrinogen, thrombi may be imaged with a scintillation camera (4,5). Unfortunately, the thrombus uptake of radio iodinated fibrinogen is poor when the thrombus is several days old (6) , resulting in low thrombus-to blood ratios; this makes imaging difficult, especially in regions of large blood pooi. Thakur et al. ( 7) have recently reported a method for labeling platelets with indium-i 1i. Preliminary experiments in dogs indicated uptake of labeled platelets in venous thrombi, permitting scintigraphic visualization of thrombi as old as 72 hr at the tim