Thrombus imaging with 99mTc-HMPAO-labeled platelets and 111In-labeled monoclonal antifibrin antibodies.

Eighteen patients with suspicion of deep venous thrombosis (DVT) in the lower extremities were imaged both with autologous 99mTc-HMPAO-labeled platelets (Tc-PLT) and 111In-labeled monoclonal antifibrin antibodies (In-MoAbs) on the same day. Presence or absence of thrombosis was verified by venography. Tc-PLT was given i.v. followed after 30 min by In-MoAbs. Anterior and posterior projections of the lower extremities were obtained with a large field-of-view gamma camera at 5 to 25 min, 2 h, 4 to 6 h, and 20 h after administration of the marker. Both Tc-PLT and In-MoAbs detected DVT well but less frequently than venography. Thrombi were visualized at 2 to 4 h after injection. The quality of images was better with Tc-PLT than with In-MoAbs. In the patients treated during the study, heparin significantly (p < 0.01) inhibited the uptake of Tc-PLT but not of In-MoAbs. We conclude that both Tc-PLT and In-MoAbs are suitable agents for the detection of DVT especially in patients without anticoagulation.