The validity of radiolabeled anti fibrin antibody for deep vein thrombosis imaging.

Having previously established the specificity of a newly developed radiolabeled polyclonal anti fibrin antibody (AFA) for tagging fibrin depositions, clinical experiments for validation of this agent for imaging deep vein thromboses (DVT) were carried out in comparison with labeled human serum albumin (HSA) and labeled platelets. Patients with DVT were studied with dual tracers on a computerized scintillation camera, four with simultaneous application of 131I-AFA and 99mTc-HSA, and eight with 131I-AFA and 111In-platelets. The results showed that: a) Labeled AFA predominantly delineated thrombi while labeled HSA prevailingly delineated blood pool within a particular vein. b) Labeled AFA was found to be superior in both ways to labeled platelets for DVT imaging, i.e. by imaging effect and by semiquantitative "thrombus:blood pool" (obtained in counts/pixel) ratio index (RI). Average RI with SD obtained with labeled AFA (9 patients) was 2.44 +/- 0.48 and 1.55 +/- 0.27 with labeled platelets (7 patients). The results indicate that a monoclonal AFA, if labeled with 99mTc, 111In or 123I, might have potential for an optimum agent for DVT imaging.