PURPOSE: To determine the feasibility of detecting thrombi using a fibrin-specific gadolinium-based magnetic resonance imaging contrast agent, EP-2104R. METHODS: Subjects with confirmed thrombus in the venous system (n = 14), or in the heart, or arterial system (n = 38) were enrolled. Patients were imaged before and at various times following a 4 mumol/kg intravenous bolus injection of EP-2104R: <1 hour (N = 16), 2 to 6 hours (N = 36), and/or 20 to 36 hours (N = 33). Images were assessed by investigators at each site and by a single reader not affiliated with the sites to determine whether thrombi were visible, not visible, or further enhanced with EP-2104R. A subset of data was analyzed quantitatively by measuring a signal intensity relative to background tissue. RESULTS: Overall, 29 thrombi were visible before contrast administration, 3 of 14 in the venous system, and 26 of 38 in the arteries and heart. Thrombi generally enhanced in signal after EP-2104R injection, and an additional 7 were visualized. After contrast, 4 of 14 thrombi were visible in the venous system, and 32 of 38 in the arteries and heart. Thrombi were more conspicuous when imaged at 2 to 6 hours post EP-2104R compared with within 1 hour, because of lower blood background. Quantitatively, the post: pre signal intensity ratio was 1.90 at 2 to 6 hours post injection (standard deviation = 1.08, N = 20, P < 0.001); and 2.04 (standard deviation = 1.29, N = 19, P < 0.0025) for the 20 to 36 hours time point. There were no serious adverse events considered related to study drug. CONCLUSION: EP-2104R enhanced magnetic resonance imaging detects thrombi not readily visible in precontrast screening and gives additional enhancement of thrombi that are visible in precontrast imaging.

Department of Radiodiagnostic Hospital Na Homolce Praha Czech Republic