Differentiation of White, Mixed, and Red Thrombi: Value of CT in Estimation of the Prognosis of Thrombolysis—Phantom Study

PURPOSE: To test with serial computed tomographic (CT) scans whether white, mixed, and red thrombi could be differentiated according to their CT attenuation. MATERIALS AND METHODS: Platelet-enriched plasma and whole blood were mixed to produce samples with hematocrit levels of 0, 0.005, 0.03, 0.15, and 0.35. A thrombin solution was added, and after 2 hours the retracted clots were transferred into polyethylene tubes with a length of 4 cm and an inner diameter of 3 mm. Ten probes of each sample were placed into a plastic box filled with a solution of gelatin, gadopentetate dimeglumine, and distilled water. Ten tubes filled with gelatin served as control. With this phantom, the CT numbers of white, mixed, and red thrombi were measured over 144 hours. CT was performed with a multisection scanner and a collimation of 0.5 mm. Statistical analyses were performed for differences between groups and over time. RESULTS: The CT numbers of white, mixed, and red thrombi differed significantly (P .05). CONCLUSION: With CT it appears feasible to differentiate thrombi according to their hematocrit level and thus estimate the effectiveness of thrombolysis.