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) for most time measurements, except for white and mixed thrombi which had a low hematocrit level at 24 and 144 hours (P >.05). CONCLUSION: With CT it appears feasible to differentiate thrombi according to their hematocrit level and thus estimate the effectiveness of thrombolysis. (C) RSNA, 2003.