LAUSR

Purpose There are growing data to suggest that clot composition can impact revascularization outcomes and strategies in large vessel occlusion patients. In many centers, MRI is the primary modality of acute stroke imaging so identifying clot composition on MRI imaging may be important. We performed an in vitro study to determine the MR signaling characteristics of stroke clots of various compositions. Methods Fifteen thrombus analogs of five compositions (n=3 for each composition) [Group A, fibrin-rich (95% plasma:5% RBCs); Group B, fibrin-rich (75% plasma:25% RBCs); Group C, intermediate (50% plasma:50% RBCs); Group D, RBC-rich (25% plasma:75% RBCs,) and Group E, RBC-rich (5% plasma:95% RBCs)] were scanned with fast spin-echo (FSE) T2WI (TR/TE 2500/101 milliseconds (ms)) and quantitative T2* mapping sequence. Signals from FSE T2WI were collected, and thrombus T2* relaxation time (TT2*RT) was measured in all the groups. Correlation between the thrombus-T2* relaxation time and red blood cell content was analyzed. Results Signal intensity changed gradually from high (bright) to low (dark) from Group A to E gradually from all the 3 clots in each group, which indicated the signal intensity was decreased as the composition of RBC increased. The average TT2*RT decreased from 60 ms (green) to 25 ms (red) from fibrin-rich clot to RBC-rich clot (Group A to E), which reflected inverse correlation between thrombus-T2* relaxation time and red blood cell content (figures A to E). Conclusion FSE T2 WI and quantitative T2* mapping MR can help in characterization of emboli in large vessel occlusion patients. Disclosures Y. Ding: None. M. Abbassi: None. J. Felmlee: None. D. Dai: None. R. Kadirvel: None. D. Kallmes: None. W. Brinjikji: None.