A Study on the Distinction between Thrombus and Blood Stasis in Left Atrial Appendage using Dual Energy CT before Radiofrequency Catheter Ablation

In atrial fibrillation patients who performed Dual Energy Computed Tomography and Transesophageal Echocardiography before Radiofrequency Catheter Ablation, Cut-off values were derived from images of Dual Energy blended image, iodine maps, Zeff, and 70 & Sn150 kV in distinguishing thrombus from blood stasis, and the usefulness and optimal evaluation method were studied. The previous study analyzed the concordance rate of CT reports and TEE results in 18 thrombus patients and 80 blood stasis patients, and the ratio was measured by setting ROI in the filling defect of the ascending aorta and left atrial appendage in each DECT image. Sensitivity and specificity were analyzed through the ROC curve and Cut-off value was obtained. The follow-up study quantitatively evaluated 5 thrombus patients and 13 blood stasis patients by applying Cut-off value to images of DECT, and analyzed the concordance rate by comparing the results of the TEE. In previous studies, the concordance rate between CT and TEE results of qualitative evaluation was 80.6%. The ROC curve analysis results of the measurement method obtained with DECT showed that all sensitivity was 100%, and specificity and AUC were measured the highest in Iodine maps. In subsequent studies, which quantitatively evaluated CT by applying Cut-off value, the concordance rate of measurement methods using iodine maps was 93.9%, up about 13.3% from previous studies. It is believed that a quantitative evaluation method using the Cut-off value of iodine maps for patients with limited TEE before RFCA can be an alternative to the TEE to distinguish thrombus in the left atrial appendage.