Usefulness of electron beam tomography in the prone position for detecting atrial thrombi in chronic atrial fibrillation

Objective: We compared the usefulness of electron beam tomography (EBT) in the prone position relative to that in the supine position for detecting atrial thrombi. Methods: We studied 96 patients with chronic atrial fibrillation, of whom 71 were scanned in the supine position and 25 were scanned in the prone position. Electron beam tomography was performed twice after contrast medium injection to obtain early- and late-phase images. Results: Filling defects were detected in 13 patients in the supine position by EBT. Transesophageal echocardiography (TEE) revealed a thrombus in the region of the filling defect in 9 patients. In 4 patients, filling defects in the left atrial appendage were not confirmed as thrombi by TEE. Filling defects were detected in 4 patients in the prone position, all of which were confirmed as thrombi by TEE. Conclusion: Electron beam tomography in the prone position is an effective technique for reducing false-positive results in the detection of atrial thrombi.