The optimal cardiac phase for detecting the thrombi of the left atrial appendage on multi-slice computed tomography in patients with atrial fibrillation.

We evaluated patients with atrial fibrillation (Af) to define the optimal phase for ECG-gated image reconstruction for multi-slice CT (MSCT) of the left atrial appendage (LAA). We performed MSCT scans in 37 patients with Af, and we reconstructed multi-planar reformation images of the LAA, defined by the absolute delay (ms) immediately after the T wave, and by the relative delay (%). For visual analysis of the image quality for each image, a four-grade scoring system (poor to excellent) was used by two blinded, independent reviewers. Images obtained by absolute delay and by relative delay were classified as being of poor, fair, good, or excellent quality in 2, 2, 8, and 25 cases, and in 18, 11, 8, and 0 cases, respectively. This phase-definition strategy in Af patients is more effective by absolute delay than by relative delay, and MSCT could provide an alternative diagnostic assessment of LAA thrombi.