Accessory appendages of the left atrium as seen during 64-slice coronary CT angiography

Purpose To document the frequency and variations in number and anatomical shape of accessory appendages of the left atrium as seen on 64-slice cardiac CT. Methods and materials Retrospective review of the anatomy of the left atrium as depicted by cardiac CT using the acquisition protocol designed for coronary CT Angiography and performed in 166 patients over a 6-month period with a 64-slice ECG-gated CT scanner (Siemens Medical Solutions). The local IRB provided a waiver of informed consent for this retrospective study. Structures less than 5 mm in shape were excluded, as well as large accessory pulmonary veins. Results Seventeen (17) of 166 patients (10%) had 18 accessory left atrial appendages (only one patient had two). Fifteen (15) accessory appendages were located along the right upper atrial wall and measured 0.9 x 0.6 x 0.5 cm(3) +/- 0.2 x 0.2 x 0.1 (Type 1). Three (3) were located along the left lower atrial wall, and were larger (0.9-2.5 cm cross-section) (Type 2). The right upper accessory appendages were mostly shaped like small diverticuli and the left lower ones were shaped like flat cauliflower expansions. Conclusions Accessory left atrial appendages were visualized in 10% of 166 patients during 64-slice coronary CT angiography.