Epipericardial fat pad: CT findings.

Epicardial and mediastinal fat around the apex of the heart may produce the classic appearance of a cardiac fat pad filling in the anterior cardiophrenic angle on a lateral chest radiograph. A review of 50 computed tomographic (CT) scans of the chest that were normal save for possible cardiomegaly, together with chest radiographs obtained within a 14-day interval, revealed a wide variation in the configuration of this fat pad in 16 patients (32%). Depending on geometric circumstances, the fat pad may produce a well-marginated region of increased density, a region of increased density with poor margination, or an area of reduced density lying anterior to the heart. In an additional four patients (8%), however, a simulation of a cardiac fat pad was produced by cardiomegaly alone or by relative levoposition of the heart. In these four patients, the left side of the heart contacted the chest wall on the left over a larger than normal area and thereby excluded lung from the vicinity, simulating the appearance of a fat pad where none existed.