77 year-old female with atrial arrhythmias who had a questionable mass by echocardiography.

Figure 1: Axial black blood spin echo imaging shows a high signal intensity mass in the interatrial septum.

Figure 2: Fat-suppressed axial black blood spin echo image (STIR) shows that the signal intensity in the lesion completely decreases, consistent with a fatty tumor or lipoma of the interatrial septum.

Lipoma of the interatrial septum.

Characterization of cardiac masses is a useful advantage of MR imaging over other modalities. Fat-suppression methods are useful for distinguishing hemorrhagic from fatty masses. Contrast enhancement can be useful to distinguish solid tumors from thrombi. In addition, cine gradient echo imaging can be performed to assess the physiologic effects of masses on cardiac and valvular function.