SCMR 22nd Annual Scientific Sessions
Description of Clinical Presentation: A 21-year-old female with no prior medical history was found to have a right atrial (RA) mass on chest CT following a motor vehicle accident. CMR was performed to evaluate the RA mass, with findings consistent with cardiac lipoma (Figure 1). Patient was monitored over the course of the next year, during which she reported intermittent episodes of palpitations, lightheadedness, and dyspnea. An event monitor showed episodes of supraventricular tachycardia with heart rate up to 190 beats per minute. Her symptoms were felt to likely be secondary to the RA mass, and she was referred to cardiac surgery for resection. She underwent resection of the mass, with histopathology confirming the diagnosis of lipoma (Figure 2). Her symptoms resolved following lipoma resection.
Diagnostic Techniques and Their Most Important Findings: CMR was performed on a Siemens 1.5 T scanner. An oval-shaped mass measuring 38 mm x 25 mm was noted on the lateral aspect of the right atrium, causing some compression of the SVC. The mass was hyperintense on Half-Fourier Acquisition Single-shot Turbo spin Echo (HASTE) imaging (1A), with signal intensity similar to subcutaneous adipose tissue. Steady State Free Precession (SSFP) showed a heterogenous mass with chemical shift artifact at the blood/mass interface (1B). T1-weighted spin echo images showed a hyperintense mass (1C), with reduced signal intensity with application of fat-saturation (1D). While the fat-saturation T1w sequence did not fully suppress the signal from the mass, the signal intensity of the mass appeared similar to adipose tissue. On Short T1 Inversion Recovery (STIR), the mass was hypointense (1E). Native T1 mapping (1F) showed much lower T1 values in the mass compared to the myocardium, while pre-contrast T2 mapping (1G) showed T2 values in the mass that were higher than the myocardium, both of which were similar to the epicardial fat. There was no contrast uptake in the mass on first pass perfusion (1H). Signal was high on late gadolinium enhancement (LGE) imaging, similar to fat (1I). Taken together, these findings were consistent with a diagnosis of cardiac lipoma.
Learning Points from this Case: Cardiac lipomas are rare, accounting for 8% of benign primary cardiac tumors. Usually discovered incidentally, they rarely can cause symptoms. As in this case, symptoms can include vena cava obstruction or arrhythmias. Treatment for symptomatic lipomas is surgical resection.  Key findings on CMR to diagnose lipoma include high signal intensity on T1-weighted imaging that suppresses with application of a fat-saturation pulse. While the signal is high on LGE imaging, it is important to note that this is due to fat, which has a relatively short T1, rather than being due to contrast uptake. An important learning point is that while, as in this case, complete signal suppression may not be seen on fat-saturation sequences, comparing the signal intensity in the mass to the subcutaneous adipose tissue can help with the diagnosis.