Detection of Cardiac Metastasis by Positron-Emission Tomography–Computed Tomography
A 59-year-old woman was referred for staging of breast cancer with known hepatic metastases before inclusion in a chemotherapy trial. She had undergone breast-conserving surgery and adjuvant radiotherapy 8 years earlier at primary diagnosis. On a routine CT scan, a right atrial mass measuring 25×22 mm was detected (see Figure 2). The polyp-like pedunculated appearance and the location at the crista terminalis were suggestive of a myxoma. At the time of diagnosis, the ECG was unremarkable and the patient did not suffer from any symptoms (eg, congestive heart failure, tachycardia, arrhythmia) attributable to the lesion.
For further evaluation of the lesion, a combined PET-CT scan was performed on the Philips Gemini System. The PET study was obtained 45 minutes after intravenous administration of 276 MBq fluorine-18-fluorodeoxyglucose (F-18-FDG) at normal blood glucose level, and the CT scan was acquired during a single breath-hold 50 seconds after administration of 120 mL of contrast (623 mg/mL iopromid). The mass showed an intense focus of FDG uptake (single-pixel maximal standardized uptake value-lean 9.2), suggestive of a neoplastic process (Figure 1). A follow-up examination 4 months later showed that the mass grew from an initial size of 25×22 mm to 33×27 mm, and thus confirmed the diagnosis (Figure 2).
The use of F-18-FDG is based on the observations that malignant cells accumulate more glucose than normal cells caused by their predominantly glycolytic catabolism. There have been case reports of atrial myxoma and its appearance in PET, which showed only a moderately elevated glucose metabolism. In contrast, our patient’s lesion had intense FDG uptake, which is consistent with the observation that most metastases from breast cancer exhibit an elevated glucose metabolism. Although the tumor was not removed surgically and thus a histological examination was not possible, the progression in size supports the diagnosis of a malignant tumor.
The case demonstrates the potential of PET-CT in the detection and differentiation of cardiac masses. We presume that the incidence of cardiac metastases is higher than generally accepted and that the increasing use of PET-CT will lead to a higher rate of detection.