Not everything that shines is gold, normal uptake in crista terminalis on FDG PET/CT masquerading as a tumor thrombus approaching right heart

The crista terminalis is a structure found in the right atrium, traversing along the posterolateral wall between the superior vena cava and the inferior vena cava. In some cases, the physiologic activity of F-18 FDG in crista terminalis can be mistakenly identified as a malignant mass, as was the situation in our case. Therefore, it is essential to have a thorough understanding of benign/physiologic uptake in normal anatomical structures and their variants when interpreting cardiac imaging. In this report, we present the case of a 79-year-old female patient who had recently been diagnosed with breast cancer. An 18F-FDG (fluorodeoxyglucose) PET/CT scan imaging assessment as part of staging revealed intense metabolic activity in the right atrium corresponding to prominent soft tissue. Subsequent assessment using transesophageal echocardiography (TEE) ultimately confirmed the diagnosis of a prominent crista terminalis, which is a normal anatomical variant.