Background: The crista terminalis is a variation of normal anatomical structure within the right atrium which may be misdiagnosed with an abnormal atrial mass normally visualized in the standard views on the transthoracic echocardiogram.
Case presentation: In this case presentation, we demonstrated a rare case report describing the accidental discovery of a right atrial mass-like structure in a 54-year old Asian man without physical discomfort during an echocardiographic examination. These findings naturally caused some concern as the differential diagnosis such as right atrial myxoma or thrombus and further examination were organized. The subsequent positron emission tomography/magnetic resonance imaging (PET/MRI) differentiated a true right atrial mass from a strip extending into the atrium in accordance with prominent crista terminalis.
Conclusion: A preferable understanding of the complex anatomy and PET/MRI appearance of a prominent crista terminalis will minimize the misdiagnosis of this structure and avoiding unnecessary anxiety and more invasive examinations.
Keywords: Crista terminalis; Echocardiogram; PET/MRI; Right atrial mass.