MRI of right atrial pseudomass: is it really a diagnostic problem?

To determine whether the high proportion of patients reported to have prominence of normal right atrial structures by MRI may lead to inappropriate diagnosis of intracardiac tumors.

One hundred forty-nine subjects were examined by spin-echo MRI: patients with cardiac (no. 40), pericardial (no. 30), or thoracic aortic disease (no. 40) and mediastinal tumor (no. 15), and normal volunteers (no. 24). Imaging was reviewed to determine the frequency of a prominent crista terminalis/Chiari network and the likelihood of misdiagnosis of cardiac tumor.

Prominent intraatrial structures were seen in 59% of subjects, a single prominent nodule in 36%, an intraatrial strand in 13%, and both in 10%. In no case were these findings originally or on review thought to represent a pathological mass or was it felt likely that they could reasonably be misinterpreted as such.

Normal structures within the right atrium, such as the crista terminalis and Chiari network, may be seen more commonly with MRI than with other imaging modalities. An appreciation of the frequency with which these findings are seen should prevent inappropriate misdiagnosis of pathological masses when none is present.