Horse Among Zebras: Unusual Imaging Features of a Right Atrial Thrombus (QF_TH_041)

Thursday, January 30, 2025

5:00 PM – 5:10 PM East Coast USA Time

Location: Blue Room PreFunction - Kiosk 1

Presenting Author(s)

TC

Thurl Cledera, MD, FPCR

Cardiothoracic Imaging Fellow
St. Luke's Medical Center Global City, Philippines

Primary Author(s)

TC

Thurl Cledera, MD, FPCR

Cardiothoracic Imaging Fellow
St. Luke's Medical Center Global City, Philippines

Co-Author(s)

JL

Jerald Garvin Lim, MD

Staff Radiologist, Program Director of Cardiothoracic Imaging Fellowship
St. Luke's Medical Center Global City, Philippines, Philippines
MS

Maria Helga F. Sta. Maria, MD, FSCMR

Cardiologist
St. Luke's Medical Center Global City, Philippines

Description of Clinical Presentation: This case is of an 81/M, known hypertensive, non-diabetic, CAD status post 3 vessel PCI, asymptomatic, who was admitted for incidental finding of right atrial mass on 2D echocardiography. No other comorbid or significant surgical history/catheter placement. Patient was then worked up with transesophageal echocardiography which further characterized the mass as pedunculated, mobile, and attached to the right atrial wall, which then prompted further work-up with cardiac MRI to assess tissue characteristics. CMR then confirmed a pedunculated mass attached by a stalk to the crista terminalis, while first-pass perfusion showed minimal enhancement. Due to imaging features, considerations now include the possibility of a myxoma versus thrombus. The patient then eventually underwent minimally invasive cardiac surgery, with the resected mass confirmed by pathology as a compacted thrombus rather than a myxoma.

Diagnostic Techniques and Their Most Important Findings: Transthoracic Echocardiography - LVEF of 57%, normal LV dimensions with normal contractility and systolic function, normal RV dimension with normal contractility and systolic function. Biatrial dilatation with suspicious right atrial mass.

Transesophageal Echocardiography - Dilated RA size, pedunculated mobile well-circumscribed round echogenic density measuring 3 cm x 4 cm with an area of 9 cm2 attached to the right atrial wall adjacent to the SVC.

Cardiac MRI with Contrast - Spherical, partially mobile, right atrial mass attached by a small stalk to the crista terminalis. First pass perfusion showed minimal contrast enhancement. Gadolinium-enhanced images show some degree of minimal contrast enhancement of the mass.

Learning Points from this Case:

Knowledge of the normal cardiac structures that can mimic mass, pathologies that can be localized in a specific area of the heart, and imaging features are of utmost importance to the cardiac imager. Cardiac MRI is superior to other imaging modalities for mass characterization, which was immensely helpful in this case. Myxomas are more commonly seen in the left atrium rather than the right, with features of smooth borders and the presence of a stalk favoring this diagnosis. Intracardiac thrombus on the other hand is the overall most common mass, specifically thrombi in the right atrium are found to be associated with chronic intravenous catheter use which was not present in our patient. First-pass perfusion may help in most cases, with myxoma showing enhancement, while thrombus does not. An imaging pitfall is that chronic organized thrombus may show enhancement, which may simulate mass. This case perfectly illustrates the nuance of imaging features of a commonly seen mass presenting in an infrequent location in the heart.