1353874 - Characterization of cardiac masses by magnetic resonance

We present 2 clinical cases of cardiac masses and the role of MRI to reach the proper diagnosis. The first case is a 45-year-old male, with history of thyroid goiter for 20 years, dysphagia and weight loss in the last 2 months. Contrast-enhanced CT with a mass in the left neck of thyroid origin, which displaces the trachea and esophagus (image 1), as well as a hypodense heterogeneous image in the appendage of the right atrium. Biopsy of the thyroid gland reporting anaplastic thyroid carcinoma. For adequate characterization of cardiac masses, cardiac MRI is performed, finding: in  cine sequence, a mass in the right atrial appendage, heterogeneous with defined borders; in the right atrium, two homogeneous masses; at the level of the free wall of the right ventricle, another homogeneous mass is observed; in the T1 W sequence these masses are isointense, T1 FAT SAT without evidence of fat, in T2 W they are hypointense, T1 GRE do not perfuse and do not present late enhancement in the post-contrast with inversion of >600 ms, which suggests thrombi. The PET CT study with 18 FDG shows metabolism in the periphery of the thyroid lesion with a hypodense central zone suggestive of necrosis, pulmonary nodules, abdominal implants and muscle lesions, with increased metabolism compatible with secondary deposits, hypodense images in the right atrium and now in the left ventricle that are associated with focal hypermetabolism with SUV max 12.2, compatible with tumor thrombi (image 2).  

The second case is a 20-year-old male with a history of resection of a tumor in the central nervous system in childhood, with symptoms of heart failure and an echocardiogram showing a mass in the right atrium, for which cardiac magnetic resonance imaging was performed to characterization finding: in cine sequence isointense homogeneous mass, T1 W isointense, T2 W hypointense, FAT SAT do not suppress, does not perfuse, does not present late gadolinium enhancement (with 500ms inversion time). The study of the pathological piece confirms that it is a thrombus (image 3).


Diagnostic Techniques and Their Most Important Findings:

Although echocardiography remains the first-line imaging modality used in patients with intracardiac mass, this technique has several limitations and is highly dependent on the availability of a good "window," and even then, it is possible to that cannot provide a comprehensive answer due to the limited field of view and the inability to characterize the tissue. Cardiac MRI has evolved as a gold standard method for mass evaluation and is increasingly used for confirmation and localization, evaluation of size, shape, relationship to surrounding structures, as well as hemodynamic impact and mass characterization.


Learning Points from this Case:

Thrombi are the most common intracavitary masses. MRI is an optimal diagnostic method for the diagnosis; due to the absence of vascularity, the late enhancement technique is the sequence with the highest sensitivity (82-88%) and specificity (99-100%), even more so if a longer inversion time is used (500- 600ms).