Quick Fire Session
SCMR 22nd Annual Scientific Sessions
Background: The diagnosis of cardiac sarcoidosis (CS) is challenging. Endomyocardial biopsy is invasive, has low sensitivity, and is not without risk. Several sets of diagnostic criteria incorporating histologic, clinical and imaging findings have been developed; however, these are limited by the absence of a gold standard and lack of external validation (1). In this study, we present our preliminary experience using simultaneous, integrated 18FDG-positron emission tomography/magnetic resonance imaging (PET/MR) for evaluation of suspected CS.
Methods: In this IRB approved, HIPAA compliant study allpatients ≥18 years of age who had an integrated cardiac PET/MR to evaluate suspected CS between March 2017 and August 2018 and provided informed consent were included. Any patient with a known diagnosis of cardiac sarcoidosis was excluded. Patients were instructed to follow a high-fat, low-carbohydrate diet for 24 hours before imaging. A PET scan demonstrating focal or patchy 18FDG uptake in the myocardium was defined as a positive study. Late gadolinium enhancement (LGE) within the myocardium on MRI, with morphology suggestive of CS was considered a positive result. The presence of extracardiac sarcoidosis, left ventricular ejection fraction, arrhythmias, and use of immunosuppressive therapy were ascertained by review of the electronic medical record.
Results: A total of 43 patients (mean age 58.8 ± 10.9) underwent 44 PET/MR studies. The table shows the imaging results and related clinical data. Twenty two patients (51%) had 23 studies that were positive for evidence of CS (6 PET+/MR-, 6 PET-/MR+, 11 PET+/MR+), 17 (74%) of whom had known extracardiac sarcoidosis, including 13 (57%) with biopsy-proven disease. Twenty one patients (49%) had no imaging evidence of CS (PET-/MR-), 12 (57%) of whom had extracardiac sarcoidosis, including 10 (48%) that were biopsy-proven. Of the 23 with positive studies, 10 (43%) satisfied Heart Rhythm Society (HRS) criteria for CS (2). None of the 21 negative studies met HRS criteria. For the PET+/MR- patients, 3 patients demonstrated focal on diffuse uptake in the lateral wall, 1 patient had global diffuse uptake, 1 patient had patchy uptake and 1 patient had apical uptake consistent with hypertrophic cardiomyopathy. One patient initially had a PET+/MR+ study, and repeat imaging after initiation of immunosuppression was PET-/MRI+. Interestingly, in some PET+/MR+ cases, the site of myocardial uptake did not always correlate with the site of LGE.
Conclusion: Simultaneous PET/MR is a sensitive dual imaging modality that may detect evidence of CS that would otherwise be missed on PET or MR alone. Likewise, a negative PET/MR study provides stronger evidence against CS than negative findings on single modality imaging. Future prospective studies are needed to determine whether PET/MR can help guide management and improve outcomes in patients with suspected CS.