Utility of 18F-FDG PET/CT and Cardiac MRI in Early Cardiac Sarcoidosis.

Abstract

Background and aims: Although ¹⁸F-FDG-PET/CT and CMR are commonly used to diagnose cardiac sarcoidosis(CS), their clinical utility in early- vs. late-stage disease is unclear. The objective of this study was to compare the diagnostic utility of 18-fluorodeoxyglucose positron emission tomography/computed tomography(¹⁸F-FDG-PET/CT) and cardiac magnetic resonance imaging(CMR) in patients with early- and late-stage CS.

Methods: Data of 110 consecutive patients with biopsy-proven CS from the Granulomatous Myocarditis Registry were analyzed. All patients underwent ¹⁸F-FDG0PET/CT and CMR within 2 weeks of initial clinical presentation. Patients were divided into early-(<6 months) and late-stage groups based on the time since their first cardiac presentation. Myocardial uptake and late gadolinium enhancement(LGE) were qualitatively and quantitatively assessed. Complete clinical,echocardiographic, and radiological responses were assessed after 4-6 months of immunosuppressive therapy(IST).

Results: Among the 102 patients in the final analysis(44.1±10.3 years;LV ejection fraction[LVEF], 43.1±9.5%),54.9% and 45.6% received early and late diagnosis, respectively. Abnormal myocardial uptake on ¹⁸F-FDG-PET/CT 100%) was observed in all patients with early CS, while only 73.2% showed LGE on CMR(p<0.001). The diagnostic yield of ⁸F-FDG-PET/CT and CMR was similar in late CS(91.3%vs.97.8%,p=0.498). Patients with early CS had a higher myocardial SUV_max and more extensive LV involvement than those with late CS. Complete response to IST was more common in patients with early CS than in those with late CS(62.5%vs.47.8%,p=0.019). In the early CS cohort, patients without LGE had a higher rate of complete response following IST than those with LGE (86.7%vs.53.7%,p=0.025).

Conclusion: In patients with early CS,¹⁸F-FDG-PET/CT appears to be more sensitive and useful than CMR for diagnosis and assessment of response to IST.