Diagnostic and prognostic value of T2 mapping in cardiac sarcoidosis

Background: 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) is commonly used to assess active inflammation in patients with cardiac sarcoidosis (CS); however, it is burdensome for routine follow-up. Late gadolinium enhancement identifies myocardial fibrosis but has limited ability to evaluate active inflammation. T1 and T2 mapping techniques enable the detection of myocardial inflammation without radiation exposure or contrast agents. Nevertheless, their diagnostic and prognostic utility in CS remains insufficiently defined. Methods: Thirty-nine patients who underwent both 3T cardiac magnetic resonance and 18F-FDG PET to diagnose CS were enrolled (mean age 61 ± 15 years, 69 % male). Twenty-one patients were diagnosed with CS (CS-positive group), and 18 patients without CS comprised the CS-negative group. Receiver-operating characteristic analysis assessed the ability of T1 and T2 mapping to discriminate between groups. In the CS-positive group, associations between mapping parameters and the primary outcome were evaluated. Results: Left ventricular ejection fraction did not differ significantly between groups. T2 and extracellular volume fraction were significantly higher in the CS-positive group than in the CS-negative group. Maximum T2 demonstrated strong discriminatory performance, with an area under the curve of 0.817. Both maximum and mean T2 were independently associated with the primary outcome after adjustment for age, sex, brain natriuretic peptide, and estimated glomerular filtration rate (maximum T2: hazard ratio 1.156, p = 0.036; mean T2: hazard ratio 1.525, p = 0.01). Conclusion: T2 mapping effectively distinguished patients with CS from those without CS and may provide prognostic information in patients with CS.