Abstract Body (Do not enter title and authors here): Introduction: ¹⁸F-FDG PET has been used for the evaluation of active inflammatory lesions in cardiac sarcoidosis (CS), but it is burdensome for patients to perform as a routine follow-up. Late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) that can detect myocardial fibrosis is limited in its ability to assess active inflammation. T2 mapping has been shown to detect myocardial inflammation in myocardial diseases without radiation exposure and contrast agents (Figure). However, the ability of T2 mapping for discriminating inflammatory myocardium has not been fully clarified in patients with CS.

Hypothesis: We assessed the hypothesis that T2 mapping has potential for the discrimination of inflammatory myocardium in patients with CS.

Methods: Twenty-seven subjects who underwent CMR at 3T and ¹⁸F-FDG PET to diagnose CS were enrolled. Fourteen subjects were diagnosed as CS due to LGE and myocardial FDG uptake on ¹⁸F-FDG PET (PET-positive group). Thirteen subjects showed no myocardial FDG uptake (PET-negative group). NativeT1, T2, and extracellular volume fraction (ECV) were measured using a 16-segment model. Receiver-operating characteristic (ROC) curve analysis was performed to evaluate T1 and T2 mapping in discriminating between active and inactive inflammatory segments in the PET-positive group.

Results: Mean native T1, native T2 and ECV showed no significant differences between the PET-positive and the PET-negative groups. However, maximum T2 values, which were highest ones in the 16 segments, were significantly higher in the PET-positive group than the PET-negative group (51.3 ± 7.7 ms vs 45.7 ± 3.6 ms, p = 0.014). In the PET-positive group, ROC analysis showed AUC of 0.72 in native T2, 0.61 in native T1, and 0.68 in ECV for discriminating inflammatory myocardium. The optimal cutoff value of native T2 was 45.7 ms, and the diagnostic performance had a sensitivity of 44.4 %, specificity of 93.3 %, positive predictive value of 88.1 %, and negative predictive value of 60.1 %.

Conclusion: T2 mapping is a promising approach for the discrimination of inflammatory myocardium without radiation exposure and contrast agents in patients with cardiac sarcoidosis.