Abstract Body (Do not enter title and authors here): Background: Cardiac sarcoidosis (CS) is a rare, but potentially life-threatening manifestation of systemic sarcoidosis. While both cardiac magnetic resonance imaging (CMRI) and fluorodeoxyglucose positron emission tomography (FDG-PET) are widely used as non-invasive imaging modalities, their relative diagnostic accuracy remains unclear. We aimed to evaluate the diagnostic performance of CMRI compared to FDG-PET for detecting CS.
Methods: A systematic literature search was conducted across PubMed, EMBASE, and Cochrane CENTRAL through May 2025 to identify studies evaluating the diagnostic accuracy of CMRI and/or FDG-PET for CS. Studies were included if they reported sufficient data to calculate diagnostic accuracy metrics against a clinical or histological reference standard. A bivariate random-effects model was used to estimate pooled sensitivity, specificity, diagnostic odds ratios (DOR) along with corresponding 95% confidence intervals (CI). The positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (LR+), negative likelihood ratio (LR-) and Youden Index were also calculated. A summary receiver operating characteristic (SROC) diagnostic model was used to calculate the area under curve (AUC) and evaluate overall diagnostic performance. A p-value <0.05 was considered significant in all cases.
Results: A total of 41 studies were included, out of which 23 reported data for CMRI and 32 for FDG-PET. CMRI demonstrated significantly superior overall diagnostic performance compared to FDG-PET (p = 0.013 for AUC comparison) for the detection of cardiac sarcoidosis. Pooled sensitivity and specificity for CMRI were 0.90 (95% CI: 0.85-0.94) and 0.82 (95% CI: 0.69-0.90) respectively, both higher than FDG-PET, which showed a sensitivity of 0.78 (95% CI: 0.69-0.84) and specificity of 0.78 (0.72-0.84). CMRI also yielded a greater DOR of 41.7 (95% CI: 19.40-89.6) versus 12.50 (95% CI: 7.71-20.30), AUC of 0.92 (95% CI: 0.82-0.91) versus 0.83 (0.74-0.83) and YI of 0.72 (95% CI: 0.59-0.80) versus 0.56 (95% CI: 0.47-0.63) compared to FDG-PET.
Conclusion: CMRI demonstrated a significantly greater diagnostic performance for detection of CS compared to FDG-PET with a superior sensitivity, specificity, DOR, AUC and YI, highlighting CMRI as a more robust imaging modality for CS. However, direct comparative studies and standardized diagnostic criteria remain essential to confirm these findings and guide clinical imaging strategies.