Assessing PET/CT's diagnostic accuracy in idiopathic myopathies.

Objective: Recent studies have utilized fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) specifically to diagnose cases of idiopathic inflammatory myopathies (IIM), excluding inclusion body myositis (IBM). Conversely, carbon-11 (¹¹C) labeled Pittsburgh compound B (PIB)-PET imaging is exclusively used for the detection of IBM. This research is designed to evaluate the diagnostic accuracy of PET/CT in identifying IIM by employing rigorous diagnostic accuracy testing methodologies.

Materials and methods: A systematic review and meta-analysis were conducted across multiple databases including PubMed, and Embase. We focused on the diagnostic utility of PET/CT in IIM, assessing sensitivities, specificities, and deriving likelihood ratios (LR+ and LR-). The study was registered with PROSPERO (CRD42022343222).

Results: This systematic review identified 635 citations, of which 10 eligible trials were included, with a total of 419 participants. The results indicated a sensitivity of 0.86 (0.81-0.90), and a specificity of 0.93 (0.88-0.96). The synthesis of LR revealed the LR+ of 10.35 (6.31-16.98), and LR-of 0.15 (0.07-0.32). The summary receiver operating characteristic curve (SROC) showed an area under the curve (AUC) of 0.9658. Regarding IBM, the sensitivity was 0.84 (0.60-0.97), and the specificity was 1 (0.69-1). The synthesis of LR showed the LR+ of 9.61 (1.46-63.15) and an LR- of 0.21 (0.09-0.51). For disease activity, the sensitivity was 0.96 (0.92-0.99), and the specificity was 0.91 (0.084-0.96). The synthesis of LR showed an LR+ of 9.43 (5.39-16.51) and an LR- of 0.05 (0.02-0.11).

Conclusion: Positron emission tomography/CT has great potential for accurately diagnosing and monitoring patients with IIM, and may have implications for their clinical management.