Color Doppler Ultrasound Versus Magnetic Resonance Imaging for Diagnosing Giant Cell Arteritis: A Systematic Review and Meta-Analysis.

Rapid diagnosis of giant cell arteritis (GCA) is essential to prevent ischemic complications. Color Doppler ultrasound (CDUS) and high-resolution magnetic resonance imaging (MRI) are increasingly used as alternatives or adjuncts to temporal artery biopsy, but their comparative diagnostic performance remains uncertain. We performed a systematic review and bivariate random-effects meta-analysis of diagnostic accuracy studies in adults with suspected GCA. Studies reporting extractable 2×2 data against temporal artery biopsy, or accepted clinical reference standards when biopsy was unavailable, were included. Risk of bias was assessed using Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2). Pooled sensitivity, specificity, diagnostic odds ratios (DOR), and summary receiver operating characteristic (ROC) curves were calculated, with evaluation of heterogeneity and publication bias. Thirty-nine studies, including 3,619 patients, met the inclusion criteria. Thirty-one studies assessed CDUS (2,766 patients) and 12 evaluated MRI (853 patients). For CDUS, the median sensitivity was 0.83 (range 0.17-1.00) and the median specificity was 0.88 (range 0.59-1.00), with a median DOR of 24.9 and substantial between-study variability. MRI demonstrated a median sensitivity of 0.88 (range 0.61-1.00), a median specificity of 0.92 (range 0.71-1.00), and a higher median DOR of 72.0, with more consistent estimates. Evidence of small-study or publication bias was observed for MRI (p≈0.0004) and was borderline for CDUS (p≈0.055). QUADAS-2 assessments were generally favorable, though common limitations included variable blinding, heterogeneous imaging protocols, and differences in corticosteroid timing. MRI demonstrates higher and more consistent diagnostic performance than CDUS. CDUS can achieve high accuracy in experienced centers but shows notable operator dependence. Both modalities support imaging-based diagnostic pathways for GCA, with the choice influenced by local expertise, resource availability, and corticosteroid exposure.