Impact of Diffusion‐Weighted Magnetic Resonance Imaging Parameters on Diagnostic Accuracy for Thyroid Nodules: A Systematic Review and Meta‐Analysis

Background Surgery is the gold standard to differentiate benign from malignant thyroid nodules, but it is invasive and often unnecessary in indeterminate cases. Diffusion‐Weighted MRI (DW‐MRI) has emerged as a promising, non‐invasive tool, though its accuracy and the impact of acquisition parameters remain unclear. Purpose To evaluate the diagnostic accuracy of DW‐MRI in distinguishing malignant from benign thyroid nodules and identifying influencing acquisition parameters. Study Type Systematic Review and Meta‐analysis (researchregistry11482). Population 2073 patients, 2403 thyroid nodules (1067 malignant). Field Strength/Sequence DW‐MRI at 3.0T or 1.5T. Assessment A systematic search of Pubmed, Embase, Cochrane Library, Scopus, and Web of Science was conducted through July 2025 following the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses of Diagnostic Test Accuracy guidelines. Studies on DW‐MRI in thyroid nodules were included. Risk of bias and applicability were assessed using QUADAS‐2. Statistical Tests A bivariate random‐effects model estimated pooled sensitivity (SE), specificity (SP), and area under the curve (AUC). Univariable and multivariable meta‐regressions explored the influence of DW‐MRI parameters. Subgroup analyses and pooled Apparent Diffusion Coefficient (ADC) comparisons were also performed. Results were considered statistically significant at p < 0.05. Results Thirty‐seven studies were included. DW‐MRI showed pooled SE 0.84, SP 0.87, and AUC 0.91, confirmed in studies at low risk of bias (AUC 0.80). Univariable meta‐regression revealed that 3.0T field strength reduced SP, while < 5 averages and acquisition matrix ≥ 130 increased SE. Nodule size ≥ 10 mm and circular region of interest improved SP. Multivariable analysis confirmed increased SE with b ‐values > 2 and improved SP with b ≥ 1000, while 3.0 T remained associated with reduced SP. Malignant nodules showed lower ADC (1.08 vs. 1.73 × 10 −3 mm 2 /s vs. 1.70 × 10 −3 mm 2 /s for benign), especially with b ≥ 1000. Data Conclusion DW‐MRI shows good diagnostic accuracy for thyroid nodule assessment, although it is influenced by both technical and methodological factors. Level of Evidence 3. Technical Efficacy Stage 3.