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

Abstract

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 x 10(-3) mm(2)/s vs. 1.70 x 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.