Diagnostic Accuracy of Multiple MRI Parameters in Dealing with Incidental Thyroid Nodules.

Background: Different MRI parameters have been studied for evaluating thyroid nodules. Diffusion-weighted imaging (DWI) and T2 imaging sequences with considerable efficacy in evaluating soft tissue tumors merit further assessment for thyroid nodule investigation.

Method: We evaluated incidental thyroid nodules (ITNs) reported on head and neck MRI studies. The T2 signal intensity (SI), T2 signal intensity ratio (SIR), value, and apparent diffusion coefficient (ADC) values of the thyroid nodule were obtained for every patient. The patients were referred to the radiology department for the thyroid nodule ultrasound study. Finally, 33 participants (37 thyroid nodules) who were scheduled for fine needle aspiration and cytology (FNAC) were enrolled. Regarding the FNAC results, the nodules were divided into malignant and benign groups. The two groups' MRI parameters were compared using a two samples independent test, and the cutoff values were estimated by analyzing the receiver operating characteristics plot.

Results: The T2 signal intensities, SIR, values, and ADC values were significantly higher in the benign group than malignant. The cutoff points of 230 (AUC = 0.759), 3.38 (AUC = 0.754), 37 (AUC = 0.759), and 1.73 (AUC = .690) were obtained for T2 values, SIR, values, and ADC values, respectively.

Conclusion: T2, SIR, , and ADC values are reliable for discriminating benign from malignant ITNs. However, further studies with a larger sample size are needed to provide more accurate mean values, identify outliers, and reduce confounding factors and bias.