Role of diffusion-weighted magnetic resonance imaging in differentiating benign from malignant thyroid nodules

ABSTRACT Background and Objectives: Thyroid nodules are very prevalent. Recent advancements in magnetic resonance imaging (MRI) methods may be beneficial for diagnosis. This study aimed to assess the diagnostic precision of diffusion-weighted imaging (DWI) and the apparent diffusion coefficient (ADC) in distinguishing between benign and malignant thyroid nodules. Materials and Methods: A total of 34 individuals diagnosed with potentially concerning thyroid nodules were included in the study. Patients underwent history taking, clinical examination, thyroid profile, thyroid ultrasound, fine-needle aspiration biopsy (FNAB), and DWI. ADC values were calculated for thyroid nodules. Suspicious lesions by FNAB were referred for surgery. Results: Fifteen patients – who had a suspected FNAB (category III, IV, and V) – were operated on. Eight patients were found to have malignant nodule, while seven had benign pathology. Malignant thyroid nodules exhibited a restricted diffusion pattern characterized by a lower ADC value (0.80 ± 0.1 × 10 −3 mm 2 /s), whereas benign nodules displayed a facilitated diffusion pattern with a higher ADC value (1.30 ± 0.2 × 10 −3 mm 2 /s), P < 0.001. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of DWI in differentiating benign from malignant thyroid nodules were 100%, 92.3%, 80%, 100%, and 94.1%, respectively. The cutoff value ≤0.90 of ADC ratio had a high significant diagnostic importance in diagnosing thyroid malignancy. Conclusion: DWI is a safe, noninvasive diagnostic technique of a great value in differentiating benign thyroid nodules from malignant ones. It can decrease the unnecessary surgical referral when the results of preoperative FNAB are inconclusive.