Is it Possible to Use Diffusion weighted MRI to Distinguish and Discriminate between Pathological Subtypes of Benign and Malignant Thyroid Nodules ?

Background:Fine needle aspiration cytology (FNAC) is an accurate technique for diagnosis of thyroid nodules, however, 10% are non-diagnostic. As a result, there is a need for an alternative diagnostic technique. Water molecular motion in lesions and healthy tissues can be quantitatively measured with the help of diffusion-weighted imaging (DWI). The net diffusion of the water molecules is expressed in terms of the apparent diffusion coefficient (ADC).Aim of the study:Our goal was to evaluate the usefulness of ADC values in differentiating malignant from benign thyroid nodules, as well as pathological subtypes of each group with FNAC correlation.Materials and methods:Seventy patients with 70 thyroid nodules were included in this prospective study done during the period between January 2022 and March 2024. Each patient's thyroid gland nodules were examined by diffusion-weighted imaging then intended to have ultrasound guided FNAC.Results:The mean ADC value for the benign group is higher than that for malignant nodules. The mean ADC at b = 1000 was 1.02 ± 0.381 in benign lesions but in malignant lesions it was 0.73 ± 0.323 with a statistical significant difference in between P<0.001.We observed a considerable overlapping in ADC values of different pathological sub types within each group of either malignant or benign nodules with a statistically insignificant difference (P value ranged from 0.056 to 0.063). Conclusions: ADC values can be used to discriminate benign from malignant thyroid nodules; however it is not possible to distinguish between several histological subtypes of each group.