[Value of diffusion weighted imaging in diagnosis of nodular lesions of thyroid: a preliminary study]

To investigate the value of magnetic resonance diffusion weighted imaging (DWI) in the differential diagnoses of malignant and benign thyroid lesions.

Using echo planner imaging sequence with b value of 0, 100, 200, 300 and 400 s/mm(2) respectively, DWI was performed in 60 patients of focal thyroid lesions. The diagnosis was confirmed by pathological examination (benign, n = 30; malignant, n = 30). Apparent diffusion coefficient (ADC) values were measured. The differences were analyzed between two groups.

With b value of 0, 100, 200, 300 and 400 s/mm(2) respectively, there were statistical differences in ADC values between benign and malignant lesions. The ADC value of malignant lesions was smaller than that of benign lesions (P < 0.05). Among different b values, 400 s/mm(2) was the most optimal one to diagnose thyroid nodular lesions. DWI with a b value of 400 s/mm(2) had a proper signal-to-noise ratio (SNO). And ADC value could be measured correctly. With a b value of 400 s/mm(2) and ADC of 1.475 × 10(-3) mm(2)/s, receiver operating characteristic curve was plotted. In the diagnosis of malignant lesions, the sensitivity and specificity were 93.3% and 96.7% respectively.

The ADC value of malignant thyroid nodular lesions is smaller than that of benign lesions. The values of DWI and ADC are important in the differential diagnoses of nodular thyroid lesions.