Application of diffusion-weighted MR imaging in the diagnosis of thyroid disease

Abstract

Objective To analyze and summarize the characteristics of thyroid diseases on the MR diffusion-weighted imaging.Methods Forty-two patients with thyroid lesions,including 10 males and 32 females [age range 20-72 years,mean age (42 + 13) years] underwent MR DWI before surgery and biopsy.The diagnoses of thyroid lesions were confirmed by pathological results.ADC values of benign and malignant nodules,with different b values (b values was 300,500 and 800 s/mm2),were generated by using post-processing software Functool of GE company(USA).The independent-samples t test was used and ROC curve was made to evaluate the diagnostic efficiency of the ADC values by using statistical software SPSS 12.0.Results Histologically,there were 28 benign lesions and 14 malignant lesions.Benign lesions included 20 cases of thyroid adenoma,6 cases of nodular goiter and 2 cases of Hashimoto's thyroiditis respectively.Malignant lesions consisted of 11cases of thyroid papillary carcinoma,2 cases of follicular thyroid cancer,and 1case of dysplasia.mean ADC value of benign thyroid lesions was (2.39 ±0.38) ×10 -3 mm2/s and mean ADC value of malignant thyroid lesions was ( 1.60 ± 0.56) × 10 -3 mm2/s with b value of 300 s/mm2.The statistical difference was significant between them( t =5.35,P ＜ 0.05 ).The statistical difference of mean A DC values,between benign and malignant nodules with b value of 500 s/mm2 [ (1.85 +0.33 ) × 10 -3 mm2/s and ( 1.65 ± 0.42 ) × 10 -3 mm2/s ],was insignificant ( t =1.70,P ＞ 0.05 ).The statistical difference of mean ADC values,between benign and malignant nodules with b value of 800 s/mm2 [ ( 1.61± 0.30) × 10 -3mm2/s and( 1.44 +0.29) × 10 -3mm2/s],was insignificant (t =1.76,P ＞0.05 ).ROC curve indicated that the ADC value of 1.98 × 10-3 mm2/s or higher was the cut-off value for differentiating benign from malignant cold thyroid nodules,with a sensitivity of 85.7％,and a specificity of 78.6％.Conclusions The image quality is best with b value of 300 s/mm2.Mean ADC value of benign lesions was significantly higher than mean ADC value of malignant lesions with b value of 300 s/mm2. Key words: Thyroid disease; Diffusion magnetic resonance imaging