Role of quantitative diffusion-weighted MRI and 1H MR spectroscopy in distinguishing between benign and malignant thyroid nodules

Abstract

Background and purpose: The imaging characterization of thyroid nodules is mandatory to exclude malignancy. The purpose of this study is to evaluate the role of quantitative diffusion MRI and 1H MR spectroscopy in differentiation between benign and malignant Thyroid nodules. Methods: From February 2012 to May 2013, prospective study was conducted on 25 patients with 41 thyroid nodules (11 males, 14 females, age range, 16–74 years with mean 45.3 years) collected from wards and clinics of Internal Medicine and General Surgery Departments, 20 healthy individuals as control cases were included in the study. 1.5-T 1H-MR spectroscopy (at echo-times (TE) 144 and 35 ms) and diffusion-weighted imaging (b value 0, 250 and 1000 s/mm2) were performed and the results were correlated with histopathological results. Results: The mean ADC of the malignant thyroid nodules (13 nodules) was 0.59 ± 0.24 × 10−3 mm2/s while that of the benign thyroid nodules (28 nodules) was 1.78 ± 0.21 × 10−3 mm2/s (p value <0.0001). Choline is present in all malignant nodules (13 nodules) and two benign nodules (mild elevation) while absent in 26 other benign nodules. Choline/creatine ratio in malignant nodules ranged from 1.3 to 5.4, while in two benign nodules it was 0.9 and 1.1. The sensitivity, specificity, PPV, NPV and overall accuracy of diffusion and MRS in differentiating benign from malignant thyroid nodules were 100%, 93%, 96%, 100% and 79%, respectively. Conclusion: MRS and diffusion WI are useful noninvasive diagnostic modalities in differentiation between benign and malignant thyroid nodules.

Keywords

• Thyroid
• Diffusion
• ADC
• MR spectroscopy