Solitary thyroid nodule: Diagnostic yield of combined diffusion weighted imaging and magnetic resonance spectroscopy

Aim: The scope of this study is to evaluate the combined application of MR-DWI and MRS in differentiating between benign and malignant thyroid nodules. Materials and methods: Total of 42 patients was enrolled in this study. DWI was done and ADC values were calculated. MRS was done and Choline peak as well as Cho/Cr ratio was evaluated. Results: Patients were categorized into benign group (28 patients) (20 adenomatous nodules and 8 follicular adenomas) and malignant group (14 patients: 8 papillary carcinomas, 4 follicular carcinoma, 1 medullary carcinoma, and 1 anaplastic carcinoma).The mean ADC values of benign nodules showed significantly high values than malignant ones (1.84 ± 0.36 versus 0.87 ± 0.35 Ã 10â3 mm2/s respectively (p < 0.0001).While no significant difference was detected among the ADC values of different benign lesions among different malignant pathological types.By analyzing the ROC curve, the area under the curve (AUC) was (0.97) with ADC cutoff value of 1.5 Ã 10â3 mm2/s was able in differentiating benign and malignant thyroid nodules with sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 85.7, 89.2, 80.0, 92.5% respectively while KAPPA test = 0.73 and p < 0.0001.All malignant thyroid nodules had a significant choline peak (n = 14, 100%) at MR spectroscopy (Figs. 2 and 3) while benign nodes showed choline peak in only two cases (n = 3, 10.7%).The mean Cho/Cr ratio showed significant higher values in malignant thyroid nodules compared to the benign ones (3.1 ± 0.85 versus 1.09 ± 0.13) (p = 0.001).While no detected significant difference of Cho/Cr ratio among different types of malignancy (2.86 ± 0.66, 2.95 ± 0.90, 4.21 and 4.53 for papillary carcinomas, follicular carcinoma, medullary carcinoma, and anaplastic carcinoma respectively, p = 0.85).The MRS sensitivity, specificity PPV and NPV in differentiating between benign and malignant thyroid nodules were as following 100, 89.3, 82.4 and 100% respectively while Kappa test was 0.84 and p < 0.0001. Combination of both DWI and MRS showed higher diagnostic values than each of DWI and MRS alone with sensitivity, specificity, PPV and NPV of 100, 96, 93.3 and 100% respectively while Kappa test was 0.94 of and p value