Differentiation between Graves' disease and painless thyroiditis by diffusion-weighted imaging, thyroid iodine uptake, thyroid scintigraphy and serum parameters

Abstract

Abstract. The aim of the present study was to assess the apparent diffusion coefficient (ADC) in diffusion-weighted imaging (DWI), thyroid radioactive iodine uptake (RAIU), thyroid scintigraphy and thyrotropin receptor antibody (TRAb) levels in the differential diagnosis between Graves' disease (GD) and painless thyroiditis (PT). A total of 102 patients with GD and 37 patients with PT were enrolled in the study. DWI was obtained with a 3.0-T magnetic resonance scanner, and ADC values were calculated. RAIU and thyroid scintigraphy were performed. Tissue samples were obtained from patients with GD (6 cases) following thyroidectomy, and from patients with PT (2 cases) following biopsy. Receiver operating characteristic (ROC) curves were drawn, optimal cut-off values were selected, and the sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) were assessed. It was found that the ADC, TRAb and RAIU were significantly higher in GD than in PT (P<0.05). ROC curves showed areas under the curves for RAIU, ADC and TRAb that were >0.900. RAIU was the reference method. Sensitivity, specificity, accuracy, PPV and NPV were 96. 078, 91.892, 95.000, 97.059 and 89.474% for ADC, and 88.235, 75.676, 84.892, 90.909 and 70.000% for TRAb, after the optimal thresholds of 1.837x10 -3 mm 2 /sec and 1.350 IU/ml were determined respectively. Histopathology showed that tissue cellularity in PT was much higher than in GD due to massive lymphocytic infiltration. The results of the present study indicate that RAIU, ADC and TRAb are of diagnostic value for differentiating between GD and PT. DWI has great potential for thyroid pathophysiological imaging because it reflects differences in tissue cellularity between GD and PT.

Role of Diffusion-Weighted Magnetic Resonance (MR) Imaging in Differentiation Between Graves’ Disease and Painless Thyroiditis

“…One study reported that the optimal threshold ADC value that was used to differentiate Graves’ disease from painless thyroiditis was 1.837×10 –3 mm 2 /sec, with sensitivity, specificity, accuracy, PPV, and NPV of 96.078, 91.892, 95.000, 97.059 and 89.474%, respectively [ 27 ]. Another study added that the ADC value was significantly higher in patients with Graves’ disease in comparison to patients with painless thyroiditis ( P = 0.05); the mean ADC values of the thyroid gland in Graves’ disease were 3.47, 2.25 and 1.64×10 –3 mm 2 /sec, and in Hashimoto thyroiditis they were 2.53, 1.76, 1.28×10 –3 mm 2 /sec for b -values of 100, 600, and 1000 sec/mm 2 , respectively.…”

“…This process is associated with a diffuse lymphocytic infiltration in the thyroid gland. Hypercellularity in painless thyroiditis leads to numerous structural components and membranes, resulting in greater impedance and restriction of diffusion of water molecules, which leads to lower ADC values [ 24 , 26 , 27 ].…”

“…One study reported that the optimal threshold of TRAb that was used to differentiate Graves’ disease from painless thyroiditis was 1.350 IU/ml, with sensitivity, specificity, accuracy, PPV, and NPV of 88.235%, 75.676%, 84.892%, 90.909%, and 70.000% respectively [ 27 ].…”

“…Diffusion-weighted MR imaging was used for characterization of thyroid nodules [ 21 – 23 ], evaluation of diffuse thyroid diseases [ 24 ], assessment of Graves’ disease activity, and prediction of therapeutic outcomes [ 25 ]. Two recent studies discussed the role of diffusion-weighted MR imaging in differentiating between Graves’ disease, Hashimoto’s thyroiditis, and painless thyroiditis [ 26 , 27 ].…”

Thyroid scintigraphy in the management of benign thyroid disease

“…[13][14][15] Unlike iodide however, pertechnetate after its trapping does not undergo organification. 2,16 Apart from the thyroid gland, NIS is also expressed on choroid plexus, salivary glands, gastric mucosa, lactating mammary glands and ciliary body of eyes. Technetium 99m pertechnetate is readily available from a Molybdenum-99/ Tc-99m generator which is usually available within all nuclear medicine departments.…”