Differentiation Of Diffuse Thyroid Diseases By Diffusion-Weighted Magnetic Resonance Imaging

Objective:To evaluate the role of diffusion-weighted imaging (DWI) apparent diffusion coefficient (ADC) values in differentiation of diffuse thyroid diseases on3.0T.Materials and Methods:From Jul2010to Feb2012, a total of101patients with diffuse thyroid disease in Tianjin Medical University General Hospital were included in the present study after informed consent being obtained. The patients were diagnosed on the basis of physical and sonographic findings and the results of thyroid functional laboratory tests. Among of them,82patients were with Graves’disease (GD);11patients were with Hashimoto thyroiditis (HT);8patients were with subacute thyroiditis (SAT). After the serological tests and sonographic examination, all the patients underwent MR examination one day to seven days prior to clinical therapy. Fifteen healthy volunteers were also included in the study with informed consent. All MR examinations were performed on a3.0T system (Signa Excite HDx, General electrical company, U.S.) with an eight-channel head and neck phased-array coil. Axial fast recovery fast spin echo (FRFSE) T2WI and axial fast spin echo (FSE) T1WI were acquired. Fast spin echo diffusion weighted imaging (FSE-DWI) with b value0and1000s/mm2was obtained in addition to the conventional sequences. The ADC values were calculated in an offline workstation (ADW4.3, General electrical company, U.S.) and a false colored ADC mapping were constructed with registering to T1WI. Two attending physicians measured the ADC values of the thyroid parenchyma for three times on upper pole, middle portion and lower pole of both lobes. The ADC values of the thyroid glands according to T] weighted images and T2weighted images were measured with an electronic cursor to define the region of interest (ROI). The ADC values of the diffuse thyroid diseases groups and normal control group were compared by one-way ANOVA with SPSS17.0software. The optimist diagnostic threshold of ADC for differentiating diffuse thyroid diseases was determined by receiver operating characteristic (ROC) analysis. The relationship between ADC values of the diseased thyroid glands and the serological testing results including serum free triiodothyronine (FT3), free thyroxine (FT4), thyrotrophin receptor antibody (TRAb), thyroid stimulating hormone (TSH), thyroglobulin antibody (TGAb) and thyroid peroxidase (TPOAb) levels was analyzed respectively by linear regression analysis. A P<0.05was considered to be statistically significant. Result:1.The mean ADC values of GD group was mean2.25±0.17×10-3mm2/s, ranged1.86～2.60×10-3mm2/s;The mean ADC values of HT group was1.47±0.32×10-3mm2/s,ranged0.96～2.07×10-3mm2/s;The mean ADC values of SAT group was1.56±0.45×10-3mm2/s,ranged0.67～2.29×10-3mm2/s;The mean ADC values of normal control group was1.69±0.34×10-3mm2/s,ranged1.30～2.02×10-3mm2/s.2.Mean ADC values of GD patients were compared with those for HT and SAT patients,as well as the normal control group,the P values were0.000between all the three.HT was compared with normal control group,the P values was0.020.HT was compared with SAT,was not statistically significant.SAT was compared with normal control group,and was not statistically significant.3.An ADC of over2.02×10-3mm2/s was the value of which makes the accuracy of diagnosing Graves disease the highest from our results predictive of Graves disease. Using this threshold,Graves’s disease was correctly diagnosed in76of the82patients,with a sensitivity and specificity of92.7%and100%.An ADC of over1.85×10-3mm2/s was the value of which makes the accuracy of diagnosing Graves disease the highest from our results in differentiation GD and SAT. Using this threshold,Graves’s disease was correctly diagnosed in82of the82patients,with a sensitivity and specificity of100%and87.5%.4.The ADC values of the thyroid gland in patients with diffuse diseases revealed positive linear correlation with FT3,FT4and TRAb,the P values were0.000between all the three by Pearson correlation analysis,while the ADC value revealed negative linear correlation with TSH(P=0.014).The relationship between ADC value and TGAb and TPOAb was not significantly correlated(P=0.244,P=0.171).Conclusion:Diffusion-weighted MR imaging could play a role in differentiation among diffuse thyroid diseases.The ADC value in diffuse thyroid diseases positively correlated with serum FT3. FT4and TRAb level,but negatively correlated with serum FSH level.