Preliminary Study Of Intravoxel Incoherent Motion Diffusion Weighted Imaging Of The Parotid Gland In Patients With Differentiated Thyroid Cancer After Radioiodine Therapy

Purpose:Radiation damage to the salivary gland is a common complication of radioiodine therapy(RIT)for the patients with differentiated thyroid cancer(DTC).To investigate the feasibility of using intravoxel incoherent motion(IVIM)diffusion weighted imaging(DWI)to detect radiation-induced changes of normal-appearing parotid glands of the patients after radioiodione therapy for differentiated thyroid cancer.Materials and Methods:We prospectively analyzed 20 patients with RIT-induced sialadenitis and 20 matched healthy control(HC)participants in our study.IVIM-DWI imaging of the parotid gland was performed using a 3.0 T MR scanner.One questionnaire was used to quantitatively assess the related symptoms.The patients were divided into intermediate and late groups according to the time interval from the last RIT to MR scan.The IVIM-DWI imaging parameters(pseudodiffusion coefficient,D*;perfusion fraction,f;tissue diffusivity,D)were obtained using a biexponential model,and then compared among different groups using the one-way analysis of variance(ANOVA)test.Correlations between significant parameters and symptom score were assessed using Spearman’s correlation analysis.Results:The f and D value differed significantly(f,P=0.016;D,P=0.006)among different groups,while D*value did not(P=0.188).Post hoc analysis showed that f and D value of intermediate group were significantly higher than those of HC group(f,P=0.012;D,P=0.004),while no significant differences between late group and HC group(f,P=0.852;D,P=0.707).Significant positive correlation was found between f value and the total symptom score of the patients in intermediate group(P=0.028,r=0.762).Conclusion:The IVIM-DWI might be feasible to detect the radiation-induced changes of parotid glands in the patients after radioidione therapy for DTC.