Values Of DWI Texture Analysis In Predicting Pathological Subtypes And Stages Of Thymic Epithelial Tumors

Background Thymic epithelial tumors?TETs?are the most common primary malignant tumors of the anterior mediastinum in adults,accounting for 47%of anterior mediastinum tumors,15%²1.7%of mediastinal tumors and 0.2%¹.5%of adult malignant tumors.Surgical resection range,World Health Organization?WHO?pathological classification and Masaoka-Koga staging are recognized independent prognostic factors for TETs.Clinical management of TETs is mainly dependent on the pathological subtypes and stages.Therefore,it is critically important to accurately identify the risk grades of TETs before treatment for guiding treatment decision-making.Currently,imaging examination plays a crucial role in the diagnosis,treatment decision-making and prognosis evaluation of TETs before treatment.Computed tomography?CT?and conventional magnetic resonance imaging?MRI?are used as routine imaging modalities for TET patients,and they can provide detailed morphologic information regarding tumor location,size,shape,homogeneity,infiltration,and so on.However,since these examination methods mostly depend on qualitative parameters for diagnosis,it is difficult to objectively and quantitatively evaluate the pathological subtypes and stages of TETs.With the continuous innovation and development of computer technology and medical image processing methods,medical image texture analysis technology has began to be applied in clinical practice.Image texture analysis based on medical image intensity and spatial distribution characteristics of each pixel for the mathematical analysis and calculation,to quantify tumor heterogeneity due to changes in genome subtypes,cell proliferation or apoptosis,metabolic activity,vascular structure,and other factors.Comparing with morphological analysis of conventional imaging,texture parameters provide a more detailed and quantitative information on tumor composition by using a pixel-by-pixel analysis.However,there is no research to confirm whether diffusion-weighted imaging?DWI?texture analysis can improve the efficacy in predicting the risk grades of TETs.Therefore,the purpose of this study is to evaluate whether magnetic resonance?MR?image texture analysis technology can improve the predictive efficacy of pathological subtypes and stages of TETs.Objectives To explore the value of combining apparent diffusion coefficients?ADC?and texture parameters from diffusion-weighted imaging?DWI?in predicting the pathological subtypes and stages of thymic epithelial tumors?TETs?.Methods Fifty-seven patients with TETs confirmed by pathological analysis were retrospectively enrolled.ADC values and optimal texture feature parameters were compared for differences among low risk thymoma?LRT?,high risk thymoma?HRT?and thymic carcinoma?TC?by one-way ANOVA,and between early and advanced stage of TETs were tested using the independent sample t test.Receiver operating characteristic?ROC?curve analysis was performed to determine the differentiating efficacy.Results The ADC values in LRT and HRT were significant higher than the value in TC?P=0.004 and 0.001,respectively?,also in early stage were significant higher than ones in advanced stage of TETs?P<0.001?.Among all texture parameters analyzed in order to differentiate LRT from HRT and TC,the V₃₁₂12 achieved higher diagnostic efficacy with an AUC of 0.875,and combination of ADC and V₃₁₂ achieved the highest diagnostic efficacy with an AUC of 0.933,for differentiating the LRT from HRT and TC.Furthermore,combination of ADC and V₁₀₃₀ achieved a relatively high differentiating ability with an AUC of 0.772,for differentiating early from advanced stages of TETs.Conclusions DWI texture analysis is useful in differentiating TET subtypes and stages.Combination of ADC and DWI texture parameters improved the differentiating ability of TET grades,which could potentially be useful in clinical practice regarding the TETs evaluation before treatment.