The value of intravoxel incoherent motion diffusion weighted imaging parameters combined with texture analysis of primary lesion of rectal adenocarcinoma to predict preoperation non-enlarged lymph node metastasis / 中华放射学杂志

ABSTRACT

Objective:To investigate the value of intravoxel incoherent motion diffusion weighted imaging (IVIM-DWI) parameters combined with T 2WI texture analysis of primary lesions of rectal adenocarcinoma in preoperative prediction of lymph node metastasis with short diameter ≤9 mm. Methods:Retrospective analysis was performed on 115 cases of rectal adenocarcinoma confirmed by surgical pathology in Affiliated Provincial Hospital of Anhui Medical University from June 2015 to October 2020. All patients underwent total mesorectal resection and received conventional rectal MRI and IVIM-DWI scan before surgery. According to the pathological results of lymph node, the patients were divided into lymph node metastatic group ( n=44) and non-metastatic group ( n=71). IVIM-DWI parameters of primary rectal adenocarcinoma were measured including apparent diffusion coefficient (ADC), diffusion coefficient (D), pseudo diffusion coefficient (D *) and perfusion fraction (f). The region of interest (ROI) of the whole lesion of rectal adenocarcinoma was delineated on axial T 2WI; then the ROIs were imported into GE Analysis Kit software to extract 3D texture feature. The differences of IVIM-DWI parameters and texture feature parameters were compared between two groups using independent sample t test or Mann-Whitney U test. The optimal texture feature parameters with independent predictive function were screened by multivariate logistic regression. Then the texture feature model and combined model based IVIM-DWI and texture feature parameters were established. The receiver operating characteristic (ROC) curves were used to evaluate the performances of IVIM-DWI, texture feature parameters, texture feature model and combined model in predicting lymph node metastasis in patients with rectal adenocarcinoma. The area under the ROC curve (AUC) were compared with DeLong test. Results:Among all the IVIM-DWI parameters, the D * and f values of primary rectal adenocarcinoma were significantly different between the lymph node metastasis group and the non-lymph node metastasis group ( Z=3.39, P=0.001, Z=-3.06, P=0.002); no statistical significance was found in the ADC and D values between two groups (both P>0.05). A total of 828 texture feature parameters were obtained based on T 2WI of primary lesion of rectal adenocarcinoma, among which 3 optimal texture feature parameters were selected, including firstorder_Skewness, shape_Sphericity and glcm_Idn. The ROC curve results showed that the AUC of D * and f were 0.689 and 0.670, respectively. The AUC of 3 texture feature parameters were 0.651, 0.628, 0.631, respectively. The AUC of texture feature model and the combined model were 0.775 and 0.803. The AUC of combined model was larger than D *, f and the three texture feature parameters (all P<0.05). Conclusion:IVIM-DWI parameters combined with T 2WI texture feature parameters in primary lesion of rectal adenocarcinoma show good diagnostic efficacy in preoperative prediction of lymph node metastasis with short diameter≤9 mm.