RESUMEN
Objective To investigate the clinical value of high-resolution magnetic resonance imaging(HR-MRI)combined with nomogram model in predicting the risk factors of positive circumferential resection margin(CMR)in rectal cancer surgery.Methods A retrospective analysis was conducted on preoperative data from 107 rectal cancer patients who underwent surgery and were confirmed by pathology.SPSS 2 5.0 software was used for univariate statistical analysis of potential risk factors for positive CRM,and after independent risk factors were selected,multivariate logistic regression analysis was performed to classify the risk factor categories.R software(4.2.0 version)was used to establish the nomogram model,and a curve was drawn to evaluate the model.The receiver operating characteristic(ROC)curve was used to show specificity and sensitivity,the area under the curve(AUC)was used to evaluate discriminative ability,the calibration curve was used to evaluate calibration,the decision curve analysis(DCA)was used to evaluate clinical benefit,and the model was internally validated using the Bootstrap method.Results Tumor located in the lower rectum[P=0.01,odds ratio(OR)=8.71],maximum diameter of tumor perpendicular to the intestinal tube(≥18.86 mm±5.32 mm)(P=0.01,OR=1.24),extramural vascular invasion(EMVI)(P＜0.01,OR=0.03),and mesorectal lymph node metastasis(P=0.01,OR=0.15)were independent risk factors for positive CRM in rectal cancer.The nomogram model established based on these factors had a training set AUC of 0.921(sensitivity 0.83,specificity 0.93),a validation set AUC of 0.912(sensitivity 0.87,specificity 0.82),a Bootstrap internal validation corrected AUC of 0.92,and a consistency index(C-index)of 0.92,indicating good discriminative ability,calibration,and clinical benefit value.Conclusion HR-MRI combined with nomogram model predicted that tumor located in the lower rectum,maximum diameter of tumor perpendicular to the intestinal tube ≥(18.86±5.32)mm,EMVI,and mesorectal lymph node metastasis are closely related to positive CRM in rectal cancer.