Histogram Analysis of dynamic contrast-enhanced magnetic resonance imaging to predict extramural venous invasion in rectal cancer

Background: To explore the potential of histogram analysis (HA) of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in the identification of EMVI in rectal cancer patients. Methods This retrospective study included preoperative images of 194 rectal cancer patients at our hospital between May 2019 and April 2022. Postoperative histopathological examination served as reference standard. Mean values of DCE-MRI quantitative perfusion parameters ( K trans , K ep and V e ) and other HA features calculated from these parameters were compared between pathological EMVI-positive and EMVI-negative groups. Multivariate logistic regression analysis was performed to establish the prediction model for pathological EMVI-positive status. Diagnostic performance was assessed and compared using the receiver operating characteristic (ROC) curve. The clinical usefulness of the best prediction model was further measured with patients with indeterminate MRI-defined EMVI (mrEMVI) score 2(possibly negative) and score 3 (probably positive). Results Mean values of K trans and V e in EMVI-positive group were significantly higher than those in EMVI-negative group ( P  = 0.013 and 0.025, respectively). Significant differences in K trans skewness, K trans entropy, K trans kurtosis and V e maximum were observed between two groups ( P  = 0.001,0.002, 0.000 and 0.033, respectively). The K trans kurtosis and K trans entropy were identified as independent predictors for pathological EMVI. The combined prediction model had the highest area under the curve (AUC) at 0.926 for predicting pathological EMVI status and further reached the AUC of 0.867 in subpopulations with indeterminate mrEMVI scores. Conclusion Histogram Analysis of DCE-MRI K trans maps may be useful in preoperative identification of EMVI in rectal cancer, particularly in patients with indeterminate mrEMVI scores.