Predictive value of histogram parameters based on synthetic MRI for extramural venous invasion of rectal cancer / 中华放射学杂志

ABSTRACT

Objective:To assess the predictive value of histogram parameters derived from synthetic MRI for extramural venous invasion (EMVI) of rectal cancer.Methods:Totally 76 patients with pathologically proven rectal adenocarcinoma were enrolled in this retrospective study from November 2018 to December 2019 in Cancer Hospital, Chinese Academy of Medical Sciences. All participants underwent preoperative rectal MRI examination including MAGiC within 4 weeks before surgery. The status of EMVI on MRI was independently assessed by one junior and one senior radiologist. Histogram parameters were extracted from T 1, T 2 and proton density (PD) mapping, including mean, variance, maximum, minimum, 10 th percentile, median, 90 th percentile, energy, kurtosis, entropy and skewness. With postoperative pathological result as the gold standard, the patients were divided into EMVI-positive group ( n=18) and EMVI-negative group ( n=58). The Mann-whitney U test was used to compare the differences in histogram parameters between the two groups. The ROC curves were used to explore the predictive performance for assessing EMVI. The logistic regression analysis was used to combine the assessment of radiologists with parameters whose area under the ROC curve (AUC)>0.7. The Delong test was used to analyze the differences of diagnostic efficacy between different methods in predicting EMVI. Results:Significant differences of the energy of T 1, T 2 and PD mapping and skewness of PD mapping were observed between the EMVI-positive and EMVI-negative group ( P<0.05), with the AUC of 0.744, 0.728, 0.708 and 0.652. The AUC of junior radiologist in evaluating EMVI was 0.711, and the AUC of the combination with energy of T 1, T 2 and PD mapping was 0.817, showing a statistically significant difference ( Z=2.281, P=0.023). The AUC of senior radiologist in evaluating EMVI was 0.837, and the AUC of the combination with energy was 0.856. There was a significant difference in AUC between junior and senior radiologists in assessing EMVI ( Z=2.587, P=0.010), while there was no significant difference between junior radiologist combined with energy and senior radiologist ( Z=0.578, P=0.563). Conclusion:The histogram parameters based on quantitative mapping of synthetic MRI were useful for predicting EMVI of rectal cancer.