Predictive value of ADC histogram analysis in 2 cm peritumoral edema zone for spatial pattern of recurrence in glioblastoma

To evaluate the predictive value of apparent diffusion coefficient（ADC）histogram in preoperative magnetic resonance imaging（MRI）of the 2 cm peritumoral edema zone for spatial pattern of recurrence in IDH wild-type glioblastoma（GB）.

A case-control study was performed on 50 patients with IDH wild-type GB treated with standard protocol, diagnosed by pathology as tumor recurrence and accepted regular follow-up MRI in Department of Neurosurgery of Army Medical Center of PLA from January 2012 to December 2021. The postoperative spatial recurrence patterns were divided into the local recurrence group（n=28）and the non-local recurrence group（n=22）according to whether the distance between the recurrence foci and the operative cavity was more than 2 cm or not. According to the maximum level of tumor enhancement in axial planes of enhanced MRI, the corresponding level of ADC images were selected. Mazda software was used to outline the region of interest（ROI）along the edge of the 2 cm range of peritumoral edema for histogram analysis. The histogram parameters of the 2 groups with different spatial patterns of recurrence were statistically analyzed, and the area under the curve（AUC）was obtained by receiver operating characteristic curve to evaluate the diagnostic efficacy.

Among the 50 patients with recurrent GB, progression-free survival（PFS）and overall survival（OS）in the local recurrence group were longer than those in the non-local recurrence group（median PFS: 6.6 vs 4.6 months; median OS: 15.4 vs 12.4 months）, and the differences were statistically significant（PFS: log-rank Chi-square=4.325, P=0.038; OS: log-rank Chi-square=4.022, P=0.045）. Variance, kurtosis and Perc.90% of the 9 features extracted from ADC histogram were statistically significant differences between the 2 groups（P<0.05）. Variance had the best diagnostic efficiency（AUC: 0.804, sensitivity: 75.00%, specificity: 81.82%）. Among the 4 multivariate logistic regression models constructed based on the variance, kurtosis and Perc.90%, the model constructed by the combination of variance, kurtosis and Perc. 90% had the best diagnostic efficiency（AUC: 0.878, sensitivity: 78.57%, specificity: 86.36%）.

The characteristic parameters of the preoperative ADC histogram in peritumoral edema zone can be used as an imaging marker to predict the different spatial patterns of postoperative recurrence in patients with IDH wild-type GB.