Accurate detection of glioblastoma infiltration and early peri -enhancing changes that predict recurrence remains challenging. We present a three-dimensional (3D) quantitative framework to characterize the peri -enhancing zone (PEZ) on baseline and follow-up MRI and examine whether baseline ADC and CBV differentiate regions that subsequently recur from those that remain stable. We retrospectively analyzed patients with IDH wild-type glioblastoma who developed local recurrence within 12 months post-resection. The contrast-enhancing tumor core including the necrotic region, and surrounding FLAIR hyperintensity were segmented in 3D on diagnostic MRI. Local recurrence was identified on follow-up MRI as abnormal T1 enhancement contiguous with the initial T1-enhancing core and mapped onto baseline images. The PEZ (up to 5 voxels surrounding the T1-enhancing core) was divided by FLAIR signal into hyperintense (PEZ FLAIR+ ) and non-hyperintense (PEZ FLAIR- ) subvolumes. Within these subvolumes, voxels overlapping with future T1 abnormalities were classified as recurrence-prone tissue (PEZ T1+ ), while voxels without subsequent enhancement were designated as normal remaining tissue (PEZ T1- ), yielding four analytical subvolumes for quantitative region-of-interest–based analysis. Mean ADC and CBV were calculated per subvolume and compared using Wilcoxon signed-rank tests and Pearson correlations. Of 101 eligible patients, 59 developed local recurrence and 46 were included in the final analysis. The mean PEZ T1+ volume was 6312 ± 4131 mm 3 , with approximately 30% located in (PEZ FLAIR- ). Within PEZ FLAIR+ , PEZ T1+ regions showed 8.2% lower ADC (p≈0.0007) and 13.5% higher CBV (p≈0.006) than PEZ T1- , with significant ADC–CBV correlation (p < 0.0005). No significant differences or correlations were observed in PEZ FLAIR- . 3D volumetric analysis of the PEZ reveals distinct ADC and CBV signatures in regions predisposed to recurrence, which are not apparent on conventional MRI. Differences were confined to FLAIR-hyperintense regions, highlighting the need for novel imaging strategies to detect at-risk tissue in FLAIR-normal PEZ. Importantly, we present a new 3D evaluation approach linking baseline and follow-up MRI that can be applied to investigate other clinical and research questions in brain tumor imaging.
Bertalan et al. (Thu,) studied this question.