Early imaging biomarker of MRI within 1-cm margin surrounding surgical cavity predicting the progression of lower grade gliomas: dual-centers experience.

Introduction: More than 80% of postoperative tumor recurrences were within 1 cm of the postoperative tumor margin; therefore, characterizing the cavity microenvironment with a 1 cm margin was valuable for early warning of the progress after Lower grade gliomas (LGGs) surgery.

Aim: To investigate the clinical utility of apparent diffusion coefficient (ADC) values within 1 cm of the postoperative tumor margin for predicting the postoperative progression of LGGs.

Methods: The clinical and imaging data of patients with glioma from the First Hospital of Qinhuangdao and Affiliated Hospital of ChengDe Medical College were collected as the training group and external validation group, respectively. The mean ADC value within 1 cm of the margins surrounding the surgical cavity was measured by two senior radiologists. Patients were divided into high- and low-risk subgroups based on the optimal ADC threshold determined using the X-tile software. Kaplan-Meier survival curves were constructed to capture the differences in progression-free survival (PFS) between the groups. The independent risk factors for PFS were determined using Cox proportional hazards models.

Results: The inter-observer agreement was significant for the max ADC (ICC = 0.902) and min ADC (ICC = 0.884). X-tile determined the optimal threshold of the training group to be 1345 × 10^-3 mm/s, dividing patients into low-risk and high-risk groups. The high-risk group exhibited a significantly shorter PFS than that of the low-risk group. In the external validation group, poor prognosis in the low-risk group was significantly correlated with mADC. Univariate and multivariate Cox regression analyses indicated that the mADC was an independent risk factor for LGGs recurrence (p < 0.05).

Conclusions: ADC values within 1-cm of the margin surrounding the residual cavity are risk factors for the first postoperative progression of LGGs, which should be added in routine postoperative surveillance protocols to predict the PFS of patients with LGG.