Although more aggressive resection and higher extent of resection (EoR) of low-grade gliomas (LGGs) may result in longer survival of the patients, aggressive resection of insular LGGs remains challenging due to tumors’ relationship with complex surrounding functional structures.

     To provide high-class evidence regarding the impact of 1.5T intra-operative MRI (iMRI) on the resection of insular LGGs, we conducted a prospective randomized trial.

     Adult patients with non-contrast-enhancing insular lesions suspicious of LGGs were eligible to enter this trial.

     Patients were randomized to undergo either iMRI guided or conventional micro-neurosurgical tumor resection. For the iMRI group, pre- and intra-operative 1.5T MRI images were obtained to perform volumetric analyses to assess the EoR. For the control group, both pre- and early post-operative 1.5T MRI images were acquired. After the inclusion of 81 patients (iMRI group, 40 cases; control group, 41 cases), we performed a preliminary analysis.

     There were no significant differences in patient age (p=0.32) or preoperative tumor sizes (p=0.47) between the two treatment groups. EoR was significantly higher, and postoperative tumor volume was significantly lower in the iMRI group than in the control group (p<0.05). On the other hand, post-operative long-term (<3months) morbidity was significantly lower in the iMRI group than in the control group (p<0.05).

     This is a prospective single-center study.

     The use of iMRI appears to be associated with a higher rate of gross total as well as sub-total tumor resections compared to conventional microneurosurgery.

     Aggressive resection of insular LGGs with iMRI didn’t increase the long-term morbidity.