Assessing Postoperative Motor Risk in Insular Low-Grade Gliomas Patients: The Potential Role of Presurgery MRI Corticospinal Tract Shape Measures

Background: Insular low-grade gliomas (LGGs) are surgically challenging due to their proximity to critical structures like the corticospinal tract (CST).

Purpose: This study aims to determine if preoperative CST shape metrics correlate with postoperative motor complications in insular LGG patients.

Study type: Retrospective.

Population: 42 patients (mean age 40.26 ± 10.21 years, 25 male) with insular LGGs.

Field strength/sequence: Imaging was performed using 3.0 Tesla MRI, incorporating T1-weighted magnetization-prepared rapid gradient-echo, T2-weighted space dark-fluid with spin echo (SE), and diffusional kurtosis imaging (DKI) with gradient echo sequences, all integrated with echo planar imaging.

Assessment: Shape metrics of the CST, including span, irregularity, radius, and irregularity of end regions (RER and IER, respectively), were compared between the affected and healthy hemispheres. Total end region radius (TRER) was determined as the sum of RER 1 and RER 2. The relationships between shape metrics and postoperative short-term (4 weeks) and long-term (>8 weeks) motor disturbances assessing by British Medical Research Council grading system, was analyzed using multivariable regression models.

Statistical testing: Paired t-tests compared CST metrics between hemispheres. Logistic regression identified associations between these metrics and motor disturbances. The models were developed using all available data and there was no independent validation dataset. Significance was set at P < 0.05.

Results: Short-term motor disturbance risk was significantly related to TRER (OR = 199.57). Long-term risk significantly correlated with IER 1 (OR = 59.84), confirmed as a significant marker with an AUC of 0.78. Furthermore, the CST on the affected side significantly had the greater irregularity, larger TRER and RER 1, and smaller span compared to the healthy side.

Data conclusion: Preoperative evaluation of TRER and IER 1 metrics in the CST may serve as a tool for assessing the risk of postoperative motor complications in insular LGG patients.

Level of evidence: 2 TECHNICAL EFFICACY: Stage 2.