MRI-based, three-dimensionally assessed tumor burden and growth velocity to predict visual acuity deterioration in optic pathway glioma - results of a retrospective longitudinal analysis.

Purpose: Optic pathway gliomas (OPGs) bear a high risk of visual acuity (VA) impairment, while balancing disease-related morbidity and potential therapy-related sequelae remains challenging. We assess the predictive value of MRI-based, three-dimensionally assessed tumor burden and growth velocity for VA outcomes in NF1-associated and sporadic OPGs.

Methods: Thirty-three OPG patients were longitudinally observed over a median follow-up period of 10.3 years, while sequential tumor volumetry was performed to assess tumor burden and tumor growth velocity. VA was assessed as minimal angle of resolution (logMAR) with age-appropriate measures during regular ophthalmology visits.

Results: During observation, therapeutic intervention was initiated in 64% of individuals due to VA deterioration or radiological progress. Impaired VA occurred in 55 vs 80% of NF1-associated vs sporadic OPG patients, respectively, while blindness of at least one eye occurred in 36% of individuals. Tumor burden showed significant correlation with VA impairment at diagnosis and individual logMAR change during follow-up (R² = .22, p = .011), while individual tumor growth velocity during follow-up showed correlation with VA deterioration in non-NF1 OPG (R² = .35, p = .04). ROC analyses identified a threshold tumor burden (> 11.1 cm³, AU ROC 0.76) and growth velocity (> 0.1 cm³/month, AU ROC 0.81) to predict loss of VA with modest sensitivity and specificity.

Conclusion: These data indicate a predictive value of three-dimensionally assessed tumor burden and growth velocity for VA outcomes in OPG. Prospective evaluation within future trials may facilitate further implementation for advanced stratification, potentially identifying patients who may benefit from early therapeutic intervention.