Preliminary assessment of an MRI-based grading system for leptomeningeal disease: an exploratory prognostic framework

Current diagnostic approaches of leptomeningeal disease (LMD) rely heavily on cerebrospinal fluid (CSF) cytology, which shows significant limitations and the requirement for invasive procedures. We aim to develop an MRI-based grading scores for LMD diagnosis and prognosis that address current diagnostic limitations and provide standardized, reproducible assessment criteria.

We conducted a retrospective analysis of 32 adult cancer patients evaluated for suspected LMD. Two experienced neuroradiologists independently assessed MRI studies using our novel grading system, which incorporates leptomeningeal enhancement/intensity patterns (grades 1-6), Evans index for hydrocephalus assessment, brain metastases characteristics, and spinal involvement. Confirmation of LMD cases was employed using dual confirmation approach combining CSF cytology and follow-up MRI.

Our MRI grading system demonstrated promising inter-observer performance. Inter-rater reliability between two attending level neuroradiologists was excellent (ICC = 0.953, P-value < 0.001) using a cutoff score of 2 or higher, the system demonstrated comparable performance. Risk stratification analysis revealed clear prognostic value, with mortality rates of 8.6% for low-risk patients (Grade 1-2), 50% for medium-risk patients (Grade 3-4), and 80.0% for high-risk patients (Grade 5 +). The Kaplan-Meier survival curves demonstrate a statistically significant difference in overall survival between patients with varying grades (p-value of 0.00011). Notably, survival probability drops steeply in the Grade 5 + group early on, suggesting that higher LMD burden is associated with rapid clinical deterioration. In contrast, low risk patients appear to have a more indolent course.

Our preliminary findings detail a promising approach in evaluating LMD patients which offers valuable prognostic information for clinical decision making. Furthermore, the high inter-rater reliability across various tumor types further encourages the potential utility of this approach, although further research on a broader population is needed before clinical implementation.