MRI-based morphological and spatial characteristics of leptomeningeal metastasis: prognostic value in non-small cell lung cancer.

[BACKGROUND] Leptomeningeal metastasis (LM) represents a devastating complication of non-small cell lung cancer (NSCLC), with limited survival and poorly defined imaging-based prognostic markers.

[PURPOSE] This study evaluated the combined prognostic value of MRI-based morphological and spatial patterns in NSCLC patients with LM, whose prognostic relevance remains poorly defined.

[METHODS] We retrospectively reviewed 71 NSCLC patients with LM confirmed by 3.0T black-blood MRI, selected from 109 initially screened after applying exclusion criteria. Patients were classified into linear (n=41) and mixed (n=30) morphological subtypes based on MRI, and stratified by the number of involved brain regions (>3 vs. ≤3). Clinical, imaging, and survival data were analyzed using Kaplan-Meier estimates and multivariate Cox regression to identify independent prognostic factors.

[RESULTS] The mixed subtype exhibited a significantly higher lesion burden than the linear subtype (26.86 ± 26.72 vs. 7.25 ± 10.95, p<0.001). Involvement of more than three brain regions was associated with significantly shorter median overall survival (14 vs. 24 months, p=0.016). Multivariate analysis identified several independent adverse prognostic factors: increased lesion number (HR = 1.02, 95% CI: 1.01-1.03, p<0.01), temporal lobe invasion (HR = 1.96, 95% CI: 1.07-3.58, p=0.029), Regionsinvolved (HR = 0.52, p=0.020).

[CONCLUSION] MRI-based morphological subtyping and spatial distribution provide significant prognostic value in NSCLC-LM. The mixed morphology, extensive brain involvement (>3 regions), and invasions of specific location such as the tempoarl lobe is associated with poorer survival outcomes. These findings support the use of MRI phenotyping for risk-adapted clinical management in NSCLC-LM.