Magnetic resonance image features of children ependymoma and correlation between programmed cell death ligand 1 expression and pathological features in tumor tissues

Background and objective The incidence of ependymoma is higher in children than in adults, and it is a major cause of poor prognosis in pediatric patients. This study aimed to analyze the multimodal magnetic resonance imaging (MRI) characteristics of pediatric ependymoma and the correlation between programmed death-ligand 1 (PD-L1) expression in tumor tissues and clinicopathological features. Methods Fifty pediatric patients with pathologically confirmed ependymoma were enrolled. MRI, diffusion-weighted imaging (DWI), and proton magnetic resonance spectroscopy ( 1 H-MRS) features were evaluated according to WHO grading. PD-L1 positivity was detected in both lesional and adjacent normal tissues, and its relationship with clinicopathological characteristics and survival rate was analyzed. Results apparent diffusion coefficient (ADC)min, rADC, and NAA/Cr ratios were significantly lower in WHO grade III patients than in grades I, II, and II–III, while Cho/Cr was significantly higher ( P  < 0.05). The PD-L1 positivity rate was significantly higher in tumor tissues (52 %) than in adjacent normal tissues (18 %) ( P  < 0.05). PD-L1 expression was significantly elevated in patients with tumor diameter ≥2 cm, partial resection, moderate-to-poor differentiation, and WHO grade III ( P  < 0.05). At the 10-month follow-up, the survival rate of PD-L1-positive patients (57.7 %) was significantly lower than that of PD-L1-negative patients (83.3 %) ( P  < 0.05). Conclusion DWI can differentiate between ependymoma grades and improve preoperative diagnostic efficiency. Elevated PD-L1 expression in tumor tissue is associated with aggressive features and may serve as a marker for assessing short-term prognosis in pediatric ependymoma. MRI-DWI and 1 H-MRS parameters (ADCmin, rADC, NAA/Cr, Cho/Cr) reflect tumor grade and malignancy, while PD-L1 expression correlates with invasiveness and outcome. Their combination provides a more comprehensive basis for disease evaluation and prognostic assessment in pediatric ependymoma.