Clinical and Magnetic Resonance Findings for the Diagnosis of Recurrent Tumors versus Radiation-Induced Secondary Tumors of Malignant Pediatric Brain Tumors of the Posterior Fossa

The latency period was significantly longer in RISTs than in RTs (152.5 vs. 22 months, P < 0.001). None of the RISTs arose from the primary surgical bed or exhibited leptomeningeal seeding. Benign RISTs tended to be well-defined and showed homogeneous enhancement. In contrast, malignant RISTs largely resembled RTs morphologically but demonstrated larger tumor volumes and higher apparent diffusion coefficient (ADC)_min and ADC ratios (all P < 0.05). Receiver operating characteristic analysis revealed that latency was the strongest discriminator between malignant RISTs and RTs (area under the receiver operating characteristic curve [AUC] = 0.90), followed by tumor volume (AUC = 0.81), ADCmin (AUC = 0.76), and ADC ratio (AUC = 0.72) CONCLUSIONS: In patients with MPBTPF who undergo surgery and radiotherapy, RISTs can be distinguished from RTs by clinical and MRI features, which may help guide early treatment planning.