Diffusion characteristics of pediatric pineal tumors

BACKGROUND: Diffusion weighted imaging (DWI) has been shown to be helpful in characterizing tumor cellularity, and predicting histology. Several works have evaluated this technique for pineal tumors; however studies to date have not focused on pediatric pineal tumors. OBJECTIVE: We evaluated the diffusion characteristics of pediatric pineal tumors to confirm if patterns seen in studies using mixed pediatric and adult populations remain valid. MATERIALS AND METHODS: This retrospective study was performed after Institutional Review Board approval. We retrospectively evaluated all patients 18 years of age and younger with pineal tumors from a single institution where preoperative diffusion weighted imaging as well as histologic characterization was available. RESULTS: Twenty patients (13 male, 7 female) with pineal tumors were identified: seven with pineoblastoma, four with Primitive Neuroectodermal Tumor (PNET), two with other pineal tumors, and seven with germ cell tumors including two germinomas, three teratomas, and one mixed germinoma-teratoma. The mean apparent diffusion coefficient (ADC) values in pineoblastoma (544 ± 65 × 10⁻⁶ mm²/s) and pineoblastoma/PNET (595 ± 144 × 10⁻⁶ mm²/s) was lower than that of the germ cell tumors (1284 ± 334 × 10⁻⁶ mm²/s; p < 0.0001 vs pineoblastoma). One highly cellular germinoma had an ADC value of 694 × 10⁻⁶ mm²/s. CONCLUSION: ADC values can aid in differentiation of pineoblastoma/PNET from germ cell tumors in a population of children with pineal masses.