phosphocreatine and Medulloblastoma

Therapy and tumor-related effects such as hypoperfusion, internal hydrocephalus, chemotherapy, and irradiation lead to significant motor and cognitive sequelae in pediatric posterior fossa tumor survivors. A distinct proportion of those factors related to the resulting late effects is hitherto poorly understood. This study aimed at separating the effects of neurotoxic factors on central nervous system metabolism by using H-1 MR spectroscopy to quantify cerebral metabolite concentrations in these patients in comparison to those in age-matched healthy peers.. Fifteen patients with World Health Organization (WHO) I pilocytic astrocytoma (PA) treated by resection only, 24 patients with WHO IV medulloblastoma (MB), who additionally received chemotherapy and craniospinal irradiation, and 43 healthy peers were investigated using single-volume H-1 MR spectroscopy of parietal white matter and gray matter.. Concentrations of N-acetylaspartate (NAA) were significantly decreased in white matter (p < 0.0001) and gray matter (p < 0.0001) of MB patients and in gray matter (p = 0.005) of PA patients, compared to healthy peers. Decreased creatine concentrations in parietal gray matter correlated significantly with older age at diagnosis in both patient groups (MB patients, p = 0.009, r = 0.52; PA patients, p = 0.006, r = 0.7). Longer time periods since diagnosis were associated with lower NAA levels in white matter of PA patients (p = 0.008, r = 0.66).. Differently decreased NAA concentrations were observed in both PA and MB groups of posterior fossa tumor patients. We conclude that this reflects a disturbance of the neurometabolic steady state of normal-appearing brain tissue due to the tumor itself and to the impact of surgery in both patient groups. Further incremental decreases of metabolite concentrations in MB patients may point to additional harm caused by irradiation and chemotherapy. The stronger decrease of NAA in MB patients may correspond to the additional damage of combined irradiation and chemotherapy on neuroaxonal cell viability and number.

Topics: Adolescent; Adult; Age Factors; Antineoplastic Combined Chemotherapy Protocols; Aspartic Acid; Astrocytoma; Brain; Case-Control Studies; Cerebellar Neoplasms; Chemoradiotherapy; Child; Child, Preschool; Creatine; Female; Humans; Infant; Infratentorial Neoplasms; Leukoencephalopathies; Magnetic Resonance Spectroscopy; Male; Medulloblastoma; Phosphocreatine; Sex Factors; Young Adult

We report here on a correlation between proton magnetic resonance spectroscopy (MRS) spectra obtained in children with posterior fossa tumors and tumor histology and grading. Twenty-six children (age 1-16) were investigated before surgery by using single-voxel proton MRS. All examination were performed on a 1.5 T MR scanner by using single-voxel (8 cm3) with PRESS sequence (TR 1600 ms, TE 270 ms, NEX 256). Spectra of N-acetylaspartate (NAA), choline containing compounds (Cho), creatine and phosphocreatine (Cr) and lactate (Lac) were evaluated. Absolute concentrations of the metabolites were measured and their ratios were calculated. Correlation between these and tumor histology and grading were then determined. Concentration of Cho and Lac, and Cho/NAA ratio were the major statistically significant parameters for discrimination between benign (WHO grade I and II) and malignant tumors (WHO grade III and IV), in particular between pilocytic astrocytomas and medulloblastomas. Discrimination between individual histological types within malignant and benign tumor groups was not possible. Proton MRS of pediatric posterior fossa tumors seems to be helpful in prediction of tumor grading and histology. Specific character of the examination requires establishing of the individual standards for every MR scanner.

Topics: Adolescent; Aspartic Acid; Astrocytoma; Child; Child, Preschool; Choline; Creatine; Diagnosis, Differential; Female; Humans; Infant; Infratentorial Neoplasms; Lactic Acid; Magnetic Resonance Spectroscopy; Male; Medulloblastoma; Phosphocreatine; Protons; Severity of Illness Index