CT evaluation of effects of cranial radiation therapy in children

A retrospective evaluation was completed of 49 children who received conventional cranial radiation therapy for primary central nervous system and/or skull-base neoplasia and who had follow-up CT studies. In these children, abnormalities in normal parenchyma away from the tumor itself were surprisingly frequent, with or without chemotherapy. Generalized volume loss or atrophy was the most frequent abnormality (51%), but in this population it may have resulted from a variety of causes. Calcification in nontumorous parenchyma was common (28%) with or without chemotherapy. The most frequent site of calcification was subcortical at the gray-white junction. Calcification was progressive over 1-2 years and correlated pathologically with mineralizing microangiopathy and dystrophic calcification with demyelination. White-matter abnormalities other than those associated with shunt malfunction and tumor edema occurred in 26% of the patients. Both white-matter abnormalities and calcification occurred predominantly in younger children, particularly those under 3 years old at the time of radiation therapy. Of the 21 children who received chemotherapy in this series, only two received methotrexate. White-matter abnormalities and calcifications occurred with similar frequency in children with and without chemotherapy; thus, radiation therapy is the most likely cause of these findings.