Cranial computed tomography during treatment of childhood lymphocytic leukemia. Factors predisposing to abnormalities.

Twenty-three children with acute lymphocytic leukemia (ALL) were examined by computed tomography (CT) of the head on two occasions more than 11 months apart. The first CT was performed at the time of diagnosis in 11 children, who were re-examined while still in their first complete remission. They had received prophylactic central nervous system (CNS) treatment consisting of intrathecal methotrexate supplemented by irradiation in 7 cases and intermediate dose methotrexate in 4 cases. Twelve children were receiving treatment for CNS relapse. This included therapeutic irradiation and intrathecal methotrexate. Abnormal CT developed in 7 children. Three CT scans demonstrated areas of decreased attenuation coefficient, one with intracerebral calcifications. In 5 patients, dilatation of the ventricles and cortical sulci had developed. All CT abnormalities occurred in children in remission after CNS relapse. These results indicate that prophylactic treatment including cranial irradiation with 24 Gy and low cumulative doses of methotrexate is a safe procedure. Patients with CNS leukemia are at risk of developing CNS abnormalities, when they receive treatment with cranial irradiation and methotrexate. The risk is not correlated with age or sex of the child, the duration of the disease, the dose of irradiation or the cumulative dose of methotrexate.