No abstract

With the advent of chemotherapy, mortality rates in acute lymphoblastic leukaemia (ALL) have decreased, but complications in the central nervous system have appeared. These include direct involvement of the brain itself and the development of chemotherapy-related encephalopathy as a delayed reaction. In most reported cases, this encephalopathy is believed to be due to necrotising angiitis arising from the combination of chemotherapy with adjuvant radiotherapy. We report the cases of four children with ALL who had been treated with high-dose intravenous and intrathecal chemotherapy but no radiation therapy, and who were admitted to hospital because of seizures. CT of the brain revealed the presence of diffuse periventricular white matter hypodensities in all cases and subcortical hyperdense foci in three cases. MRI showed diffuse hyperintense white matter lesions on T2-weighted images in all four patients; hypointense changes were observed on susceptibility-sensitive FLASH sequences in the hyperdense foci seen on CT as well as changes that were hyperintense on T1-weighted images. It was, therefore, concluded that the lesions corresponded to a leukoencephalopathy with calcific deposits. These findings are of a pure form of methotrexate encephalopathy causing seizures.

Age at study ranged from 23 5/7-43 0/7 postmenstrual weeks. Brain maturation starts in the central area and proceeds towards the parieto-occipital cortex. The frontal cortex develops last. Transition to degrees 1, degrees 2 and, degrees 3 starts at week 25, 32 and 35 in the central cortex and is completed at week 34, 36 and 39, respectively. Our data compare favourably with the two previously published reports about brain maturation. Early MR imaging seems therefore to be suited to study maturation of the fetal brain. This may be of pathophysiological relevance in neonatal intensive care and neurological follow-up studies.

Diffusion-weighted MR (DWI) is becoming an established method for the investigation of cerebral ischemia. Its value in spinal ischemia has to be demonstrated. We report on a patient presenting with postoperative paraparesis who underwent emergency MRI of the spine with echo-planar diffusion-weighted imaging which showed an area of hyperintensity corresponding to a decrease of diffusion as measured by the apparent diffusion coefficient. On follow-up imaging spinal stroke was confirmed. In conclusion, spinal echo-planar MR imaging can demonstrate ischemic changes despite strong echo-planar artifacts. It could become an important adjunct to the management of patients with suspected spinal ischemia.