 MRI BRAIN: There are multiple diffusion restricting oval lesions throughout the cerebral hemispheres, within the white matter. The largest area is in the left paramedian frontal lobe, with a slightly less circumscribed appearance. Additional lesions are seen in the left parietal centrum semiovale, left frontal lobe deep white matter, left paramedian parietal subcortical and deep white matter, right frontal lobe deep white matter, and left paramedian/midline splenium of the corpus callosum. A smaller area of mild diffusion hyperintensity is seen along the right occipital horn, with more impressive ADC hypointensity noted. There is questioned minimal punctate and linear enhancement in this region, although this could relate to a developmental venous anomaly given the multiple scattered other developmental venous anomalies noted, most prominent in the right frontal and parietal lobes.The lesions demonstrate mild central T2/FLAIR hypointensity, with peripheral rim of subtle FLAIR hyperintensity. The splenial lesion does demonstrate more diffuse mild FLAIR hyperintensity. There is no associated susceptibility artifact.The ventricles and sulci are prominent consistent with mild to moderate global volume loss greater than expected for the patient's stated age. The cisterns remain patent. There is no midline shift or mass effect. No extra-axial fluid collection is identified.Normal flow-voids are demonstrated in the major intracranial vascular structures. The midline structures and craniocervical junction are within normal limits. MRA HEAD: The intracranial internal carotid arteries are normal in course and caliber. There is a mildly hypoplastic left A1 segment. The middle and anterior cerebral arteries are otherwise unremarkable. The vertebral arteries, basilar artery, and posterior cerebral arteries are normal in course and caliber. There is no evidence of flow-limiting stenosis or aneurysm.MRV HEAD: The superior sagittal sinus, inferior sagittal sinus, transverse sinuses, sigmoid sinuses, straight sinus, vein of Galen, internal cerebral veins, and several visualized cortical veins are patent. There is no evidence of venous thrombosis.
1. No acute infarct.2. Multiple oval areas of diffusion restriction throughout the cerebral white matter, including the left paramedian/midline splenium of the corpus callosum. No definite associated enhancement with only mild associated FLAIR abnormalities and central lower T2 signal. Differential diagnosis includes primarily neurotoxicity secondary to intrathecal methotrexate given the patient's history, although follow-up to resolution of imaging findings is recommended to exclude the possibility of underlying leukemic involvement such as chloromas.Reference article: Diffusion-Weighted MR Imaging of Early Methotrexate-Related Neurotoxicity in Children, AJNR 2005 26: 1686-1689 2. Questioned punctate enhancement in the region of the right occipital horn incidentally noted which could relate to a tiny developmental venous anomaly given the multitude of other scattered DVAs seen.3. Unremarkable MRA and MRV of the head.