Brain MRI patterns after brexu-cel–associated ICANS. (A) MRI T2 FLAIR sequence showing focal hyperintensity at the right occipital horn. White arrow indicates the area of hyperintensity, visualized across axial (left), coronal (middle), and sagittal (right) cuts. The T2 hyperintense lesion is periventricular and located at the CSF and brain parenchymal border. (B) Additional MRI T2 FLAIR changes seen from patient examined in panel A. There is abnormal T2 hyperintensity and cortical fullness of right hemispheric parietal-occipital gyri. There is 1 area of notable T2 hyperintensity also on the contralateral side seen in the axial image to the right. As arrows indicate, these lesions contour along the meningeal surface of the brain. (C) MRI DWI sequence showing abnormal signal hyperintensity in the posterior right hemisphere. The multipunctate lesion has an atypical appearance at the juxtaposition of 3 cortical gyri and does not follow a specific vascular territory. (D) MRI ASL sequence from 2 patients with ICANS grade 3. Color maps further highlight the asymmetric hyperemia seen in the left hemisphere of both patients. (E) MRI T2 FLAIR sequence from a patient with preexisting white matter disease who then experienced grade 3 ICANS. The extension of white matter T2 hyperintensity increases between baseline before treatment (left column) and after treatment during ICANS (right column). Column images are axial views and arranged from rostral to caudal. (F) MRI DWI sequence from the same patient as in panel E, who experienced acute visual changes during grade 3 ICANS and found to have bilateral optic disk edema. White arrow indicates subtle increase in optic nerve DWI signal, left greater than right, that is seen in the postinfusion axial sequence (right) compared with baseline scan (left).