Patient with metastatic small cell lung cancer status post whole brain radiation therapy. There is marked interval regression of the previously seen multiple intra-axial and extra-axial lesions. There is interval resolution of the right frontal dural metastasis with interval decrease in size of the adjacent T2 hyperintense lesion, measuring 11 x 19 mm (AP x TR), previously 36 x 16 mm. There is interval increase in the T2/FLAIR signal at the right frontal horn periventricular white matter, which approaches and is adjacent to the T2 hyperintense lesion medially. There are multiple T1- and T2/FLAIR hyperintensities corresponding to the previously seen supra- and infratentorial lesions with associated susceptibility artifact. There may be minimal, if any, residual enhancement associated with the previously seen lesions. The previously seen right dural thickening and enhancement has resolved. There is interval increase in size of the ventricles, which may be on the basis of ex vacuo dilatation and decreased mass effect from previously seen lesions, as the sulci are also more prominent. There is also increased periventricular FLAIR hyperintensity. There is no midline shift or herniation. There previously seen partially imaged mass at the right C2 level has regressed.
1. Marked interval regression of multiple supratentorial and infratentorial intracranial metastases. No new enhancing lesion. Interval resolution of right dural thickening and enhancement.2. Slight interval increase in size of the ventricles, which may be on the basis of ex vacuo dilatation, as the sulci are also more prominent. There is also interval increase in periventricular FLAIR hyperintensity which may be related to treatment change, however, given the slight increase in caliber the ventricular system, component of transependymal CSF flow cannot entirely be excluded. Suggest close follow up to exclude the possibility of developing communicating hydrocephalus. 