Fig. 3
![Fig. 3](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs40644-019-0241-5/MediaObjects/40644_2019_241_Fig3_HTML.png)
FDG-PET (a) in a patient with systemic lymphoma shows abnormal intracranial uptake (asterisk), consistent with secondary CNS involvement. This is localised to the hypothalamus on the post-contrast MRI (b). The post-contrast MRI (c) also demonstrates more extensive leptomeningeal disease than is appreciable on PET, including along the ependymal surface of the fourth ventricle (arrow)