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Figure 1. A 22-year-old female with a medical history of acute lymphocytic leukaemia. (a) Post-contrast CT scan shows a ring-enhancing cystic lesion in the left frontal lobe. The lesion is hypointense on (b) the T1 weighted image and (c) hyperintense on the T2 weighted image with a focal peripheral oedema and a mild mass effect. A small pus-fluid level in the dependent portion of the lesion is shown. (d) Post-contrast T1 weighted image shows a ring-enhancing cystic lesion with several enhancing daughter nodules. With (e) the diffusion weighted image, the signal intensity of the lesion is hypointense with a corresponding marked hyperintensity on (f) the apparent diffusion coefficient (ADC) map. The small gravity-dependent portion is hyperintense on the diffusion weighted imaging (DWI) and shows hypointense signal intensity on the ADC map, indicating restricted diffusion.
