FIG 2. Case 4: 28-year-old man with AIDS who presented with psychomotor slowing and hemianopsia. Stereotactic biopsy revealed PML.

A–C, Initial MR study, March 1998. Axial FLAIR-FSE (10000/150, TI = 2600) image (A) shows scalloped, high-signal-intensity lesion in the parietooccipital white matter with extension to dorsal part of the corpus callosum on both sides (arrow). There is no mass effect. The lesion is hypointense on noncontrast T1-weighted SE (550/20) image (B). No enhancement is observed on contrast-enhanced T1-weighted SE (550/20) image (C).

D–F, Follow-up MR study, May 1998 (4 weeks after the start of HAART). FLAIR-FSE (10000/150, TI = 2600) image (D) shows progression of the white matter lesion (arrow) with involvement of the right parietal white matter and contralateral occipital white matter. Increased hypointensity is evident on noncontrast T1-weighted (550/20) image (E). Contrast-enhanced T1-weighted (550/20) image shows no enhancement (F)