MAGNETIZATION-TRANSFER STUDY OF HIV ENCEPHALITIS AND PROGRESSIVE MULTIFOCAL LEUKOENCEPHALOPATHY

PURPOSE: To ascertain whether the use of magnetization transfer (MT) i n MR imaging can characterize tissue destruction in human immunodefici ency virus (HIV)-positive patients with presumed progressive multifoca l leukoencephalopathy (PML) or HIV encephalitis. METHODS: Brain MR stu dies that included MT were obtained in three groups: 11 healthy contro l subjects, 10 HIV-positive patients with clinical and radiologic find ings of PML, and 13 HIV-positive patients with HIV encephalitis. MT ra tios (MTRs) were calculated in PML and HIV encephalitis lesions and in normal-appearing white matter in the patients and control subjects. R ESULTS: PML lesions revealed a dramatic decrease in MTR (22% +/- 2.3). HIV encephalitis lesions had statistically significantly higher MTR v alues (40% +/- 3.8) than PML lesions. The MTR of normal-appearing whit e matter was significantly higher in the control subjects (47% +/- 2.3 ) than in the PML group (46% +/- 3.3) or the HIV encephalitis group (4 4% +/- 2.6). CONCLUSION: MTR determinations suggest the possibility of distinguishing PML from HIV encephalitis and of indicating whether HI V encephalitis is involved in white matter that appears normal on conv entional MR images.