Use of diffusion-weighted imaging to evaluate the initial response of progressive multifocal leukoencephalopathy to...

IRIS occurs in a small percentage of patients with AIDS following the initiation of HAART. Because PML lesions have a characteristic DWI/ADC appearance, our purpose was to determine if DWI/ADC measurements of PML lesions can be used to follow HAART treatment response and/or identify patients at risk for IRIS.

Six patients with AIDS and PML who had recently started HAART were retrospectively identified. On the basis of clinical history, patients were classified as having slow (non-IRIS) or rapid (IRIS) progression. Images were obtained at pre-HAART (time point 1) and post-HAART (time point 2). ADC parameters were measured and compared by using the 2-tailed t test.

Seven lesions (4 rapidly progressing, 3 slowly progressing) were identified. Lesions from patients with rapid clinical progression had higher maximal ADC ratios at time point 1. There were also significant correlations between ADC parameters, time to clinical deterioration, and JCV titers.

The ADC parameters of PML lesions were different for patients with rapid-versus-slow clinical progression. In our preliminary experience, ADC was helpful in diagnosing rapid clinical progression and IRIS. ADC values may correlate with the pathologic changes in PML lesions following HAART therapy.