Segmentation of Progressive Multifocal Leukoencephalopathy Lesions in Fluid‐Attenuated Inversion Recovery Magnetic Resonance Imaging

BACKGROUND AND PURPOSE: The authors compared the reproducibility of a manual and a semiautomated technique for the quantitation of white-matter lesions in magnetic resonance imaging (MRI). METHODS: Volumes of white-matter lesions were determined using fluid-attenuated inversion recovery MRI in 23 AIDS patients with progressive multifocal leukoencephalopathy. Manual outlining was compared to an automated method based on region growing and adaptive thresholding. RESULTS: Lesion volumes from the 2 methods correlated well (61 lesions, r = 0.99, P < 10(-4)), although the volumes differed substantially (12.8% +/- 13.7%). Interscan, intrasubject reproducibility was better for the automated than the manual method (2.9% +/- 3.2% vs 12.4% +/- 16.2% volume difference, P = .02). CONCLUSION: The automated algorithm appeared more reproducible, which renders it superior to the manual method for longitudinal studies.