Abstract: Objective To improve diagnosis level based on MRI features of progressive multifocal leukoencephalopathy (PML) in AIDS patients. Method Retrospective analysis of 27 AIDS patients with PML confirmed by pathology or clinical diagnosis in Beijing You'an Hospital, Capital Medical University from May 2015 to March 2022. We analyzed MRI features of PML in AIDS patients to explore the characteristic features. Result All of 27 patients of PML in AIDS patients in our study were male with average age of (38 ± 9) years. All of 27 patients of PML in AIDS patients in our study equipped multiple lesions in subcortical. 26 (96.3%) lesions of PML in AIDS patients were asymmetrically distributed, and 1 (3.7%) involved cerebral cortex. There were 23 (85.19%) cases of supratentorial lesions, 14 (51.85%) cases of infratentorial lesions, and 10 (37.04%) cases of supratentorial and infratentorial lesions. Among patients with supratentorial lesions, many brain areas were involved, including 18 (66.67%) in the parietal lobe, 17 (62.96%) in the frontal lobe, 12 (44.44%) in the temporal lobe, 6 (22.22%) in the occipital lobe, 3 (11.11%) cases in splenium of corpus callosum. The cases with supratentorial lesions were multilobed. Regarding patients with infratentorial lesions, 8 (29.63%) cases were involved in the cerebellum, 4 cases (14.81%) in the pons, 3 cases (11.11%) in the medulla oblongata, 2 (7.41%) cases in the pontine arm. All patients equipped multiple lesions [27 cases (100%)] which were asymmetrically located in subcortical [26 cases (96.3%)]. 18 cases (66.67%) showed “Milky way sign” on T₂WI. 17 cases (62.96%) showed high signal at the edge of the lesion on DWI. 27 cases were no space occupying effect, and brain atrophy in 2 cases (7.41%). 19 cases had MRI enhancement scan, only 1 case (5.26%) was enhanced, showing punctate and linear enhancement. Conclusion PML in AIDS patients mainly presented multiple and asymmetric demyelinating lesions under the bilateral frontal parietal occipital cortex. “Milky way sign” on T₂WI was a characteristic feature of PML in AIDS patients. The distribution range of lesions was inconsistent with the distribution area of cerebral vessels. The edge of lesions on DWI can show high signal. But there was not obvious diffusion limitation, and space occupying effect of lesions, and enhanced signal in enhancement phases. MRI examination combines with the clinical history, physical sign and laboratory examination of patients, it can obviously improve the diagnostic accuracy.

Key words: Acquired immunodeficiency syndrome, Progressive multifocal leukoencephalopathy, Magnetic resonance imaging, Diagnosis, Differential diagnosis