Acquired immunodeficiency syndrome-associated cytomegalovirus encephalitis: clinical, imaging, and follow-up characteristics of 11 cases.

Background: Patients with acquired immunodeficiency syndrome (AIDS) are susceptible to cytomegalovirus (CMV) infection due to compromised immune function, with CMV encephalitis carrying high mortality especially in those with extremely low CD4⁺ T-lymphocyte counts (<50 cells/µL). Current literature consists primarily of case reports and small cross-sectional studies, lacking large-scale systematic analyses and longitudinal follow-up. This study aims to investigate the clinical and magnetic resonance imaging (MRI) characteristics of AIDS patients with CMV encephalitis, providing evidence for early diagnosis and treatment. Methods: A retrospective analysis was conducted to evaluate the clinical presentations and MRI imaging characteristics of AIDS patients with CMV encephalitis. Results: Eleven patients (8 males, 3 females; median age 45 years, range, 25-59 years) were included in the study. The median peripheral CD4⁺ T-lymphocyte count was 18 (interquartile range, 8-53) cells/µL; eight patients (72.7%) had <50 cells/µL. MRI features: lesions were solitary in 4 (36.4%) and multiple in 7 (63.6%) patients, yielding a total of 51 intracranial foci. In terms of distribution, there were 15 lesions in the cerebellum (29.4%), eight lesions in the frontal lobe (15.7%), five lesions each in the brainstem, basal ganglia, and ependyma (9.8% each), three lesions each in the occipital lobe, parietal lobe, thalamus, and corpus callosum (5.9% each), and one lesion in the insula (2.0%). In terms of the signal characteristics, on T1-weighted imaging (T1WI), the lesions were iso- and hypointense in 11 (21.6%) and 40 (78.4%) cases, respectively; on T2-weighted imaging (T2WI)/fluid-attenuated inversion recovery (FLAIR), the lesions were iso- and hyperintense in 5 (9.8%) and 46 (90.2%) cases, respectively; and on diffusion-weighted imaging (DWI), the lesions were hyperintense in 48 lesions (94.1%). The apparent diffusion coefficient (ADC) values were low in 31 (60.8%) lesions, isointense in 8 (15.7%), and high in 8 (15.7%). Among the 8 patients (33 lesions) who underwent contrast-enhanced MRI, 18 lesions (54.5%) showed no enhancement, while nodular and ring-like enhancements were observed in 6 (18.2%) and 9 (27.3%) lesions, respectively. Four-year post-discharge follow-up: at discharge, eight patients showed improvement, one was discharged against medical advice, and two died. During the 4-year post-discharge follow-up, five patients were lost, and four developed immune reconstitution inflammatory syndrome (IRIS). Conclusions: MRI provides excellent visualization of intracranial lesions in AIDS patients with CMV encephalitis, and exhibits disease-specific imaging characteristics. Beyond its diagnostic value, MRI serves as a reliable non-invasive tool for the longitudinal monitoring of therapeutic response and immune reconstitution events.