Objective: To review the magnetic resonance imaging (MRI) features and explore the histopathological basis of heroin-associated encephalopathy (HE).
Methods: The data were collected from 34 established HE cases diagnosed with epidemiological evidence, clinical manifestations, MRI findings and laboratory examination. Histopathological sections were obtained in 10 cases. All patients were examined with T1WI, T2WI and FLAIR using 1.5T MRI scanner. Four patients died and autopsy was performed in 2 of them. Eight patients underwent stereotactic cerebral biopsy and the results of pathological examination were compared with the MRI findings.
Results: All the 34 cases had low signals in T1WI but high signals in T2WI. Extensive involvement of the hemispheres beyond the cerebellar tentorium, brain stem and cerebellum was identified in 85.3% of the cases, and less than 10% had lesions involving only one of these three structures. Most of the lesions involved mainly the white matter, and 91.2% of the cases showed involvement of the bilateral hemispheres. Specific MRI features were found to help in HE diagnosis: lesions compromising the hemispheres beyond the cerebellar tentorium presented with the pattern resembling the Chinese character "eight", a hollow pattern was found in brain stem involvement, and "butterfly wing" pattern in cerebellar involvement. The abnormal signals were caused mainly by demyelination and vacuole formation in the white matter, and these vacuoles resulted in the sponge-like appearance of the white matter containing fluid.
Conclusion: MRI can provide strong evidence for HE diagnosis and can be informative of the involvement, position and aggravation of the lesions with some characteristic MRI features. In most of the cases, a MRI-based diagnosis can be consistent with histopathological diagnosis.