Abstract: Objective To evaluate the value of MR in diagnosis of toxoplasmic encephalitis. Methods A retrospective study of 17 AIDS patients with toxoplasmic encephalitis who underwent MRI examination.MR findings of these patients were described.According to the changes of the central nervous system symptoms after treatment,the cases were divided into two groups,including a group with favorable outcomes(n=10) and another group with poor outcomes(n=7). Results ① Multiple-lesion was a common finding for toxoplasmic encephalitis.② Lesions distributed diffusely,could be detected in both supratentorial and subtentorial areas, and could be most commonly found in both the boundary area of cortex and medulla,and the thalamus-basal ganglia area.③ The majority of lesions presented as nodules,with wide edema.④ Lesions were mainly of hypo intensity on T1WI images and hyper intensity on T2WI images.The opposite signal intensity could be detected in certain lesions with hemorrhage.On contrast enhanced images, the lesions showed ring-like enhancement.Target sign can be detected on T2WI, FLAIR and contrast enhanced images.⑤ Oversize and hemorrhage might be signs for poor outcome according to the statistical analysis(χ2=14.405 and 14.912,respectively,P<0.05). Conclusion MR is important in diagnosis of toxoplasmic encephalitis in AIDS patients,and some signs may indicate poor prognosis.

Key words: Acquired immunodeficiency syndrome, Toxoplasmic encephalitis, Magnetic resonance imaging