CT Findings Of The Brain Lesions In AIDS

Objective:To investigate the clinical manifestations and CT findings of the brain lesions in AIDS in order to improve the skills of their diagnosis and differential diagnosis.Methods:Retrospectively analyzed the clinical informations and imaging findings of the brain lesions in 72 cases with AIDS, which all cases were given plane CT scan while 12 cases had CT enhancement scan. Compared CT positive rate, CT features, and their relation to CD4+T lymphocytes among different brain lesions. In addition, studied the mortality rate in different cerebral changes by group comparison.Results:1.39 cases had abnormal CT pictures in 72 patients with AIDS. Among the abnormal CT findings, there were 10 cases with HIV encephalitis,6 with toxoplasmic encephalopathy,4 with cryptococcal meningitis, and 19 with tuberculous meningitis. The incidence rates of CT abnormalities were different in different disorders (P=0.03).2. CT changes and comparison of the brain lesions in AIDS included (1) 3 cases of low signal intensity in 10 HIV encephalitis patients, and no positive findings in one CT enhancement scan; 2 of enlargement of ventricular system; 7 of cerebral atrophy with obvious enlargement of sulcus, cisterna, and cerebral fissure, among them 5 cases with large subarachnoid cavity while only 2 with sucus widened. (2) 6 cases with toxoplasmic encephalopathy were given both plane and enhancement CT scan.6 pictures with low signal intensity in plane CT,3 of bluring border while 3 of clear border were detected; 4 cases of circular changes were found in enhancement CT scan; 5 with mass effect and 1 with enlargement of ventricular system were discovered. (3) In 4 cases of cryptococcal meningitis, CT pictures showed 1 of low signal intensity,1 of enlargement of lateral ventricle and the third ventricle (hydrocephalus),2 of cerebral atrophy, and 1 with both narrow ventricle and sulcus, cisterna disappeared (cerebral hernia). (4) In 19 cases of tuberculous meningitis, CT changes included 12 of low signal intensity,2 of mass effect, 3 of enlargement of ventricular system,4 of hydrocephalus, and 5 of clear border. There were 2 cases with meningeal enhancement and 1 with circular enhancement among 5 cases of CT enhancement scan. Comparison of CT findings in different brain lesions:(1) Low signal intensity:the incidence rate of toxoplasmic encephalopathy was higher than that of HIV encephyalitis(P=0.011). (2) Mass effect:the incidence rate of toxoplasmic encephalopathy was higher than that of HIV encephyalitis(P=0.001); the incidence rate of toxoplasmic encephalopathy was higher than that of tuberculous meningitis (P=0.002). (3) Cerebral atrophy:the incidence rate of HIV encephalitis was higher than that of toxoplasmic encephalopathy (P=0.011); the incidence rate of HIV encephyalitis was higher than that of tuberculous meningitis (P=0.000); the incidence rate of cryptococcal meningitis was higher than that of tuberculous meningitis (P=0.024).3. The relationship between opportunistic infections and the brain lesions of AIDS, reduction of CD4+T lymphocyte count and HIV encephalitis were found close. When CD4+T lymphocyte count decreased to less than 200/μl, the infections occurred in a higher morbidity rate. There was statistically significant difference of CD4+T lymphocyte count between tuberculous meningitis and the other disorders (Z=-2.784, P=0.005).4. The mortality rate was high in AIDS victims at the advanced stage.10 of 39 cases suffering from AIDS had died during hospitalization. There was no statistically significant difference of death rate between the group of AIDS accompanied by tuberculous meningitis and that of non-tuberculous disorders (P=0.716).Conclusion:1. CT findings of the brain lesions in AIDS include low signal intensity, mass effect, enlargement of ventricular system, hydrocephalus, circular enhancement, enhancement of meninges, cerebral atrophy, etc. These pictures occurred singly or together. The most common change was low signal intensity.2. The morbidity rate of AIDS accompanied by the brain lesions increased greatly with the reduction of CD4+T lymphocyte count. When CD4>100/μl,<200/μl, tuberculous infection was common while toxoplasmic and cryptococcal opportunistic infections occurred if CD4<50/μl.3. The mortality rate was extremely high in AIDS patients accompanied by cerebral infection, esp. presented with imaging abnormalities. Accordingly, it is extraordinary important to increase the imaging diagnostic level of AIDS with HIV encephalitis and opportunistic infections.