艾滋病合并脑内寄生虫感染的临床及影像表现

Clinical and imaging manifestations of AIDS complicated with intracerebral parasitic infection

HIV是一种嗜神经病毒,HIV感染的T淋巴细胞可通过血脑屏障进入中枢神经系统内,作用于少突胶质细胞,破坏其所支持的髓鞘,形成严重的多阶段性脱髓鞘病变,如HIV脑炎导致的AIDS痴呆综合征和进行性多灶性白质脑病。HIV感染后,人体免疫系统遭到严重破坏,导致患者对在健康人本来无害的一些致病微生物和寄生虫呈高度易感性,即产生机遇性感染。如AIDS合并弓形虫脑病,人感染后多呈隐性感染,在免疫功能低下的AIDS病人宿主中,弓形虫直接引起中枢神经系统损害,诊断与治疗不及时且病死率高。艾滋病合并弓形虫脑病的MRI表现特点主要包括:(1)弓形虫脑病的发病部位以额叶、基底节及丘脑和脑干为主,而脑室、脑室管膜很少受侵;(2)颅内见多发病灶,其形态以类圆形或结节状为主;(3)病灶的MRI信号主要表现为T1WI低信号,如果病灶T1WI出现高信号,考虑为病灶内少量出血的可能;T2WI多为高信号;增强后病灶的强化形式主要表现为环形强化、花瓣样和结节样强化。磁共振T1WI增强后的"靶征"具有一定的诊断意义。

HIV is a neurotoxic virus. HIV-infected T lymphocytes can enter the central nervous system through the blood-brain barrier and target oligodendrocytes and damage its support of the myelin sheath. This reaction will cause serious multi-stage demyelinating lesions,such as HIV encephalitis caused by AIDS dementia syndrome and the development of multi-focal white matter encephalopathy. After HIV infection,the human immune system has been severely damaged which will trigger opportunistic infections,resulting in healthy people who were not sensitive to some pathogenic microorganisms and parasites become highly susceptible. Such as AIDS combined with toxoplasmosis encephalopathy,it normally causes recessive infection. Among the AIDS patients with low immune function,toxoplasmosis directly caused the central nervous system damage and due to the delayed diagnosis and treatment,the fatality rate is high. The MRI features of AIDS complicated with toxoplasmosis mainly include:(1)The most of pathogenic sites are the frontal lobe,basal ganglia,thalamus and brainstem,while ventricular and ventricular tubular membranes are rarely invaded.(2) The morphology of intracranial lesions is mainly circular or nodular.(3)The MRI signal of lesion is mainly T1WI low signal. If there is a high signal in the lesion T1WI,there is a possibility of a small amount of bleeding in the lesion; T2WI is mostly high signal,and the enhanced form of developed lesion is mainly manifested as annular reinforcement,petal-like and nodule enhancement. As a result,the "target sign" after the enhancement of magnetic resonance T1WI signal has certain diagnostic significance..