Computed tomography aspects of cerebral toxoplasmosis in AIDS

We followed by CT 19 AIDS patients with cerebral toxoplasmosis. Diagnosis of cerebral toxoplasmosis was assessed on radiological and clinical basis, including the therapeutic response. CT allowed to confirm brain lesions (40 lesions in 19 patients) and to follow the evolution with treatment. Analysis of the CT features of these brain lesions permits to define some characteristic findings, though not pathognomonic. These lesions share common characteristics with other granulomatous diseases or with brain abscesses. The most frequently observed features are: target lesions (74%) with contrast enhancement (95%), frequently multiple (53%), associated with a hypodense area of oedema (100%), and responsible for a mass effect (79%). Under treatment, we observed improvement in 89%, resulting either in complete disappearance of the lesions (16%), disappearance of one or more contrast enhancing (46%) or hypodense (6%) areas, or volumetric regression of the hypodensities (50%). We conclude that CT is a good first-step examination for the detection and follow-up of cerebral toxoplasmosis in AIDS patients. MRI, a method with a higher sensitivity but still less accessible, may be considered at the present time as a second-step examination for those patients with solitary lesions on CT, or for symptomatic patients with normal CT.     

Technetium-99m hexamethylpropylene amine oxime leucocyte scintigraphy in the differential diagnosis of cerebral abscesses

The diagnosis of brain abscess is often difficult, as the clinical symptoms are not specific. Computed tomography (CT) and magnetic resonance imaging (MRI) are highly sensitive, but different cerebral lesions, especially neoplasms, can have the same ring-like contrast enhancement. Brain abscess is a severe illness requiring rapid diagnosis to choose the most appropriate therapy. Technetium-99m hexamethylpropylene amine oxime (HMPAO)-labelled leucocyte scintigraphy is commonly used to detect an inflammatory process. The aim of this study was to present the results obtained with leucocyte scintigraphy in 65 patients with intracranial mass lesions and clinical findings compatible to or suggestive of brain abscess. The final diagnosis, based on surgery, clinical findings and stereotatic puncture, was brain abscess in 17 patients, primary brain neoplasm in 22, brain metastasis in 16, lymphoma in 2, cysticercosis in 2, hematoma in 2 and cerebral infarction in 4. 99mTc-HMPAO leucocyte scintigraphy was positive in all abscess cases. The scan was negative in the rest of the patients examined, with the exception of one lesion, which was finally diagnosed as a tumour (1 false-positive). All patients who did not have false-negative scans were treated with steroids. The sensitivity, specificity and diagnostic accuracy of leucocyte scintigraphy was 100%, 97.8% and 98.4%, respectively. In conclusion, in our experience, leucocyte scintigraphy is a valuable aid in the differential diagnosis between abscess and neoplasm.     

Technetium-99m hexamethylpropylene amine oxime leucocyte scintigraphy in the differential diagnosis of cerebral abscesses

The diagnosis of brain abscess is often difficult, as the clinical symptoms are not specific. Computed tomography (CT) and magnetic resonance imaging (MRI) are highly sensitive, but different cerebral lesions, especially neoplasms, can have the same ring-like contrast enhancement. Brain abscess is a severe illness requiring rapid diagnosis to choose the most appropriate therapy. Technetium-99m hexamethylpropylene amine oxime (HMPAO)-labelled leucocyte scintigraphy is commonly used to detect an inflammatory process. The aim of this study was to present the results obtained with leucocyte scintigraphy in 65 patients with intracranial mass lesions and clinical findings compatible to or suggestive of brain abscess. The final diagnosis, based on surgery, clinical findings and stereotatic puncture, was brain abscess in 17 patients, primary brain neoplasm in 22, brain metastasis in 16, lymphoma in 2, cysticercosis in 2, hematoma in 2 and cerebral infarction in 4. ^99mTc-HMPAO leucocyte scintigraphy was positive in all abscess cases. The scan was negative in the rest of the patients examined, with the exception of one lesion, which was finally diagnosed as a tumour (1 false-positive). All patients who did not have false-negative scans were treated with steroids. The sensitivity, specificity and diagnostic accuracy of leucocyte scintigraphy was 100%, 97.8% and 98.4%, respectively. In conclusion, in our experience, leucocyte scintigraphy is a valuable aid in the differential diagnosis between abscess and neoplasm. Received 25 April and in revised form 12 August 1999     

Brain SPECT with 201-thallium in AIDS patients

Brain lymphoma is a late complication in AIDS. Lymphoma incidence is increasing in AIDS patients due to the introduction of HAART and prolongation of these patients' life expectancy. This work aims to evaluate the usefulness of brain SPECT with 201Tl in patients with AIDS who present focal brain lesions in computed tomography (CT).Methods: Seventeen patients with neurologic symptoms and focal neurologic lesions in the CNS (central nervous system) were studied. The images were interpreted as positive when the intensity of the focal deposit of the tracer was greater than that of the adjacent tissue. The SPECT results were compared with serologic data, clinical evolution and/or radiologic follow-up and cerebral biopsy.Results: SPECT images showed focal uptake of radiotracer in 3 patients. All three died shortly after the SPECT was performed. All of them had negative serology for toxoplasmosis. Four patients were diagnosed of progressive multifocal leukoencephalopathy and the ten remaining cases had a good clinical and/or radiologic response.Conclusions: Brain SPECT with 201Tl is a very useful non-invasive technique for the differential diagnosis of cerebral focal lesions in AIDS patients.     

AIDS相关性脑病的18F-FDG PET/CT表现

目的:探讨18F-FDG PET/CT在AIDS相关性脑病中的应用价值.方法:对7例AIDS患者行PET/CT检查,并分析其影像学表现.结果:7例患者分别为弓形体病、弓形体病合并脑结核、胶质瘤、脑囊虫病、脑结核、进行性多灶性白质脑病和周皮细胞瘤.结论:18F-FDG PET/CT可以对AIDS颅内病变行定位、定量、定性...     

Computed tomographic findings in cerebral toxoplasmosis in adults

The clinical and computerized tomographic (CT) findings in 10 patients with cerebral toxoplasmosis are reviewed. All patients with cerebral toxoplasmosis were homosexuals and/or intravenous drug users, and all patients had other manifestations of AIDS. Two presented with focal seizures, 4 presented with focal neurological deficit which progressively worsened, and 4 had evidence of diffuse neurological dysfunction (altered consciousness, generalized seizures). CT showed a single lesion in 3 patients and multiple lesions in 7 patients. Two patients had hypodense nonenhancing lesions(s). Eight patients had hypodense lesions with peripheral or nodular enhancement. The lesions were more commonly located in the cerebral hemispheres and subcortical gray matter nuclear masses (thalamus, basal ganglia). The finding of a hypodense lesion with a central slightly hyperdense noncalcified region that showed dense nodular homogeneous enhancement was quite characteristic of cerebral toxoplasmosis, but this pattern may also be seen in other neurological conditions including brain lymphomas.     

AIDS合并脑内、肺内机遇性感染的影象学诊断研究

目的：研究AIDS合并脑内、肺内机遇性感染的影像表现及其与AIDS确诊的相关性。方法：101例AIDS患中合并脑内(22例)和肺内(24例)机遇性感染均经MRI检查，部分病人还经Gd-DTPA增强及CT扫描。结果：在一些典型的合并脑内机遇性感染患中，CT平扫显示脑实质内多发低密度区，增强后病变呈异常强化、MRI显示两侧大脑自质广泛长T1、长T2异常信号，个别病人伴少量出血，Gd-DTPA增强后，脑实质内病变呈多发环状、螺旋形明显异常强化。在典型的合并肺内机遇性感染患中，CT示右肺大片状高密度区、左侧胸腔内积液。结论：AIDS合并脑内、肺内机遇性感染的影像表现无特异性征象，确诊需靠血清HIV检验。     

Neuroradiologic findings in AIDS: a review of 200 cases

The radiologic studies of 200 consecutive AIDS patients with neurologic symptoms were evaluated to determine their diagnostic specificity and prognostic value. Of 81 patients with initially normal CT scans, four (5%) later developed progressive neurologic illness. Of 75 patients with CT evidence of diffuse cerebral atrophy, 12 (16%) later developed CT abnormalities or had postmortem CNS disease. CT scans showed mass lesions initially in 44 patients and later in an additional seven patients. Although toxoplasma gondii infection was the most frequent cause of these lesions, the CT characteristics of cerebral toxoplasmosis are too nonspecific to warrant diagnosis without biopsy. Preliminary evidence suggests that MRI may be more sensitive than CT in detecting intracranial disease in patients with AIDS.     

Preliminary study of patients with vertigo and dizziness using 123I-IMP

To study the application of cerebral blood flow scintigraphy with 123I-IMP for the evaluation of central dizziness, the difference in 123I-IMP accumulation between the right and left cerebellar hemispheres was determined as an asymmetry index (A.I.) in 8 normal subjects and compared with A.I. from patients with central dizziness. According to estimated lesions, 123I-IMP findings were compared with CT findings. The normal subjects had A.I. of 5.8 +/- 2.1%, whereas 36 patients with central dizziness had A.I. of 12.7 +/- 7.5%. On the basis of an A.I. of 8% or more as an abnormal finding on IMP scintigraphy, 11 of the 14 patients with estimated lesions of cerebellar hemispheres and 16 of the 20 with those of the whole cerebellum including the vermis were evaluated to have had abnormalities. Seven of 11 with estimated lesions of the brainstem and 4 of 5 with vertebrobasilar arterial insufficiency were evaluated to have had abnormalities. The findings of 123I-IMP cerebral blood flow scintigraphy were in good agreement with clinical symptoms in patients with central dizziness with estimated lesions of the cerebellar hemispheres, suggesting the possibility that this method is more useful than CT.     

Lesion size determines accuracy of thallium-201 brain single-photon emission tomography in differentiating between intracranial malignancy and infection in AIDS patients

BACKGROUND AND PURPOSE: Discrimination between enhancing mass lesions in acquired immunodeficiency syndrome (AIDS) patients with conventional CT and MR imaging remains difficult. We determined the effect of lesion size on thallium-201 brain single-photon emission tomography (SPECT) imaging in differentiating primary brain lymphoma from cerebral toxoplasmosis. METHODS: We retrospectively identified 35 AIDS patients with a total of 48 focal enhancing mass lesions on contrast-enhanced brain CT and/or MR images who subsequently underwent thallium-201 brain SPECT imaging. The thallium index of each lesion was evaluated on the basis of the ratio of mean uptake in the lesion compared with the corresponding contralateral side. Receiver operator curves were drawn to determine the optimal thallium index threshold. The effect of lesion size on scan accuracy was evaluated. RESULTS: Malignant lesions in 20 patients had a mean thallium index of 2.4 (range, 1-11). Infectious lesions in 15 patients had a mean thallium index of 1.6 (range, 1-3.6). Twenty-five lesions were <2 cm (14 malignant, 11 nonmalignant) and 23 lesions were > or =2 cm (14 malignant, 9 nonmalignant). Thallium index was not a significant predictor of malignancy in the lesions <2 cm by using the logistic regression (P = .27). Receiver operator curve analysis by using thallium index of 2 in small lesions yielded 50% sensitivity and 82% specificity. In contrast, thallium index was a significant predictor of malignancy in lesions > or =2 cm (P < .01), yielding 100% sensitivity and 89% specificity. CONCLUSION: Lesion size is a significant determinant of the accuracy of thallium-201 brain SPECT imaging, which should be the initial diagnostic tool for lesions > or =2 cm.     

CT and MRI: prognostic tools in patients with AIDS and neurological deficits

Summary To determine the prognostic value of CT and MRI in AIDS we studied the survival of patients with neurological involvement, in relation to the initial imaging results. Twenty-six initial CT and 15 MRI examinations of 41 patients were reviewed for the presence of cerebral atrophy and/or focal lesions. The mean survival time of patients with initially normal imaging was longer (700±89 days) than that of patients with isolated cerebral atrophy (326±65) or isolated focal lesions (202±97). The shortest survival (78±44 days) was found in patients with both cerebral atrophy and focal lesions. The risk of death in patients with focal lesions alone 6.4 times higher, and in patients with both changes 19.3 times higher than in patients with initially normal imaging. Cerebral imaging with CT and/or MRI thus allows identification of AIDS-related cerebral changes and may contribute to assessment of prognosis.     

艾滋病合并新型隐球菌脑膜脑炎的影像学表现

目的:探讨艾滋病合并新型隐球菌脑膜脑炎的影像特点,并与非艾滋病患者新型隐球菌脑膜脑炎作对比分析.方法:回顾分析经病原学证实的12例艾滋病和14例非艾滋病合并新型隐球菌脑膜脑炎患者头颅CT及MRI的表现,比较艾滋病合并新型隐球菌脑膜脑炎与非艾滋病患者新型隐球菌脑膜脑炎的影像差别.结果:艾滋病患者局限性脑水肿和脑内强化病灶明显少于非艾滋病患者(0/10,0/10;4/9,4/7,P<0.05),VR间隙扩大、胶样假囊、脑膜强化和脑积水、脑萎缩两者间无明显差异(P>0.05).结论:艾滋病合并新型隐球菌脑膜脑炎的影像表现与非艾滋病患者新型隐球菌脑膜脑炎相仿,但患者炎症反应的影像表现轻于非艾滋病患者,结合临床有助于艾滋病合并新型隐球菌脑膜脑炎的诊断.     

CT and 99mTc-DMSA scintigraphy in adult acute pyelonephritis: a comparative study

PURPOSE: The aim of this prospective study was to evaluate the relative value of CT and (99m)Tc-DMSA scintigraphy in the diagnosis of acute pyelonephritis (APN) in adult patients suspected of having urinary tract infection. METHOD: The study was conducted in 36 patients presenting with symptoms suggestive of urinary tract infection. Plain B-mode sonography, CT with contrast medium, and (99m)Tc-DMSA scintigraphy of the kidneys were performed in all patients. Both CT and (99m)Tc-DMSA scintigraphy were performed within 72 h after admission. RESULTS: Twelve patients with clinical and biological signs of urinary tract infection had no CT or (99m)Tc-DMSA scintigraphy abnormalities. Among these patients, lower urinary tract infection was found in 10 patients and 2 patients had ureteral obstruction. In the 24 remaining patients, the diagnosis of APN was made. Among these patients, a correlation was found between CT and (99m)Tc-DMSA scintigraphy in 11 cases. In two cases, both examinations were normal, and in nine cases, both were abnormal. In 11 cases of the 13 remaining patients, abnormal CT was found with normal (99m)Tc-DMSA scintigraphy, whereas the 2 last cases had normal CT and abnormal (99m)Tc-DMSA scintigraphy results. In two cases, bilateral lesions found on CT manifested as unilateral abnormalities on (99m)Tc-DMSA scintigraphy images. CONCLUSION: The diagnosis of APN in adult patients is based on clinical presentation and biological findings. Few studies have compared (99m)Tc-DMSA scintigraphy with CT in the detection of parenchymal involvement in APN. We conclude that CT is more accurate than (99m)Tc-DMSA scintigraphy in the detection of APN lesions in adult patients.     

艾滋病脑内合并机遇性感染的影像学诊断

目的研究艾滋病（AIDS）合并脑内机遇性感染的影像学表现，评估CT，MRI对脑内机遇性感染的诊断能力。方法56例AIDS合并脑内机遇性感染的病人均通过CT和MRI检查，25例又经GD—DTPA增强扫描。结果56例AIDS出现脑内机遇性感染的影像表现，其中，脑弓形体感染8例，病毒性脑炎2例，结核瘤2例，结核性脑膜炎2例，隐球菌感染脑膜炎和脑脓肿2例，梅毒瘤4例．淋巴瘤3例，脑白质脱髓鞘病4例，脑梗死13例，脑萎缩4例，HIV脑动脉血管狭窄、痉挛8例，上颌窦炎3例，右侧额叶囊肿伴Veger腔形成1例。结论AIDS合并脑内机遇性感染的影像表现有一定特点，CT和MRI扫描对颅内机遇性感染的诊断有重要意义，但在临床定性诊断时需要结合实验室检测和组织活检。     

Prognostic value of FDG-PET in malignant lymphoma.

Lymphomas have represented an indication for nuclear medicine investigations for 30 years. Gallium-67 scintigraphy has been shown to be a valuable complementary method in Hodgkin's disease and non-Hodgkin lymphoma for detecting viable residual lesions after chemotherapy and for diagnosis of a relapse. Thallium-201 is of interest in differentiating cerebral lymphomas from infectious lesions in AIDS patients but less useful in extra-cerebral lymphomas. PET with fluorine-18-FDG is more accurate than 67Ga in lymphoma. In patients with a positive PET scan after chemotherapy an early relapse occurs in up to 100%, while more than 80% of patients with a negative PET will have a long-term remission. Most studies show that FDG-PET is significantly correlated with patient outcome whereas there is much weaker or even no correlation for CT. The main reason is that PET is not bound to morphological criteria like lymph node size while CT is often not able to differentiate between residual tumour and post-therapeutic fibrosis. Therefore, based on a considerable number of clinical studies, FDG-PET gains increasing significance for staging, restaging and therapy monitoring in malignant lymphomas.     

艾滋病并发脑感染的CT表现

目的探讨艾滋病病毒中枢神经系统感染的影像学特征及诊断。方法对14例确认艾滋病合并中枢神经系统感染患者的CT影像进行分析。结果艾滋病脑炎10例,均无占位效应。脑萎缩现象5例,其中2例单独存在,3例与病灶并存。平扫病变呈片状低密度,以脑白质受累为主;6例累及双侧多个脑叶,分布不对称;2例位于左脑。其中2例增强无强化。巨细胞病毒感染1例,平扫两枕叶见片状低密度,对称分布。弓形体脑病3例,2例见等密度灶并周围水肿,1例显示脑脓肿征象。结论根据CT影像特征,结合流行病学询问,可提出本病疑似诊断。     

粘多糖贮积症的颅脑CT及MRI表现

目的:探讨粘多糖贮积症的颅脑CT及MRI表现特征.方法:对经临床和实验室检查确诊为粘多糖贮积症的6例患者行颅脑CT及MRI扫描,分析其影像学表现.6例患者均行CT平扫,其中2例行CT增强扫描;6例患者中4例行MRI检查,其中1例行增强扫描.结果:CT平扫6例中4例显示两侧大脑半球白质内散在低密度灶,增强后病灶未见强化;1例仅见脑室扩大,1例未见异常.MRI检查4例中2例显示脑实质多发小囊状信号由脑室边缘向各脑叶呈放射状分布,脑白质病变呈斑片状长T1、长T2信号,增强后所有脑内病灶均未见强化;1例脑室扩大,白质减少;1例仅显示脑白质信号异常.MRI还显示3例齿状突发育不良伴周围软组织增厚,2例颅颈结合区硬脑脊膜增厚伴椎管狭窄.本组1例行脑组织活检,电镜显示神经元内有空泡状包涵体及斑马体.结论:粘多糖贮积症的颅脑CT及MRI表现有一定特征,可在一定程度上为临床诊断、估计病损程度、监察病变进程及选择治疗方案提供依据.     

Equivocal findings on cranial CT but apparent cerebral lesion(s) on conventional radionuclide imaging

Four patients with different disease entities (multiple cerebral metastases, cerebral infarct, cerebritis, and encephalitis) in whom x-ray computed tomography was either equivocal or negative showed apparent cerebral lesions by radionuclide studies. Equivocal CTs in the patients with multiple cerebral metastases or cerebral infarction may be attributed to the contraindication of contrast media and/or lack of cooperation during the examination procedure. In patients with cerebritis or encephalitis, radionuclide studies have proven to be more sensitive than CT early in the infectious disease process. In certain circumstances it is clinically beneficial and cost effective to evaluate the patient primarily by radionuclide scintigraphy.     

Primary central nervous system lymphoma: CT and pathologic correlation

CT findings of 15 patients with histologically proven primary central nervous system (CNS) lymphoma were reviewed with pathologic correlation in order to evaluate variable CT patterns. There were a total of 32 lesions. Of the 15 patients studied, seven had acquired immunodeficiency syndrome (AIDS), all diagnosed within the past 3 years. The CT observations of eight non-AIDS patients were consistent with findings reported previously. Most of the lymphomatous lesions were either hyper- or isodense, round or oval masses with homogeneous contrast enhancement and variable surrounding edema. Pathologic examination showed tightly packed preserved lymphoma cells without necrosis. In AIDS patients, rim or ring enhancement of lymphoma, indistinguishable from brain abscess, was frequently seen. Histologic examination consistently showed extensive tumor necrosis with preservation of viable tumor cells at the periphery. A third and infrequent CT pattern was multiple infiltrative nonnodular solid enhancement with extensive edema. Pathologic correlation showed infiltrating viable tumor cells without necrosis. The rim- or ring-enhancing brain lesion seen in AIDS patients can either be an abscess or a primary lymphoma; proper tissue collection is essential for correct diagnosis and appropriate treatment.     

AIDS脑部病变影像学表现分析

目的总结AIDS脑部病变影像学表现,为AIDS脑部病变的影像诊断提供依据。方法回顾性分析19例神经系统型AIDS患者脑部CT和MRI表现。结果5例HIV脑炎中,3例表现为双侧大脑半球白质区对称性异常信号,2例表现为脑萎缩。2例弓形体脑炎影像学表现为基底节区和额顶叶多发密度或/和信号异常,增强T1WI呈多发环状高信号。3例脑淋巴瘤分别表现为双侧大脑半球单发或多发结节,周围伴水肿,增强T1WI呈结节状或不均匀强化。3例脑梗塞表现为基底节区局限性低密度影。2例进行性多灶性白质脑病表现为额顶叶脑白质区多发斑片状异常信号。1例霉菌感染表现为脑干信号异常,增强T1WI呈环状强化;1例霉菌性脑膜炎和2例单纯颅内压增高患者,影像学无异常表现。结论CT和MRI检查可以发现大部分AIDS脑部病变,并可根据影像学表现和其它相关检查做出定性诊断。