Pre- and posttreatment MR imaging findings in lead encephalopathy

A 41-year-old man suspected of having lead poisoning was evaluated with MR imaging before and after British antilewisite therapy. The MR imaging findings showed bilateral symmetric involvement of the occipital lobe, affecting predominantly the gray-white matter junction and the subcortical white matter. A right cerebellar lesion was noted, with focal hyperintensities involving the gray-white matter. Similar lesions were seen in the temporal, parietal, and frontal regions. These lesions resolved after chelation therapy.     

Diffusion-weighted MR imaging findings of acute necrotizing encephalopathy

Multiple, symmetrical brain lesions affecting the bilateral thalami and cerebral white matter, which often show a concentric structure on CT and MR images, characterize acute necrotizing encephalopathy (ANE) of childhood. We describe the imaging findings of a 2-year-old child with ANE obtained with diffusion-weighted MR imaging. We discuss the significance of these findings, as well as the pathophysiology of ANE lesions, with reference to the appearance of the disease as revealed by diffusion-weighted MR imaging.     

MR findings in Hashimoto encephalopathy

A 35-year-old Korean woman had Hashimoto encephalopathy of varying MR imaging appearance over 5 years that ranged from that of transient subcortical ischemia to that of gradually evolving multifocal signal intensity change accompanied by unilateral cerebellar atrophy. Thus, the MR imaging appearance of Hashimoto encephalopathy may simulate an ischemic stroke, multiple tumors or granulomas, or even a degenerative process.     

MR imaging of metronidazole-induced encephalopathy: lesion distribution and diffusion-weighted imaging findings

BACKGROUND AND PURPOSE: MR imaging features of metronidazole-induced encephalopathy (MIE) have not been fully established. This study was undertaken to determine the topographic distributions and diffusion-weighted imaging (DWI) findings of MIE. MATERIALS AND METHODS: We retrospectively evaluated the initial MR images (n = 7), including DWI (n = 5), and follow-up MR images (n = 4) after drug discontinuation in 7 patents with clinically diagnosed MIE. The topographic distributions of lesions were evaluated on MR images, and DWI signal intensities and apparent diffusion coefficient (ADC) values of the lesions were assessed. RESULTS: MR images demonstrated bilateral symmetric T2 hyperintense lesions in the cerebellar dentate nucleus (n = 7), midbrain (n = 7), dorsal pons (n = 6), medulla (n = 4), corpus callosum (n = 4), and cerebral white matter (n = 1). Brain stem lesions involved the following: tectum (n = 5), tegmentum (n = 4), red nucleus (n = 3) of the midbrain, vestibular nucleus (n = 6), and a focal tegmental lesion involving the superior olivary nucleus (n = 6) and abducens nucleus (n = 4) of the pons and vestibular nucleus (n = 4) and inferior olivary nucleus (n = 1) of the medulla. DWI (n = 5) showed isointensity or hyperintensity of lesions, and the decreased ADC value was found only in the corpus callosum lesions (n = 2). All detected lesions were completely reversible at follow-up except for the single corpus callosum lesion with an initial low ADC value. CONCLUSION: Brain lesions were typically located at the cerebellar dentate nucleus, midbrain, dorsal pons, medulla, and splenium of the corpus callosum. According to DWI, most of the lesions in MIE probably corresponded to areas of vasogenic edema, whereas only some of them, located in the corpus callosum, corresponded to cytotoxic edema.     

Subcortical arteriosclerotic encephalopathy: brain stem findings with MR imaging

Magnetic resonance images of 44 patients who had varying degrees of supratentorial signal abnormalities compatible with subcortical arteriosclerotic encephalopathy (SAE) were reviewed for posterior fossa findings. Brain stem lesions frequently accompanied supratentorial SAE and were seen as multiple, fairly symmetric areas of poorly defined, increased signal intensity on axial T2-weighted images. Involvement was generally confined to the central portions of the mid and upper pons. The typical appearance of brain stem involvement by SAE and its probable pathogenesis are reviewed.     

Human fascioliasis: MR imaging findings of hepatic lesions

Our objective was to describe MR imaging findings of liver lesions in human fascioliasis. The MR imaging of the liver was performed in 29 patients with fascioliasis. Seventeen patients were women and 12 were men, with a mean age of 47.5 years (age range 17–75 years). Hepatic lesions were grouped into five types based on their signal characteristics. Three patients had normal imaging findings. One or more lesions were observed in the other 26 patients. The lesion types and the frequency of appearances were as follows: hyperintensity of the liver capsule on T2-weighted images (n=16, 55.2%); ill-defined slightly hyperintense areas on T2-weighted images (n=18, 62.1%); lesions which were hypointense on T1-weighted and hyperintense on T2-weighted images (n=10, 34.5%); hypointense on T1-weighted images and centrally hypo- or hyperintense, surrounded by peripherally less hyperintense area on T2-weighted images (n=4, 13.8%); and hypointense foci or ill-defined hypointense areas on T1- and T2-weighted images (n=10, 34.5%). We describe the MR imaging features of the disease. Our findings may help the differential diagnosis in which fascioliasis should be added to the list. Electronic Publication     

Nontumorous hepatic arterial-portal venous shunts: MR imaging findings

PURPOSE: To determine the magnetic resonance (MR) imaging findings of small nontumorous hepatic arterial-portal venous (arterioportal) shunts in the liver. MATERIALS AND METHODS: MR images in 25 patients with 38 small nontumorous arterioportal shunts verified with surgery or follow-up imaging were included in this study. The causes of arterioportal shunts were iatrogenic causes in 11 patients and/or cirrhotic changes in the remaining patients. Nonenhanced T1- and T2-weighted images and multiphase contrast material-enhanced dynamic images were retrospectively reviewed and compared with conventional hepatic arteriograms to determine the MR characteristics related to the focal hemodynamic changes. RESULTS: On arterial-dominant-phase dynamic MR images, 29 (76%) of the 38 arteriographically suggested nontumorous arterioportal shunts displayed abnormal findings distinguished against the surrounding hepatic parenchyma, including wedge-shaped (n = 14), nodular (n = 9), or irregularly outlined (n = 6) areas of focal contrast enhancement. The signal intensity on nonenhanced T1- and T2-weighted images of the corresponding areas appeared unremarkable except for three wedge-shaped high-signal-intensity areas (three [8%] of 38) on T2-weighted images accompanied by prolonged contrast enhancement. Most (24 [83%] of 29) areas of abnormal signal intensity were located at the periphery of the liver parenchyma. CONCLUSION: A small nontumorous arterioportal shunt should be considered one of the causes of focal parenchymal hyperperfusion abnormalities on contrast-enhanced dynamic MR images of the liver in the absence of abnormal signal intensity on static MR images.     

MR脑血流灌注成像在亚临床肝性脑病中的应用

目的用MR灌注成像技术评价亚临床肝性脑病(SHE)患者的脑血流灌注模式。方法对12例经神经心理试验诊断为SHE的患者和10例年龄和教育程度相匹配的健康志愿者进行MR平扫和灌注成像,分别测量双侧尾状核头、苍白球、壳核、丘脑和额叶白质的脑血容量(CBV)、脑血流量(CBF)和平均通过时间(MTT),并以同侧额叶脑白质作为参照进行统计分析。结果SHE患者各感兴趣区与白质的比值:CBV值分别是1.32±0.25、1.19±0.46、1.51±0.20、1.69±0.53;CBF值分别为1.64±0.50、1.61±0.65、2.06±0.61、2.23±0.75;MTT值分别是0.83±0.17、0.76±0.20、0.78±0.19、0.78±0.17。志愿者相应部位CBV值为1.32±0.33、1.02±0.29、1.44±0.37、1.66±0.57;CBF值为1.36±0.24、1.08±0.28、1.55±0.51、1.58±0.64;MTT值为0.95±0.18、0.91±0.19、0.93±0.15、0.93±0.13。SHE患者较正常组MTT明显缩短,双侧丘脑、右侧尾状核头达到统计学意义的降低(P<0.05);CBF明显升高,左侧苍白球达到统计学意义的升高(P<0.05);CBV无明显变化。结论SHE患者基底节区灌注增加是血流从皮质到基底节区的重新分布,这是对运动前区、运动区功能缺陷及注意力缺陷的代偿反应,与皮质-基底节-丘脑-皮质环路密切相关。     

Primary hepatic angiosarcoma: findings at CT and MR imaging

PURPOSE: To evaluate and describe cross-sectional imaging findings in patients with pathologically confirmed primary hepatic angiosarcoma. MATERIALS AND METHODS: Findings from imaging examinations in 13 patients with pathologically confirmed primary hepatic angiosarcoma were retrospectively reviewed (computed tomographic [CT] images obtained in 10 patients and magnetic resonance [MR] images obtained in five patients were available for review). Two gastrointestinal radiologists evaluated lesion number, size, attenuation and signal intensity characteristics, and the pattern and degree of contrast material enhancement. Medical records were reviewed for clinical features associated with angiosarcoma. RESULTS: Angiosarcoma appeared as multiple nodules (n = 6), as dominant masses (n = 6), or as a diffusely infiltrating lesion (n = 1). Multiple nodules were hypoattenuating at unenhanced and contrast material--enhanced CT (six of six patients). When dominant masses were encountered at MR imaging, T2-weighted MR imaging demonstrated heterogeneous internal architecture (four of four patients) similar to that of hepatocellular carcinoma. Multiphase contrast-enhanced CT and MR images showed dominant masses to have heterogeneous and progressive enhancement (three of three patients). Clinical features associated with angiosarcoma included splenic metastases (six of 13 patients), thrombocytopenia (seven of 13 patients), disseminated intravascular coagulation (four of 13 patients), and hemolytic anemia (three of 13 patients). CONCLUSION: Primary hepatic angiosarcoma exhibits a spectrum of appearances that reflect its varied pathologic features.     

Solitary hepatic infantile hemangioendothelioma: dynamic gadolinium-enhanced MR imaging findings

We report the MRI findings of a solitary hepatic infantile hemangioendothelioma (IHE) diagnosed in a 14-day-old girl. To the best of our knowledge, only one report has illustrated the dynamic gadolinium-enhanced MR imaging features of IHE previously. Compounding the rarity of presentation as a solitary mass, the gadolinium-enhanced MRI appearance in our case is unique, because the IHE showed an early rim-like pseudocapsular enhancement followed by progressive fill-in of the lesion on delayed imaging.     

高血压脑病发病机制及相关MRI表现

高血压脑病（hypertensive encephalopathy ,HE）是内科较为常见的急症,常发生在重症高血压患者,其发病机制目前较为公认的主要有血管痉挛学说和脑血管自动调节功能崩溃学说。M RI在高血压脑病诊断、鉴别诊断、疗效观察及预后评定中有重要帮助,以下主要通过 M RI不同成像技术方法,包括常规平扫、弥散加权成像、磁共振血管成像（MRA）、磁共振波谱成像（MRS）、磁共振增强扫描、磁共振灌注成像（PWI）及磁敏感成像（SWI）,综合起来阐述该病各有何种表现,就其相关临床发病机制予以综述。     

Diffusion MR findings in cyclosporin-A induced encephalopathy

Cyclosporin encephalopathy is a well-known entity, which is clinically characterized by altered mental status, vision problems, focal neurological deficits and seizures. The exact pathophysiology of the cyclosporin encephalopathy has not yet been defined. We report the diffusion-weighted MR imaging and proton MR spectroscopy findings in a case of cyclosporin encephalopathy. The white-matter lesions with reversible restricted diffusion supported the hypothesis of reversible vasospasm induced by the cyclosporin.     

Hypertensive encephalopathy: findings on CT, MR imaging, and SPECT imaging in 14 cases.

Hypertensive encephalopathy is a syndrome consisting of headache, seizures, visual changes, and other neurologic disturbances in patients with elevated systemic blood pressure. The purpose of this study was to analyze the imaging findings in 14 patients with hypertensive encephalopathy. CT (n = 13), MR (n = 12), and single-photon emission computed tomography (n = 2) examinations performed in these patients before and after resolution of symptoms were reviewed. Eight had the preeclampsia-eclampsia syndrome, and six had hypertensive encephalopathy due to other causes. CT and MR findings in all patients having these examinations were indicative of edema in the cortex and subcortical white matter in the occipital lobes. Two of the 14 patients also had similar findings in the cerebellum and frontal lobes. Single-photon emission computed tomography showed increased vascular perfusion adjacent to areas that appeared abnormal on CT and MR. The findings on the imaging studies resolved on follow-up examinations performed after the hypertension was corrected. Our results suggest that the radiologic findings associated with hypertensive encephalopathy may be useful in establishing the diagnosis in the appropriate clinical setting.     

Wernicke encephalopathy: MR findings in five patients

Wernicke encephalopathy is a disease usually related to chronic alcoholism. The clinical diagnosis is often difficult to establish, and CT is unable to provide specific findings. MR follow-up studies in five patients affected by Wernicke encephalopathy were performed with the aim of establishing the sensitivity of MR in depicting the typical diencephalic/mesencephalic lesions. All subjects had MR imaging in the acute phase of the disease and were reexamined 6-12 months later, at which time they were in good health. Three of them also had CT scanning. On MR, hyperintense areas seen surrounding the third ventricle and aqueduct during the acute phase of the disease had disappeared or diminished on follow-up evaluations. The third ventricle and aqueduct were dilated. We suggest that these findings reflect the natural evolution of Wernicke encephalopathy. The MR findings in Wernicke encephalopathy enable early diagnosis of the disease, which has a positive effect on both treatment and prognosis.     

Wernicke encephalopathy: MR findings in two patients

Wernicke encephalopathy is a serious neurologic disorder caused by vitamin-B1 or thiamine deficiency. In the literature the characteristic symmetric paraventricular lesions of Wernicke encephalopathy are hyperintense on T2-weighted sequences spin-echo (SE) and enhance on T1-weighted SE sequences after intravenous gadolinium administration in the acute phase. We present two patients in the acute phase of Wernicke encephalopathy with special reference to the MR imaging. One of our reported cases is special because of the MR demonstration of a hemorrhagic focus in the caput of the right nucleus caudatus. The other case demonstrates no enhancement on SE T1-weighted sequences after intravenous gadolinium administration. Received: 1 July 1998; Revision received: 19 January 1998; Accepted: 20 January 1998     

Wernicke encephalopathy: MR findings in five patients

Wernicke encephalopathy is a disease usually related to chronic alcoholism. The clinical diagnosis is often difficult to establish, and CT is unable to provide specific findings. MR follow-up studies in five patients affected by Wernicke encephalopathy were performed with the aim of establishing the sensitivity of MR in depicting the typical diencephalic/mesencephalic lesions. All subjects had MR imaging in the acute phase of the disease and were reexamined 6-12 months later, at which time they were in good health. Three of them also had CT scanning. On MR, hyperintense areas seen surrounding the third ventricle and aqueduct during the acute phase of the disease had disappeared or diminished on follow-up evaluations. The third ventricle and aqueduct were dilated. We suggest that these findings reflect the natural evolution of Wernicke encephalopathy. The MR findings in Wernicke encephalopathy enable early diagnosis of the disease, which has a positive effect on both treatment and prognosis.     

Lead encephalopathy: CT and MR findings

Lead is toxic to many organ systems, among them bone marrow, muscles, kidneys, endocrine glands, joints, and nervous system. Encephalopathy is a rare but severe complication of lead poisoning. Lead toxicity is much less common in adults. Adult lead poisoning results primarily from exposure by inhalation in the workplace. In this report, two cases of adult toxic encephalopathy due to lead poisoning are presented with CT and MR findings.     

Cirrhosis: Multiobserver analysis of hepatic MR imaging findings in a heterogeneous population

To investigate the magnetic resonance (MR) imaging findings of hepatic cirrhosis and the potential of MR imaging in differentiating cirrhosis from other hepatic abnormalities, three observers with different levels of expertise in MR imaging (specialist, experienced radiologist, and novice with special training) reviewed hepatic MR imaging examinations of 52 patients with biopsy-proved presence (n = 29) or absence (n = 23) of cirrhosis. All examinations included motion-compensated T1-weighted, T2-weighted, and flow-sensitive gradientecho images. For all three observers, linear signal irregularity was more accurate than other findings. For the final diagnosis of cirrhosis, the specialist was most sensitive (76% at high threshold, 97% at low threshold), followed by the novice with special training (31% and 79%, respectively). Specificity was 100% for all observers at high threshold and 78%, 96%, and 87% for expert, experienced, and trained novice observers, respectively, at low threshold. Sensitivity did not vary regardless of severity of fibrosis, as determined independently by a hepatopathologist. MR imaging has the potential of offering a comprehensive noninvasive evaluation of patients with suspected cirrhosis, but considerable expertise is required at present.