MR of aqueductal stenosis: evidence of a broad spectrum of tectal distortion

The MR scans of 18 patients with nontumoral aqueductal stenosis and six patients with neoplastic stenosis of the aqueduct were reviewed in order to document and understand the variable appearance of the aqueduct and periaqueductal region on MR. The mesencephalic tectum is often distorted in patients with benign aqueductal narrowing. This distortion results in a number of different MR appearances ranging from an elongated and thin to a short and broad tectum. When compressed by a dilated suprapineal recess, the distorted tectum is sometimes difficult to differentiate from the bulbous enlargement caused by a tectal glioma. Patients in whom distortion of the tectum is the result of hydrocephalus and aqueductal stenosis should be recognized to avoid unnecessary diagnostic procedures and misdiagnosis.     

Tectal tumors of childhood: clinical and imaging follow-up.

PURPOSEThis study was done to determine which clinical and imaging findings best correlate with outcome in children with tectal tumors.METHODSA retrospective review was done of the medical records and imaging studies of 32 children (16 boys and 16 girls; mean age, 8 years) with tectal tumors. Eight children had CT, 11 had MR imaging, and 13 had both CT and MR studies. Findings from surgical and pathologic reports as well as from follow-up examinations (mean follow-up period, 5 years; range, 3.6 months to 17 years) were included in the review.RESULTSAll patients had hydrocephalus and all but one required CSF diversion. The tectum was the center of the tumor in all cases and the majority of the tumors appeared isodense on CT scans, isointense on T1-weighted MR images, and hyperintense on T2-weighted images. Twenty patients required no further treatment. In this group, the mean maximum tumor diameter was 1.8 cm and enhancement occurred in two cases. At follow-up, 18 patients had stable tumor size, one had an increase in tumor size with cyst formation but no worsening of symptoms, and one had a decrease in tumor size. Twelve patients required further treatment (excision and/or radiotherapy) because of progression as indicated by either increased tumor size or worsening of symptoms. In this group, the mean maximum tumor diameter was 2.5 cm and contrast enhancement occurred in nine cases. Further follow-up in this group showed decreased tumor size in eight and stable residual tumor in three.CONCLUSIONTectal tumors in childhood have variable behavior. MR imaging assists in the clinical determination of which children need treatment beyond CSF diversion. Larger tumor size and enhancement are radiologic predictors of the need for further treatment.     

Wernicke encephalopathy: MR findings at clinical presentation in twenty-six alcoholic and nonalcoholic patients

BACKGROUND AND PURPOSE: Wernicke encephalopathy is a severe neurologic disorder that results from a dietary vitamin B1 deficiency. It is characterized by changes in consciousness, ocular abnormalities, and ataxia. This study was undertaken to analyze and compare findings on MR imaging and neurologic symptoms at clinical presentations of patients with Wernicke encephalopathy with and without a history of alcohol abuse. MATERIALS AND METHODS: A multicenter study group retrospectively reviewed MR brain imaging findings, clinical histories, and presentations of 26 patients (14 female, 12 male) diagnosed between 1999 and 2006 with Wernicke encephalopathy. The age range was 6-81 years (mean age, 46 .6+/-19 years). RESULTS: Fifty percent of the patients had a history of alcohol abuse, and 50% had no history of alcohol abuse. Eighty percent showed changes in consciousness, 77% had ocular symptoms, and 54% had ataxia. Only 38% of the patients showed the classic triad of the disease at clinical presentation. At MR examination, 85% of the patients showed symmetric lesions in the medial thalami and the periventricular region of the third ventricle, 65% in the periaqueductal area, 58% in the mamillary bodies, 38% in the tectal plate, and 8% in the dorsal medulla. Contrast enhancement of the mamillary bodies was statistically positively correlated with the alcohol abuse group. CONCLUSIONS: Our study confirms the usefulness of MR in reaching a prompt diagnosis of Wernicke encephalopathy to avoid irreversible damage to brain tissue. Contrast enhancement in the mamillary bodies is a typical finding of the disease in the alcoholic population.     

MRI of pineal region tumours: relationship between tumours and adjacent structures

A variety of tumours may arise in the pineal region; accurate diagnosis is important in the selection of treatment and prognosis. A retrospective analysis of the MRI studies of 25 patients with pathologically proven pineal region tumours was performed, focused on the relationship between the tumour and neighbouring structures. Compression of the tectal plate was classified as expansive or invasive, and compression of the corpus callosum as inferior, anterior or posterior. In 10 of the 14 patients (71%) with germ cell tumours tectal compression was of the invasive type; 8 patients (57%) had multiple tumours and in 13 (93%) the tumour margins were irregular. Teratomas were readily diagnosed because of characteristic heterogeneous signal intensity. Pineal cell tumours were differentiated from germ cell tumours by their rounded shape, solid nature, sharp margins, and expansive type of tectal compression. Meningiomas were characterised by their falcotentorial attachments, posterior callosal compression, and a low-intensity rim on T2-weighted images. Gd-DTPA injection enabled clear demonstration of the site and extent of tumour spread and was useful in differentiating cystic and solid components. The appearances described, while not pathognomonic, are helpful in the differential diagnosis of pineal region tumours, and valuable in planning appropriate treatment.     

Benign cystic pineal lesions by magnetic resonance imaging

In the course of examining 1,000 patients with various neurological complaints, 17 were found to have abnormalities in the region of the pineal gland. Fourteen had no hydrocephalus or symptoms referable to the region of the midbrain but a well-defined region of the high signal on T2 weighted images was demonstrated on magnetic resonance imaging. The other three patients proved to have pineal tumors. All patients had computed tomography examinations prior to magnetic resonance imaging. We believe that the pineal lesion in the 14 asymptomatic patients is a benign cyst not previously reported prior to the advent of magnetic resonance imaging. These benign lesions should be kept in mind in evaluating masses of the pineal region.     

Arterial hyperintensity on fast fluid-attenuated inversion recovery images: a subtle finding for hyperacute stroke undetected by diffusion-weighted MR imaging

BACKGROUND AND PURPOSE: Diffusion-weighted MR imaging is generally acknowledged to be more sensitive in detecting acute stroke than is conventional MR imaging. Our purpose in the present study was to evaluate the utility of fast fluid-attenuated inversion recovery (FLAIR) MR imaging compared with that of diffusion-weighted MR imaging for the diagnosis of hyperacute stroke. METHODS: We reviewed patient records and cerebral MR images from all patients in a 13-month period from whom diffusion-weighted and fast-FLAIR imaging were obtained within 6 hours after symptom onset (n = 11). Special attention was paid to the presence or absence of arterial hyperintensity on FLAIR images and abnormally high-signal regions on diffusion-weighted images in the affected vascular territories. RESULTS: Arterial hyperintensity was found in eight of 11 patients, all of whom had embolic or thrombotic infarctions with middle cerebral arterial (MCA) distribution. Arterial hyperintensity was negative in the remaining three patients; the vascular territories were the posterior circulation region in two of these patients and the MCA region in one, and the types of infarction in these same patients were lacunar in two and embolic in one. Regions with high-signal diffusion abnormalities relevant to the patients' symptoms were found in 10 of 11 patients. One patient showed no diffusion abnormalities but the presence of arterial hyperintensity in the affected MCA territory on the initial MR examination, and manifested embolic infarction along with arterial hyperintensity on the initial FLAIR image. CONCLUSION: Although diffusion-weighted MR imaging is highly sensitive to stroke, diffusion-weighted MR imaging alone may not rule out a possible infarction. Arterial hyperintensity on FLAIR images can precede diffusion abnormalities and may provide a clue to the early detection of impending infarction.     

MRI findings of Wernicke encephalopathy revisited due to hunger strike

BACKGROUND AND PURPOSE: The purpose of this study was to determine the characteristic magnetic resonance imaging (MRI) findings among a group of patients who presented with Wernicke encephalopathy (WE) due to the neurological complications of a long-term hunger strike (HS). METHODS: MRI studies also including the fluid-attenuated inversion recovery (FLAIR) sequence and diffusion-weighted imaging (DWI) of six male patients with WE aged from 25 to 38 years (mean age 31 years) were evaluated. RESULTS: In all subjects, T2-weighted sequences, FLAIR and DWI revealed a signal hyperintensity within the posteromedial thalami and surrounding the third ventricle. In particular, on coronal images, the hyperintense areas around the third ventricle showed a suggestive "double wing" configuration. We observed an increased signal on proton-density and T2-weighted images in the mamillary bodies of three patients. Four patients demonstrated additional hyperintensities within the periaqueductal region and/or the tectal plate. At least one lesion area in five of six patients demonstrated contrast enhancement. CONCLUSION: The consistent imaging findings of our study suggest that MRI is a reliable means of diagnosing WE. Acute WE is sometimes underdiagnosed, yet early diagnosis and treatment of WE is crucial in order to avoid persistent brain damage. MRI, including postcontrast T1-weighted imaging, DWI beneath standardized T2-weighted imaging, and FLAIR sequences may prove to be a valuable adjunct to clinical diagnosis and to provide additional information in acute and/or subacute WE.     

Aqueduct compression from venous angioma: MR findings.

Vascular compression as the cause of aqueductal stenosis is rare. In a 16-year-old girl with hydrocephalus, MR imaging provided evidence of aqueductal stenosis caused by a venous angioma in the tectum and midbrain. This indicates the usefulness of MR imaging for the evaluation of obstructive hydrocephalus.     

非酒精性Wernicke脑病临床特点及MRI表现

目的探讨非酒精性Wernicke脑病(WE)病人临床特点及MRI表现。方法回顾性分析经临床证实的10例非酒精性WE病人临床特点及MRI表现。结果胃肠道疾病所致反复呕吐、急性胰腺炎及妊娠剧烈呕吐为主要发病诱因。精神或意识改变为最常见临床表现。10例病人中仅1例为单发病灶,余9例均为多部位受累,病变部位包括双侧丘脑内侧及三脑室周围区(8例)、中脑导水管周围区(7例)、中脑顶盖(6例)、乳头体(4例)、四脑室底(4例)、小脑蚓部(1例)。所有病灶均于T2WI或T2FLAIR上呈对称性高信号。8例行DWI扫描,病灶呈高或稍高信号。1例行MRI增强检查,病灶呈轻度强化。4例于治疗后复查颅脑MRI,均见病灶缩小或消失。结论非酒精性WE的颅脑MRI表现具有特征性,结合病史及临床表现有助于做出早期诊断。     

MR imaging of periventricular leukomalacia in childhood

Eight children with clinical and radiologic abnormalities consistent with periventricular leukomalacia were investigated with MR imaging of the brain that employed both inversion-recovery and T2-weighted spin-echo imaging sequences. The more precise delineation of white and gray matter on inversion-recovery images as compared with CT allows a detailed demonstration of the anatomic features of periventricular leukomalacia; specifically, a reduced quantity of white matter in the periventricular region and centrum semiovale and, in more severe cases, cavitated infarcts that replace the immediate periventricular white matter. The T2-weighted spin-echo and short inversion time inversion-recovery images demonstrated abnormally increased signal in white matter that appeared normal on CT scans and only minimally abnormal on conventional inversion-recovery images. These abnormalities most probably represent white matter gliosis that extends beyond the immediate periventricular regions. MR recognition of cerebral white matter abnormalities associated with periventricular leukomalacia may confirm the clinical suspicion of this diagnosis in children with spastic diplegia or quadriplegia.     

Wernicke encephalopathy: MR findings and clinical presentation

Wernicke encephalopathy (WE) is a severe neurological disorder caused by vitamin B1 deficiency. The aim of the study was to analyse MRI findings typical for this disease and to evaluate the significance of their correlations with clinical symptoms. Magnetic resonance images and clinical features of 12 patients with WE were analysed. The patients underwent MR imaging within 3–14 days after onset of clinical symptoms. In 7 of 12 patients MR imaging showed symmetrical diencephalic and midbrain lesions. Postcontrast T1-weighted images from 5 of 9 patients examined during the initial 6 days of acute WE showed a subtle enhancement of the mamillary bodies, the tectal plate, the periaqueductal area and the periventricular region of the third ventricle including the paramedian thalamic nuclei. In addition, T2-weighted and fluid-attenuated inversion recovery (FLAIR) images revealed hyperintense signals in these regions (except for 2 patients where the mamillary bodies were normal). Hyperintense lesions on T2-weighted images without any enhancement on postcontrast T1-weighted images were detected in 2 patients by MR imaging performed 11 or 14 days after onset of WE. Patients with hyperintensities on T2-weighted images of the periventricular region of the third ventricle and the paramedian thalamic nuclei had poor recovery from their mental dysfunction. The MR examination in case of WE shows a typical pattern of lesions in 58% of cases. Enhancement of the mamillary bodies, the periventricular region of the third ventricle including the paramedian thalamic nuclei, and the periaqueductal area on postcontrast T1-weighted images can be observed in the initial period after clinical onset of symptoms and are characteristic signs of the acute stage of WE. Hyperintense lesions in the periventricular region and the paramedian thalamic nuclei on T2-weighted and FLAIR images in the subacute stage of WE and enhancement on postcontrast T1-weighted images of the mamillary bodies and the paramedian thalamic nuclei are indicators of poor prognosis despite vitamin B1 substitution. Electronic Publication     

Wernicke脑病的临床与MRI诊断

目的:探讨Wernicke脑病(WE)的MRI表现,提高对该病的认识。方法:回顾性分析8例WE患者的临床资料及MRI表现。结果:8例患者中4例于第三脑室旁、乳头体、丘脑内、导水管周围白质区呈对称性损害,2例以乳头体、四叠体损害为主,2例症状较重者,除上述部位信号异常外,其脑干及小脑内见广泛异常信号;所有病灶均表现为T1WI低信号、T2WI高信号、FLAIR序列明显高信号改变。4例患者治疗前后行DWI(b=1000s/mm2)检查显示病灶呈高、等信号,3例治疗前ADC值下降,1例无变化,治疗后ADC值均升高。结论:WE的MRI表现具有特征性,MRI及DWI对该病的早期和进展期患者的诊断和判断预后具有重要价值。     

Diffusion-weighted imaging in transient global amnesia exposes the CA1 region of the hippocampus

Introduction Transient global amnesia (TGA) is characterized by a sudden onset of anterograde amnesia without alteration of consciousness or personal identity. Interestingly, recent studies have reported a high frequency of small high-signal abnormalities in the hippocampus with diffusion-weighted (DW) imaging, and ischemia has been proposed as an etiology of TGA. We hypothesized that TGA lesions occur preferentially in the CA1 region of the hippocampus, known to be susceptible to ischemia. Methods Over a 30-month period 34 patients with TGA underwent MRI including DW imaging within 4 days of symptom onset. Patients with high-signal abnormalities in the hippocampus on the initial DW images underwent subsequent DW and T2-weighted imaging in the coronal plane to identify the precise lesion locations. Results Fourteen patients had small (1–3 mm) high-signal abnormalities in the hippocampus unilaterally on DW images. One of these patients had two lesions in one hippocampus and therefore in total 15 lesions were identified: four in the hippocampal head, and 11 in the body. Eleven lesions in ten patients with available coronal images were clearly demonstrated on both coronal DW and T2-weighted images and were localized to the lateral portion of the hippocampus, corresponding to the CA1 region. Conclusion Lesions associated with TGA were localized exclusively to the lateral portion of the hippocampus corresponding to the CA1 region. This finding supports the ischemic etiology of TGA; however, the pathophysiological mechanism involved requires further study.     

In vivo evaluation of white matter pathology in patients of progressive supranuclear palsy using TBSS

Introduction

The purpose of this research is to study white matter (WM) changes in patients of progressive supranuclear palsy (PSP) using automated analysis of diffusion tensor imaging (DTI) indices.

Methods

This was a prospective study comprising of 24 patients of PSP and 26 matched healthy controls. Fractional anisotropy, mean diffusivity (MD), axial diffusivity, and radial diffusivity (RD) changes were studied in the WM of the PSP patients using an automated analysis technique, tract-based spatial statistics (TBSS). Two subtypes of PSP, i.e., classic Richardson’s syndrome (PSP-RS) and parkinsonian type (PSP-P), were also compared among themselves to identify relative severity of WM changes as well as identify spatial distribution of the differences. Clinicoradiological correlation was done to determine the strength of correlation between WM abnormalities identified using TBSS and clinical scores.

Results

There were areas of significant abnormality seen in the frontoparietal cerebral WM, thalamus, midbrain tectum, superior cerebellar peduncle, and cerebellar WM. The abnormalities were more spatially widespread on MD and RD maps. Compared to PSP-P, the patients of PSP-RS had more spatial abnormalities localized to the frontal WM. There was no correlation between the observed WM changes and clinical rating scales.

Conclusions

The TBSS analysis showed widespread WM abnormalities in PSP patients including areas which have been shown to be involved in previous pathological studies. PSP-RS showed more severe white matter abnormality compared to the PSP-P subtype.     

Intravenous myocardial imaging performed serially early and late after acute myocardial infarction

The accuracy and sensitivity of myocardial imaging using intravenous Rb-81 in delineating the extent and subsequent changes in regional myocardial perfusion abnormalities were examined serially in 12 patients one to 510 days after an acute myocardial infarction. Definite regions of decreased Rb-81 uptake were noted in 10 patients with transmural infarction. There was excellent correlation between the site of perfusion abnormalities, the electrocardiographic infarct location and the region of segmental wall motion disorders. Follow-up studies revealed in 8 of 11 patients a decrease in the extent of the perfusion defect, which was associated with an improvement in the extent and/or severity of regional wall motion disorders. Conversely, wall motion abnormalities did not change in the remaining three patients in whom perfusion abnormalities persisted unchanged. We conclude that intravenous myocardial imaging permits visualization of myocardial perfusion abnormalities early after acute myocardial infarction. Serial imaging allows detection of changes in the extent of perfusion abnormalities, and, thus, might provide useful information with respect to the patient's prognosis and the effects of therapeutic interventions.Dr. O'Rourke is a Teaching Scholar of the American Heart Association. Supported in part by National Heart and Lung Institute Myocardial Infarction Research Unit Contract NOI-HV-81332 and Arteriosclerosis Grant # HL 14197     

Wilson's disease: computed tomography and magnetic resonance imaging findings

The condition of a patient with Wilson's disease was evaluated by magnetic resonance imaging (MRI) on initial presentation of the illness. The examination revealed mild atrophy of the superior vermis. Symmetric areas of increased signal intensity on T2-weighted images were detected in the anterior thalami, mesencephalic tectum and tegmentum. Marked symmetric hypointensities appeared in the head of caudate, pallida, substantia nigra and red nuclei. The histopathology of Wilson's disease suggests that these hypointensities may be secondary to the presence of protein-bound copper.     

脑性瘫痪的MRI特征

目的:探讨脑性瘫痪(脑瘫)患儿的头颅MRI表现及其与脑瘫类型的关系。方法:回顾性分析81例脑瘫患儿的临床资料与MRI表现。结果:81例脑瘫患儿MRI异常率为85.2%,痉挛型双瘫、四肢瘫、偏瘫、不随意运动型脑瘫、共济失调型脑瘫、肌张力低下型脑瘫和混合型脑瘫MRI异常率分别为92.9%、100%、100%、60%、87.5%、50%和81.8%。各类型脑瘫的MRI异常表现不同,痉挛型双瘫以脑室周围白质软化(PRL)为主,偏瘫型突出表现为单侧脑损伤,四肢瘫表现为广泛、弥漫、双侧脑损伤,不随意运动型表现为基底节病变或PVL,共济失调型绝大部分存在先天性小脑发育不全。结论:MRI有助于评价各型脑瘫的病理特点,对脑瘫病因的推测有帮助。     

Comparison of venous digital subtraction angiography and aortography in patients with peripheral vascular disease of the lower limbs

Twenty-eight patients referred for peripheral vascular imaging were investigated by both venous digital subtraction angiography and conventional aortography. A comparison of the two techniques revealed that, in the femoral region, venous digital subtraction angiography demonstrated all the abnormalities shown by aortography but missed three major and eight minor stenoses in the iliac region, due largely to bowel artefacts.     

Longstanding tectal tumors: proton MR spectroscopy and diffusion MRI findings.

Four patients with longstanding tectal tumors are included in this study. The tectal lesion in a neurofibromatosis type 1 (NF1) patient was due to a hamartoma, while others represented gliomas. On spectroscopy, decreased NAA peaks with resultant decreases in the NAA/Cho, and NAA/Cr ratios were observed in two patients. In three patients, on diffusion MRI the tectal tumors were hyperintense on b=1000 s/mm(2) (heavily diffusion-weighted) images. On apparent diffusion coefficient (ADC) maps, they had high signal, and high ADC values (mean=1.20 x 10(-3)mm(2)/s), compared to normal cerebral parenchyma. Diffusion MRI findings suggested that tectal tumors had a relatively high nuclear to cytoplasmic ratio (high-signal on b=1000 s/mm(2) images) in association with a relatively loose intercellular matrix (high ADC values).     

The role of 99mTc-diphosphonate bone SPECT/CT in the ankle and foot

The evaluation of the osseous ankle and foot pathology often poses a clinical and diagnostic challenge because of the complex anatomy and structural biomechanics of the region. Further investigation involves a multimodality imaging approach. Although both structural and functional imaging techniques have their strengths, namely, the high specificity of the former and superior sensitivity of the latter, they also have a number of limitations when used in isolation. These include the inability to determine the functional significance of pathological anatomical abnormalities or to further characterize or localize abnormal metabolic activity. The development of integrated single-photon emission computed tomography/computed tomography systems has aimed to overcome the limitations of separate anatomical and functional imaging techniques. This may be of particular value in ankle and foot assessments, in which multiple joints may be affected by different pathologies. This review article aims to highlight the role of both structural and functional imaging techniques, with particular emphasis on the incremental value of single-photon emission computed tomography/computed tomography in evaluation of this complex anatomical region.