Wernicke's encephalopathy: is diffusion-weighted MRI useful?

We present the clinical and magnetic resonance imaging (MRI) findings of five patients with acute Wernicke's encephalopathy. T2-weighted and fluid-attenuated inversion recovery (FLAIR) images demonstrated symmetrical hyperintense lesions within the dorsomedial thalami, periaqueductal white matter, and the tectum of the midbrain. None of the lesions enhanced with gadolinium. In addition to conventional MRI sequences, we performed diffusion-weighted imaging (DWI). In all patients, DWI showed symmetrical pathologic thalamic and midbrain signal hyperintensities more distinctly than did conventional T2-weighted or FLAIR sequences. The apparent diffusion coefficient (ADC) map images showed slight signal reductions in four patients, suggesting restricted diffusion within these regions. In one patient, the signal intensity within the affected thalami was isointense with the ipsilateral basal ganglia on ADC map images. For enhanced detection of pathology, we conclude that DWI should be included in the imaging protocols of patients suspected to suffer from Wernicke's encephalopathy.     

Diffusion MR Imaging of Postoperative Bilateral Acute Ischemic Optic Neuropathy

A 57-year-old woman experienced bilateral acute ischemic optic neuropathy after spine surgery. Routine MR imaging sequence, T2-weighted image, showed subtle high signal intensity on bilateral optic nerves. A contrast-enhanced T1 weighted image showed enhancement along the bilateral optic nerve sheath. Moreover, diffusion-weighted image (DWI) and an apparent diffusion coefficient map showed markedly restricted diffusion on bilateral optic nerves. Although MR findings of T2-weighted and contrast enhanced T1-weighted images may be nonspecific, the DWI finding of cytotoxic edema of bilateral optic nerves will be helpful for the diagnosis of acute ischemic optic neuropathy after spine surgery.     

Creutzfeldt-Jakob disease: comparative analysis of MR imaging sequences

BACKGROUND AND PURPOSE: MR imaging has played an increasingly important role in the diagnosis of Creutzfeldt-Jakob disease (CJD) since basal ganglia abnormalities on T2-weighted images have been described; thus, the aim of our study was to compare the value of different MR images in the diagnosis of CJD. METHODS: One hundred fifty-seven patients with CJD underwent MR imaging examinations. Ninety-two patients were neuropathologically confirmed, and 65 were clinically classified as having CJD through the CJD Surveillance Unit (probability of 95%). There was no standardized MR imaging protocol; thus, the examinations included 143 T2-weighted, 43 proton attenuation (PD)-weighted, 84 fluid-attenuated inversion recovery (FLAIR), and 44 diffusion-weighted images (DWI). The MR images were reviewed for pathologic changes of the basal ganglia, thalamus, and cerebral cortex. RESULTS: Cortical abnormalities were present in 70 patients (45%) and were visible in 80% (35/44) of all available DWI examinations. The basal ganglia were affected in 94 patients (60%), in particular in the caudate nucleus; the most sensitive sequences were DWI (64%) and PD-weighted (63%). A thalamic involvement was more frequently diagnosed on PD-weighted images (19%) and DWI (14%) than on FLAIR or T2-weighted images. CONCLUSION: PD-weighted images and DWI showed better results in the diagnosis of signal intensity changes in the basal ganglia compared with T2-weighted or FLAIR images; however, in the diagnosis of cortical changes, DWI was clearly superior. Our data suggest that DWI is the most sensitive MR imaging technique in the diagnosis of CJD.     

Diffusion-weighted magnetic resonance imaging and magnetic resonance spectroscopy in the evaluation of focal cerebral tubercular lesions

Purpose: To review magnetic resonance (MR) diffusion-weighted imaging (DWI) and spectroscopy findings in patients with focal cerebral tuberculosis and to assess whether these techniques can adequately characterize focal cerebral tubercular lesions.

Material and Methods: Sixteen patients with single or multiple lesions were evaluated on a 1.5T MR system. DWI was performed with three 'b' values of 50, 500, and 1000 s/mm² and the apparent diffusion coefficient maps were calculated. MR spectroscopy was performed using the point-resolved single-voxel technique with 2 echo time values of 135 ms and 270 ms. The signal intensities of the tubercular lesions on diffusion images and the apparent diffusion coefficients (ADCs) of their centers, along with MR spectroscopy findings, were analyzed in relation to their T2-weighted MR appearances.

Results: DWI identified 17 of the 20 lesions evaluated. Increased signal intensity was seen in 9 of the 17 lesions. The ADCs of the lesions ranged from 0.406 to 2.64×10^-3 mm²/s (mean±SD: 1.038±0.609 mm²/s). Most of the lesions with hyperintense centers on T2-weighted images were of increased intensity on diffusion images, while those with hypointense centers on T2-weighted images were of decreased signal intensity on diffusion images. However, no statistical difference in the ADCs was found between lesions with increased and those with decreased signal intensity centers on T2-weighted images. MR spectroscopy revealed a lipid peak at 0.9-1.3 ppm in all of the 14 lesions evaluated. An increase in normalized choline:creatine ratio was found in all the lesions in which the spectra were obtained with the voxel, including a variable portion of the lesion wall.

Conclusion: DWI and MR spectroscopy help in determining the nature of cerebral tubercular lesions; however, since the findings are varied, they do not help in specific characterization.     

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。     

Neonatal citrullinemia: comparison of conventional MR, diffusion-weighted, and diffusion tensor findings

Conventional MR, diffusion-weighted, and diffusion tensor imaging were performed in an 8-day-old girl with citrullinemia. She had severe hyperammonemia for several days. On conventional T2-weighted MR images, symmetric, confluent high signal intensity was found in the bilateral thalami, basal ganglia, cortex, and subcortical white matter. Diffusion-weighted imaging demonstrated decreased apparent diffusion coefficient in these areas, reflecting cytotoxic edema. Follow-up MR imaging at the age of 4 months revealed subcortical cysts, ulegyric changes, and atrophy, which were most prominent in the occipital lobes. Diffusion tensor imaging revealed decreased anisotropy throughout the brain, consistent with diffuse injury to the oligodendro-axonal unit. Diffusion-weighted and diffusion tensor imaging are valuable techniques for the detection of irreversible brain damage and for the characterization of hyperintense lesions on T2-weighted MR images in patients with the neonatal form of citrullinemia.     

Diffusion-Weighted MR Imaging in Biopsy-Proven Creutzfeldt-Jakob Disease

Objective

To compare conventional and diffusion-weighted MR imaging in terms of their depiction of the abnormalities occurring in Creutzfeldt-Jakob disease.

Materials and Methods

We retrospectively analyzed the findings of conventional (T2-weighted and fluid-attenuated inversion recovery) and diffusion-weighted MR imaging in four patients with biopsy-proven Creutzfeldt-Jakob disease. The signal intensity of the lesion was classified by visual assessment as markedly high, slightly high, or isointense, relative to normal brain parenchyma.

Results

Both conventional and diffusion-weighted MR images demonstrated bilateral high signal intensity in the basal ganglia in all four patients. Cortical lesions were observed on diffusion-weighted MR images in all four, and on fluid-attenuated inversion recovery MR images in one, but in no patient on T2-weighted images. Conventional MR images showed slightly high signal intensity in all lesions, while diffusion-weighted images showed markedly high signal intensity in most.

Conclusion

Diffusion-weighted MR imaging is more sensitive than its conventional counterpart in the depiction of Creutzfeldt-Jakob disease, and permits better detection of the lesion in both the cerebral cortices and basal ganglia.     

非酮症高血糖性舞蹈病的CT、MRI表现

目的 通过分析非酮症高血糖性舞蹈病的CT和MRI表现与临床表现之间的关系,以探讨该疾病的影像诊断价值.方法 回顾性分析6例非酮症高血糖性舞蹈病的影像表现和临床资料.6例均行CT平扫,其中1例行MR扫描.6例中3例行CT复查,1例行MR复查.结果 6例患者CT均表现为一侧或两侧纹状体密度增高,均累及壳核,其中5例同时累及苍白球外侧部或尾状核;3例CT复查表现为受累纹状体密度减低或密度增高影消失.1例T1WI表现为两侧豆状核高信号,T2WI表现为低信号;MRI复查示受累豆状核T1WI和T2WI信号无变化.所有患者的舞蹈病症状均在血糖控制后2～6 d内消失.结论 典型的CT和MRI表现有助于非酮症高血糖性舞蹈病的诊断     

Detection of hyperacute parenchymal hemorrhage of the brain using echo-planar T2*-weighted and diffusion-weighted MRI

We investigated the usefulness of echo-planar imaging (EPI) as well as T2^*-weighted and diffusion-weighted MRI (DWI) to identify hyperacute hemorrhage (within 24 h after ictus) in the brain. Seven patients were examined 3.5 to 24 h after onset of symptoms using a whole-body 1.5-T MR system. Two diffusion-weighted sequences were run to obtain isotropic and anisotropic diffusion images. Apparent diffusion coefficients (ADC) were calculated from the isotropic diffusion images. All DWI images as well as the T2*-weighted EPI images showed the hematomas as either discrete, deeply hypointense homogeneous lesions, or as lesions of mixed signal intensity containing hypointense areas. We conclude that even in the early phase after hemorrhage, sufficient amounts of paramagnetic deoxyhemoglobin are present in intracerebral hemorrhages to cause hypointensity on EPI T2^*-weighted and DWI images; thus, use of ultrafast EPI allows identification of intracerebral hemorrhage. Received: 21 March 2000 Revised: 26 July 2000 Accepted: 27 July 2000     

Magnetic resonance imaging of myositis ossificans: analysis of seven cases

Myositis ossificans typically presents as soft tissue swelling with progressive ossification on radiographs. Since magnetic resonance imaging (MRI) is commonly used to evaluate soft tissue masses, we analyzed eight MR examinations in seven patients with myositis ossificans to determine if typical patterns were present. One acute lesion had homogeneous intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Two subacute lesions had low signal intensity margins with slightly increased signal intensity centers on T1-weighted images and very high signal intensity on T2-weighted images. Five chronic lesions had two different patterns. All five were well-defined with low signal intensity borders. Three had signal intensity patterns characteristic of fat on T1-weighted and T2-weighted images. The other two lesions had intermediate signal intensity on T1-weighted images and slightly increased signal intensity on T2-weighted images.We conclude that typical MR appearances of myositis ossificans do exist. A low signal intensity rim is a common finding. However, these patterns are not unique to myositis ossificans and resemble those that have been reported in other lesions. It is important to be aware of the spectrum of MR findings of myositis ossificans when considering the differential diagnosis of a soft tissue mass.     

SSH-EPI diffusion-weighted MR imaging of the spine with low b values: is it useful in differentiating malignant metastatic tumor infiltration from benign fracture edema?

Objective  Conventional MR sequences are sometimes not helpful in differentiating benign from pathologic fractures. Our aim was to evaluate the usefulness of single-shot echo-planar imaging sequences (diffusion-weighted imaging (DWI)/SSH-EPI) with low b value in differentiating malignant metastatic tumor infiltration of vertebral bone marrow from benign vertebral fracture edema. Materials and methods  A total of 47 patients, 20 with benign fractures and 27 with tumor infiltration, were included in this prospective study. Diffusion-weighted MR images were obtained by single-shot echo-planar imaging technique with diffusion gradient (b = 300 s/mm²; TR/TE, 1,400/100), using a 1.5 T MR scanner. T1- and T2-weighted images and short inversion time inversion-recovery images were available for all 64 lesions. The lesions on DWI/SSH-EPI were categorized as having hypo-, iso-, or hyperintense signal intensity relative to normal vertebrae by two experienced radiologists. Results  We evaluated signal intensity patterns on DWI/SSH-EPI in 64 lesions, which showed low signal intensity on T1-weighted images in both benign fractures and metastasis. With the exception of sclerotic metastases in two patients, malignant metastatic tumor infiltration was hyperintense with respect to normal bone marrow on diffusion-weighted images; all but four benign vertebral fractures were isointense with respect to normal bone marrow. Conclusion  Single-shot echo-planar imaging sequences (DWI/SSH-EPI) with low b value provided excellent distinction between metastatic tumor infiltration and benign vertebral fracture edema. Hyperintense signal intensity on DWI/SSH-EPI was highly specific for the diagnosis of metastatic tumor infiltration of the spine.     

眶壁转移瘤的CT和MRI诊断

目的分析研究眶壁转移瘤的CT和MRI特点,提高诊断准确率.方法回顾性分析23例经手术病理证实的眶壁转移瘤的CT和MRI表现,成人组16例,儿童组7例.所有病例均行CT平扫与MR平扫和增强扫描.结果16例成年患者CT表现均为溶骨性骨质破坏和眼眶不规则肿块,9例骨质破坏区邻近的颅内可见扁平不规则肿块;16例MRI表现为骨质破坏区邻近的眼眶和颅内均可见略长T1、略长T2信号的不规则软组织影,增强后呈明显强化.7例儿童患者CT表现均为溶骨性骨质破坏和眼眶不规则肿块,其中2例可见垂直针状高密度影,3例骨质破坏区邻近的颅内可见扁平不规则软组织肿块;MRI显示7例骨质破坏区邻近的眼眶内和6例颅内可见略长T1、略长T2信号不规则的软组织影,其中1例为双侧,增强后呈明显强化;7例双侧眶骨、4例斜坡和双侧岩尖及1例双侧颞骨鳞部骨髓腔呈略长T1、略长T2信号影,增强后呈明显强化.结论眶壁转移瘤的CT和MRI表现有一些特点,有助于诊断和鉴别诊断.     

Portal-systemic encephalopathy: presence of basal ganglia lesions with high signal intensity on MR images

Sixteen patients with cirrhosis of the liver underwent cranial magnetic resonance (MR) imaging and transarterial portography to evaluate the relationship between basal ganglia lesions and portal-systemic collateral vessels. No neuropsychiatric disturbance was observed in any of the patients at the time of the MR examination, but four patients with portal-systemic encephalopathy were included in the study. Basal ganglia lesions, characterized by increased signal intensity on T1-weighted MR images, were observed in nine of the 16 patients, including the four with portal-systemic encephalopathy. These nine patients had large portal-systemic collateral vessels that were more than 10 mm in diameter. These collateral vessels were receiving blood from the superior mesenteric vein (SMV) in all nine patients. The lesions involved the globus pallidus and portions of internal capsules in a bilateral and symmetric fashion and did not exhibit mass effect. The authors conclude that there may be a significant relationship between high-intensity basal ganglia lesions and large portal-systemic collateral vessels receiving blood from the SMV.     

MR imaging of skeletal metastases from medulloblastoma

The findings of MR imaging in 3 patients with bone metastases from medulloblastoma are reported. The first patient showed focal lesions of low signal intensity on T1-weighted spin echo images at a time when bone scintigraphy was negative for metastases. This patient later developed extensive osteosclerotic lesions visible on plain films. The bone marrow of the second patient showed diffuse low signal intensity on T1-weighted images. After chemotherapy the signal intensity of the bone marrow increased which correlated with a return of normal hematopoietic tissue. A response to chemotherapy was also found on MR imaging and repeat bone marrow biopsies in a third patient. A consistent finding was a low signal intensity on pre-gadolinium images, but the pattern (focal or diffuse abnormal signal intensity) was different in each patient. To our knowledge, this is the first report on MR imaging findings in bone metastases from medulloblastoma.     

颅内原发性中枢神经系统淋巴瘤的MRI研究

目的研究颅内原发性中枢神经系统淋巴瘤（PCNSL）的MRI表现特点。资料与方法回顾性分析23例颅内PCNSL的MRI表现。抽取恶性胶质瘤30例、颅内转移瘤30例,共60例归为非PCNSL组作为对照。观察肿瘤部位、分布、信号、形态,并进行统计学分析。结果颅内PCNSL好发于深部脑组织,如胼胝体、丘脑及基底节区,多发病灶多呈区域性分布;肿瘤T2WI多呈等或稍高信号,甚至低信号,扩散加权像（DWI）呈均匀高信号;增强扫描多呈均匀明显强化,肿瘤周围可见“尖突征”。与非PCNSL组之间差异有统计学意义（P〈0．01）。结论颅内PCNSL影像表现多样,但具有一定特征。     

MR imaging and proton MR spectroscopy in A-to-G substitution at nucleotide position 3243 of leucine transfer RNA.

MR imaging of the brain in a 38-year-old woman with maternally inherited diabetes and deafness (MIDD) showed extensive subcortical and basal ganglia high signal intensity on T2-weighted studies though she was neurologically asymptomatic. High-signal-intensity changes were also seen in the basal ganglia on T1-weighted studies. Proton MR spectroscopy showed increased lactate, an increased choline/creatine ratio, and a decreased N-acetylaspartate/creatine ratio. Our observations suggest that patients with MIDD may have subclinical neurologic dysfunction identifiable by proton MR spectroscopy.     

Diffusion-weighted MR imaging (DWI) in spinal cord ischemia

Introduction Spinal cord infarction is a rare clinical diagnosis characterized by a sudden onset of paralysis, bowel and bladder dysfunction, and loss of pain and temperature perception, with preservation of proprioception and vibration sense. Magnetic resonance imaging (MRI) usually demonstrates intramedullary hyperintensity on T2-weighted MR images with cord enlargement. However, in approximately 45% of patients, MR shows no abnormality. Diffusion-weighted MR imaging (DWI) has been widely used for the evaluation of a variety of brain disorders, especially for acute stroke. Preliminary data suggest that DWI has the potential to be useful in the early detection of spinal infarction.Methods We performed DWI, using navigated, interleaved, multishot echo planar imaging (IEPI), in a series of six patients with a clinical suspicion of acute spinal cord ischemia.Results In all patients, high signal was observed on isotropic DWI images with low ADC values (0.23 and 0.86×10⁻³ cm²/s), indicative of restricted diffusion.Conclusion We analyzed the imaging findings from conventional MR sequences and diffusion-weighted MR sequences in six patients with spinal cord infarction, compared the findings with those in published series, and discuss the value of DWI in spinal cord ischemia based on current experience. Although the number of patients with described DWI findings totals only 23, the results of previously published studies and those of our study suggest that DWI has the potential to be a useful and feasible technique for the detection of spinal infarction.     

Chronic acquired hepatic failure: MR imaging of the brain at 1.5 T

The results of MR imaging of the brain at 1.5 T in 42 adults with non-Wilsonian chronic hepatic failure are reported. T1-weighted images demonstrated increased signal in the globus pallidus in 30 patients and in the putamen in 21, while T2-weighted images demonstrated no corresponding alteration in signal intensity. Symmetric low intensity in the central portion of the globus pallidus on spin-density and T2-weighted images in two patients correlated with regions of calcification on CT scans. Increased intensity on T1-weighted images also occurred in the mesencephalon surrounding the red nucleus (17/42) and in the quadrigeminal plate (4/42). Three patients demonstrated increased intensity in the pons on T2-weighted images unassociated with clinical brainstem dysfunction. Increased intensity on T1-weighted images was seen in the anterior pituitary in 28 of 35 patients. Alterations in signal intensity were not demonstrated in the cerebral cortex or cerebellum. MR findings did not correlate with laboratory indices of hepatic or thyroid function, with histologic liver diagnosis, or with neurologic status at the time of MR evaluation. Increased signal intensity in the basal ganglia, pituitary gland, and mesencephalon surrounding the red nuclei is characteristic of chronic hepatocellular dysfunction. Deposition of an as yet unidentified paramagnetic substance or altered intracellular water relaxation associated with the proliferation of astrocyte cytoplasmic organelles is postulated as the likely mechanism for this previously undescribed MR manifestation of chronic acquired hepatic failure.     

Studying neonatal bilirubin encephalopathy with conventional MRI,MRS, and DWI

Introduction  The purpose of this study was to evaluate the diagnostic value of conventional magnetic resonance imaging (MRI), proton magnetic resonance spectroscopy (¹H-MRS), and diffusion-weighted imaging (DWI) for neonatal bilirubin encephalopathy. Methods  We collected conventional MRI in 24 neonates with neonatal bilirubin encephalopathy. We performed ¹H-MRS and DWI sequences to nine of the 24 patients and seven age-matched healthy control subjects. Multiple-voxel ¹H-MRS data were acquired using PRESS pulse sequence with TE = 135 ms and TR = 1500 ms. The spectroscopic regions of interest were the bilateral basal ganglia and thalamus with a 1.0 mL spatial resolution. The data from DWI were collected by using a single shot-spin echo-echo planar imaging sequence with TR/TE: 2900/98, and imaging regions were also focused on the bilateral basal ganglia and thalamus. Results  Nineteen of the 24 patients had abnormal T₁-weighted image hyperintensity in the globus pallidus, but these lesions appeared as normal T₂-weighted image intensity in the same region. Ten of the 24 patients had T₁-weighted image high signal intensity in the subthalamic nucleus and appeared as normal intensity in the region for the T₂-weighted images. The peak area ratios of NAA/Cho and NAA/Cr were significantly decreased (t-test, P < 0.05) in the patients compared to the controls in the basal ganglia. Conclusion  Conventional MR imaging and ¹H-MRS are important complementary tools in the diagnosis of neonatal bilirubin encephalopathy. The study provides important information for applying these MR modalities to evaluate neonates with bilirubin encephalopathy.     

A preliminary study revealing a new association in patients undergoing maintenance hemodialysis: manganism symptoms and T1 hyperintense changes in the basal ganglia

BACKGROUND AND PURPOSE: Patients undergoing parenteral nutrition and those with portosystemic encephalopathy secondary to chronic liver disease and acquired and congenital portosystemic venous shunts frequently present manganese deposition in the basal ganglia, detected by MR imaging as hyperintense areas on T1-weighted sequences. We also observed similar abnormalities in the basal ganglia of patients with chronic renal failure undergoing maintenance hemodialysis. Our aim was to evaluate the pallidal signal intensity on T1-weighted images in a series of patients undergoing hemodialysis, with further evaluation of serum manganese levels and neurologic correlation, comparing them with patients with chronic renal failure without dialytic treatment. MATERIALS AND METHODS: We performed MR imaging examinations in 9 patients with chronic renal failure, 5 of whom were undergoing hemodialysis. An experienced neuroradiologist scrutinized the presence of symmetric hyperintensities in the basal ganglia on T1-weighted sequences. We also determined the serum manganese levels and performed the neurologic evaluations in all patients. RESULTS: All patients undergoing hemodialysis presented elevated serum manganese levels and symmetric hyperintensities within the globus pallidus. In this group, 4 patients presented with parkinsonian symptoms, myoclonus, and syndromes with vestibular and vestibular-auditory symptoms. The patients without dialytic treatment presented with neither bilaterally increased T1 MR imaging signal intensity within the globus pallidus nor symptoms of manganism. CONCLUSION: Our preliminary results demonstrated the occurrence of bilateral pallidal hyperintensity on T1-weighted images in all patients undergoing hemodialysis associated with high serum manganese levels, revealing a new association.