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PubMed2006

Persistent infarct hyperintensity on diffusion-weighted imaging late after stroke indicates heterogeneous, delayed, infarct evolution.

BACKGROUND AND PURPOSE: Some infarcts have persistently hyperintense areas on diffusion-weighted MRI (DWI) even at 1 month after stroke, whereas others have become isointense to normal brain. We hypothesized that late DWI hyperintensity reflected different infarct evolution compared with areas that were isointense by 1 month. METHODS: We recruited patients prospectively with ischemic stroke, performed DWI and perfusion-weighted MRI (PWI) on admission, at 5 days, 14 days, and 1 month after stroke, and assessed functional outcome at 3 months (Rankin Scale). Patient characteristics and DWI/PWI values were compared for patients with or without "still hyperintense" infarct areas on 1-month DWI. RESULTS: Among 42 patients, 27 (64%) had "still hyperintense" infarct regions at 1 month, mostly in white matter. Patients with "still hyperintense" regions at 1 month had lower baseline apparent diffusion coefficient ratio (ADCr; mean+/-SD 0.76+/-0.12 versus 0.85+/-0.12; hyperintense versus isointense; P<0.05), prolonged reduction of ADCr (repeated-measures ANOVA; P<0.01), no difference in baseline perfusion but delayed normalization of mean transit time (P<0.05) and cerebral blood flow ratios (repeated measures ANOVA; P<0.05), initially more severe stroke, and worse 3-month outcome than patients whose lesions were isointense by 1 month. CONCLUSIONS: The late DWI lesion hyperintensity emphasizes the heterogeneity in temporal evolution of stroke injury and suggests ongoing "ischemia." Lower baseline ADCr precedes delayed perfusion normalization, suggesting that worse cell swelling impedes reperfusion. Further study is required to determine underlying mechanisms and any potential for subacute intervention to improve recovery.

Adult↗
PubMed2003

Basic principles of diffusion-weighted imaging.

In diffusion-weighted MRI (DWI), image contrast is determined by the random microscopic motion of water protons. During the last years, DWI has become an important modality in the diagnostic work-up of acute ischemia in the CNS. There are also a few promising reports about the application of DWI to other regions in the human body, such as the vertebral column or the abdomen. This manuscript provides an introduction into the basics of DWI and Diffusion Tensor imaging. The potential of various MR sequences in concert with diffusion preparation are discussed with respect to acquisition speed, spatial resolution, and sensitivity to bulk physiologic motion. More advanced diffusion measurement techniques, such as high angular resolution diffusion imaging, are also addressed.

Artifacts↗
PubMed2003

Pure dysarthria due to small cortical stroke.

The authors describe six patients who presented with dysarthria as their isolated or major symptom from a small cortical stroke. Five had infarction and one had hemorrhage. In the patients with ischemic stroke, the lesions were identified by diffusion-weighted MRI but not by T-2 weighted MRI. The lesions were located lateral to the precentral knob usually at the most lateral part of the imaging. The presumed pathogenesis included embolism in five patients and hypertensive hemorrhage in one.

Adult↗
PubMed2000

[An autopsy case of primary cerebellar-pontine angle epidermoid carcinoma].

A 65-year-old man developed right facial palsy and six months later experienced sudden unconsciousness and right hemiplegia. On admission he had severe nuchal rigidity, decreased visual acuity, and a hearing disturbance. A CT scan and angiography failed to reveal any lesions in the brain, but CSF cytology showed undifferentiated malignant cells with a high level of neuron-specific enolase. A postcontrast CT scan and MRI demonstrated diffuse meningeal enhancement and a faintly rim-enhanced cystic lesion at the cerebellopontine angle. The patient died four months after admission, and postmortem examination revealed meningeal dissemination of squamous cell carcinoma, probably arising from an epidermoid cyst at the cerebellopontine angle. Microscopic examination revealed squamous epithelial debris and a foreign body reaction in portions of the cyst wall and in the surrounding subarachnoid space near the base of the cyst. Rim enhancement of the cyst on MRI and the microscopic findings indicated that the recurrent headaches may have been the result of chemical aseptic meningitis caused by spontaneous leakage of the cyst's contents.

Aged↗
PubMed1992

Serial MRI in Fukuyama type congenital muscular dystrophy.

Serial MRI of the brain of a female infant with Fukuyama type congenital muscular dystrophy (FCMD) is presented. Initial MRI revealed diffuse abnormal signal in the cerebral white matter extending peripherally. On follow-up studies, the abnormal signals disappeared or decreased from the posterior to anterior, and from central to peripheral. These changes in signal intensity correlate well with the process of myelination as demonstrated in histochemical studies. It appears that the abnormal signals in FCMD are caused by delayed myelination. When abnormal signal intensity is seen in the cerebral white matter of a developmentally delayed infant, serial MRI may be used to follow the course of the illness.

Ankle Joint↗
PubMed2006

[Case of intracranial hypotension responsive to oral prednisolone].

A 31-year-old female patient with headache and nausea was admitted to our hospital, although there were no apparent neurological abnormalities except headache. Cerebrospinal fluid (CSF) pressure was 40 mmH2O on the first lumbar puncture and CT showed some fluid in the left maxillary sinus. She gradually developed orthostatic headache despite antibiotics, hydration and analgesics. MRI showed diffuse meningeal thickening and enhancement. CSF pressure was 0 mmH2O on the second lumbar puncture and RI cisternography demonstrated early excretion to the kidneys. She was diagnosed with intracranial hypotension due to CSF leakage. An autologous 10ml blood patch on the lumbar epidural space did not relieve the orthostatic headache. However, headache disappeared one day after oral intake of 40mg prednisolone. During the next three months, oral prednisolone was tapered off. Three months after the onset of the illness, MRI did not show either meningeal thickening or enhancement. We concluded that oral prednisolone was effective in a case of intracranial hypotension.

Administration, Oral↗
PubMed2000

Presence of delayed myelination and macrocephaly in the sister of a patient with vacuolating leukoencephalopathy with subcortical cysts.

Leukoencephalopathy with swelling and a discrepantly mild clinical course ("van der Knaap disease") is a recently identified syndrome. It is characterised by macrocephaly occurring during the first year of life, initially normal or nearly normal development, and slowly progressive ataxia and spasticity with initial preservation of intellectual functions. MRI shows diffuse abnormality in signal intensity, as well as swelling of the hemispheral white matter with subcortical cyst-like spaces in the fronto-parietal and anterior temporal areas. It is thought to have an autosomal recessive mode of inheritance, since many patients have consanguineous parents and more than one affected patient is often present within the same family. We report on two sibs: a 5-year old boy affected with "van der Knaap disease" and his macrocephalic sister whose first MRI (2 years 6 months) showed delayed myelination, which led us to suspect the same disease as her brother, however with subsequent normalisation at the second MRI (3 years 6 months).

Brain Diseases↗
PubMed1998

[The clinical application of diffusion weighted magnetic resonance imaging to acute cerebrovascular disorders].

Diffusion is a measure of motion freedom and is a sensitive parameter to characterize the tissue at the microscopic level. The methods of measuring in vivo diffusion by magnetic resonance imaging (MRI) have been based mainly on the addition of two motion-probing gradients (MPG) to the spin echo sequence to produce signal attenuation for the spins moving at random. The resultant MR images reflect the intravoxel incoherent motions (IVIM), which contain both water molecule diffusion and perfusion in the capillary network, and can be quantified by an apparent diffusion coefficient (ADC). Diffusion weighted MRI, acquired from IVIM MR imaging by the addition of the very strong MPG predicate water diffusion and anisotropy. High signal or reduced ADC can be observed in case of the slower diffusion. The anisotropy depends upon the orientation of the subjects and the gradients. Greater signal attenuation (faster diffusion) can be observed when the relative orientation of white matter tracts to the MPG is parallel as compared to that obtained with a perpendicular alignment. This anisotropy may preclude the detection or delineation of an ischemic lesion. Diffusion tensor trace has been designated to eliminate this anisotropy effect. In ischemic animal models, low signal (fast diffusion) and high signal (slow diffusion) have been noted in the vasogenic edema and cytotoxic edema, respectively. High signal appears only in case of cerebral blood flow below 15-20 ml/100 g per minute, a value identical to the threshold of tissue at high energetic metabolism and ion homeostasis. ADC value decreases following the cerebral vessel occlusion, or remains unchanged when collateral circulation develops. It has been speculated that reduction in ADC reflects the water shift from extracellular space to intracellular space due to the membrane permeability and/or intracellular osmolality increase. These results suggest that diffusion weighted MRI correlates well with the cell metabolism, and cytotoxic edema plays an important role in the acute cerebral stroke. In clinical setting of acute cerebral ischemia, diffusion weighted MRI may detect superacute infarction by showing high signal (slower ADC) over the 6 hours following the insult, whereas conventional MRI generally fails to do so. In chronic liquefied cerebral infarction, increased ADC, or attenuated signal are the most frequent findings, suggestive of an elevated diffusion. Therefore, diffusion weighted MRI improves early diagnosis of stroke and help differentiate acute from chronic stroke. One disadvantage of diffusion weighted MRI is motion artifact, which may be reduced by the introduction of a navigator echo to correct for the phase shift caused by the first imaging echo, or by the utility of ultrafast imaging technique, such as echo planar. Another shortcomings is the susceptibility artifact incorporating the diffusion weighted MRI. The eddy current may also result from the strong gradients, producing shiftlike artifact. Such artifacts can be compensated for by appropriate shaping of the current pulses sent into the gradient coils, or by use of shielded gradients. As with rapid progresses in perfusion imaging of ischemia penumbra, misery perfusion and luxury perfusion, new insight into the diffusion weighted MRI will be significant.

Acute Disease↗
PubMed2002

[Correlation of diffusion-weighted magnetic resonance imaging with neurological deficits in sporadic Creutzfeldt-Jakob Disease].

This case report describes the sporadic Creutzfeldt-Jakob disease (CJD) of a 53-year-old man who initially complained about vertigo and dizziness. Within 18 weeks, he developed impaired memory, hemineglect, and sensory impairment of the left half of the body. A CSF tap was positive for 14-3-3 protein and showed increased tau protein, neuron-specific enolase (NSE), and the astroglial protein S-100 B. The EEG showed right temporal sharp waves without periodicity. Diffusion-weighted MRI revealed hyperintensities in the right temporo-occipital cortex which corresponded well with hypometabolic areas in a PET scan and the neurological and neuropsychological deficits. The morphological FLAIR T2 MRI showed no pathological changes. Within 20 weeks, the patient developed severe dementia with decreased spatial orientation and myoclonia, became incontinent, and was confined to bed. He died within 22 weeks after the first presentation of symptoms.

Creutzfeldt-Jakob Syndrome↗
PubMed1998

Transient global brain ischemia in young and aged rats: differences in severity and progression, but not localisation, of lesions evaluated by magnetic resonance imaging.

A model of transient global brain ischemia consisting of bilateral occlusion of common carotid arteries for 10 min and mild hypoxia (15% O2-85% N2) for 20 min was studied by means of MRI in young and aged Fischer 344 rats (3-4 and 24-26 months, respectively). Ischemia was assessed by full suppression of spontaneous EEG activity, which reappeared and normalized similarly in the two age-groups. The survival of young with respect to aged rats was considerably higher both at 24 h (20/20, i.e. 100% vs 12/16, i.e. 75%) and at 48 h (16/20, i.e. 80% vs 6/16, i.e. 38%). The localisation of brain lesions, their severity and progression were evaluated by a diffusion-weighted MRI (DWI) sequence at 24 and 48 h post-ischemia. There were no DWI-detectable lesions in eight out of 20 young and two out of 12 aged rats. The localisation of DWI-detected lesions was rather similar in rats of the two age-groups. In fact, the cerebral cortex, mainly parietal, occipital and temporal lobes were damaged in 83% of young and 90% of aged rats. The respective percentages for the thalamus were 83 and 60%, for the striatum 58 and 50%, and for the hippocampus 25 and 30%. The lesions present in the cerebral cortex and the thalamus were considerably more severe in aged than in young rats. In conclusion, in spite of similar localisation of ischemic lesions in the two age-groups, their incidence was higher, appearance more rapid and severity more pronounced in aged with respect to young rats. This resulted in a considerably higher mortality of the former. The overall data indicate that the age issue is very important in experimental ischemia research.

Aging↗
PubMed1999

A case of xanthogranulomatous cholecystitis.

Xanthogranulomatous cholecystitis (XGC) is an uncommon, focal or diffuse destructive inflammatory disease of the gallbladder that is assumed to be a variant of conventional chronic cholecystitis. A 36-year-old male was admitted to Chonnam National University Hospital with a 10-day history of right upper quadrant pain with fever. 15 years ago, he was first diagnosed as having hemophilia A, and has been followed up in the department of Hematology. Computed tomogram (CT) revealed a well-marginated, uniform, marked wall thickening of the gallbladder with multiseptate enhancement. Magnetic resonance imaging (MRI) demonstrated diffuse wall thickening of the gallbladder by viewing high signal foci with signal void lesions. After factor VIII replacement, exploration was done. On operation, the gallbladder wall was thickened and the serosa were surrounded by dense fibrous adhesions which were often extensive and attached to the adjacent hepatic parenchyma. There was a small-sized abscess in the gallbladder wall near the cystic duct. Dissection between the gallbladder serosa and hepatic parenchyma was difficult. Cross sections through the wall revealed multiple yellow-colored, nodule-like lesions ranging from 0.5-2 cm. There were also multiple black pigmented gallstones ranging from 0.5-1 cm. The pathologic findings showed the collection of foamy histiocytes containing abundant lipid in the cytoplasm and admixed lymphoid cells. Histologically, it was confirmed as XGC. We report a case with XGC mimicking gallbladder cancer in a hemophilia patient.

Adult↗
PubMed1998

[A lateralized reduction of NAA in a case of corticobasal degeneration (CBD): application of proton magnetic resonance spectroscopy (1H-MRS)].

We studied the application of proton magnetic resonance spectroscopy (1H-MRS) in a case of corticobasal degeneration. A 73-year-old woman was referred to our hospital for dysarthria and clumsiness in right arm movement. Intelligence was normal and neither ideational apraxia or ideomotor apraxia were observed. Her speech was slurred and extremely slow. Neurological findings showed a limitation of ocular upward gaze movement, impaired smooth pursuit in the horizontal gaze, rigidity, limb kinetic apraxia and cortical sensory disturbance in the right arm. Magnetic resonance imaging (MRI) showed diffuse brain atrophy, especially in the left fronto-parietal cortex around the central sulcus. A positron emission tomography (PET) study showed diffuse decrement of cerebral blood flow, dominantly in the left hemisphere. The decrease in the uptake of 18F-Fluoro-deoxyglucose also revealed glucose hypo-metabolism, especially in the left frontal and parietal lobe. 1H-MRS by the multivoxel method showed a decrease in N-acetylaspartate (NAA)/Creatine to 1.0 in the left basal ganglia and temporal lobe, compared to the values between 1.4 and 1.7 in the right basal ganglia. These findings indicated that 1H-MRS might detect neuronal loss or degeneration when MRI showed minimal cortical atrophy. This study, the first application of 1H-MRS in a case of corticobasal degeneration, showed that this method was useful for the evaluation of pathophysiological changes in corticobasal degeneration.

Aged↗
PubMed2000

Prognostic value of perfusion- and diffusion-weighted MR imaging in first 3 days of stroke.

The aim of this study was to evaluate the differences in cerebral perfusion seen on mean transit time (MTT) and cerebral blood volume (CBV) maps and to assess the subsequent prognostic value of the MTT-DWI (diffusion-weighted MRI) and CBV-DWI mismatch in the first three days of stroke on lesion enlargement and clinical outcome. In 38 patients, imaged 1-46 h after onset of symptoms, lesion volumes on proton-density (PD)-weighted MRI, DWI and PWI (both MTT and CBV maps) were compared with lesion volumes on follow-up PD-weighted scans, and to clinical outcome (National Institutes of Health Stroke Scale, Barthel index, and Rankin scale). The MTT-CBV, MTT-DWI and CBV-DWI mismatches were compared with change in lesion volume between initial and follow-up PD-weighted scans. Lesion volume on both DWI and PWI correlated significantly with clinical outcome parameters (p < 0.001) with strongest correlation for lesion volume on CBV. Perfusion-diffusion mismatches were found for both CBV and MTT and correlated significantly with lesion enlargement on PDweighted imaging with strongest correlation for the CBV-DWI mismatch. The CBV-DWI mismatch has the highest accuracy in predicting lesion size on follow-up imaging and in predicting clinical outcome. Lesion volume measurements on CBV maps have a higher specificity than on PD-weighted, MTT or DWI images in predicting clinical follow-up imaging and in predicting clinical outcome.

Adult↗
PubMed1996

[Permanent paraplegia following epidural and general anesthesia: two case reports].

Case-1: A 72-year-old woman with no past neurological history was scheduled for a rectum resection under general combined with epidural anesthesia. An epidural catheter was introduced at T11-12 interspace without any difficulties. During the operation, she had hypotensive episode needing dopamine, but waked up from anesthesia without any event. When she became alert, she complained muscle weakness and loss of sensation in both lower extremities. On the day after surgery, she became quadriplegic and completely insensitive under Th4 level, but her MRI of the spine showed no abnormal findings. A month after the operation, her MRI showed diffuse spinal degeneration below C4 level and she had flaccid paralysis below Th1 with complete sensory loss below Th7 level. Case-2: A 62-year-old man with no past neurological history was scheduled for gastrectomy under general combined with epidural anesthesia. An epidural catheter was placed via T12-L1 without any difficulty. Operative course was uneventful and awakening from anesthesia was normal. He showed muscle weakness and hypesthesia of lower extremities two hours after the operation, and we stopped continuous injection of epidural anesthesia. His paralysis became worse but MRI of his spine showed no abnormality on the day after the operation. He became complete flaccid paralytic and had complete sensory loss below T7 level. The MRI examination two weeks after the operation showed degeneration below middle thoracic spinal cord. His neurologic symptoms have not improved for two years. The etiology of neurologic deficits of these two case is not obvious although the relation between epidural anesthesia and neurologic symptoms was most likely.

Aged↗
PubMed1998

A simplified method to measure the diffusion tensor from seven MR images.

Analytical expressions of the diffusion tensor of water, D, and of scalar invariants derived from it, are given in terms of the intensities of seven diffusion-weighted images (DWIs). These formulas simplify the post-processing steps required in diffusion tensor imaging, including estimating D in each voxel (from the set of b-matrices and their corresponding DWIs), and then computing its eigenvalues, eigenvectors, and scalar invariants. In a study conducted using artifact-free DWIs with high diffusion weighting (bmax approximately 900 s/mm2, maps of Trace(D) and the Relative and Lattice Anisotropy indices calculated analytically and by multivariate linear regression showed excellent agreement in brain parenchyma of a healthy living cat. However, the quality of the analytically computed maps degraded markedly as diffusion weighting was reduced. Although diffusion tensor MRI with seven DWIs may be useful for clinical applications where rapid scanning and data processing are required, it does not provide estimates of the uncertainty of the measured imaging parameters, rendering it susceptible to noise and systematic artifacts. Therefore, care should be taken when using this technique in radiological applications.

Animals↗
PubMedDate not supplied

Experience with diffusion-weighted imaging in an acute stroke unit.

We performed diffusion-weighted MRI (DWI) on a standard 1.5-tesla MRI scanner using a high-speed stimulated echo pulse sequence (turboSTEAM) in 9 stroke patients and 9 control subjects to investigate whether this technique can be used clinically to assist in ischaemic stroke diagnosis within the time frame for potential therapy. Stroke patients underwent DWI between 3.75 h and 3 days after stroke onset. Three patients were studied on more than one occasion. DWI was normal in the 9 controls. Seven of 9 stroke patients showed areas of increased signal on DWI. DWI detected cerebral ischaemia 3.75 h after stroke onset when both CT and T2-weighted MRI were normal. In 6 DWI-positive patients studied at later times, increased signal on T2-weighted images was present at the same time. Two patients had normal CT, T2-weighted and DWI images; both made good neurological recoveries. For the routine assessment of stroke patients, DWI implemented on a standard MRI system can provide additional information of clinical value to that obtained with conventional pulse sequences. In particular it facilitates early detection of cerebral ischaemia during the first few hours after stroke.

Adult↗
PubMed2000

["Ghost and mimicry-tumor"--primary CNS lymphoma].

In recent years, the frequency of primary cerebral lymphoma (PCNSL) has increased, even among immunocompetent patients. In order to treat the disease optimally, early diagnosis is important. We present three patients with atypical courses of this disease and stress the importance of PCNSL in the differential diagnosis for optimal treatment. In a 75-year-old man, a space-occupying, radiopaque, enhancing CNS lesion disappeared completely after biopsy and short steroid therapy. One year later, the tumor recurred on the other side and again regressed after steroid therapy. The first biopsy showed signs of a papillary tumor, so a choroid plexus papilloma was suspected initially. A 57-year-old woman developed progressive bilateral hearing dysfunction. Lymphocytic pleocytosis led to a primary diagnosis of chronic lymphocytic meningitis. During the further course of disease, the patient developed multiple space-occupying cerebral lesions. Stereotactic biopsy revealed PCNSL. Despite combined chemo- and radiotherapy, a relapse occurred. A 49-year-old woman rapidly developed memory and concentration disturbances. Computed tomography revealed diffuse edema in both hemispheres and MRI detected severe, diffuse, white matter lesions. The CSF revealed lymphocytic pleocytosis including plasma cells. Herpes encephalitis and, after lack of clinical improvement and progression of the MRI changes, acute disseminated encephalomyelitis (ADEM) were suspected. Corticosteroid treatment was initiated. After enormous clinical improvement, a clinical relapse occurred and MRI detected bitemporal and singular space-occupying lesions in the corpus callosum and hypothalamus. Finally, open biopsy showed PCNSL. However, on examination of the treatment history of patient 1, the initial diagnosis must be revised; a PCNSL seems most probable. The phenomenon of tumor remission under steroid administration is rare. In patients 2 and 3, atypical clinical signs and symptoms delayed diagnosis of PCNSL. This tumor can mimic diverse neurological diseases and remit following corticosteroid treatment alone. In unclear cerebral disease, biopsy should be performed early for exact diagnosis and optimal treatment.

Aged↗
PubMedDate not supplied

Magnetic resonance assessment of acute and chronic stroke.

This article describes the important role of magnetic resonance imaging (MRI) in noninvasively assessing human focal ischemic stroke. Conventional MRI, diffusion-weighted and/or perfusion-weighted imaging have been used to facilitate both the qualitative and quantitative evaluation of heterogeneity of ischemic brain tissue. Further, by combining 2 or more magnetic resonance parameters, tissue-signature models have been developed that may be used as surrogate markers of tissue histopathology to characterize ischemic tissue as salvageable, necrotic, or tissue in transition to necrosis. Magnetic resonance tissue-signature models and results are presented. Dynamic changes in the evolution of ischemic tissue to infarction are also discussed. Recovery from acute stroke was studied with blood oxygenation level-dependent functional MRI to investigate the neural mechanisms for recovery from aphasia after stroke.

Acute Disease↗