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PubMedDate not supplied

Detection of intracranial hemorrhage: comparison between gradient-echo images and b0 images obtained from diffusion-weighted echo-planar sequences on 3.0T MRI.

In this study, we compared the effectiveness of b0 echo-planar MR images (EPI) imaging with gradient recalled echo (GRE) in detecting acute hemorrhage. Brain images in 69 patients who suffered from acute infarction were reviewed. Nine of them had suffered from acute hemorrhage. Comparing b0EPI and GRE images side-by-side, we found no significant different effectiveness in detecting hemorrhage (P = .522, > or =.05). We concluded that b0EPI imaging could detect hemorrhagic lesions as effectively as GRE can without additional acquisition time.

Adult↗
PubMed1999

Brain MRI in peripartum seizures: usefulness of combined T2 and diffusion weighted MR imaging.

Peripartum seizure is a serious disease with significant morbidity and mortality for women and their unborn children. The underlying etiologies are varied, with eclampsia and venous stroke being the most common causes. T2 weighted MR images of the brain show hyperintense lesions in either condition. Diffusion weighted MR images (DWI) of the brain is abnormal in strokes. We report three cases of eclampsia with abnormal T2 weighted images, but normal DWI. Diffusion weighted MR images in association with T2 weighted MR images can be extremely helpful in evaluation of women with new onset peripartum seizures.

Adolescent↗
PubMed2005

Comparing 0.2 tesla with 1.5 tesla intraoperative magnetic resonance imaging analysis of setup, workflow, and efficiency.

RATIONALE AND OBJECTIVES: To compare low-field with high-field intraoperative magnetic resonance imaging (MRI) in respect to setup, workflow, and efficiency. MATERIALS AND METHODS: A total of 750 patients were investigated either with a 0.2 T (March 1996-July 2001) or a 1.5 T (April 2002-August 2004) MRI system adapted for intraoperative use. RESULTS: With the low-field setup, 330 patients were examined in 65 months; with the high-field setup, 420 patients were examined in 29 months, which is a 2.8-fold increase in cases per month (14.5 versus 5.1) reflecting improved ease of use. Concerning intraoperative workflow, the time for preparation to start intraoperative imaging decreased fivefold (2 minutes instead of 10 minutes); navigation was applied more often with 57% versus 51% (240/420 versus 167/330), whereas functional data were integrated in 35% versus 39% (84/240 versus 65/167). Application of navigation updates was doubled (22% versus 11%; 53/240 versus 18/167). Image acquisition time was reduced by a factor of two, allowing a more detailed imaging protocol, whereas the image quality is clearly improved in the high-field setup, where there was no difference between the standard preoperative image quality compared with the intraoperative quality. This contributed to an increased detection of tumor remnants and extended resections in pituitary (36% versus 29%; 47/129 versus 17/59) and glioma surgery (41% versus 26%; 38/93 versus 28/106). CONCLUSION: Compared with the low-field setup, the high-field setup results not only in clearly superior image quality and increased imaging armamentarium, contributing to increased rates of detected tumor remnants, but also in a distinct improvement of intraoperative workflow. Furthermore, intraoperative high-field MRI offers various modalities beyond standard anatomic imaging, such as magnetic resonance spectroscopy, diffusion tensor imaging, and functional MRI.

Brain Diseases↗
PubMed2005

1.5 T: intraoperative imaging beyond standard anatomic imaging.

Intraoperative high-field MRI with integrated microscope-based neuronavigation is a safe and reliable technique providing immediate intraoperative quality control. Major indications are pituitary tumor, glioma, and epilepsy surgery. Intraoperative high-field MRI provides intraoperative anatomic images at high quality that are up to the standard of pre- and postoperative neuroradiologic imaging. Compared with previous low-field MRI systems used for intraoperative imaging, not only is the image quality is clearly superior but the imaging spectrum is much wider and the intraoperative work flow is improved. Furthermore, high-field MRI offers various modalities beyond standard anatomic imaging, such as magnetic resonance spectroscopy, diffusion tensor imaging, and functional MRI.

Brain Diseases↗
PubMed2004

[Diffusion-weighted magnetic resonance imaging in hypoglycemic coma].

Hypoglycemia is a classic cause of coma and can result in irreversible neuronal loss. Until now, the main prognostic factors were depth of hypoglycemia and duration of coma. We report the case of a 55-Year-old woman who suffered severe hypoglycemic coma with abnormal cortico- subcortical diffusion weighted MR images. These MRI abnormalities preceded severe atrophy of these cerebral areas. This findings suggests that diffusion abnormalities in hypoglycemic coma may be related to neuronal loss and may thus have prognostic value.

Alcoholism↗
PubMed2003

Rapid clinical deterioration in a patient with multi-focal glioma despite corticosteroid therapy: a quantitative MRI study.

A patient with high-grade multi-focal glioma deteriorated rapidly despite high dose corticosteroid therapy (dexamethasone: 16 mg/day). MRI was used to measure diffusion tensor parameters and longitudinal relaxation time (T1) values of peritumoural oedematous brain before and after commencing steroid treatment. Forty-eight hours after steroid treatment there was no evidence of brain oedema reduction. Specifically, regions of oedematous brain showed a significant increase in mean diffusivity ( ) with a significant decrease in diffusion anisotropy (p < 0.05), but without any change in T1 values. These quantitative MRI data were mirrored by the rapid deterioration seen when assessing the patient clinically. This case shows that quantitative MRI can not only measure steroid treatment response but also failure in patients with malignant gliomas.

Brain Neoplasms↗
PubMed2003

Thalamic involvement in multiple sclerosis: a diffusion-weighted magnetic resonance imaging study.

BACKGROUND AND PURPOSE: Injury to deep gray matter structures in multiple sclerosis (MS) has been suggested by recent neuro-imaging and neuropathology studies. Diffusion-weighted magnetic resonance imaging (MRI) can assess tissue damage with greater sensitivity than conventional MRI. The authors' objective was to assess thalamic gray matter damage by diffusion-weighted imaging in MS patients. METHODS: This was a retrospective study performed at a tertiary care, university-affiliated comprehensive MS center of 82 MS patients and 43 controls. The main outcome measures were thalamic apparent diffusion coefficients (ADCs), whole-brain atrophy (brain parenchymal fraction), fluid-attenuated inversion recovery (FLAIR) hypertense lesion volume, and clinical course. RESULTS: ADCs in the left thalamus were higher in MS patients (0.741 +/- 0.044 x 10(-3) mm2/s) than controls (0.723 +/- 0.036 x 10(-3) mm2/s) (P = .027) and higher in secondary progressive MS patients (0.761 +/- 0.044 x 10(-3) mm2/s) than relapsing-remitting MS patients (0.735 +/- 0.032 x 10(-3) mm2/s) (P = .029). ADCs in the right thalamus were higher in secondary progressive MS patients (0.784 +/- 0.069 x 10(-3) mm2/s) than controls (0.757 +/- 0.038 x 10(-3) mm2/s) (P = .033). In the MS group, left thalamus ADCs correlated negatively with brain parenchymal fraction (r = -0.30, P = .008), total left hemispheric FLAIR lesion volume correlated with ADCs in the left (r = 0.35, P = .001) and right (r = 0.39, P < .001) thalami, and total right hemispheric FLAIR lesion volume correlated with ADCs in the left (r = 0.31, P = .006) and right thalami (r = 0.22, P = .048). CONCLUSION: MS patients have increased water diffusion in the thalamus that is partly associated with clinical course, lesion load, and whole-brain atrophy. Both indirect and direct mechanisms of gray matter injury may play a role in the pathophysiology of MS.

Adult↗
PubMed2006

Bolus tracer delivery measured by MRI confirms edema without blood-brain barrier permeability in diffuse traumatic brain injury.

INTRODUCTION: Previous studies have shown that edema formation after diffuse traumatic brain injury (TBI) with secondary insult is cytotoxic and not vasogenic. This assumption is based on observations of reduced apparent diffusion coefficient (ADC) and lack of significant accumulation of intravascular tracer in brain tissue. However, ADC reduction does not exclude vasogenic edema, and intravascular tracer can only accumulate when it reaches the tissue and is not perfusion limited. This study aims to confirm tissue delivery of intravascular tracer and lack of BBB opening during a phase of rapid brain swelling after diffuse TBI. METHODS: Rats were exposed to either TBI using the impact acceleration model combined with 30 minutes of hypoxia and hypotension, or sham injury. At 2 or 4 hours after injury, ADC and tissue water content were assessed using MRI. Gd-DTPA was given followed by a combination of rapid T2 imaging (60 seconds) and T1 imaging (30 minutes). Signal intensity changes were analyzed to determine a bolus effect (dynamic susceptibility contrast) and longer-term tissue accumulation of Gd-DTPA. RESULTS: Mean increase in cortical water content on the left was 0.8% at 2 hours, 2.1% at 4 hours; on the right it was 0.5% at 2 hours and 1.7% at 4 hours (p < 0.05). Mean ADC reduction over 4 hours was 0.04 x 10(-3) mm2/s on the left and 0.06 x 10(-3) mm2/s on the right. Kinetic analysis of signal intensity changes after Gd-DTPA showed no significant difference in inward transfer coefficient (BBB permeability) between sham injury and 2 or 4 hours post-injury. T2 imaging showed consistent tissue delivery of a bolus of Gd-DTPA to the tissue at 2 and 4 hours post-injury, comparable to sham animals. CONCLUSIONS: Progressive cerebral edema formation after diffuse TBI occurred during ADC reduction and without continued BBB permeability. Tissue delivery of Gd-DTPA was confirmed, verifying that lack of tracer accumulation is due to an intact BBB and not to limited perfusion.

Animals↗
PubMed2006

Modest MRI signal intensity changes precede delayed cortical necrosis after transient focal ischemia in the rat.

BACKGROUND AND PURPOSE: Diffusion-weighted imaging (DWI) hyperintensities and apparent diffusion coefficient (ADC) hypointensities are MRI features of acute stroke. DWI alterations during ischemia recover with early reperfusion, but they can reappear later. Pronounced signal abnormalities early after stroke are associated with infarction, but the significance of subtle changes is unclear. Here we evaluated the degree and time course of regional signal intensity changes during the first 24 hours of reperfusion after transient ischemia, and we related them to the progression of the histopathological damage. METHODS: Rats (n=54) were subjected to 1-hour intraluminal middle cerebral artery occlusion to assess the dynamics of MRI signal intensity changes during the initial 24 hours and their correspondent histopathological features: 2,3,5-triphenyltetrazolium chloride (TTC) staining, and hematoxylin and eosin, and immunoreactivity to 70-kDa heat shock protein and to astroglial and microglial markers. RESULTS: This model of ischemia caused early striatal infarction but delayed necrosis in the cortex. The striatum showed marked MRI changes from 4 hours of reperfusion. By 12 hours, the striatal ADC signal intensity ratio to the homologous contralateral region was 30% reduced, and the TTC staining evidenced infarction. Contrarily, the cortical ADC ratio was only 15% reduced, and TTC staining was normal at 12 hours. After this time, the cortex showed sudden and pronounced (>30%) ADC signal intensity changes coincidentally with the manifestation of infarction, accompanied with severe vacuolation and unambiguous signs of neuronal and astroglial death. CONCLUSIONS: These findings suggest that minor changes in ADC signal intensity early after ischemia should not be underestimated because they may be harbingers of delayed infarction.

Animals↗
PubMed2004

[Identification of ictal foci by EEG and MR apparent diffusion coefficient map in a case of human herpesvirus 6-associated encephalopathy].

We report here a 1-year-old boy with human herpesvirus 6 (HHV 6) -associated encephalopathy. On the 3rd day of fever, he had a generalized tonic seizure followed by mild disturbance of consciousness, which recovered completely the next day. Two days later, he had skin rash of exanthema subitum, and his consciousness declined frequently. EEG demonstrated rhythmic wave bursts originating from central areas bilaterally, followed by a generalized spike-and-wave complex which was associated with disturbed consciousness. We made the diagnosis of a status of complex partial seizures. Because the focal discharge on ictal EEG, MRI was performed. In the subcortical white matter of the frontal-parietal lobes, there were high signals on diffusion-weighted MRI, the apparent diffusion coefficient of which was much lower than that of normal controls. The affected areas soon disappeared with improvement of clinical symptoms. The transient MRI findings may indicate reversible cytotoxic brain edema. He showed no neurological sequelae as yet.

Brain↗
PubMed1998

Chronological changes in brain MRI, SPECT, and EEG in neurosarcoidosis with stroke-like episodes.

Neurosarcoidosis with recurrent stroke-like episodes has been reported only rarely in the literature. We repeatedly measured brain magnetic resonance images (MRI), SPECT, and electroencephalograms (EEG) in a 32-year-old male patient with this condition. In the acute stage of the episodes, he showed semi-coma followed by severe dysphasia; left-frontal EEG delta wave activities and left-sided hyperperfusion SPECT were noted. Gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) MRI findings were aggravated diffusely in the convalescent stage of the disease rather than in the acute stage. The EEG and SPECT findings were clearly reflective of an early stage of acute encephalomeningitis caused by the neurosarcoidosis, and thus are more useful than MRI for evaluation of the acute inflammatory process in this condition.

Adult↗
PubMed2004

Magnetic resonance diffusion imaging of ovarian masses: a first experience with 12 cases.

OBJECTIVE: The objective of the study was to determine the feasibility of using apparent diffusion coefficient (ADC) measurement for the differential diagnosis of malignancy in ovarian masses. MATERIALS AND METHODS: Twelve cases involving ovarian masses were imaged using spin echo diffusion magnetic resonance imaging (MRI). Five cases involved malignant ovarian masses, on the basis of postoperative histologic examination, and the rest involved benign masses. The ovarian masses were imaged in vivo (10 cases) before surgery and ex vivo (8 cases) after surgical resection. Diffusion-weighted data were corrected for motion using the phase data from unweighted data in nine cases. Multifactorial analysis of variance was used to evaluate the effects of malignancy, location (in vivo versus ex vivo), and motion correction on the measurement of ADC intensity and texture. RESULTS: Motion correction caused an undesirable spatial smoothing of the ADC maps and a significant interaction (p=0.047) was found between location and motion correction. ADC value (p=0.028) and texture (p=0.001) differences were found between malignant and nonmalignant ovarian masses. CONCLUSION: Measurement of ADC intensity and texture has the potential to differentially diagnose malignancy in individual ovarian masses if the problem of image motion artifact can be eliminated through the use of faster imaging sequences.

Adult↗
PubMed2004

Five patients with a recently described novel leukoencephalopathy with brainstem and spinal cord involvement and elevated lactate.

Recently, a novel leukoencephalopathy syndrome was described in eight patients with a distinct pattern of MRI abnormalities. Here we describe the clinical, laboratory, and MRI findings in five new, unrelated patients. The clinical picture was homogeneous with onset in childhood, a slowly progressive course, variable mental deficits, signs of pyramidal and cerebellar dysfunction and sometimes dorsal column dysfunction. In two patients, a minor head trauma was followed by neurological deterioration and fever. No underlying metabolic defect was found. In two patients serum lactate was elevated, but no evidence of a mitochondrial defect was found. MRI showed variably extensive, diffuse, or spotty cerebral white matter abnormalities and a selective involvement of particular brainstem tracts. The tracts involved included the pyramidal tracts, sensory tracts, superior and inferior cerebellar peduncles, and intraparenchymal trajectories of the trigeminal nerve. In four patients spinal MRI was performed and revealed involvement of tracts over the entire length depicted. Single voxel proton MRS in three patients revealed increased lactate within the abnormal white matter. The uniform and highly characteristic MRI findings, in combination with the similarities in clinical and MRS findings, provide evidence for a distinct nosological entity.

Brain Stem↗
PubMed2005

MR tractography with diffusion tensor imaging in clinical routine.

Using MRI, we demonstrated that the depiction of the cerebral white matter fiber tracts has become a routine procedure. Diffusion tensor (DT) sequences may be analyzed with combined volume analysis and tractography extraction software, giving indirect visualization of white matter connections. We obtained DT data from 20 subjects with normal MR imaging and five patients presenting cerebral diseases such as brain tumors, multiple sclerosis and stroke, with five patients explored on two different MR scanners. Data were transferred to dedicated workstations for anatomical realignment, determination of voxel eigenvectors and calculation of fiber tract orientations in a region of interest. In all subjects, axonal directions underlying the main neuronal pathways could be delineated. Comparisons between diseased regions and contralateral areas demonstrated changes in voxel anisotropy in injured regions, revealing possible preferential fiber orientations within diffuse T2 hyperintensities. Rapid data processing allows imaging of the normal and diseased fiber pathways as part of the routine MRI examination. Therefore, it appears that whenever white matter disease is suspected a tractography can be performed with this fast and simple method that we proved to be reliable and reproducible.

Adult↗
PubMed1997

Syndrome of orthostatic headaches and diffuse pachymeningeal gadolinium enhancement.

OBJECTIVE: To characterize clinical and imaging features, biopsy findings, etiologic factors, and outcome in the syndrome of intracranial hypotension, headaches, and diffuse pachymeningeal gadolinium enhancement on magnetic resonance imaging (MRI). MATERIAL AND METHODS: We describe our experience with 26 consecutive patients with orthostatic headaches and diffuse pachymeningeal gadolinium enhancement, for all of whom clinical, imaging, and follow-up data were available. For 10 patients who had undergone meningeal biopsy, slide material was also reviewed. RESULTS: The 15 men and 11 women ranged from 24 to 76 years of age. All 26 patients had postural headaches; in 22 patients, the headaches were completely alleviated by recumbency. Nausea or emesis, neck pain, horizontal diplopia, changes in hearing, photophobia, upper limb pains or paresthesias, visual blurring, or dysgeusia was noted in some of the patients. Cardinal MRI features were diffuse pachymeningeal gadolinium enhancement (100%), subdural collections of fluid (69%), and evidence of descent of the brain (62%) that sometimes resembled type I Chiari malformation. Cerebrospinal fluid (CSF) opening pressures were 40 mm or less in only 46%. In three patients, CSF pressures were consistently no less than 90 and as high as 130 mm of water. A variable pleocytosis of 5 or more cells/mm3 was noted in 15 patients (more than 40 cells/mm3 in 4 patients). A variable increase in CSF protein was noted in at least one spinal tap in 23 patients. Six patients had overdraining CSF shunts; CSF leak was documented in another 11 patients. Shunt revision or ligation and surgical correction of the leak led to a resolution of the clinical and MRI abnormalities in all cases thus treated. Improvement occurred with epidural blood patch in four patients. Three of the 12 patients treated supportively have remained symptomatic. Histologically, a thin subdural zone of fibroblasts and thin-walled vessels was noted in an amorphous matrix. Two patients with prolonged symptoms had a more pronounced proliferative reaction. CONCLUSION: The syndrome of low-pressure headaches and pachymeningeal gadolinium enhancement is being recognized with increasing frequency. The source of the CSF leak can be demonstrated in many patients. Meningeal abnormalities are likely attributable to decreased CSF volume and hydrostatic CSF pressure changes. The prognosis is typically good.

Adult↗
PubMed2003

[Multiple sclerosis: imaging, diagnostic criteria and differential diagnosis].

Multiple sclerosis (MS) is the most common demyelinating inflammatory disease of the central nervous system (CNS), presenting with multifocal, disseminated inflammatory lesions referred to as plaques. Magnetic resonance imaging (MRI) typically depicts multiple, round to oval, circumscript lesions predominantly involving periventricular and subcortical white matter, brainstem and cerebellum. More recent investigations have demonstrated that the macroscopically visible plaques only present the tip of the iceberg: Already early in its course, MS causes neuroaxonal damage and diffusely involves the entire brain parenchyma including normal appearing white matter. These changes are reflected by strongly T1w hypointense lesions and atrophy of early onset, by reduction of the neuronal Marker N-acetylaspartate (NAA) on spectroscopy, by a decrease of the magnetization transfer ratio (MTR), by an increased in diffusibility and decreased anisotropy on diffusion-weighted imaging (DWI). MRI imaging is an important tool in the diagnosis of MS by revealing the characteristic spatial and temporal dissemination of the cerebral and spinal manifestations of this disease. Diagnostic criteria increase the diagnostic specificity and allow better differentiation from other diseases with multifocal white matter abnormalities.

Aspartic Acid↗
PubMed2005

Diffusion-weighted magnetic resonance imaging allows noninvasive in vivo monitoring of the effects of combretastatin a-4 phosphate after repeated administration.

The noninvasive assessment of anticancer treatment efficacy is very important for the improvement of therapeutic window. The purpose of the present study was to evaluate the antitumoral effects of the vascular targeting agent, combretastatin A-4 phosphate (CA-4-P), at selected time points after repeated intraperitoneal drug administrations (25 mg/kg), using diffusion-weighted magnetic resonance imaging (DW-MRI). The experiments were performed during an overall follow-up period of 3 weeks on WAG/Rij rats with subcutaneously growing rhabdomyosarcomas. Each animal served as its own baseline. The DW-MRI studies were quantified by calculating the apparent diffusion coefficient (ADC) for different low and high b-values to separate the effects on tumor vasculature and cellular integrity. The changes in ADC as well as the extent of necrosis development (proportional to the tumor volume), measured on the MR images, were of comparable magnitude after each treatment. All ADC values showed a significant decrease at 6 hours, followed by a significant increase at 2 days for various CA-4-P administrations. DW-MRI allowed us to monitor both reduction in perfusion and changes in the extent of tumor necrosis after CA-4-P injection. Repeated CA-4-P administration retains efficacy in rat rhabdomyosarcomas, with similar findings after each drug administration.

Animals↗