Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Diffusion MRI”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 901 records · Page 50Linked to original sources
PubMedDate not supplied

Magnetic resonance imaging and diffusion-weighted images of cystic meningioma: correlating with histopathology.

BACKGROUND AND PURPOSE: Cystic meningiomas are quite rare, accounting for between 2% and 4% of all intracranial meningiomas. To better understand all the types of cystic meningiomas with magnetic resonance imaging (MRI), diffusion-weighted imaging (DWI) and histopathology, we attempted to correlate the MRI and DWI features of cystic meningiomas with the histopathological findings. METHODS: We collected 15 cases of cystic meningiomas diagnosed between 1993 and 2000 (5 men and 10 women, 41-80 years old). Fifteen patients had conventional MRI and 14 patients had CT scan. DWI was also performed in three patients. Apparent diffusion coefficient (ADC) images were also done. In the classification of cystic meningiomas, we adopted Worthington's classification, which divides cystic meningiomas into five groups. RESULTS: Tumor resection was performed in all patients. Tumor locations were as follows: convexity (10), falx (2), pterion (2) and lateral ventricle (1). Regarding the types of cystic lesion, type I (3), type II (3), type III (3), type IV (1) and type V (5) were found. Histopathologically, there were six atypical, four meningothelial, two malignant, one fibroblastic, one angiomatous and one transitional. Intratumoral cystic meningiomas were more common in atypical types. Peritumoral cystic meningiomas were more common in meningothelial and atypical types. The cystic portion of the three cystic meningiomas was hypointense or mildly hyperintense on DWI. ADC ratio (ADCR) of DWI for cyst part of two type I cystic meningiomas was 1.25 and 0.82; for cyst part of one type III was 4.04. CONCLUSIONS: It is important to recognize the neuroimaging features of the cystic meningiomas. Conventional MRI and DWI may play an important role in the preoperative radiological evaluation and the recognition of these types of cysts for proper surgical treatment.

Adult↗
PubMed2000

[A young adult female case of Wilson's disease presenting with mental disorder and frontal lobe signs].

We report a young adult female case of Wilson's disease presenting with mental disorder and frontal lobe signs. The patient was admitted to our neurological unit on October 4, 1999 because of schizophrenia-like symptom, dysphagia, dysarthria and gait disturbance. She showed slowly progressive rigidity and dystonia. Her parents were the second cousins. Neurological examination revealed bilateral pyramidal and extrapyramidal signs, frontal lobe signs (include the imitation behavior). Tendon reflexes were slightly exaggerated in all extremities. Bilateral Babinski, Chaddock and Hoffmann signs were positive. Her verbal IQ on the Wechsler Adult Intelligence Scale-revised was 49. Biochemical examination revealed low plasma copper and ceruloplasmin concentration. Cerebrospinal fluid was normal. Cranial MRI demonstrated diffuse brain atrophy and enlargement of the lateral ventricles. T2-weighted images of the MRI demonstrated hyperintense signal in both thalamus and basal ganglia. SPECT showed hypoperfusion in the left frontal lobe, both thalamus and basal ganglia. EEG revealed diffuse theta wave. The diagnosis of Wilson's disease was made and the treatment of D-penicillamine 900 mg per day was started. This hypoperfusion of SPECT and EEG findings improved after 2 months under D-penicillamine therapy. Neurological findings showed slight improvement. A few Wilson's disease patients presenting with mental disorder have been reported. Wilson's disease should always be considered in differential diagnosis of mental disorders. We emphasize the importance of early diagnosis and treatment of Wilson's disease.

Adolescent↗
PubMed2004

Characterization of central nervous system structures by magnetic resonance diffusion anisotropy.

Diffusion-weighted magnetic resonance imaging (MRI) provides information about tissue water diffusion. Diffusion anisotropy, which can be measured with diffusion tensor MRI, is a quantitative measure of the directional dependence of the diffusion restriction that is introduced by biological structures such as nerve fibers. Diffusion tensor MRI data was obtained in the brain, brain stem, and cervical spinal cord. For each region, scans were performed in four normal volunteers. Fractional anisotropy (FA), an index of diffusion anisotropy, was measured within regions of interest located in the corpus callosum, capsula interna, thalamus, caudate nucleus, putamen, brain cortex, pyramidal tract of the medulla, accessory olivary nucleus, dorsal olivary nucleus, inferior olivary nucleus, spinal white and gray matter. The highest FA value was measured in the corpus callosum (81 +/- 3%). The values of the other areas decreased in the following order: pyramidal tract in the medulla (72 +/- 1%), spinal white matter (65 +/- 4%), capsula interna (62 +/- 3%), accessory olivary nucleus (36 +/- 2%), spinal gray matter (35 +/- 5%), dorsal olivary nucleus in the medulla (29 +/- 2%), thalamus (28 +/- 2%), inferior olivary nucleus (15 +/- 2%), putamen (13 +/- 2%), caudate nucleus (13 +/- 2%), and brain cortex (9 +/- 1%). Our results indicate that the underlying fiber architecture, fiber density, and uniformity of nerve fiber direction affect anisotropy values of the various structures. Characterization of various central nervous system structures with diffusion anisotropy is possible and may be useful to monitor degenerative diseases in the central nervous system.

Anisotropy↗
PubMed2002

A case of diffuse neurofibrillary tangles with calcification.

We report a 79-year-old female with atypical senile dementia with Fahr-type calcification. The patient started to show memory disturbance at the age of 75 years, followed by visual hallucination, stereotypy, personality changes such as irritability, aggression and disinhibition. Brain computed tomography (CT) demonstrated bilateral and symmetric calcification of the basal ganglia and thalamus. Magnetic resonance imaging (MRI) revealed diffuse cortical atrophy pronounced in the fronto-temporal areas. On MRI T1-weighted images the calcified areas showed a mixture of low- and high-intensity signals. Based on the overlapping clinical symptoms of Alzheimer's disease and Pick's disease, together with the brain CT and MRI findings, we clinically diagnosed the patient as having 'diffuse neurofibrillary tangles with calcification' (DNTC). The characteristics of psychiatric symptoms and neuroradiological findings in DNTC are discussed.

Aged↗
PubMed2005

Diffusion-weighted MR study of femoral head avascular necrosis in severe acute respiratory syndrome patients.

PURPOSE: To evaluate the apparent diffusion coefficient (ADC) of femoral head avascular necrosis (AVN) in severe acute respiratory syndrome (SARS). MATERIALS AND METHODS: Seventy-nine SARS patients with hip pain underwent both conventional and diffusion-weighted MRI (b-value=0-1000 seconds/mm(2)). The abnormal regions on the diffusion-weighted images were outlined by using the conventional images as guides, and the ADCs were calculated. The ADC differences between normal and AVN femoral heads were compared. RESULTS: Of the 158 hips examined, 28 had AVN (11 with bilateral hip AVN, three with right hip AVN, and three with left hip AVN). The mean ADC was markedly greater in the AVN femoral head (1.66 x 10(-3) mm(2)/second+/-0.20) than in the normal femoral head (0.47 x 10(-3) mm(2)/second+/-0.082; P<0.0001). There was no overlap between the normal and AVN femoral heads. CONCLUSION: DWI can provide valuable information regarding the diffusion properties of femoral head AVN, and markedly increased diffusion was identified in AVN.

Adult↗
PubMed2003

Leukoencephalopathy with patchy lesions, temporal cystic degeneration, and normal head size.

A 5 yr old girl is reported with patchy white matter lesions, cystic degeneration of the temporal tips, normal cortex, and normal cerebellum, documented by FLAIR, and diffusion-weighted MRI. This condition differed from the entity megalencephalic leukoencephalopathy with cysts by lack of diffuse involvement of the white matter and cortical thinning, by presence of a normal head size, and existence of a non-progressive, severe clinical condition. Occurrence of cystic degeneration in the temporal tips distinguished the condition from other leukoencephalopathies. This leukoencephalopathy appears to be a new distinct entity.

Brain Diseases↗
PubMed1997

Glycine site antagonist attenuates infarct size in experimental focal ischemia. Postmortem and diffusion mapping studies.

BACKGROUND AND PURPOSE: The glycine site on the N-methyl-D-aspartate (NMDA) receptor complex offers a therapeutic target for acute focal ischemia, potentially devoid of most side effects associated with competitive and noncompetitive NMDA antagonists. METHODS: A novel glycine receptor antagonist, ZD9379, was studied in 70 Sprague-Dawley rats using the suture occlusion model of permanent middle cerebral artery occlusion (MCAO). In the first experiment, 20 rats received an initial bolus of vehicle or 10 mg/kg ZD9379 (n = 10 in each group) 30 minutes after MCAO, followed by a continuous infusion of the same dose per hour for 4 hours. Diffusion-weighted MRI with echo-planar acquisition was used to generate maps of the apparent diffusion coefficient (ADC) of water. In a second experiment, 50 rats were assigned to five groups: vehicle and 10, 5, 2.5, and 1 mg/kg ZD9379 (n = 10 in each group) with the same dosing protocol but no imaging. In both experiments, infarct volume was determined by 2,3,5-triphenyltetrazolium chloride staining. RESULTS: In the first experiment, before therapy was begun, there was no significant difference in ADC-derived ischemic lesion volume between the two groups. Over time, the 10-mg/kg ZD9379-treated rats had a significant delayed regional recovery of reduced ADC values in the peripheral parietal cortex (P = .0156). Postmortem corrected infarct volume at 24 hours after MCAO was significantly smaller in the group treated with 10 mg/kg ZD9379 than in the vehicle group (119.2 +/- 52.2 versus 211.2 +/- 50.0 mm3 [mean +/- SD]; P = .0008; a reduction of 43.6%). In the second experiment, postmortem corrected infarct volumes in rats receiving 10, 5, and 2.5 mg/kg ZD9379 were significantly smaller than in those receiving vehicle, a reduction of 42.6%, 51.4%, and 42.9%, respectively (P = .0001). CONCLUSIONS: This study demonstrates that 2.5- to 10-mg/kg doses of ZD9379 initiated 30 minutes after MCAO significantly reduced infarct size. Diffusion mapping disclosed a delayed treatment effect of this glycine antagonist in focal ischemia, confirmed by the postmortem study.

Animals↗
PubMed1999

Evaluation of early reperfusion and i.v. tPA therapy using diffusion- and perfusion-weighted MRI.

OBJECTIVE: To characterize the effects of recombinant tissue plasminogen activator (rt-PA) therapy and early reperfusion on diffusion-weighted (DWI) and perfusion-weighted imaging (PWI) changes observed following acute ischemic injury. METHODS: Twelve patients were evaluated prospectively using echo planar DWI and bolus tracking PWI. Six patients received i.v. rt-PA 0.9 mg/kg and were compared with six patients who did not. Patients receiving rt-PA were initially imaged (T1) 3 to 5 hours postictus (mean, 4 hours 20 minutes) whereas those not treated with tissue plasminogen activator (tPA) were imaged 4 to 7 hours postictus (mean, 5 hours, 25 minutes). Follow-up imaging was performed 3 to 6 hours (T2), 24 to 36 hours (T3), 5 to 7 days (T4), and 30 days (T5) after the first scan in all patients. Lesion volumes were measured on both DWI and time-to-peak maps constructed from PW images. RESULTS: PWI was performed successfully at T1 and T3 in 11 of 12 patients. In the group that received i.v. tPA, initial PWI volumes were less than DWI volumes in five of six patients (83%), whereas only one of five patients (20%) not receiving tPA had PWI < DWI volume (p = 0.08). PWI normalized by 24 to 36 hours (T3) in 6 of 11 patients (early reperfusers), with 5 of 6 of these early reperfusers having received tPA. The aggregate apparent diffusion coefficient (ADC) values for the early reperfusers were consistently higher at T2 (p = 0.04), T3 (p = 0.002), and T4 (p = 0.0005). Five of six patients with early reperfusion demonstrated regions of elevated ADC within the ischemic zone (mean ipsilateral ADC/contralateral ADC, 1.46 +/- 0.19) by 24 to 36 hours, whereas none of the nonearly reperfusers showed these regions of elevated ADC (p = 0.015). CONCLUSION: Early reperfusion is seen more frequently with i.v. tPA therapy. In addition, the study showed that ADC may undergo early increases that are tied closely to reperfusion, and marked ADC heterogeneity may exist within the same lesion. Early reperfusion is seen more frequently with i.v. tPA therapy.

Aged↗
PubMed2001

[Diagnostic problems in brain abscess: 45 cases].

BACKGROUND AND PURPOSE: We analysed the difficulties encountered in the differential diagnosis between brain abscess and brain tumor and their influence on treatment and outcome. METHODS: - Forty-five adults with brain abscess operated on between 1993 and 1999 were retrospectively reviewed. We studied preoperative diagnosis, clinical, radiological, bacteriological findings, surgical procedure, primary sources of infection and outcome. RESULTS: Preoperative diagnosis was right in 55.6% (25/45), wrong in 22.2% (10/45) and doubtful in 22.2% (10/45). Diffusion-weighted MR imaging was successfully used in 4 doubtful cases to make the differential diagnosis between abscess and tumor. When the preoperative diagnosis was right, the surgical procedure was a burr-hole aspiration in 73.3% (22/25) whereas when it was wrong, an excision was performed in 60% (6/10) of the cases. Aspiration was the last diagnostic investigation in 80% (8/10) of doubtful cases. Microbacterial organisms were identified in 75.5% (34/45) of the cases and primary cause of infection in 62.2% (28/45). The outcome depended on clinical status on admission, preoperative diagnosis and surgical procedure. In four cases, diffusion-weighted MRI allowed differential diagnosis between brain abscess and tumor through calculation of the Apparent Diffusion Coefficient which is low in abscess and high in cystic tumor. CONCLUSION: The diagnosis of brain abscess remains difficult in certain patients. Correct preoperative diagnosis influences the decision on the appropriate surgical procedure and helps improve outcome.

Adult↗
PubMed1996

[MRI and computer-assisted tomography in Kufs disease. Apropos of a familial form].

Kufs disease is the adult form of ceroid neurolipofuscinosis, and an uncommon cause of degenerative nervous system disease affecting young adults. We present here 4 cases of family form revealed by a demential syndrome. In all 4 patients MRI showed diffuse cortical atrophy predominant in the parietal regions. In 3 of these 4 patients MRI also exhibited a low signal in T2-weighted sequences on the putamens. There was no abnormality of the white matter. Diagnosis was made by cerebral biopsy in one case and by rectal biopsy in all other cases. Although the MRI images are not specific, they must be used when the diagnosis of Kufs disease is suspected in young patients with demential syndrome.

Adult↗
PubMed1996

[MR imaging in patients with bone marrow metastases of neuroblastoma].

Sixty patients with neuroblastoma or ganglioneuroblastoma underwent MRI 87 procedures to detect and follow up bone marrow metastases. The detection of bone marrow metastases by MRI was evaluated with aspiration cytology. Relationships were investigated between bone metastases and bone marrow metastases that were morphologically classified as nodular and diffuse by MRI findings. The usefulness of MRI was also studied in evaluating the effect of chemotherapy. MRI showed bone marrow metastases in all of 17 patients, but aspiration cytology proved metastases in only 7 of 17. Bone metastases were proven by bone scintigraphy or bone X-ray in 5 of 15 patients, and only diffuse bone marrow metastases were accompanied with bone metastases. After or during chemotherapy, 10 patients were examined by MRI more than two times. Bone marrow metastases disappeared in 9, decreased in size in 3, did not change in one and recurred at another site in one. It was observed from MRI findings that in the early stage, bone marrow metastases are nodular, but along with progress of the disease, they become diffuse and invade the bone cortex. If chemotherapy was effective, bone marrow metastases were decreased in size or disappeared completely.

Bone Marrow Neoplasms↗
PubMed1991

The use of gradient flow compensation to separate diffusion and microcirculatory flow in MRI.

This paper describes a new MR imaging technique termed Modified Stejskal Tanner versus Flow Compensation (MST/FC) for the separation of diffusion and microcirculatory flow. The theory behind the sequence is explained, along with a five-component model of microcirculation applicable to any "perfusion" imaging technique. Phantom data is presented showing that (1) diffusion effects can be matched between MST and FC (suggesting the possibility of flow-compensated diffusion imaging), and (2) the technique is a quantitative method of separating diffusion and slow (less than 0.25 mm/s) tortuous flow through a Sephadex column. Furthermore, animal images show the technique to be feasible and quantitative in measuring rat brain microcirculation under normal, vasodilated (hypercarbia), and no-flow (post mortem) conditions.

Acetone↗
PubMed2000

Spreading waves of transient and prolonged decreases in water diffusion after subarachnoid hemorrhage in rats.

Diffusion-weighted MRI (DWI), which can detect cortical spreading depressions (SDs) as propagating waves of reduced apparent diffusion coefficient (ADC) of water, was used to investigate whether spreading depression occurs after subarachnoid hemorrhage (SAH) induced by endovascular perforation in the rat. Eleven rats underwent SAH while positioned in the magnet. The ADC measurements had a temporal resolution of 12 sec. Transient decreases in ADC to 74 +/- 5% of pre-SAH values were observed in three rats after SAH, which propagated over the cortex with an average speed of 4.2 +/- 0. 6 mm/min, consistent with an SD wave. Furthermore, in all 11 rats, a wavefront of reduced ADC, which did not resolve within the 12 min observation period, spread at a speed of 3.2 +/- 1.7 mm/min in the ipsilateral cortex, and again is consistent with the speed of SD propagation. Therefore, spreading depression-like cellular depolarization is a consequence of acute subarachnoid hemorrhage in rats. Magn Reson Med 44:110-116, 2000.

Animals↗
PubMed2002

Diffusion of water in large demyelinating lesions: a follow-up study.

We studied five patients with multiple sclerosis with one plaque of demyelination more than 2 cm in diameter, using conventional and diffusion-weighted MRI, soon after the onset of symptoms and over 1-36 months. The orientationally averaged diffusion coefficient was increased in all the acute lesions, and increased further during follow-up in three. There was a strong correlation between and the degree of low signal on T1-weighted images. The quantitative information provided by allowed delineation of different diffusion patterns in large MS lesions, that may reflect heterogeneity of the anatomical substrate.

Adult↗
PubMed2005

Effect of the Glycine Antagonist Gavestinel on cerebral infarcts in acute stroke patients, a randomized placebo-controlled trial: The GAIN MRI Substudy.

BACKGROUND AND PURPOSE: Gavestinel, GV150526, is a selective antagonist at the glycine site of the N-methyl-D-aspartate receptor. The safety and efficacy of GV150526 were studied in two phase III randomized placebo-controlled clinical trials of acute ischemic stroke patients within 6 h from onset [The Glycine Antagonist in Neuroprotection (GAIN) International and GAIN Americas Trials]. A planned MRI substudy within these trials investigated the effect of gavestinel on infarct volume. METHODS: Patients enrolled in the GAIN trials at designated MRI substudy sites were eligible if they had a pretreatment acute cortical lesion on diffusion-weighted MRI of at least 1.5 cm diameter or 5 cm(3). Final lesion assessment was performed on T(2)-weighted MRI at month 3. Blinded image analysis was performed centrally. The primary hypothesis was that gavestinel would attenuate lesion growth from baseline relative to placebo. RESULTS: A total of 106 patients were eligible, 75 (34 gavestinel, 41 placebo) of whom had month 3 scans (primary analysis population). No effects of gavestinel on infarct volume were observed in the primary or other analyses. However, significant associations of lesion volume to clinical severity and outcomes were observed. Ischemic lesion volume decrease was predictive of substantial clinical improvement. CONCLUSION: Consistent with the clinical outcomes in the GAIN trials, no effects of gavestinel on ischemic infarction was observed. Concordance of results of the clinical outcome trials with those of this infarct volume substudy as well the associations of infarct volume to clinical outcomes further support the potential role of infarct volume as a marker of outcome in dose finding and proof of principle acute stroke trials.

Cerebral Infarction↗
PubMed2005

Multiparametric MRI and ultrasound findings in patients with internal carotid artery dissection.

In this study, clinical, MRI, and ultrasound findings in 33 patients with 37 MRI-confirmed internal carotid artery dissections (ICADs) were investigated. In 24 of 37 (64.9%) diffusion-weighted MRI (DWI) revealed acute ischemic brain lesions. ICADs with subsequent DWI lesions usually had a concentric position of the mural hematoma (14 of 24; 58.3%). In contrast, ICADs without DWI lesions (13 of 37; 35.1%) demonstrated an eccentric position of the mural hematoma (10 of 13; 76.9%), sometimes without ultrasound abnormality (5 of 13; 38.5%), while nonischemic clinical signs were frequent (11 of 13; 84.6%). A hemodynamic stroke pattern with comparatively large ischemic lesions along the hemodynamic risk zones was noted in 7 of 24 patients (29.2%).

Brain↗
PubMed2002

Acute vertebral body compression fractures: discrimination between benign and malignant causes using apparent diffusion coefficients.

Diffusion weighted MRI was performed on patients with acute vertebral body compression. The usefulness of the apparent diffusion coefficient (ADC) in differentiating between benign and malignant fractures was evaluated. A total of 49 acute vertebral body compression fractures were found in 32 patients. 25 fractures in 18 patients were due to osteoporosis, 18 fractures in 12 patients were histologically proven to be due to malignancy, and 6 fractures in 2 patients were due to tuberculosis. Signal intensities on T(1) weighted, short tau inversion recovery (STIR) and diffusion weighted images were compared. ADC values of normal and abnormal vertebral bodies were calculated. Except for two patients with sclerotic metastases, benign acute vertebral fractures were hypointense and malignant acute vertebral fractures were hyperintense with respect to normal bone marrow on diffusion weighted images. Mean combined ADCs (ADC(cmb); average of the combined ADCs in the x, y and z diffusion directions) were 0.23 x 10(-3) mm(2) s(-1) in normal vertebrae, 0.82 x 10(-3) mm(2) s(-1) in malignant acute vertebral fractures and 1.94 x 10(-3) mm(2) s(-1) in benign acute vertebral fractures. The differences between ADC(cmb) values were statistically significant (p<0.001). The ADC is useful in differentiating benign from malignant acute vertebral body compression fractures, but there may be overlapping ADC values between malignant fractures and tuberculous spondylitis.

Acute Disease↗
PubMed1985

Is it now time to acquire magnetic resonance imaging? Issues and concerns.

Magnetic resonance imaging (MRI) is a diagnostic modality that permits images of a variety of pathologic conditions to be acquired safely and painlessly with remarkable anatomic detail. In research sites and in a few clinical locations, MRI has become the definitive diagnostic tool for many neurological conditions and promises to become a valuable modality for diagnosing thoracic, abdominal, pelvic, and perhaps even breast and eye diseases. Despite its accolades, MRI's diffusion and adoption are at the center of a storm of controversy. The spread of MRI to non-research hospitals throughout the country--even to those with large neurology services--has not yet been shown to be clinically appropriate or cost effective. This article examines the accumulated information on MRI in order to help the administrator and trustees of a typical acute-care hospital to decide whether their community needs--and is able to support--an MRI service. Rather than reviewing the ever-changing frontiers of MRI research, this assessment considers the issues that are of immediate concern to hospital decisionmakers who must answer the question, "Should we plan to buy an MRI system in 1985?"

Capital Expenditures↗