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At least 1,369 records · Page 76Linked to original sources
PubMed2001

Magnetic resonance imaging of the post-mortem autistic brain.

Magnetic resonance imaging (MRI) is a valuable, noninvasive tool for understanding structural abnormalities in the brain. The M.I.N.D. Institute at UC Davis has developed a protocol utilizing MRI to investigate anatomical differences in the post-mortem brain by applying a proton density weighted imaging sequence for optimal differences in image intensity (contrast) between gray and white matter. Images of the brain obtained prior to distribution of tissue and further neuropathological examination provide a record of how the brain appeared prior to tissue processing. The virtual representation of the whole brain can also be subjected to additional analyses, such as measuring the volume of brain regions or area of the cortical surface. We describe our procedures for carrying out post-mortem MRI of the human brain.

Autistic Disorder↗
PubMed1999

Presurgical evaluation of patients with epilepsy and normal MRI: role of scalp video-EEG telemetry.

When considering surgery for intractable partial seizures, even with high resolution MRI, some patients do not show structural abnormalities. The aim was to consider whether these patients were likely to proceed to surgical treatment after scalp video-EEG telemetry. All patients undergoing presurgical evaluation at the National Hospital for Neurology and Neurosurgery between 1995 and 1997 were reviewed and 40 were identified without definite MRI abnormalities. None of 40 disclosed a well localised epileptogenic zone concordant with other tests that would have allowed the patient to proceed directly to surgery. In five of the 40, evaluation led to a hypothesis that could be tested by intracranial studies; three proceeded to surgery. It is suggested that high quality MRI is performed first when surgical evaluation is undertaken and if negative the patient carefully counselled before proceeding with any investigations, as successful resective surgery is an unlikely outcome in such MRI negative cases.

Adolescent↗
PubMed2001

Structural asymmetries in the human brain: a voxel-based statistical analysis of 142 MRI scans.

The use of computational approaches in the analysis of high resolution magnetic resonance images (MRI) of the human brain provides a powerful tool for in vivo studies of brain anatomy. Here, we report results obtained with a voxel-wise statistical analysis of hemispheric asymmetries in regional 'amounts' of gray matter, based on MRI scans obtained in 142 healthy young adults. Firstly, the voxel-wise analysis detected the well-known frontal (right > left) and occipital (left > right) petalias. Secondly, our analysis confirmed the presence of left-greater-than-right asymmetries in several posterior language areas, including the planum temporale and the angular gyrus; no significant asymmetry was detected in the anterior language regions. We also found previously described asymmetries in the cingulate sulcus (right > left) and the caudate nucleus (right > left). Finally, in some brain regions we observed highly significant asymmetries that were not reported before, such as in the anterior insular cortex (right > left). The above asymmetries were observed in men and women. Our results thus provide confirmation of the known structural asymmetries in the human brain as well as new findings that may stimulate further research of hemispheric specialization.

Adolescent↗
PubMed1997

Detection of joint pathology by magnetic resonance imaging in patients with early rheumatoid arthritis.

Magnetic resonance imaging (MRI) permits the visualization of anatomical structures not appreciated by conventional radiographic imaging, and may assess inflammatory disease and its progression with greater sensitivity than conventional radiography. In this study of 30 patients with early rheumatoid arthritis (RA), which could be considered as a pilot study because of the relatively small number of patients, we compare MRI of the knee and the fifth metatarsophalangeal joint with clinical and radiographic findings. A parallel study of 10 healthy individuals served as a reference group. In all but one of the 30 patients, MRI revealed some kind of joint abnormality, whereas conventional radiography was normal in 14 patients. The present study thus suggests that MRI may detect inflammatory and/or destructive joint changes in patients with early RA, and that these changes may occur in the absence of clinical symptoms or signs and/or radiographic signs in the examined joint. If these data prove to be confirmed in further controlled studies, MRI may be of importance both for the assessment of prognosis and for the decision to treat in the early critical stages of RA.

Adult↗
PubMed2004

Spinal and spinal cord infection.

This review article includes infections of the vertebral body, intervertebral disc, ligaments and paravertebral soft tissues, epidural space, meninges and subarachnoid space, and the spinal cord. A wide range of infective organisms may be implicated and the incidence of some, notably tuberculosis, is rising due to increased immunocompromise and other factors. Imaging plays a key role in early diagnosis of these diseases, which may be severe and potentially life threatening. Infection may be acquired by the hematogenous route, by infection from contiguous structures or from direct inoculation. Of available imaging techniques, CT and MRI offer the clinically most valuable methods of evaluating all the structures potentially involved in infection. Although many signs are non-specific, indication is given of where appearances raise strong suspicion of infection. The extent of the inflammatory process is well evaluated by imaging, particularly in terms of severity and morbidity of clinical sequelae, which may be severe. Early investigation is mandatory and as MRI presently has the key role in investigation, it should be employed at an early stage of clinical suspicion.

Diagnosis, Differential↗
PubMed1996

Comparison of magnetic resonance imaging and Laser Doppler Anemometry velocity measurements downstream of replacement heart valves: implications for in vivo assessment of prosthetic valve function.

BACKGROUND AND AIM OF THE STUDY: The non-invasive, in-vivo assessment of prosthetic valve function is compromised by the lack of accurate measurements of the transvalvular flow fields or hemodynamics by current techniques. Short echo time magnetic resonance imaging (MRI) may provide a method for the non-invasive, in vivo assessment of prosthetic valve function by accurately measuring changes in the transvalvular flow fields associated with normal and dysfunctional prosthetic valves. The objectives of these in vitro experiments were to investigate the potential for using MRI as a tool to measure the complex flow fields distal to replacement heart valves, and to assess the accuracy of MRI velocity measurements by comparison with Laser Doppler Anemometry (LDA), a gold standard. METHODS: The velocity fields downstream of tilting disc, bileaflet, ball and cage, and pericardial tissue valves were measured using both three-component LDA and MRI phase velocity encoding under a steady flow rate of 22.8 l/min, simulating peak systolic flow. The valves were tested under normal and stenotic conditions to assess the MRI capabilities under a wide range of local flow conditions, velocities and turbulence levels. A new short echo time MRI technique (FAcE), which allowed velocity measurements in stenotic jets with high turbulence, was tested. RESULTS: Good overall agreement was obtained between the MRI velocity measurements and the LDA data. The MRI velocity measurements adequately reproduced the spatial structure of the flow fields. In most cases peak velocities were accurately measured to within 15%. CONCLUSIONS: The results indicate that the FAcE MRI method has the potential to be used as a diagnostic tool to assess prosthetic valve function.

Aortic Valve↗
PubMed2006

Cine magnetic resonance imaging with single-shot fast spin echo for evaluation of dysphagia and aspiration.

The aim of this study was to determine the feasibility of and interest in evaluation of swallowing using dynamic magnetic resonance imaging (cine-MRI) in patients with dysphagia and aspiration caused by an abnormal pharyngeal phase of swallow. A cohort of six patients previously treated for head and neck cancer with persistent dysphagia and/or aspiration were evaluated an average of 47 months after treatment. The morphology and mobility of the oral, oropharyngeal, and laryngeal structures were analyzed using cine-MRI using single-shot fast spin echo technology. The qualitative observations were compared with a clinical fiberoptic swallowing evaluation. Swallowing physiology was analyzable for dry (saliva) swallow in all patients. MRI was well-tolerated by all six patients and no clinical aspiration occurred during the MRI. In five of six cases, further information on the cause of dysphagia was obtained using cine-MRI compared with the clinical evaluation alone. In the remaining case, cine-MRI confirmed the clinical evaluation. Cine-MRI using the dry swallow technique is feasible and without risk in patients with clinical aspiration. Cine-MRI is complementary to clinical evaluation of swallowing in patients with an abnormal pharyngeal phase of swallowing resulting from treatment of cancer.

Adult↗
PubMed1984

Gated MRI of cardiac and paracardiac masses: initial experience.

Ten cardiac and paracardiac masses were studied with magnetic resonance imaging (MRI) to evaluate the utility of this new method for determining the nature, location, and extent of such masses. The masses were intramural lesions (two cases), left atrial thrombus (one case), pericardial cysts (three cases), and mediastinal masses deforming and displacing the left atrium (two cases). ECG-gated images were obtained in all patients. In each of nine cases, MRI determined the location of the mass as intracavitary, intramural, or paracardiac, without the need for exogenous contrast material. It excluded the clinical diagnosis of cardiac tumor in one case. A combination of multislice transaxial, coronal, and sagittal images established the extent of the masses and the degree of impingement on cardiac structures. This initial experience suggests that MRI can provide as much information as echocardiography, computed tomography, and angiography combined in the evaluation of cardiac and paracardiac masses.

Adolescent↗
PubMed1997

Usefulness of magnetic resonance imaging early after acute myocardial infarction.

In patients, early after acute myocardial infarction (AMI), rapid magnetic resonance imaging (MRI) techniques have been used to assess left ventricular (LV) structure, global and regional function, infarct artery patency, or contrast uptake individually. We hypothesized that MRI could be used as a comprehensive evaluation of the post-AMI patient, studying all of these parameters in < 1 hour. Twenty-seven patients were studied after first AMI. Complete examinations were performed in 23 patients, 16 with anterior and 7 with inferior wall myocardial infarction, on day 5 +/- 2 after the event. For measurement of LV structure and regional function, a breath-hold segmented k-space gradient echo tagging sequence was used. A fat-suppressed segmented k-space breath-hold sequence was used for coronary artery imaging. MRI contrast-enhanced images during bolus gadoteridol transit through the myocardium were obtained to assess first-pass contrast uptake. No adverse events were noted during the MRI scanning, which was completed in 46 +/- 5 minutes. The LV mass index, end-diastolic and end-systolic volume indexes, and ejection fraction were (mean +/- SD) 107 +/- 13 g/m2, 87 +/- 23 ml/m2, 54 +/- 20 ml/m2, and 39 +/- 12%, respectively. Intramyocardial percent circumferential shortening was 11 +/- 6% at the apex, 14 +/- 4% in the midventricle, and 15 +/- 4% at the base. Flow within all infarct arteries was visualized. Seventeen of 23 patients had regions of reduced contrast uptake on first-pass imaging with mean signal intensity of 47 +/- 24% that of remote regions. In patients with recent AMI, comprehensive assessment of LV structure and function, infarct artery patency, and regional myocardial contrast uptake was safe and feasible with MRI of < 1 hour.

Adult↗
PubMed2005

Correlation of ventricular asymmetry with metabolic asymmetry in frontotemporal dementia.

BACKGROUND AND PURPOSE: The clinical presentation of frontotemporal dementia (FTD) is often asymmetrical in terms of both its clinical features and atrophy on MRI. Asymmetry in the lateral ventricle size on structural neuroimaging in FTD patients may have clinical significance. However, this has not been systematically investigated yet. This study compares the ventricular asymmetry seen on MRI with that of the asymmetric glucose metabolism using FDG-PET in patients with FTD. METHODS: Nineteen FTD patients who underwent both brain MRI and FDG-PET were retrospectively selected. As control groups, 23 and 11 age and sex-matched healthy normal subjects underwent either brain MRI or FDG-PET, respectively. The ventricular asymmetry index (VAI) was obtained in two ways: by visual rating (VAI-V) and by measuring the lateral ventricular volumes (VAI-ROI). The hemispheric asymmetry of the glucose metabolism on FDG-PET (MAI) was assessed in three ways: 1) by visual rating (MAI-V), 2) by counting the FDG activity of each hemisphere on normalized and smoothed PET images (MAI-ROI) and 3) by counting the number of voxels with significant hypometabolism based on statistical parametric mapping results (MAI-SPM). RESULTS: The VAIs on MRI (VAI-V and VAI-ROI) were highly correlated, as were the MAIs (MAI-V, MAI-ROI, and MAI-SPM) on FDG-PET. More importantly, the VAIs on MRI and the MAIs on FDG-PET showed high correlation. CONCLUSIONS: Ventricular asymmetry in FTD patients was common (78.9%) and there was a high correlation between the ventricular structural asymmetry and the hemispheric metabolic asymmetry. Therefore, it would be reasonable to interpret that the hemisphere with larger ventricle on MRI in FTD patients is undergoing a more active degenerative process.

Adult↗
PubMedDate not supplied

Brain structure localization in positron emission tomography: comparison of magnetic resonance imaging and a stereotactic method.

A method commonly used for localization of brain regions on positron emission tomographic (PET) images is direct visualization and designation of structure on the image itself. This technique, however, is limited to portions of the brain having sufficient differential radionuclide uptake to permit the recognition of structure by observers familiar with brain anatomy. Two other methods commonly used instead of direct visualization are magnetic resonance imaging (MRI) and stereotactic methods of localization. This report compares the accuracy of a MRI method versus a stereotactic method of brain structure localization of PET. The three localization methods were analyzed for sixteen different brain regions in 5 different subjects by two independent observers. The results were converted to PET pixel size (1 pixel = .127 cm) for comparison. MRI localization differed from direct visualization by a mean and standard deviation of approximately 2 +/- 1 pixels in both the X and Y dimensions. Stereotactic localization differed from direct visualization by approximately 2 +/- 1 pixels in the X dimension and by approximately 6 +/- 2 pixels in the Y dimension. This larger variation seen with the stereotactic method may be attributed to the questionable assumption of linearity of structure location with respect to size of the inner table of the calvarium.

Adult↗
PubMedDate not supplied

Alveolar liver echinococcosis: a comparative study of three imaging techniques.

BACKGROUND: We compared the imaging findings in patients with alveolar liver echinococcosis using ultrasound (US), computerized tomography (CT) and magnetic resonance imaging (MRI) in a prospective study. PATIENTS AND METHODS: 30 patients with alveolar echinococcosis (AE) were examined with the above imaging techniques. RESULTS: 30 lesions were detected with all three methods and most lesions (n = 55) were detected with CT. Calcifications were seen in 15 lesions with US, in 21 with CT and in 16 with MRI. MRI best detected necrotic areas and multivesicuLar structures. CONCLUSION: US is the screening method of choice and should primarily be complemented by CT due to its ability to detect the greatest number of lesions and clear demarcation of the characteristic calcifications. MRI may facilitate the diagnosis in uncertain cases with noncalcified or partially calcified lesions by showing the characteristic multivesicular structure, necrotic areas and proximity to vascular structures.

Adult↗
PubMed1999

Merosin-deficient congenital muscular dystrophy: the spectrum of brain involvement on magnetic resonance imaging.

Children with merosin-deficient congenital muscular dystrophy (CMD) have striking white matter changes on T-2 weighted brain magnetic resonance imaging (MRI). There have been occasional cases with structural abnormalities, mainly involving the occipital cortex. We report our brain imaging findings in 14 children with merosin-deficient CMD. Ten cases had a severe reduction or absence of merosin on immunocytochemistry and four cases had partial reduction. All 14 cases had white matter changes, which appeared after the first 6 months of life and persisted with time. The changes were diffuse and the oldest child scanned (14 years) also showed involvement of the U fibres. Five children with total absence of merosin also had structural abnormalities. One child had moderate mental retardation and epilepsy, mainly characterised by complex partial seizures, with atypical absences, which had been difficult to treat. Brain MRI showed marked occipital agyria and pontocerebellar hypoplasia. The gyral pattern of the rest of the brain looked normal. The four other cases, all with normal intelligence, also had cerebellar hypoplasia with variable involvement of the pons. They did not, however, have neuronal migration defects. It is recognised that several forms of congenital muscular dystrophy, namely Fukuyama CMD, muscle-eye-brain disease and Walker-Warburg syndrome, have structural brain abnormalities and associated severe mental retardation. Our cases demonstrate that a range of structural malformations can also be found in a significant number of children with merosin-deficient CMD.

Adolescent↗
PubMedDate not supplied

Postmortem cryosectioning as an anatomic reference for human brain mapping.

This study examined the densitometric and topographic detail of high resolution 3D digital postmortem cryosectioned brain images. Anatomic image data and histology from cryosectioned human brain were compared to in vivo MRI for the ability to delineate neuroanatomic structure. 3D surface reconstructions in the Talairach and Tournoux atlas ("Co-planar stereotaxic atlas of the human brain", Thieme, New York, 1988) coordinate system enabled morphometric comparisons for a representative sample of neuroanatomic structures. Spatial resolution of cryosection images averaged 200 and 170 microns/pixel for whole head and brain, respectively, and 40 microns/pixel for isolated the brain regions. Anatomic detail was far superior to MRI, particularly in deep subcortical regions such as the basal ganglia and in mesencephalic nuclei and tracts. Digital repositioning in the Talairach coordinate system enabled efficient structure localization and morphometric comparison. Histology from collected tissue sections provided cytologic detail that could be mapped to its approximate 3D context. This approach permits comprehensive morphometric analyses necessary for an anatomic framework to a digital atlas of the human brain.

Aged↗
PubMed2004

Comparison of the navicular region of newborn foals and adult horses by magnetic resonance imaging.

Magnetic resonance imaging (MRI) was tested for evaluation of the soft tissue structures of the equine digit in 16 limbs, derived from three adult warmblood horses and two newborn warmblood foals. The following measuring sequences were used in sagittal, transversal and coronal planes: spin echo, gradient echo, inversion recovery. The images were made with a 1.5 Tesla Siemens scanner in a CP-Helmholtz circular coil. To compare the visualization of the same tissue structures in adult and in newborn cases the limbs were imaged with the routinely used MRI sequences that are used for mature tissues. In newborn foals the bursa podotrochlearis could not be determined with the used sequences. For both the adult and newborn limbs the most visualization of the same tissue structures including the fluid spaces and growth plates were taken by the inversion recovery sequence. T2 sequence was very informative in adult cases but moderately in newborn foals.

Animals↗
PubMed2001

Tracking brain volume changes in C57BL/6J and ApoE-deficient mice in a model of neurodegeneration: a 5-week longitudinal micro-MRI study.

Magnetic resonance imaging (MRI)-based volume measurements of brain structures are useful indicators of pending cognitive decline in humans suffering from neurodegenerative diseases. Transgenic mouse models that mimic the clinical conditions of these disorders have been developed. Noninvasive methods that can follow progression and regression of relevant pathology in these mice are therefore in great demand. In this study we tested whether high-resolution MRI (micro-MRI) in a mouse model of neurodegeneration (cerebral ischemia) could reliably track development of brain atrophy. We first established that diffusion imaging at a spatial resolution of 1.6 x 10(-3) mm(3) allowed superior visualization of forebrain, ventricles, and dorsal hippocampus in the mouse brain compared to either T2*- or T1-weighted MR imaging. Using this predetermined protocol we subsequently scanned C56BL/6J (C57) and ApoE-deficient (ApoE(-/-)) mice before and after ischemia. Four groups were studied: C57/sham (n = 9), ApoE(-/-)/sham (n = 9), C57/ischemia (n = 9), and ApoE(-/-)/ischemia (n = 11). All mice received a baseline 3D diffusion scan. One week later C57/ischemia and ApoE(-/-)/ischemia mice were exposed to 10 min of ischemia and scanned again on the 3rd and 30th postischemic day. The C57/sham and ApoE(-/-)/sham mice served as controls and were scanned at corresponding time points. Diffusion images of ApoE(-/-)/ischemia mice on the 3rd postischemic day revealed multiple localized high signal intensity areas. An increase in ventricle and a decrease in dorsal hippocampal volumes (which included the associated cortex laterally) at 30 days confirmed brain atrophy in C57 mice after ischemia. Excessive mortality of ApoE(-/-)/ischemia mice restricted statistical analysis, but ventricle enlargement postischemia was demonstrated. Our results show that volume changes in the brain of a 30-g mouse can be tracked by micro-MRI in a model of neurodegeneration. Clearly the ability to follow progression of pathology in mice will greatly aid our understanding of neurodegenerative diseases and facilitate the many possibilities to intervene pharmacologically.

Animals↗
PubMedDate not supplied

Subcortical hyperintensities on brain magnetic resonance imaging: a comparison between late age onset and early onset elderly depressed subjects.

Subcortical structural changes have been reported to occur in some elderly subjects with late age onset depression. Given the association between diseases affecting subcortical structures and affective disorders, this suggests that these structural changes may be involved in the etiology of late age onset depression in some patients. With the advent of Brain Magnetic Resonance Imaging (MRI), "in vivo" analysis of these subcortical structures is now possible. The authors report a higher occurrence of caudate (60% vs. 11%) and large deep white matter hyperintensities (60% vs. 11%) in late age onset elderly depressed subjects compared with early onset elderly depressed subjects. These results suggest that late age onset depression may be mediated by caudate and white matter structural changes in some patients.

Aged↗
PubMedDate not supplied

The role of magnetic resonance imaging and computed tomography in the treatment evaluation of retroperitoneal lymph-node metastases of non-seminomatous testicular tumors.

The role of Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) in the treatment evaluation of retroperitoneal lymph-node metastases of non-seminomatous testicular tumors (NSTT) was prospectively studied in 10 consecutive patients before, during and after chemotherapy. The results thus obtained were compared with laparotomy findings before and after chemotherapy, the histology of the primary testicular tumor, and that of retroperitoneal residual lesions after chemotherapy. MRI and CT proved to be equivalent in detection and in determining the anatomical localization and size of the retroperitoneal lymph node metastases. Unlike CT, MRI revealed unmistakable changes in the structure of the retroperitoneal lymph-node metastases during chemotherapy, for which no histological cause was found except in mature teratoma. In mature teratoma a high T2 signal was found within the metastases, corresponding with a high water content. On the basis of tumor consistency and signal intensity in the T1- and T2-weighted images, MRI cannot yet warrant any conclusion about the ultimate effect of chemotherapy.

Adolescent↗