Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Structural 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 595 records · Page 33Linked to original sources
PubMed1998

Hemicranial volume deficits in patients with temporal lobe epilepsy with and without hippocampal sclerosis.

PURPOSE: In patients with refractory temporal lobe epilepsy, studies have suggested volume deficits measured by MRI of brain structures outside the epileptogenic hippocampus. Hippocampal sclerosis (HS) is a frequent, but not obligate, finding in such patients. The present study examines the influence of the presence of HS on quantitative magnetic resonance imaging (MRI) measurements. METHODS: We analyzed 47 patients and 30 controls by quantitative MRI, including intracranial volume (ICV), hemicranial volume, hippocampal volume (HCV), and T2 relaxometry. MRI results were compared with histological findings in the resected temporal lobe. RESULTS: Histology documented HS in 35 patients (HS group) and other findings in 12 patients (no-HS group). In both groups, the hemicranial volume ipsilateral to the epileptogenic focus was significantly smaller than on the contralateral side (p < 0.004). The HCV on both sides was smaller in the HS group compared with patients without HS (p < or = 0.004). Unilateral hippocampal atrophy and increased T2 value were found in 71% of patients with HS, and bilaterally normal HCV and T2 value were found in 67% of patients without HS. CONCLUSIONS: The smaller hemicranial volume on the focus side, irrespective of the presence or absence of HS suggests a different pathogenic mechanism for the additional hemicranial volume deficit, compared to HS itself. The contralateral HCV deficit depends on the presence of HS, indicating a pathogenic connection between damage to both hippocampi.

Adult↗
PubMed2002

Congruent MRI and near-infrared spectroscopy for functional and structural imaging of tumors.

We present a combined near-infrared diffuse optical spectroscopy (DOS) and Magnetic Resonance Imaging (MRI) system for the study of animal model tumors. A combined broadband steady-state and frequency domain optical spectroscopy apparatus was integrated with the MRI. The physiological properties of tissue rendered by MRI, including vascular volume fraction and water, were compared with chromophore concentrations as determined from the parameters obtained by optical measurements. DOS measurements provided oxy-hemoglobin, deoxy-hemoglobin, and water concentration locally in tumors. A method for co-registration of the information obtained by both modalities was developed. Using Monte Carlo simulations, the optically sampled volume was superimposed on the MR images, illustrating which tissue structure was probed optically. Finally, two optical contrast agents, indocyanine green (ICG) and methylene blue (MB), were employed and their kinetics were measured by DOS system from different locations on the tumor and compared with Gd-DTPA enhancement maps obtained from MRI.

Animals↗
PubMed1996

The demonstration of gyral abnormalities in patients with cryptogenic partial epilepsy using three-dimensional MRI.

BACKGROUND: Despite the use of high-resolution magnetic resonance imaging (MRI) in the demonstration of structural abnormalities underlying chronic partial epilepsy, a significant proportion of MRI scans in such cases still appear normal when viewed conventionally as two-dimensional images, especially in extratemporal epilepsies. OBJECTIVES: To increase the yield of MRI in patients with extratemporal epilepsies. To examine specific regions of three-dimensional surface renderings of the cerebral hemispheres. DESIGN: Postprocessing of volumetric MRI data was used to detect abnormalities of gyration that may not be seen otherwise. SETTING: Scans were obtained at a hospital clinical imaging facility. PARTICIPANTS: Sixty-four subjects were studied: 33 controls, 15 patients with hippocampal sclerosis (as disease controls), and 16 patients with cryptogenic partial epilepsy that on clinical grounds was extratemporal. MAIN OUTCOME MEASURES: Gyral patterns were evaluated for abnormality by visual comparison between subjects. RESULTS: Inspection of the routine two-dimensional images had failed to demonstrate relevant underlying neocortical abnormality in any of the patients' scans. Three-dimensional reconstruction revealed abnormal gyral patterns in the frontal lobe convexity in seven of the 16 cryptogenic clinically extratemporal cases. Macrogyria was revealed in one case and increased gyral complexity with altered disposition was seen in six cases. Similar gyral patterns were not seen in any subjects from the other groups. CONCLUSION: Three-dimensional analysis of volumetric MRI data can reveal structural abnormality that is not visible when the data are viewed as two-dimensional images only.

Adult↗
PubMed2000

Electroencephalography during functional echo-planar imaging: detection of epileptic spikes using post-processing methods.

EEG has been used to trigger functional MRI of patients with focal epilepsy, but EEG can be obscured by artifacts during MR data acquisition, and no continuous correlation of EEG and MRI has been possible without limiting the image time. Artifacts caused by an MRI sequence were investigated in five healthy subjects, and an EEG of five patients with epileptic discharges was recorded during echo-planar imaging. All interfering frequencies in the EEG were discrete and defined by loop structures in the MRI sequence. In post-processing of the EEG interfering frequencies were automatically detected by comparing the frequency spectra of the EEG recorded before and during imaging. After elimination of interfering frequencies by filters in the time domain or by Fourier transform, reliable spike detection in the EEG recorded during MR data acquisition became feasible, without loss of EEG quality.

Algorithms↗
PubMed2004

Dichotic listening in children with focal epilepsy: effects of structural brain abnormality and seizure characteristics.

The study examined performance on a dichotic listening test in children with focal epilepsy. The aim of the study was to explore how factors related to brain pathology would affect ear advantage. The effects of lateralization of epileptogenic area, size and localization of structural abnormality on MRI findings, and seizure characteristics were studied. Children treated for focal epileptic seizures took part in the study (N = 35). The dichotic test consisted of pairs of words, nonwords, syllables and vowels. Results demonstrated that large congenital structural abnormality in the left hemisphere altered ear advantage whereas smaller abnormality and right-hemisphere abnormality did not. Further, epileptic seizures of left-hemisphere origin that had started at an early age affected ear advantage whereas seizure frequency at the time of the assessment did not. Children with early onset of seizures of right-hemisphere origin had a strong right-ear advantage. The total score did not differ between the groups. There was a strong negative correlation between the scores for the right-ear and the left-ear. The findings were interpreted to indicate altered functional dominance for perception of auditory, linguistic stimuli following early left-hemisphere pathology rather than unilateral functional suppression.

Adolescent↗
PubMed2006

Sectional anatomic and magnetic resonance imaging features of coelomic structures of loggerhead sea turtles.

OBJECTIVE: To compare cross-sectional anatomic specimens with images obtained via magnetic resonance imaging (MRI) of the coelomic structures of loggerhead sea turtles (Caretta caretta). ANIMALS: 5 clinically normal live turtles and 5 dead turtles. PROCEDURES: MRI was used to produce T1- and T2- weighted images of the turtles, which were compared with gross anatomic sections of 3 of the 5 dead turtles. The other 2 dead turtles received injection with latex and were dissected to provide additional cardiovascular anatomic data. RESULTS: The general view on the 3 oriented planes provided good understanding of cross-sectional anatomic features. Likewise, major anatomic structures such as the esophagus, stomach, lungs, intestine (duodenum and colon), liver, gallbladder, spleen, kidneys, urinary bladder, heart, bronchi, and vessels could be clearly imaged. It was not possible to recognize the ureters or reproductive tract. CONCLUSIONS AND CLINICAL RELEVANCE: By providing reference information for clinical use, MRI may be valuable for detailed assessment of the internal anatomic structures of loggerhead sea turtles. Drawbacks exist in association with anesthesia and the cost and availability of MRI, but the technique does provide excellent images of most internal organs. Information concerning structures such as the pancreas, ureters, intestinal segments (jejunum and ileum), and the reproductive tract is limited because of inconsistent visualization.

Abdomen↗
PubMed1992

The relationship of SPECT scans to behavioral dysfunction in neuropsychiatric patients.

The authors describe 20 neuropsychiatric inpatients consecutively evaluated in the context of routine clinical care. Patients had both a neurological and psychiatric disorder. Each was clinically evaluated as part of a psychiatric hospitalization. DSM-III-R diagnoses, electroencephalograms, magnetic resonance imaging (MRI) or computed tomography (CT) scans of the brain, single photon emission computed tomography (SPECT) scans of the brain, and cognitive testing are reported. In only three cases were SPECT, MRI (or CT), and electroencephalogram all normal. SPECT abnormalities were associated with behavioral and cognitive presentations and with the hypothesized anatomical areas of dysfunction in 16 cases. In six cases SPECT and MRI were equivalent, involving structural lesions or normal scans. In only one case did MRI (or CT) detect deficits not revealed by SPECT, which were nonspecific white matter lesions and atrophy. The authors conclude that SPECT scans may be superior to structural brain scans in detecting clinically relevant deficits in neuropsychiatric patients, particularly when physiological lesions are involved.

Adult↗
PubMed1987

Magnetic resonance imaging in psychiatry.

Magnetic resonance imaging (MRI) is a relatively new radiological technique that may be useful in the study of psychiatric illness. MRI gives detailed structural information about the brain and also allows quantification of functional change. Current areas of study relevant to psychiatry include: schizophrenia, dementia, epilepsy and, to a lesser extent, alcohol and affective disorders. The authors review the basic principles of MRI, discuss the recent application to psychiatry, indicate its potential advantages and comment on the current limitations of this imaging modality.

Brain↗
PubMed2002

Homocysteine and cognitive function in the elderly: the Rotterdam Scan Study.

BACKGROUND: Elevated plasma total homocysteine (tHcy) concentrations are associated with AD and vascular dementia, but the relation with cognitive performance in nondemented elderly people is not known. OBJECTIVE: To examine the association of tHcy and cognitive function in the elderly, and assess whether this may be mediated by structural brain changes on MRI. METHODS: The Rotterdam Scan Study is a population-based study of 1,077 nondemented elderly. Cognitive performance was assessed, and compound scores were constructed for psychomotor speed, memory function, and global cognitive function. Cerebral infarcts, white matter lesions, and generalized brain atrophy were measured on MRI. The cross-sectional relationship between tHcy levels and neuropsychological test scores was assessed by multiple regression. RESULTS: Mean tHcy level was 11.5 micro mol/L (SD 4.1). Increasing tHcy levels were associated with lower scores for psychomotor speed, memory function, and global cognitive function, and this was largely due to the association with tHcy levels in the upper quintile (>14 micro mol/L). Adjusted differences between test scores of participants in the upper quintile as compared with the lower four quintiles of tHcy were -0.26 (95% CI: -0.37; -0.14) for psychomotor speed, -0.13 (95% CI: -0.27; 0.01) for memory function, and -0.20 (95% CI: -0.30; -0.11) for global cognitive function. These associations were not mediated by structural brain changes on MRI. CONCLUSION: Elevated tHcy levels are associated with decreased cognitive performance in nondemented elderly people, and the relation was most marked for psychomotor speed. This association was independent of structural brain changes on MRI.

Aged↗
PubMed2006

Assessment of MRI abnormalities of the brainstem from patients with migraine and multiple sclerosis.

BACKGROUND: In patients with migraine, functional changes have been described in the red nucleus (RN), substantia nigra (SN) and periaqueductal gray matter (PAG). PURPOSE: To evaluate whether and at which frequency these structures are involved by MRI-detectable structural abnormalities in migraineurs and to investigate the pathogenic role of these abnormalities by assessing their frequency and extent in patients with multiple sclerosis (MS) and migraine. METHODS: On brain dual-echo scans obtained from 58 migraineurs (40 without and 18 with aura), 37 MS patients with migraine without aura and 42 MS patients without migraine, the presence of hyperintense lesions involving the brainstem structures was recorded. A test of heterogeneity between groups was used to compare the presence of lesions among patient groups. RESULTS: Lesions of RN, SN and PAG were found in all patient groups, with frequency from 57.5% to 86.5%. Significant between-group differences for all these regions were found. No difference was found between migraine patients with and without aura. Compared with MS patients without migraine, MS patients with migraine had more significant involvement of the SN (p=0.02) and RN (p<0.0001). Compared with migraine patients, MS patients with migraine had more significant involvement of the SN and PAG (p ranging from 0.009 to 0.02). CONCLUSIONS: T2-visible lesions in the brainstem are frequent in patients with migraine, but do not seem to be associated with the presence of aura. Demyelinating lesions in the RN, SN and PAG might be among the factors responsible for the presence of migraine in patients with MS.

Adolescent↗
PubMed1996

Humeral avulsion of the anterior shoulder stabilizing structures after anterior shoulder dislocation: demonstration by MRI and MR arthrography.

OBJECTIVE: To demonstrate the MRI findings of an anterior shoulder capsular avulsion from the humerus, with or without subscapularis rupture, after anterior dislocation or severe abduction external rotation injury. DESIGN AND PATIENTS: We retrospectively reviewed the MRI and MR arthrographic examinations of seven patients who were identified at surgery with avulsion of the anterior shoulder stabilizers from the humerus. MRI was correlated with clinical history and surgical results. RESULTS: MRI findings included: inhomogeneity or frank disruption of the anterior capsule at the humeral insertion (all), fluid intensity anterior to the shoulder (six patients), tear of the subscapularis tendon (six patients), dislocation of the biceps tendon (four patients), and a Hill-Sachs deformity (four patients). MR arthrography additionally found extravasation of contrast through the capsular defect (two patients). CONCLUSIONS: Our findings suggest that MRI is helpful for diagnosing humeral avulsion of the anterior glenohumeral capsule, especially when a tear of the subscapularis tendon insertion is present. MR arthrography may be of benefit for diagnosing capsular avulsion without associated subscapularis tendon abnormality.

Adult↗
PubMed2005

Altered white matter/gray matter proportions in the striatum of patients with schizophrenia: a volumetric MRI study.

OBJECTIVE: Anatomical structures of the striatum were studied in 58 patients with schizophrenia and 56 healthy comparison subjects of both genders matched for age and handedness. METHOD: Magnetic resonance imaging scans were used to measure gray matter, white matter, and CSF volumes of the caudate, putamen, and nucleus accumbens in the left and the right hemispheres. RESULTS: White matter/gray matter ratios of the striatal structures were significantly lower in patients than in healthy subjects. In patients, relative white matter volumes in the caudate and nucleus accumbens were reduced, whereas gray matter in the putamen was increased. The total accumbens volume did not differ by diagnosis, but left side accumbens was larger than right in the healthy subjects. The proportion of white matter was greater in women in both the patient and healthy comparison groups. Total caudate and putamen volumes demonstrated no differences due to diagnosis or laterality, but a negative correlation was found in patients between white matter volumes and increasing age. There were no significant correlations among total striatal volumes, white matter/gray matter ratios, age at onset of illness, or illness duration. An estimate of lifetime neuroleptic consumption was positively correlated with right gray matter volume of the putamen in male schizophrenia patients who received typical neuroleptics. CONCLUSIONS: The proportion of white matter to gray matter tissue volumes of the caudate, putamen, and nucleus accumbens is altered in medicated chronic schizophrenia patients, but the total volumes are unchanged.

Adult↗
PubMed2006

Mutant glycosyltransferases assist in the development of a targeted drug delivery system and contrast agents for MRI.

The availability of structural information on glycosyltransferases is beginning to make structure-based reengineering of these enzymes possible. Mutant glycosyltransferases have been generated that can transfer a sugar residue with a chemically reactive unique functional group to a sugar moiety of glycoproteins, glycolipids, and proteoglycans (glycoconjugates). The presence of modified sugar moiety on a glycoprotein makes it possible to link bioactive molecules via modified glycan chains, thereby assisting in the assembly of bionanoparticles that are useful for developing the targeted drug delivery system and contrast agents for magnetic resonance imaging. The reengineered recombinant glycosyltransferases also make it possible to (1) remodel the oligosaccharide chains of glycoprotein drugs, and (2) synthesize oligosaccharides for vaccine development.

Animals↗
PubMed1998

In vivo high resolution MRI of the calcaneus: differences in trabecular structure in osteoporosis patients.

The purpose of this study was to use high resolution (HR) magnetic resonance (MR) images of the calcaneus to investigate the trabecular structure of patients with and without osteoporotic hip fractures and to compare these techniques with bone mineral density (BMD) in differentiating fracture and nonfracture patients. Axial and sagittal HR MR images of the calcaneus were obtained in 50 female (23 postmenopausal patients with osteoporotic hip fractures and 27 postmenopausal controls). A three-dimensional gradient-echo sequence was used with a slice thickness of 500 micron and in plane resolution of 195 x 195 micron. Texture analysis was performed using morphological features, analogous to standard histomorphometry and fractal dimension. Additionally, BMd measurements of the hip (dual-energy X-ray absorptiometry) were obtained in all patients. Significant differences between both patient groups were obtained using morphological parameters and fractal dimension as well as hip BMD (p < 0.05). Odds ratios for the texture parameters apparent (app.) bone volume/total volume and app. trabecular separation were higher than for hip BMD. Receiver operator characteristic values of texture measures and hip BMD were comparable. In conclusion, trabecular structure measures derived from HR MR images of the calcaneus can differentiate between postmenopausal women with and without osteoporotic hip fractures.

Absorptiometry, Photon↗
PubMed1994

[Transmission electron microscopy in the structural study of superparamagnetic contrast agents for MRI].

Iron oxide nanoparticles with different crystal sizes and uniform dextran coating were synthesized and analyzed by T.E.M.. The iron oxide core dimension and homogeneity of the preparation were correlated to magnetic properties. The increasing Fe/Dextran ratio used for the synthesis was well correlated with the mean diameter and the magnetic susceptibility. The comparison of the crystal size with the particle size determined by nanosizer in solution suggest that particles consist in nanoaggregates of many crystal subunits.

Contrast Media↗
PubMed1997

[Brain structures of reading Japanese words with functional MRI].

This review examines recent progress in understanding mechanisms involved in language related brain functions using functional magnetic resonance imaging (fMRI). The main focus is to detect differences in reading processes between the ideogram (Japanese kanji) and the phonogram (Indo-European language or Japanese kana). Inferior temporal (IT) areas on the language dominant side are involved in reading both characters. A plasticity model is introduced to explain the different localizations that have been ascribed to kana or kanji, respectively. FMRI will be an important clinical application for the preoperative evaluation of patients with lesions adjacent to these areas in the near future. Activation studies involving visual imagery and other relevant clinical issues are also briefly reviewed.

Brain↗
PubMed1996

Magnetic resonance imaging of acute Maisonneuve fractures.

Magnetic resonance imaging (MRI) studies were performed on five patients with acute Maisonneuve fractures. All patients had sustained a twisting injury to their ankles and complained of ankle pain and pain over their proximal fibula. High quality images with excellent visualization of all the ankle ligamentous structures were obtained. MRI showed that the anterior inferior tibiofibular ligament was disrupted in all patients and the posterior inferior tibiofibular ligament was intact in three of five patients. Also, the anterior talofibular ligament was disrupted in all patients and the calcaneofibular ligament was ruptured in two of five patients. This raises the question of whether patients with Maisonneuve fractures have lateral ankle instability at long-term follow-up. Although the superficial deltoid ligament was disrupted in all patients, the deep deltoid ligament was intact in one patient, partially disrupted in one patient, and completely disrupted in three patients. The interosseous ligament was disrupted at the ankle in all patients, while the interosseous membrane was disrupted in the leg in all patients except one. This patient had an intact interosseous membrane despite rupture of the interosseous ligament at the ankle and the presence of a proximal one third fibula fracture.

Acute Disease↗