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At least 1,351 records · Page 75Linked to original sources
PubMed2003

Evaluation of a semiautomatic 3D fusion technique applied to molecular imaging and MRI brain/frame volume data sets.

A generally applicable 3D fusion method was evaluated using molecular imaging and MRI volumetric data sets from 15 brain tumor patients with stereotactic frames attached to their skull. Point pairs, placed on the frame only, were chosen, polynomial warping coefficients were generated to map voxels from one coordinate space to the other. The MRI frame was considered the reference structure and the standard for "correct" registration. An ANOVA test (p > 0.05) confirmed the point pair choice to be consistent. The 95% confidence interval for the t-test showed the measured distance difference between the registered volumes was within one MRI voxel. A further experiment was conducted to independently evaluate the brain registration based on testing for consistency of randomly selected interior/exterior points. A t-test result (p < 0.05) showed that the consistency (i.e., both interior or both exterior) before and after volume registration were significantly different. This fusion method may be a viable alternative when other methods fail.

Analysis of Variance↗
PubMed2002

High-resolution MRI of cardiac function with projection reconstruction and steady-state free precession.

The purpose of this study was to investigate the trabecular structure of the endocardial wall of the living human heart, and the effect of that structure on the measurement of myocardial function using MRI. High-resolution MR images (0.8 x 0.8 x 8 mm voxels) of cardiac function were obtained in five volunteers using a combination of undersampled projection reconstruction (PR) and steady-state free precession (SSFP) contrast in ECG-gated breath-held scans. These images provide movies of cardiac function with new levels of endocardial detail. The trabecular-papillary muscle complex, consisting of a mixture of blood and endocardial structures, is measured to constitute as much as 50% of the myocardial wall in some sectors. Myocardial wall strain measurements derived from tagged MR images show correlation between regions of trabeculae and papillary muscles and regions of high strain, leading to an overestimation of function in the lateral wall.

Electrocardiography↗
PubMed1989

Assessment of ovaries by magnetic resonance imaging in patients presenting with polycystic ovarian syndrome.

The demonstration of bilaterally enlarged ovaries with multiple small cysts at ultrasound is the morphological hallmark of polycystic ovarian syndrome (PCOS). However, a number of patients with clinical and biochemical diagnosis of PCOS have ovaries that are without sonographically visible discrete cysts. A better contrast resolution is obtained with magnetic resonance imaging (MRI) and enables visualization of organ structure not seen with other techniques. The purpose of the study was to relate the clinical and biochemical features of 10 patients presenting with a PCOS profile to magnetic resonance imaging and to compare these findings with those observed at ultrasound. With MRI, at least one ovary typical of PCOS could be visualized in eight patients, while this was the case in only three patients with ultrasound. The ultrasound examinations were indeed equivocal in the majority of patients (seven cases). No apparent relationship could be found between the clinical and biochemical parameters and ovarian morphology assessed by MRI or ultrasound. In summary, the present study supports the superiority of MRI technique to assess ovarian morphology over the ultrasound technology used in our study. However, the recent technological advances in ultrasound, and specifically the advent of high frequency transvaginal sonography, will be of particular interest in the study of PCOS.

Adolescent↗
PubMed1992

MRI abnormalities in adolescent bipolar affective disorder.

There is increasing evidence for structural differences in the brains of patients with affective disorders. Recent magnetic resonance imaging (MRI) studies have reported focal signal hyperintensities in the deep white matter of bipolar patients. These previous reports had focused on adult patients with prior episodes of illness. In this case report, the authors discuss a young adolescent patient during her first episode of mania and the finding of subcortical focal signal hyperintensities on brain MRI. The etiology, pathophysiology, and clinical correlates of these lesions will be reviewed.

Adolescent↗
PubMed2006

MRI volumetry and proton MR spectroscopy of the brain in Lafora disease.

PURPOSE: To determine brain involvement in Lafora disease by means of 3-T MRI volumetry and 1H magnetic resonance (MR) spectroscopy. METHODS: Ten patients with Lafora disease and 10 healthy controls were included in the study. The diagnosis of Lafora disease was proven genetically by the presence of mutations in the EPM2A gene in all patients, and their evolution was staged in three groups according to their functional state. MRI volumetry was performed by means of AX3DT1 images with assessment of the cerebellum and the brainstem, by using the program Stereonauta, and all the brain structures, by using voxel-based morphometry. [1H]MR spectroscopy was performed by using an Eclipse PRESS sequence probe system with 8-cc voxels positioned in the occipital and frontal cortexes, basal ganglia, pons, and cerebellar hemispheres. Spectral peak areas corresponding to NAA (N-acetylaspartate), creatine, and choline were obtained. RESULTS: MRI volumetry showed no statistically significant differences in patients compared with healthy controls in any of the analyzed structures. Analysis of [1H]MR spectroscopy data showed a statistically significant reduction in the NAA/creatine ratio in patients compared with controls in the frontal (p = 0.001) and occipital cortex (p = 0.043), basal ganglia (p = 0.002), and cerebellar hemispheres (p = 0.007). The NAA/choline and choline/creatine ratios were statistically significantly different in the frontal cortex (p = 0.005). No correlation was observed between the disease-evolution stage and MRI-measured volumes (range, -0.92 to 0.44) or [1H]MR spectroscopy values (range, -0.29 to 0.50). CONCLUSIONS: In our series of Lafora disease patients, [1H]MR spectroscopy was more sensitive than structural MRI to detect brain involvement. The brain cortex, especially frontal cortex, cerebellum, and basal ganglia, showed the greatest metabolic changes.

Aspartic Acid↗
PubMed2002

Structure-function correlations in patients with malformations of cortical development.

Malformations of cortical development (MCD) are a diverse group of diseases that exhibit both genetic and phenotypic heterogeneity. While previous studies have described the clinical, MRI, and/or EEG features of specific malformations, structure and function have not been correlated across a wide spectrum of these disorders. We reviewed the medical records of 22 patients with MCD due to abnormal neuronal migration and cortical organization, and correlated levels of clinical disability with specific MRI and EEG findings. The extent of abnormality on MRI was significantly correlated with clinical disability. Compared with patients with other lesions, those with lissencephaly were more disabled. Although background slowing, suppression, fast activity, and interictal epileptiform activity were not individually predictive, the overall degree of EEG abnormality was significantly correlated with clinical disability, as were alterations in the posterior head rhythm and physiologic sleep features.

Journal Article↗
PubMed1998

Development of hyperpolarized noble gas MRI.

Magnetic resonance imaging using the MR signal from hyperpolarized noble gases 129Xe and 3He may become an important new diagnostic technique. Alex Pines (adapting the hyperpolarization technique pioneered by William Happer) presented MR spectroscopy studies using hyperpolarized 129Xe. The current authors recognized that the enormous enhancement in the delectability of 129Xe, promised by hyperpolarization, would solve the daunting SNR problems impeding their attempts to use 129Xe as an in vivo MR probe, especially in order to study the action of general anesthetics. It was hoped that hyperpolarized 129Xe MRI would yield resolutions equivalent to that achievable with conventional 1H2O MRI, and that xenon's solubility in lipids would facilitate investigations of lipid-rich tissues that had as yet been hard to image. The publication of hyperpolarized 129Xe images of excised mouse lungs heralded the emergence of hyperpolarized noble-gas MRI. Using hyperpolarized 3He, researchers have obtained images of the lung gas space of guinea pigs and of humans. Lung gas images from patients with pulmonary disease have recently been reported. 3He is easier to hyperpolarize than 129Xe, and it yields a stronger MR signal, but its extremely low solubility in blood precludes its use for the imaging of tissue. Xenon, however, readily dissolves in blood, and the T1, of dissolved 129Xe is long enough for sufficient polarization to be carried by the circulation to distal tissues. Hyperpolarized 129Xe dissolved-phase tissue spectra from the thorax and head of rodents and humans have been obtained, as have chemical shift 129 Xe images from the head of rats. Lung gas 129Xe images of rodents, and more recently of humans, have been reported. Hyperpolarized 129Xe MRI (HypX-MRI) may elucidate the link between the structure of the lung and its function. The technique may also be useful in identifying ventilation-perfusion mismatch in patients with pulmonary embolism, in staging and tracking the success of therapeutic approaches in patients with chronic obstructive airway diseases, and in identifying candidates for lung transplantation or reduction surgery. The high lipophilicity of xenon may allow MR investigations of the integrity and function of excitable lipid membranes. Eventually, HypX-MRI may permit better imaging of the lipid-rich structures of the brain. Cortical brain function is one perfusion-dependent phenomena that may be explored with hyperpolarized 129Xe MR. This leads to the exciting possibility of conducting hyperpolarized 129Xe functional MRI (HypX-fMRI) studies.

Administration, Inhalation↗
PubMedDate not supplied

Pictorial essay. MRI of the glenoid labrum with gross anatomic correlation.

The objective of this pictorial essay is to illustrate the magnetic resonance image (MRI) appearance of the glenoid labrum and the perilabral structures with and without instillation of intraarticular contrast material. Ten cadaveric shoulder specimens underwent axial MRI using various MR pulse sequences. The shoulders then were transversely sectioned, and the gross morphology of the labrum and perilabral structures was evaluated and correlated with the MR images. The contrast-enhanced sequences allowed for improved anatomic visualization of the structures evaluated.

Aged↗
PubMed2003

Fusion of contrast-enhanced breast MR and mammographic imaging data.

Increasing use is being made of Gd-DTPA contrast-enhanced magnetic resonance imaging for breast cancer assessment since it provides 3D functional information via pharmacokinetic interaction between contrast agent and tumour vascularity, and because it is applicable to women of all ages as well as patients with post-operative scarring. Contrast-enhanced MRI (CE-MRI) is complementary to conventional X-ray mammography, since it is a relatively low-resolution functional counterpart of a comparatively high-resolution 2D structural representation. However, despite the additional information provided by MRI, mammography is still an extremely important diagnostic imaging modality, particularly for several common conditions such as ductal carcinoma in situ (DCIS) where it has been shown that there is a strong correlation between microcalcification clusters and malignancy. Pathological indicators such as calcifications and fine spiculations are not visible in CE-MRI and therefore there is clinical and diagnostic value in fusing the high-resolution structural information available from mammography with the functional data acquired from MRI imaging. This paper presents a novel data fusion technique whereby medial-lateral oblique (MLO) and cranial-caudal (CC) mammograms (2D data) are registered to 3D contrast-enhanced MRI volumes. We utilise a combination of pharmacokinetic modelling, projection geometry, wavelet-based landmark detection and thin-plate spline non-rigid 'warping' to transform the coordinates of regions of interest (ROIs) from the 2D mammograms to the spatial reference frame of the contrast-enhanced MRI volume. Of key importance is the use of a flexible wavelet-based feature extraction technique that enables feature correspondences to be robustly determined between the very different image characteristics of X-ray mammography and MRI. An evaluation of the fusion framework is demonstrated with a series of clinical cases and a total of 14 patient examples.

Adult↗
PubMed2004

Fusion of contrast-enhanced breast MR and mammographic imaging data.

Increasing use is being made of Gd-DTPA contrast-enhanced MRI (CE-MRI) for breast cancer assessment since it provides three-dimensional (3D) functional information via pharmacokinetic interaction between contrast agent and tumour vascularity, and because it is applicable to women of all ages as well as patients with post-operative scarring. CE-MRI is complementary to conventional X-ray mammography, since it is a relatively low-resolution functional counterpart of a comparatively high-resolution 2D structural representation. However, despite the additional information provided by MRI, mammography is still an extremely important diagnostic imaging modality, particularly for several common conditions such as ductal carcinoma in situ (DCIS) where it has been shown that there is a strong correlation between microcalcification clusters and malignancy. Pathological indicators such as calcifications and fine spiculations are not visible in CE-MRI and therefore there is clinical and diagnostic value in fusing the high-resolution structural information available from mammography with the functional data acquired from MRI. This article is a clinical overview of the results of a technique to transform the coordinates of regions of interest (ROIs) from the 2D mammograms to the spatial reference frame of the contrast-enhanced MRI volume. An evaluation of the fusion framework is demonstrated with a series of clinical cases and a total of 14 patient examples.

Breast Neoplasms↗
PubMed2001

Gd-DTPA2)-enhanced MRI of femoral knee cartilage: a dose-response study in healthy volunteers.

The negatively charged contrast agent Gd-DTPA2- distributes inversely to the cartilage fixed charged density. This enables structural cartilage examinations by contrast-enhanced MRI. In line with the development of a clinically applicable protocol for such examinations, this study describes the temporal pattern of Gd-DTPA2- distribution in femoral knee cartilage at three different doses in healthy volunteers. Nineteen volunteers (ages 21-28 years) were examined with a 1.5T MRI system. Quantitative relaxation rate measurements were made in weight-bearing central parts of femoral cartilage using sets of five turbo inversion recovery images with different inversion times. The cartilage was analyzed before and four times (1-4 h) after an intravenous injection of Gd-DTPA2- at single, double, and triple doses: 0.1, 0.2, and 0.3 mmol/kg body weight, respectively. The increase in R1 postcontrast was linearly dose-related at all times. The highest R1 values were registered at 2 and 3 h postcontrast, suggesting 2 h to be optimal in the clinical situation. The triple dose indicated a subtle compartmental difference in men, with higher contrast distribution medially than laterally. Results suggest that the triple dose is needed to detect minor cartilage matrix differences.

Adult↗
PubMed2003

Early diagnosis of Alzheimer's disease: contribution of structural neuroimaging.

To accurately predict the development of Alzheimer's disease (AD) at its predementia stage would be a major breakthrough from both therapeutic and research standpoints. In this review, our focus is on markers obtained with structural imaging--especially magnetic resonance imaging (MRI)--and on studies of subjects at risk of developing AD. Among the latter, amnestic mild cognitive impairment (MCI) is currently the most commonly accepted reference, and therefore is specially targeted in this review. MCI refers to patients with significant but isolated memory impairment relative to subjects of identical age. Consistent with established histopathological data, structural imaging studies comparing patients with early probable AD to healthy aged subjects have shown that the most specific and sensitive features of AD at this stage are hippocampal and entorhinal cortex atrophy, especially when combined with a reduced volume of the temporal neocortex. MCI patients have significant hippocampal atrophy when compared to aged normal controls. When comparing patients with probable AD to MCI subjects, hippocampal region atrophy significantly extends to the neighboring temporal association neocortex. However, only longitudinal studies of MCI subjects are suited to assess (in a retrospective way) the predictive value of initial atrophy measurements for progression to AD. Few such studies have been published so far and for the most they were based on small samples. Furthermore, the comparison among studies is clouded by differences in both populations studied and MRI methodology used. Nevertheless, comparing the initial MRI data of at-risk subjects who convert to AD at follow-up to those of nonconverters suggests that a reduced association temporal neocortex volume combined with hippocampal or anterior cingulate cortex atrophy may be the best predictor of progression to AD. These data, although still preliminary, are consistent with postmortem studies describing the hierarchical progression of tau lesions in normal aging and early stages of AD, such that damage to the medial temporal lobe and association cortex would account for the memory and nonmemory cognitive impairments, respectively, the combination of which is required to operationally define probable AD. Future research in this field should capitalize on thorough methodology for brain structure delineation, and combine atrophy measurements to cognitive and/or functional imaging data.

Aged↗
PubMed2006

Sleep exacerbation of persistent sexual arousal syndrome in a postmenopausal woman.

AIM: To investigate possible causes and treatment of persistent sexual arousal syndrome, which was exacerbated by sleep onset, in a postmenopausal subject. METHODS: A clinical examination and interviews with the patient to obtain her case history and follow-up of the effects of drug treatments. Pretreatment laboratory investigations monitored vaginal blood flow by photoplethysmography and heated electrode. Routine blood chemistry and endocrine assessments were undertaken. Magnetic resonance imaging (MRI) scans of brain, pelvis, and spinal cord and genito-sensory neural analysis of clitoral and vaginal areas were performed. A selective internal iliac artery arteriogram was utilized to check the normality of the pelvic blood supply. RESULTS: Genitalia appeared normal and uncongested. No structural abnormalities were observed in the MRI scans. Hormonal levels and blood chemistry were commensurate with the subject's postmenopausal status. Basal vaginal blood flow (heat electrode) was within the range of normal premenopausal women and showed (photoplethysmography) normal vasomotion. On becoming drowsy and falling lightly asleep in the laboratory the vaginal pulse amplitude (VPA) increased by 95% of the basal value and the low-amplitude VPAs were replaced by high-amplitude VPAs--all evidence of increased vaginal blood flow and congestion and confirming the subject's complaint of persistent sexual arousal during sleep. A simple cognitive task of repeatedly subtracting 7 from 500 out aloud did not hasten the reversion to the basal level. There was no evidence of malfunction of the brain, spinal cord, or pelvic area by MRI but genito-sensory analysis of the clitoral and vaginal area showed evidence of reduced sensory function. CONCLUSIONS: Of the treatments tried only risperidone has been effective allowing the subject to sleep throughout the night without disturbance and according to the subject has significantly reduced the aggravation of the arousal during the day.

Arousal↗
PubMed2002

Stereotaxy-based regional brain volumetry applied to segmented MRI: validation and results in deficit and nondeficit schizophrenia.

A method for postprocessing of segmented routine brain MRI studies providing automated definition of major structures (frontal, parietal, occipital, and temporal lobes; cerebellar hemispheres; and lateral ventricles) according to the Talairach atlas is presented. The method was applied to MRI studies from 25 normal subjects (NV), 14 patients with deficit schizophrenia (DS), and 14 with nondeficit schizophrenia (NDS), to evaluate their gray matter and CSF regional volumes. The two patient groups did not differ in mean age at illness onset, duration of illness, severity of psychotic symptoms, or disorganization; DS had more severe avolition and worse social functioning than NDS. For validation purposes, brain structures were manually outlined on original MR images in 10 studies, thus obtaining reference measures. Manual and automated measures were repeated 1 month apart to measure reproducibilities of both methods. The automated method required less than 1 min/operator per study vs more than 30 min for manual assessment. Mean absolute difference per structure between the two techniques was 4.8 ml. Overall reproducibility did not significantly differ between the two methods. In subjects with schizophrenia, a significant decrease in GM and increase in CSF were found. GM loss was confined to frontal and temporal lobes. Lateral ventricles were significantly larger bilaterally in NDS compared to NV and only on the right in NDS compared to DS. The finding of greater structural brain abnormalities in NDS adds to the evidence that deficit schizophrenia does not represent just the more severe end of the schizophrenia continuum.

Adolescent↗
PubMed2000

Dolichoodontoid. A rare cranio-cervical anomaly--MRI findings.

The case of a 40-year-old woman with a dolichoodontoid, a rare congenital anomaly of the cranio-cervical region, is presented. Due to summation image and overlying bony structures, plain radiographs in two planes were inconclusive. MRI revealed the hyperplasia of the odontoid process, allowed a grading of the subtype of this disorder and demonstrated its relationship to the neural structures within the foramen magnum and the upper cervical spine. Additional inflammatory disease, suspected in this patient with long standing rheumatoid arthritis could be excluded by MRI.

Adult↗
PubMed2004

[Contribution of MRI to the exploration of partial refractory epilepsy].

The development of MRI has modified clinical practices for patients with epilepsy. MRI examinations are highly contributive to the detection of structural brain abnormalities, and have a major impact on the management of patients with epilepsy. In addition to its major diagnostic role, MRI may help to assess prognosis in patients with refractory partial epilepsy. Structural abnormalities such as hippocampal sclerosis or malformations of cortical development are associated with medically refractory epilepsy. Furthermore, finding a focal lesion on MRI is a good prognostic factor in refractory patients who are candidates for surgery. The sensitivity of MRI to detect small brain lesions is currently excellent, but may be further improved by the use of high-resolution imaging, and new techniques such as quantitative methods or statistical parametric mapping (SPM). In the future, new emerging MR techniques will undoubtedly greatly contribute to improved presurgical management of patients with refractory partial epilepsy.

Anticonvulsants↗
PubMed2001

Complete pterygoidectomy--a novel method for the topographical investigation of the deep masticator space and its contents.

The complexity of the topographical anatomy of the infratemporal fossa (=masticator space) remains underappreciated because of limitations of the methods used to expose it; these methods are described and critiqued. The disposition of the lateral pterygoid (LPt) muscle in the masticator space obscures the anatomical relations of clinically significant neurovascular structures. Controversies regarding the nerve supply and actions of the two LPt heads are summarized. Since the LPt has been implicated in temporomandibular (joint) dysfunction (TMD), its precise relationships to the mandibular neurovascular structures is essential in understanding its role in TMD. We recently developed a method involving the en bloc removal of the LPt-tensor veli palatini complex along with all vital neurovascular structures. Further investigations using our method--in conjunction with contemporary imaging techniques (CT, MRI)--should help describe the detailed topography of masticatory structures. This information should help in understanding, differential diagnosis, and treatment of TMD.

Aged↗
PubMed1989

Structural brain-imaging findings in affective disorders: an overview.

In recent years, numerous reports of structural brain abnormalities found with computerized tomography (CT) scans in affective disorders (e.g., major depression, bipolar disorder) have been published. More currently, magnetic resonance imaging (MRI) studies have provided additional data on brain structure in affective disorders. In this article, the various CT and MRI findings in affective disorders are reviewed, and the clinical and research relevance of those neuroanatomical findings are presented and discussed.

Brain↗