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PubMed2005

The functional neuroanatomy of bipolar disorder: a review of neuroimaging findings.

The authors review existing structural and functional neuroimaging studies of patients with bipolar disorder and discuss how these investigations enhance our understanding of the neurophysiology of this illness. Findings from structural magnetic resonance imaging (MRI) studies suggest that some abnormalities, such as those in prefrontal cortical areas (SGPFC), striatum and amygdala exist early in the course of illness and, therefore, potentially, predate illness onset. In contrast, other abnormalities, such as those found in the cerebellar vermis, lateral ventricles and other prefrontal regions (eg, left inferior), appear to develop with repeated affective episodes, and may represent the effects of illness progression and associated factors. Magnetic resonance spectroscopy investigations have revealed abnormalities of membrane and second messenger metabolism, as well as bioenergetics, in striatum and prefrontal cortex. Functional imaging studies report activation differences between bipolar and healthy controls in these same anterior limibic regions. Together, these studies support a model of bipolar disorder that involves dysfunction within subcortical (striatal-thalamic)-prefrontal networks and the associated limbic modulating regions (amygdala, midline cerebellum). These studies suggest that, in bipolar disorder, there may be diminished prefrontal modulation of subcortical and medial temporal structures within the anterior limbic network (eg, amygdala, anterior striatum and thalamus) that results in dysregulation of mood. Future prospective and longitudinal studies focusing on these specific relationships are necessary to clarify the functional neuroanatomy of bipolar disorder.

Bipolar Disorder↗
PubMed2005

Head position and impact direction in whiplash injuries: associations with MRI-verified lesions of ligaments and membranes in the upper cervical spine.

In the present study, we compared magnetic resonance imaging (MRI) findings of soft tissue structures in the upper cervical spine between whiplash-associated disorder (WAD) patients and population-based control persons, and examined whether MRI-verified abnormalities in WAD patients were related to accident-related factors hypothesized to be of importance for severity of injury. A total of 92 whiplash patients and 30 control persons, randomly drawn, were included. Information on the accident-related factors (i.e., head position and impact direction) was obtained by a questionnaire that was answered within 1 week after the accident. The MRI examination was performed 2-9 (mean 6) years after the accident. Focus was on MRI abnormalities of the alar and the transverse ligaments, and the tectorial and posterior atlanto-occipital membranes, graded 0-3. For all neck structures, the whiplash patients had more high-grade lesions (grade 2 or 3) than the control persons (Chi-square test, p < 0.055). An abnormal alar ligament was most common (66.3% graded 2 or 3). Whiplash patients who had been sitting with their head/neck turned to one side at the moment of collision more often had high-grade lesions of the alar and transverse ligaments (p < 0.001, p = 0.040, respectively). Severe injuries to the transverse ligament and the posterior atlanto-occipital membrane were more common in front than in rear end collisions (p < 0.001, p = 0.001, respectively). In conclusion, the difference in MRI-verified lesions between WAD patients and control persons, and in particular the association with head position and impact direction at time of accident, indicate that these lesions are caused by the whiplash trauma.

Accidents, Traffic↗
PubMed2002

Metabolic and electrophysiological alterations in subtypes of temporal lobe epilepsy: a combined proton magnetic resonance spectroscopic imaging and depth electrodes study.

PURPOSE: This study compared the metabolic regional alterations, characterized by proton magnetic spectroscopic imaging ((1)H-MRSI), with electrophysiological abnormalities recorded by using depth electrodes and with structural lesions, in patients with several subtypes of temporal lobe epilepsy (TLE). METHODS: Twenty-five subjects were investigated, including 15 controls and 10 patients with drug-resistant unilateral TLE, nine of whom had structural abnormalities identified by MRI. All patients underwent noninvasive presurgical evaluation and then stereoelectroencephalography (SEEG). We performed an original metabolic exploration combining two (1)H-MRS imaging acquisitions associated with two single-voxel acquisitions (temporal poles) to map the most informative regions of interest (ROIs) including mesial and neocortical localizations. The N-acetyl aspartate/(choline+creatine) ratio was chosen as a metabolic index. SEEG analysis allowed the classification of each ROI as electrically normal or abnormal (i.e., involved in ictal and/or interictal discharges). Groups were compared by using a nonparametric Mann-Whitney U test. RESULTS: N-Acetyl aspartate/(choline+creatine) was significantly lower in all regions involved in SEEG electrophysiological epileptic abnormalities than in controls (p < 0.05). In contrast, the regions without any electrophysiological abnormalities were not metabolically different from those in controls (p > 0.05) except in one ROI. No differences between the metabolic profiles of epileptogenic and irritative zones were found. The metabolic alterations included, but also extended beyond, the lesions. The presence of metabolic abnormalities in mesial structures was not specific for the mesial subtype and generally extended outside the mesial structures. CONCLUSIONS: These results indicate that metabolic abnormalities are linked to ictal and interictal epileptiform activities rather than to structural alterations in TLE.

Adolescent↗
PubMed2005

Structural neural correlates of prosaccade and antisaccade eye movements in healthy humans.

We previously reported that prosaccade amplitude gain and antisaccade error rate are correlated with cerebellar and posterior frontal grey matter volume, respectively. This study sought to replicate and extend these findings in a sample of 32 right-handed, healthy volunteers (14 males, 18 females). Participants underwent structural magnetic resonance imaging (MRI) at 1.5 T and an off-line eye movement assessment using infrared oculography at 500 Hz. Separate blocks of prosaccades and antisaccades were carried out (60 trials each). Optimised volumetric voxel-based morphometry (VBM) implemented in SPM99 was used to investigate the relationship of saccadic performance measures to regional grey matter volume, covarying for age. A significant negative correlation was obtained between prosaccade spatial error and grey matter volume in the right inferior cerebellar lobe (lobule VIIIB, extending into the vermis, centred at x = 11; y = -64; z = -61), indicating that more grey matter volume in this area was associated with better spatial accuracy. On the antisaccade task, the error rate was significantly negatively correlated with grey matter volume in the right middle frontal gyrus (Brodmann area 6) in an area anterior to the frontal eye field (centred at x = 27; y = 18; z = 50), indicating that more grey matter volume in this area was associated with fewer antisaccade errors. These findings extend our previous observations by identifying the relationship between brain structure and saccadic performance on a spatially highly localised scale and support the validity of structural neuroimaging methods in delineating the neural mechanisms underlying human oculomotor control.

Aged↗
PubMed1998

Magnetic resonance imaging abnormalities and cognitive deficits in systemic lupus erythematosus patients without overt central nervous system disease.

OBJECTIVE: To investigate cerebral magnetic resonance imaging (MRI) abnormalities in relation to cognitive functioning in systemic lupus erythematosus (SLE) patients without a history of central nervous system (CNS) disease. METHODS: Ventricle-to-brain ratios (VBRs) and the total number of white matter hyperintensities (WMHIs) were computed in 20 female patients with non-CNS SLE using established MRI computer-generated quantification procedures. Comprehensive neuropsychological test scores across 8 domains were also obtained. RESULTS: A mean VBR of 2.83% (SD = 0.7) occurred in the non-CNS SLE patients compared with a VBR of 1.36% in a normative sample. The average number of WMHIs was 4.95 (SD = 6.0). Using a combined rating scale (VBR > 2.25%, WMHIs > 5), 7 of 20 MRI scans (35%) were classified as abnormal. Increased VBRs and larger numbers of WMHIs showed a trend association with longer duration of SLE. Thirty-five percent of the non-CNS SLE patients demonstrated neuropsychological deficits. No significant correlations were found between the VBR, total WMHIs, and cognitive scores. Comparisons of cognitively impaired and nonimpaired patients with non-CNS SLE revealed no significant differences across clinical characteristics or MRI values. CONCLUSION: Quantified MRI analyses indicated atypical brain structure and an increased number of WMHIs in a subset of non-CNS SLE patients. However, these MRI abnormalities were not associated with functional abnormalities determined by comprehensive neuropsychological testing. Therefore, MRI analyses are not likely to provide additional clinical information on cognitively impaired SLE patients who have no other evidence of CNS involvement.

Adult↗
PubMed2000

Structural brain imaging and the prevention of schizophrenia: can we identify neuroanatomical markers for young people at risk for the development of schizophrenia?

OBJECTIVE: To examine the potential role of measures derived from structural brain imaging as phenotypic markers for the development of schizophrenia. METHOD: Literature review of results of MRI-based assessments of brain structure in patients with schizophrenia, their first-degree relatives and factors that affect interpretation of such results. RESULTS: Reliable differences in brain structure can be detected in patients with schizophrenia, including those experiencing a first episode of psychosis. Further research is required to determine whether these differences are progressive, how they relate to potential confounding factors such as comorbid substance abuse and the functional consequences of the relatively subtle changes observed. CONCLUSIONS: Further research is needed before structural brain change can be considered as a phenotypic marker for those at risk of developing schizophrenia. Large-scale collaborative research in clinical and normal volunteer groups using standardised assessment protocols would enable the early identification of those findings with predictive power in at-risk populations.

Adolescent↗
PubMed1993

[FDG-PET in an amnestic and hypersomnic patient with bilateral paramedian thalamic infarction].

A 67-year-old patient was admitted to our hospital owing to coma and tetraplegia. MRI showed T2 weighed high intensity areas in the pontine tegmentum, lower aspect of the right cerebellar hemisphere, left half of medulla oblongata, and bilateral paramedian thalamus. He showed marked recovery by urokinase injection becoming able to walk in a few months, but severe amnesia and hypersomnia persisted even 5 months after onset. EEG showed diffuse alpha activity with occasional delta waves in frontal leads. Intelligence was considered normal (WAIS score; verbal IQ 97, performance IQ 102, total IQ 99), through performance on Wechsler memory Scale-R (Revised Japanese edition, WMS-R) and Benton Visual Retention Test indicated impairment of both verbal and visual memory. Verbal memory was impaired to a greater degree than visual memory (Scores of WMS-R: verbal memory index 60, visual memory index 98, index of general memory 72, attention index 95, index of delayed memory 71). He was able to finish only 0 and 1 categories on two trials of the Wisconsin Card Sorting Test. FDG (18F-fluorodeoxyglucose)-PET showed diffuse areas of decreased metabolism in bilateral thalami, frontal lobes, cingulate gyri and medial temporal lobes. The bilateral thalamic lesion seemed to affect the following structures, as judged from MRI: 1) The anterior thalamic peduncle including most of the reciprocal connections between dorsomedial nucleus of thalamus (MD nucleus) and the frontal lobe, 2) The inferior thalamic peduncle which serves as the reciprocal pathway between MD nucleus and medial temporal lobe, especially the amygdala (component of Yakovlev circuit), and 3) The inferior part of mammillothalamic tract (component of Papez circuit).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed2003

Advances in neuroimaging: management of partial epileptic syndromes.

Structural and functional neuroimaging studies are essential in the evaluation of individuals with partial epilepsy syndromes. Magnetic resonance imaging (MRI) is important to delineate structural abnormalities underlying seizure disorders, commonly including hippocampal sclerosis or cortical dysplasias. Identification of a structural lesion is often a reliable indicator of the site of seizure onset. Magnetic resonance spectroscopy (MRS) allows us to investigate cerebral metabolites and some neurotransmitters. Reduction in various metabolite concentrations has proven to be prognostically valuable when no structural abnormality is identified. Positron emission tomography (PET) using deoxyglucose demonstrates areas of reduced glucose metabolism, which are the hallmark of epileptogenic zones and usually extend beyond the underlying anatomical region. It is useful in temporal lobe epilepsy for lateralization; however, results in extratemporal lobe epilepsy have been less favorable. More promising is the use of benzodiazepine receptor ligands, which are reduced in the epileptogenic zone in a more restricted distribution. This appears to be helpful in the localization of extratemporal seizure foci. Peri-ictal single photon emission computed tomography measures increased blood flow during the ictal event and is beneficial in patients with normal MRI studies to determine lateralization and localization of the ictal onset zone. All imaging modalities should be correlated with clinical and neurophysiological data.

Brain↗
PubMed2005

Using voxel-based morphometry to map the structural changes associated with rapid conversion in MCI: a longitudinal MRI study.

Capturing the dynamics of gray matter (GM) atrophy in relation to the conversion from mild cognitive impairment (MCI) to clinically probable Alzheimer's disease (AD) would be of considerable interest. In this prospective study we have used a novel longitudinal voxel-based method to map the progression of GM loss in MCI patients over time and compared converters to non-converters. Eighteen amnestic MCI patients were followed-up for a predefined fixed period of 18 months and conversion was judged according to NINCDS-ADRDA criteria for probable AD. Each patient underwent a high-resolution T1-weighted volume MRI scan both at entry in the study and 18 months later. We used an optimal VBM protocol to compare baseline imaging data of converters to those of non-converters. Moreover, to map GM loss from baseline to follow-up assessment, we used a modified voxel-based morphometry (VBM) procedure specially designed for longitudinal studies. At the end of the follow-up period, seven patients had converted to probable AD. Areas of lower baseline GM value in converters mainly included the hippocampus, parahippocampal cortex, and lingual and fusiform gyri. Regions of significant GM loss over the 18-month follow-up period common to both converters and non-converters included the temporal neocortex, parahippocampal cortex, orbitofrontal and inferior parietal areas, and the left thalamus. However, there was significantly greater GM loss in converters relative to non-converters in the hippocampal area, inferior and middle temporal gyrus, posterior cingulate, and precuneus. This accelerated atrophy may result from both neurofibrillary tangles accumulation and parallel pathological processes such as functional alteration in the posterior cingulate. The ability to longitudinally assess GM changes in MCI offers new perspectives to better understand the pathological processes underlying AD and to monitor the effects of treatment on brain structure.

Aged↗
PubMed2006

Prediction of mechanical properties of trabecular bone using quantitative MRI.

Techniques for quantitative magnetic resonance imaging (MRI) have been developed for non-invasive estimation of the mineral density and structure of trabecular bone. The R*(2) relaxation rate (i.e. 1/T*(2)) is sensitive to bone mineral density (BMD) via susceptibility differences between trabeculae and bone marrow, and by binarizing MRI images, structural variables, such as apparent bone volume fraction, can be assessed. In the present study, trabecular bone samples of human patellae were investigated in vitro at 1.5 T to determine the ability of MRI-derived variables (R*(2) and bone volume fraction) to predict the mechanical properties (Young's modulus, yield stress and ultimate strength). Further, the MRI variables were correlated with reference measurements of volumetric BMD and bone area fraction as determined with a clinical pQCT system. The MRI variables correlated significantly (p < 0.01) with the mechanical variables (r = 0.32-0.46), BMD (r = 0.56) and bone structure (r = 0.51). A combination of R*(2) and MRI-derived bone volume fraction further improved the prediction of yield stress and ultimate strength. Although pQCT showed a trend towards better prediction of the mechanical properties, current results demonstrate the feasibility of combined MR imaging of marrow susceptibility and bone volume fraction in predicting the mechanical strength of trabecular bone and bone mineral density.

Adult↗
PubMed2001

[Reversible bilateral cortical MRI changes as sequelae of status epilepticus].

Neuroimaging may detect structural and functional changes following seizures. Magnetic resonance imaging (MRI) studies showed increased signal intensities in T2- and diffusion-weighted images, especially in the temporal cortex. We report a patient with reversible symmetrical signal abnormalities of the insular cortex after seizures. In addition, the frontal paramedian cortex and the central region were involved. There was no leptomeningeal or parenchymal enhancement on contrast-enhanced T1-weighted images, suggesting an intact blood-brain barrier. Upon follow-up examination 12 days later, the signal abnormalities resolved completely. Reversible hyperintensities on T2-weighted images are due to different causes leading to increased water content, such as demyelinisation or edema. According to published data, cytotoxic edema caused by excessive glutamate concentration and other noxious substances is assumed to be the most probable cause for these findings.

Adult↗
PubMed1998

MRI of the ageing and herniating intervertebral disc.

The role of diagnostic imaging from the patient's perspective is to provide answers to four basic questions:--what is wrong?, How bad is it?, Is it clinically relevant?, Can it be treated? In the assessment of spinal disorders, multiple modalities have evolved in an attempt to answer the questions poised. Without doubt, the advent of MRI has given this process significant benefits primarily because of the unparalleled way of depicting normal and abnormal tissues in a non-invasive manner. In particular, MRI is admirably suited to study the intervertebral disc and goes a long way in answering the first two questions, aiding in the accurate analysis of disc morphology, defining pathological states, and delineating the extent and effect of disease. This information however, needs to be equated with the clinical signs and symptoms before any decisions concerning treatment options can be made. At this point one needs to exercise some degree of prudence and remember that MRI as yet does not differentiate abnormal asymptomatic from symptomatic painful disc levels. Enhancement with gadolinium compounds may go some way in providing some answers by defining the tissue response at or around the damaged points within the disco-vertebral unit. Modern MRI scanners and techniques demonstrate exquisitely, the structural status of the disc but the functional impact of these structural alterations cannot as yet be fully determined by MRI--there lies the challenge for the future. This article reviews the current MRI knowledge concerning the ageing and herniating intervertebral disc in a clinical context, and critically appraises its present role in a practical fashion.

Aged↗
PubMedDate not supplied

[Magnetic resonance imaging in the diagnosis of nonorganic hydatid disease].

This article evaluates MRI diagnostic value in discovering of the non-organic hydatid disease. MRI data of 21 patients, suffering from parasite pathology of liver (n = 12), liver and peritoneum cavity (n = 2), liver and retroperitoneal space (n = 2), liver and thigh's muscles (n = 1), peritoneum cavity (n = 2), retroperitoneal space (n = 1), spine and paravertebral area (n = 1) were analyzed. Based on histopathological results, features of unusually localized hydatid cysts (HC) MRI- semiotics are described in detail and compared with liver echinococcosis. MRI technique for identification of some hydatid cyst's structures is shown. The authors discuss the MRI reliability in differential diagnosis of non-organic HC and several disorders (non-parasite congenital and acquired cysts, hematoma, abscess, metastasis) of the same anatomical region. They underline some MRI advantages in GD disclosing comparing with ultrasonography and computed tomography. However, serological tests are needed for diagnosis verification. The authors also postulate the importance of clinical data being taken into account for radiological conclusion.

Adult↗
PubMed2003

Post-contrast FLAIR MR imaging of the brain in children: normal and abnormal intracranial enhancement.

OBJECTIVE: To describe the normally enhancing intracranial structures on fluid-attenuated inversion recovery (FLAIR) MRI and evaluate the usefulness of postcontrast FLAIR images of the brain in the assessment of enhancing lesions by comparing postcontrast FLAIR imaging with postcontrast T1-weighted (T1-W) imaging in children. MATERIALS AND METHODS: In 218 children, 249 pre- and postcontrast FLAIR MRI examinations of the brain were obtained consecutively between August 2001 and April 2002. The normally enhancing intracranial structures on FLAIR imaging were assessed in 77 MRI studies of 74 children who showed normal intracranial imaging findings. In 86 MRI studies in 68 children who showed enhancing intracranial lesions, lesion conspicuity on postcontrast FLAIR imaging was compared with that on postcontrast T1-W imaging for all lesions ( n=107), intra-axial lesions ( n=40), or extra-axial lesions ( n=67). RESULTS: The normally enhancing intracranial structures on FLAIR MRI were the choroid plexus (99%, 76/77), pituitary stalk (84%, 65/77), pineal gland (71%, 55/77), dural sinuses (26%, 20/77), and cortical veins (9%, 7/77). Of all the enhancing lesions, lesion conspicuousness on postcontrast FLAIR imaging was better than postcontrast T1-weighted imaging in 42, equal in 28, and worse in 37. Of 40 intra-axial lesions, lesion conspicuousness on postcontrast FLAIR imaging was better in 6, equal in 10, and worse in 24. Of 67 extra-axial lesions, lesion conspicuity on postcontrast FLAIR imaging was better in 36, equal in 18, and worse in 13. Conspicuousness of extra-axial lesions was significantly better than that of intra-axial lesions on postcontrast FLAIR imaging ( P<0.001). CONCLUSIONS: The choroid plexus, pituitary stalk, pineal gland, dural sinuses, and cortical veins show normal enhancement on postcontrast FLAIR MRI in children, and postcontrast FLAIR imaging appears better than postcontrast T1-W imaging in the assessment of extra-axial enhancing lesions in children.

Adolescent↗
PubMed2006

Prediction of soft-tissue injuries in Schatzker II tibial plateau fractures based on measurements of plain radiographs.

BACKGROUND: Split-depression fractures of the lateral tibial plateau (Schatzker II) are associated with a significant risk of capsuloligamentous and meniscal injury. We hypothesized that the amount of fracture depression and widening on anteroposterior (AP) plain radiographs would correlate with the incidence of injury to these structures on magnetic resonance imaging (MRI). METHODS: Sixty-two consecutive patients with Schatzker II tibial plateau fractures had a knee x-ray series and MRI preoperatively. AP plain radiographs were measured for lateral joint line depression and condylar widening, and MRIs were evaluated for injury to soft-tissue structures around the knee. For each structure, the threshold of depression and widening that led to the greatest disparity in soft-tissue injury was determined. Multiple logistic regressions were applied to calculate whether depression and/or widening above the thresholds were predictive for injury to individual soft-tissue structures. RESULTS: When depression was greater than 6 mm and widening was greater than 5 mm, lateral meniscal injury occurred in 83% of fractures, compared with 50% of fractures with less displacement (p < 0.05). When either depression or widening was at least 8 mm, medial meniscal injury occurred more frequently (depression 53%, p < 0.05; widening 78%, p < 0.05; versus neither 15%). Lateral collateral ligament and posterior cruciate ligament tears were not seen with minimally displaced fractures (< 4 mm), but the incidence of injury approached 30% with increasing displacement. CONCLUSIONS: Due to the limited availability of MRI in some centers, correlation of lateral condylar depression and widening, as measured on plain radiographs, to injury of various soft-tissue structures may be extremely helpful in planning open or arthroscopic treatment methods. Using these guidelines, Schatzker II fractures with depression or widening approaching 5 mm deserve heightened vigilance in diagnosing and treating these concomitant soft-tissue injuries.

Adolescent↗
PubMed2004

Voxel-based morphometry of comorbid schizophrenia and learning disability: analyses in normalized and native spaces using parametric and nonparametric statistical methods.

We employed voxel-based morphometry (VBM) to compare the distributions of grey matter found in structural magnetic resonance imaging (MRI) brain scans of patients with comorbid learning disability with schizophrenia, schizophrenia alone, learning disability alone, and normal controls. Our primary aim was to replicate a previous region of interest (ROI) finding that comorbids and schizophrenics belong to the same population. Nonparametric analysis in normalized space showed no significant differences in grey matter distribution between the comorbid and schizophrenia groups. Furthermore, this analysis showed significant grey matter reductions in the comorbid and schizophrenia groups when compared to the learning-disabled or the normal controls. Parametric analysis localized the significant grey matter reductions between the normal controls and the comorbid and schizophrenia groups to the prefrontal and temporal lobes. It also identified an area of increased grey matter, on the inferior aspect of the postcentral gyrus, in the learning-disabled alone compared to the other groups. Native space parametric and nonparametric analyses, based on modulation of the normalized scans, confirmed the similarity in grey matter distribution of the comorbid and schizophrenia groups. Results confirm the ROI finding that in native space the learning-disabled group possesses the least and normal controls the most grey matter for the cohort. An increase in the basal ganglia of patients with schizophrenia vs. the learning-disabled, probably attributable to antipsychotic medication, was identified in the native space analysis. The native space results did not however register statistically significant temporal lobe reductions found under normalized analysis between schizophrenics and normal controls. This may be attributable to minor physical anomalies (MPA) in the schizophrenic cranium. Overall, these VBM results replicate previous ROI findings and are compatible with the view that comorbid learning disability with schizophrenia is a severe form of schizophrenia, rather than a consequence of learning disability. VBM has the facility to compare grey matter distributions in this structurally diverse cohort.

Adult↗
PubMed1999

MRI findings of thoracolumbar spine fractures: a categorisation based on MRI examinations of 100 fractures.

OBJECTIVE: To define the state of different structures of the fractured thoracolumbar spine which may play a role in the immediate and long-term mechanical stability on MR images and to investigate the relationship of these findings with the AO classification of spinal injuries. DESIGN: The state of the anterior longitudinal ligament, posterior longitudinal ligament, posterior ligamentous complex, cranial and caudal endplates, cranial and caudal discs and the vertebral body were defined using clinical, experimental and radiological data. The state of these structures was reported for each fracture on the MRI examinations and the different MRI features appropriate for different fracture classes were defined. PATIENTS: MRI examinations of 70 patients with 100 fractures of the thoracolumbar spine were used for this study. RESULTS: Wide variations were seen in the state of the structures studied. We could not find a definite pattern to relate these findings with the AO classification scheme. CONCLUSIONS: MR findings should be integrated into future classification schemes of thoracolumbar spine fractures. This would enable specific data about the structures involved in the stability of the spine to be acquired. Prospective studies using the criteria developed in this study may help resolve some of the controversies concerning the diagnosis and prognosis of these injuries as well as the development of new classification systems.

Humans↗
PubMed2002

Nuclear magnetic resonance of laser-polarized noble gases in molecules, materials, and organisms.

The sensitivity of conventional nuclear magnetic resonance (NMR) techniques is fundamentally limited by the ordinarily low spin polarization achievable in even the strongest NMR magnets. However, by transferring angular momentum from laser light to electronic and nuclear spins, optical pumping methods can increase the nuclear spin polarization of noble gases by several orders of magnitude, thereby greatly enhancing their NMR sensitivity. This review describes the principles and magnetic resonance applications of laser-polarized noble gases. The enormous sensitivity enhancement afforded by optical pumping can be exploited to permit a variety of novel NMR experiments across numerous disciplines. Many such experiments are reviewed, including the void-space imaging of organisms and materials, NMR and MRI of living tissues, probing structure and dynamics of molecules in solution and on surfaces, NMR sensitivity enhancement via polarization transfer, and low-field NMR and MRI.

Chemical Phenomena↗