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Features of structural brain abnormality detected in first-episode psychosis.

OBJECTIVE: Structural magnetic resonance imaging (MRI) studies that focus on first-episode psychosis avoid some common confounds, such as chronicity of illness, treatment effects, and long-term substance abuse. However, such studies may select subjects with poor short-term treatment response or outcome. In this study, the authors focus on structural brain abnormalities in never or minimally treated patients who underwent MRI scanning early in their first episode of psychosis. METHOD: The authors examined 37 patients (13 medication naive, 24 previously treated) who were experiencing their first episode of psychosis; the mean duration of symptoms was short (31 weeks). These patients were comparable in age, gender, handedness, ethnicity, and parental socioeconomic status to a group of 25 healthy comparison subjects. A three-dimensional, inversion recovery prepared, fast spoiled gradient/recall in the steady state scan of the whole brain that used 1.5-mm contiguous sections was performed to acquire a T(1)-weighted data set. Human ratings of volumetric measurement of brain structures were performed with stereological techniques on three-dimensional reconstructed MRIs. RESULTS: The patient group had significant deficits in cortical gray matter, temporal lobe gray matter, and whole brain volume as well as significant enlargement of the lateral and third ventricles. Structural deviations were found in both treatment-naive and minimally treated subjects. No relationships were found between any brain matter volumes and positive or negative symptoms. CONCLUSIONS: Structural brain abnormalities were distributed throughout the cortex with particular decrement evident in gray matter. This feature is consistent with altered cell structure and disturbed neuronal connectivity, which accounts for the functional abnormality of psychosis.

Adult↗

[Clinical, electrophysiological and MRI correlations in carpal tunnel syndrome].

UNLABELLED: Even though diagnosis of carpal tunnel syndrome is mainly based on clinical findings, other examinations are often useful for confirmation and management. The most useful of these examinations is EMG. However, EMG may be inconclusive and MRI may then be helpful. The indications for MRI in patients with carpal tunnel syndrome will be reviewed. METHOD: 20 patients with a total of 33 clinically suspected cases of carpal tunnel syndrome (CTS) underwent EMG and MRI evaluation. Clinical and EMG findings identified three groups of patients based on degree of deficit: mild, moderate, and severe. The following structures were evaluated at MRI: median nerve, retinaculum, retrotendinous fat, flexor tendons, thenar space, and muscles and bones of the wrist. Surgery was performed for 19 wrists. RESULTS: Only retinacular bowing and increased T2W signal intensity within the median nerve were significantly related to the diagnosis of CTS (sensitivity of 70% and 57% respectively). Retinacular bowing indicates increased "pressure" within the compartment (mechanical compression of the nerve) and increased T2W signal of the median nerve indicates nerve suffering. These findings correlated well with more severe cases based on clinical and EMG findings. CONCLUSION: In cases where there is discordance between clinical and EMG findings, MRI is helpful to identify patients who would benefit from surgical intervention.

Adult↗

Application of magnetic resonance imaging to evaluation of femoral neck structure in growing girls.

Conventional density measures by dual-energy X-ray absorptiometry (DXA) are confounded by increases in bone size and do not assess bone geometry. We assessed precision of magnetic resonance imaging (MRI) and used MRI, DXA, and hip structure analysis (HSA) to assess 7-mo changes in bone structure at the femoral neck in 18 prepubertal girls. At baseline, girls were 10.4 (0.5) yr, 144.0 (8.2) cm, and 35.2 (7.0) kg, on average. Total bone and cortical cross-sectional area (ToA and CoA) were calculated from high-resolution T1-weighted MRI oblique axial images of the femoral neck. We used proximal femur DXA scans (Hologic QDR-4500) and the HSA program to estimate bone cross-sectional area (CSA), and calculate section modulus. MRI precision was determined by scanning 10 volunteers (13-46 yr old) three times with and without repositioning. Precision (CVrms) was 2% for ToA and 7% for CoA. Significant correlations were observed between FN area and MRI-derived ToA (r = 0.57, p = 0.013) and CoA (r = 0.47, p = 0.050). There were significant positive changes over 7 mo by both methods. In conclusion, MRI provides useful information on femoral neck bone area in children. The reproducibility of cortical dimensions at the femoral neck needs improvement through technical modifications and appropriate analysis software.

Absorptiometry, Photon↗

Relation between medial temporal atrophy and functional brain activity during memory processing in Alzheimer's disease: a combined MRI and SPECT study.

OBJECTIVE: To investigate the relation between atrophy of the hippocampal region and brain functional patterns during episodic memory processing in Alzheimer's disease. PATIENTS AND METHODS: Whole brain structural magnetic resonance imaging (MRI) data and single photon emission computed tomography (SPECT) measures of regional cerebral blood flow (rCBF) were obtained during a verbal recognition memory task in nine subjects with mild Alzheimer's disease and 10 elderly healthy controls. Using the statistical parametric mapping approach, voxel based comparisons were made on the MRI data to identify clusters of significantly reduced grey matter concentrations in the hippocampal region in the Alzheimer patients relative to the controls. The mean grey matter density in the voxel cluster of greatest hippocampal atrophy was extracted for each Alzheimer subject. This measure was used to investigate, on a voxel by voxel basis, the presence of significant correlations between the degree of hippocampal atrophy and the rCBF SPECT measures obtained during the memory task. RESULTS: Direct correlations were detected between the hippocampal grey matter density and rCBF values in voxel clusters located bilaterally in the temporal neocortex, in the left medial temporal region, and in the left posterior cingulate cortex during the memory task in the Alzheimer's disease group (p < 0.001). Conversely, measures of hippocampal atrophy were negatively correlated with rCBF values in voxel clusters located in the frontal lobes, involving the right and left inferior frontal gyri and the insula (p < 0.001). CONCLUSIONS: Hippocampal atrophic changes in Alzheimer's disease are associated with reduced functional activity in limbic and associative temporal regions during episodic memory processing, but with increased activity in frontal areas, possibly on a compensatory basis.

Alzheimer Disease↗

A novel series of complexones with bis- or biazole structure as mixed ligands of paramagnetic contrast agents for MRI.

We describe the syntheses, physicochemical properties and biological evaluation of a novel series of complexones containing bis- or biazoles moieties and two iminodiacetic acid units as novel ligands for paramagnetic lanthanides. The complexones were prepared by reaction of the corresponding 1,1'-bishaloethylbi- or bispyrazoles with methyl iminodiacetate and subsequent NaOH hydrolysis. 1,1'-Bisbromoethyl precursors were obtained by direct alkylation with an excess of 1,2-dibromoethane, or by heating the corresponding alcohol in HCl. Sigmoidal binding isotherms and MO calculations supported as most stable structures in solution, those containing two Gd(III) atoms bound per molecule of complexone with half saturation values S(0.5) (M(-1), 22 degrees C, pH 7.2) in the range 6.5 10(-6)<S(0.5)<36.1 10(-6). Relaxivity properties [r(1), r(2), s(-1) mM(-1) Gd(III)] determined at 1.5 Tesla gave values (12.0<r(1)<17.7, 12.2<r(2)<20), improving significantly the relaxivities of reference compounds such as Gd(III)EDTA (5.2, 5.6) or Gd(III)DTPA (4.30, 4.30). These improvements involve mainly increased hydration and slower rotational motions. In vitro toxicity experiments are reported.

Animals↗

Magnetization transfer and diffusion tensor MR imaging of the optic radiations and calcarine cortex from patients with Leber's hereditary optic neuropathy.

Optic nerve abnormalities are easily detectable in patients with Leber's hereditary optic neuropathy (LHON), using magnetic resonance imaging (MRI). However, the presence of structural changes in the optic radiations and calcarine cortex of these patients is still an unresolved issue. In this study, we obtained magnetization transfer (MT) and diffusion tensor (DT) MRI to investigate the integrity of these structures in patients with LHON. Dual echo, MT- and DT-MRI scans of the brain were obtained from 10 men with LHON and 10 healthy sex- and age-matched controls. After image co-registration, we obtained MT ratio (MTR), average diffusivity (D) and fractional anisotropy (FA) maps. MTR, D and FA values for the white matter of the optic radiations and MTR and D values for the calcarine cortex were obtained using a region of interest (ROI) analysis. No macroscopic abnormalities were detected in any of the scans from LHON patients and controls. No statistically significant differences of MTR, D or FA values were found for any of the regions studied in LHON patients and healthy controls. Our results suggest that, in patients with LHON, the optic radiations and the calcarine cortex are spared from structural damage, both at a macroscopic and a microscopic level.

Adult↗

[Thyroid nodules and non-functional goiters. Diagnostic contribution of nuclear resonance imaging].

The finding of a "cold" thyroid nodular or goiter raises the problem of its potential malignancy, usually resulting in systematic surgery. Ultrasonography and computerized tomography provide accurate information concerning the size, structure and connections of these abnormalities, but they have very little to say about their histological nature. We evaluated the contribution of magnetic resonance imaging (MRI) to the histological diagnosis by attempting tissue characterization before surgery in 97 patients with nonfunctional thyroid nodule or goiter. Comparisons with the pathological study of operative specimens showed a very small percentage (1.05 percent) of false negative results in terms of malignancy, and this was due to reliable arguments for benignity which we were able to collect from MRI signal intensity and structural analysis. Without these criteria, a decisive answer would have been very difficult, as shown by the significant rate of false positive results (14.73 percent) and a specificity of only 81.8 percent if every lesion interpreted as doubtful is considered malignant. Attention is drawn to the difficulties encountered in characterizing lesion with intracystic vegetations and in distinguishing between thyroiditis and lymphoma. The possibility of obtaining frontal and sagittal sections increases the usefulness of MRI. The operator's experience is essential in interpreting the signals and deciding on the therapeutic approach.

Adult↗

[The value of neuroimaging in diagnosis of epilepsy].

Neuroimaging examines the relationship between abnormalities of brain function in epilepsy patients (seizures, impaired cognitive function, psychiatric co-morbidity etc.) and focal or more widespread brain pathology. Since the mid-1980s, the introduction of magnetic resonance imaging (MRI) into clinical neurology has had an impact on the diagnosis, treatment, and research of epilepsy only comparable with the advent of the electroencephalography (EEG) fifty years ago. MRI plays the important role of identifying single or multiple structural lesions responsible for the epileptic seizures. Thus, visual assessment of MRI plays an important role in the differentiation between symptomatic, cryptogenic, and idiopathic epilepsies. This diagnostic step leads to therapeutic decisions (medical treatment vs. surgery) and prognostic evaluations. If a structural lesion identified with MRI correlates with seizure-type, EEG and other clinical data, the likelihood of rendering the patient seizure free with epilepsy surgery is increased. Clinical research into epilepsy uses quantitative MRI (volumetry, T2-relaxometry, magnetic resonance spectroscopy [MRS], voxel-based morphometry) to reduce those cases initially labeled as cryptogenic. Quantitative MRI questions the belief that there is epilepsy without structural brain abnormality at all. Functional MRI (fMRI), positron emission tomography (PET) and single photon emission computed tomography (SPECT) demonstrate changes associated with epileptic seizures and pathology, and changes associated with EEG abnormalities and their cessation. Functional neuroimaging is also used for the identification of functional brain tissue before surgery. Physiologically or pathologically active neuronal tissue is believed to be identified by glucose or oxygen consumption (PET), cerebral blood flow (PET, SPECT, perfusion MRI), and cerebral blood oxygenation (blood oxygenation level dependent [BOLD] fMRI). PET also offers the opportunity to visualize the in-vivo distribution of neuronal receptors which are implicated in the generation, the spread, and the cessation of seizures.

Brain↗

Identification of sources of brain neuronal activity with high spatiotemporal resolution through combination of neuromagnetic source localization (NMSL) and magnetic resonance imaging (MRI).

The locations of the origin of wave M100 of the auditory evoked magnetic field in response to tone bursts of different carrier frequencies, obtained through dipole localization methods (DLM), were related to cerebral structures, displayed by coronal MRI (magnetic resonance imaging) tomograms of the respective subjects. This was done by displaying the landmarks which served as reference for the neuromagnetic measurements in MRI tomogram (reference plane). All calculated source locations project exactly onto the transverse temporal gyri (Heschl) in which the primary auditory cortex, the supposed origin of wave M100, is located. The results highlight the exceptional capabilities of a combination of these 2 non-invasive, high-resolution techniques for functional diagnosis.

Auditory Cortex↗

Probing the intracellular redox status of tumors with magnetic resonance imaging and redox-sensitive contrast agents.

Nitroxide radicals are paramagnetic contrast agents, used in magnetic resonance imaging (MRI), that also exert antioxidant effects. Participating in cellular redox reactions, they lose their ability to provide contrast as a function of time after administration. In this study, the rate of contrast loss was correlated to the reducing power of the tissue or the "redox status." The preferential reduction of nitroxides in tumors compared with normal tissue was observed by MRI. The influence of the structure of the nitroxide on the reduction rate was investigated by MRI using two cell-permeable nitroxides, 4-hydroxy-2,2,6,6,-tetramethyl-1-piperidynyloxyl (Tempol) and 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (3CP), and one cell-impermeable nitroxide, 3-carboxy-2,2,5,5,5-tetramethylpyrrolidine-1-oxyl (3CxP). Pharmacokinetic images of these nitroxides in normal tissue, tumor, kidney, and artery regions in mice were simultaneously obtained using MRI. The decay of Tempol and 3CP in tumor tissue was significantly faster than in normal tissue. No significant change in the total nitroxide (oxidized + reduced forms) was noted from tissue extracts, suggesting that the loss in contrast as a function of time is a result of intracellular bioreduction. However, in the case of 3CxP (membrane impermeable), there was no difference in the reduction rates between normal and tumor tissue. The time course of T(1) enhancement by 3CxP and the total amount of 3CxP (oxidized + reduced) in the femoral region showed similar pharmacokinetics. These results show that the differential bioreduction of cell-permeable nitroxides in tumor and normal tissue is supported by intracellular processes and the reduction rates are a means by which the intracellular redox status can be assessed noninvasively.

Animals↗

Methodological issues in volumetric magnetic resonance imaging of the brain in the Edinburgh High Risk Project.

The Edinburgh High Risk Project is a longitudinal study of brain structure (and function) in subjects at high risk of developing schizophrenia in the next 5-10 years for genetic reasons. In this article we describe the methods of volumetric analysis of structural magnetic resonance images used in the study. We also consider potential sources of error in these methods: the validity of our image analysis techniques; inter- and intra-rater reliability; possible positional variation; and thresholding criteria used in separating brain from cerebro-spinal fluid (CSF). Investigation with a phantom test object (of similar imaging characteristics to the brain) provided evidence for the validity of our image acquisition and analysis techniques. Both inter- and intra-rater reliability were found to be good in whole brain measures but less so for smaller regions. There were no statistically significant differences in positioning across the three study groups (patients with schizophrenia, high risk subjects and normal volunteers). A new technique for thresholding MRI scans longitudinally is described (the 'rescale' method) and compared with our established method (thresholding by eye). Few differences between the two techniques were seen at 3- and 6-month follow-up. These findings demonstrate the validity and reliability of the structural MRI analysis techniques used in the Edinburgh High Risk Project, and highlight methodological issues of general concern in cross-sectional and longitudinal studies of brain structure in healthy control subjects and neuropsychiatric populations.

Adolescent↗

Teratogenic effects of alcohol: a decade of brain imaging.

Heavy alcohol exposure can have serious and long-lasting effects on the developing fetal brain. In the last decade, researchers have utilized quantitative structural magnetic resonance imaging (MRI) to examine the brains of living children and adults with histories of heavy prenatal alcohol exposure. In addition to microcephaly, these studies indicated structural abnormalities in various regions of the brain, including the cerebellum, corpus callosum, and the basal ganglia. Most recently, we have utilized novel imaging and analytic techniques to study the brain as a whole in an effort to elucidate more subtle differences than was possible with earlier techniques. Results indicated displacements in the corpus callosum, increased gray matter densities in both hemispheres in the perisylvian regions, and altered gray matter asymmetry in portions of the temporal lobes in the brains of alcohol-exposed subjects. In addition, prominent shape abnormalities were observed in the brains of these subjects, with narrowing in the temporal region and reduced brain growth in portions of the frontal lobe. These results imply that brain growth continues to be adversely affected long after the prenatal insult and that the brain regions most affected may be consistent with the neurocognitive deficits characteristic of individuals prenatally exposed to alcohol.

Alcohol Drinking↗

The value of magnetic resonance imaging in carpal tunnel syndrome.

We examined 62 patients (72 hands) with carpal tunnel syndrome (CTS) by magnetic resonance imaging (MRI) of the carpal tunnel and latency measurements of the median nerve. In 32 of 72 hands a probable causative lesion of the CTS was identified by MRI, for example tenosynovitis, a cyst-like structure, or an aberrant muscle. The MRI findings were confirmed by surgery in 16 of 24 hands, slightly corrected in 5, and not substantiated in 3. In 65 of 72 hands, MRI disclosed pathology of the median nerve, most prominently an enlargement of the nerve at the level of the os pisiforme, a finding not seen during surgery. Oedema of the nerve was found in 14 of 72 hands. The distal latencies were prolonged in 62 of 72 hands. The sensory latencies correlated significantly with the MRI-determined cross-sectional area of the nerve at the level of the distal radius. The lack of other correlations suggests that partly independent features of the nerve lesion are demonstrated in each method or that the sensitivity and specificity of both methods are limited. Further experience with MRI in CTS is desirable. At present, the practical use of MRI in CTS should be restricted to special diagnostic problems such as carpal tunnel syndromes which do not respond adequately to conservative or surgical treatment.

Adult↗

Magnetic resonance imaging of the foot and ankle: correlation of normal anatomy with pathologic conditions.

Abnormalities of the foot and ankle can be difficult to diagnose by conventional examination and x-rays. Recently, magnetic resonance imaging (MRI) has emerged as a diagnostic tool for soft tissue and bony imaging. One hundred and ten normal feet and ankles were studied to define normal MRI anatomy. An additional 150 MRI scans were performed to diagnose and characterize various abnormal conditions. MRI demonstrated excellent definition of normal structures and pathologic entities. Surgical correlation with the MRI was done in 42 patients. MRI appears to be a useful examination for patients with certain soft tissue and bony abnormalities. A special oblique view also has been developed to assist in the diagnosis of injuries to the tibialis posterior, flexor hallucis longus, and flexor digitorum longus tendons.

Achilles Tendon↗

Extrinsic radiocarpal ligaments: magnetic resonance imaging of normal wrists and scapholunate dissociation.

OBJECTIVE: To determine whether magnetic resonance imaging [MRI] in planes of imaging parallel to the known course of the extrinsic radiocarpal ligaments of the wrist aids in the visualization of these structures. SUBJECTS AND METHODS: MRI was performed on 32 wrists: a single normal cadaveric wrist, 23 normal wrists in volunteers and 8 wrists in patients with known scapholunate dissociation and rotatory scaphoid subluxation. Proton-density and T2-weighted images were obtained in the sagittal plane and gradient recalled echo images in an oblique sagittal plane, selected to parallel the extrinsic radiocarpal ligaments. The images were interpreted by two musculoskeletal radiologists. Each of the six main extrinsic ligaments was assessed for visualization or nonvisualization, and the morphologic features of those visualized were documented. RESULTS: With the exception of the dorsal radioscaphoid ligament, the volar and dorsal extrinsic radiocarpal ligaments were all consistently visualized in the normal wrists. For the eight cases of scapholunate dissociation, MRI demonstrated underlying rupture or thickening of the volar radioscaphocapitate ligament in all wrists and of the dorsal radiolunate ligament in five. CONCLUSION: MRI in the true and oblique sagittal planes can consistently demonstrate the extrinsic radiocarpal ligaments of the wrist. With this technique, extrinsic ligamentous abnormality can be demonstrated in patients with scapholunate dissociation and rotatory scaphoid subluxation.

Adult↗

Magnetic resonance imaging and spectroscopic imaging of prostate cancer.

PURPOSE: We describe the practical technical aspects of magnetic resonance spectroscopic imaging (MRSI), and summarize the current and potential future status of magnetic resonance imaging (MRI) and MRSI in the diagnosis, localization, staging, treatment planning and post-treatment followup of prostate cancer. MATERIALS AND METHODS: Contemporary series of patients with prostate cancer evaluated by MRI and MRSI were reviewed, with particular respect to imaging accuracy as evaluated by histopathological correlation, and the relationship between MRI and MRSI and outcome. RESULTS: MRI and MRSI have a limited role in prostate cancer diagnosis but may be helpful for patients with a high index of suspicion and negative initial biopsy. High specificity can be achieved for sextant localization of cancer when sextant biopsy, MRI and MRSI are all positive. Volumetric localization is of limited accuracy for tumors less than 0.5 cc. Staging by MRI, which is improved by the addition of MRSI, is of incremental prognostic significance for patients with moderate and high risk tumors. MRI and MRSI may assist in surgical and radiation treatment planning, and posttreatment followup. In particular, the use of MRI to assist radiation treatment planning has been shown to improve outcome. Interventional MRI guided biopsy and therapy remain under investigation. CONCLUSIONS: Only MRI and MRSI allow combined structural and metabolic evaluation of prostate cancer location, aggressiveness and stage. MRI provides clinically and therapeutically relevant anatomical information. The technology remains in evolution, and continued advances in accuracy and use are likely.

Humans↗

Magnetic resonance imaging--a method of studying the size and asymmetry of the planum temporale.

The planum temporale is a triangular region on the upper surface of the temporal lobe. This area of the brain is important for language processing and shows a left-right asymmetry of size in most brains. Particular interest has been focused on the size and asymmetry of the planum temporale in brains of individuals with developmental dyslexia. Magnetic resonance imaging (MRI) is a method that produces excellent morphological details of organic structures. We have developed an MRI method of studying the size and asymmetry of the planum temporale in human brains. Because of considerable variation of anatomical landmarks in this cortical region of the brain, an evaluation of asymmetry is not possible in all brains. Furthermore, our experience with this method indicates that any indirect imaging technique of studying asymmetry of the planum temporale must be evaluated with caution. With this in mind, however, MRI may give valuable anatomical information about the planum temporale in individuals with anomalous language function.

Humans↗

Head and neck: high field magnetic resonance imaging versus computed tomography.

A comparative review of head and neck lesions examined with both CT and MRI showed that the location and extent of lesions can be more precisely evaluated with MRI. MRI allows better differentiation of neurogenic tumors from other lesions. Vascular structures are easily visualized on MRI without intravenous contrast and can easily be differentiated from lymph nodes. However, cystic lesions and necrotic nodes sometimes could not be differentiated from solid lesions when using MRI.

Branchioma↗