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PubMed2005

Noncontrast dynamic magnetic resonance imaging for quantitative assessment of female sexual arousal.

PURPOSE: We evaluated a noncontrast, dynamic magnetic resonance imaging (MRI) technique for quantitative evaluation of the female sexual arousal response and compared these results with those of a previously described, contrast enhanced MRI technique. MATERIALS AND METHODS: Eight normal, healthy volunteer women underwent 2 separate MRI sessions, during which they were shown audiovisual material consisting of interleaved neutral and audiovisual sexual stimulation segments. Serial high resolution MRI of the genital structures was done at 3-minute intervals during a 45-minute period. Images were analyzed in blinded fashion and measurements of clitoral volume with time were obtained for each subject. Measured clitoral volumes together with the percent change in clitoral volume during audiovisual sexual stimulation for MRI sessions 1 and 2 were compared within subjects. Results were also compared to those of prior contrast enhanced MRI studies in the same subjects. RESULTS: There was excellent intrasubject reproducibility between sessions 1 and 2 using the noncontrast MRI technique (r = 0.99). There was also excellent agreement between the current noncontrast study and prior contrast enhanced studies with a correlation coefficient of 0.89. CONCLUSIONS: Dynamic, noncontrast MRI of the female genitalia appears to be a reproducible, nonintrusive and objective way to assess quantitatively the sexual arousal response in women without sexual difficulties.

Arousal↗
PubMedDate not supplied

Magnetic resonance imaging and spectroscopy in fetal ethanol exposed Macaca nemestrina.

Magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy (1H-MRS) offer noninvasive ways to observe structural and biochemical changes which might serve as valuable diagnostic markers for detecting brain damage from prenatal ethanol teratogenesis. Cranial MR imaging and spectroscopy were performed on 20 nonhuman primates (Macaca nemestrina) with known prenatal ethanol exposures and well-documented cognitive and behavioral levels of performance. The choline: creatine ratio detected by 1H-MRS in the brain increased significantly with increasing duration of in utero ethanol exposure. These signal alterations occurred in the absence of gross structural brain anomalies (detectable by MRI) and were significantly correlated with alcohol-related cognitive and behavioral dysfunction. These observations are consistent with reports of elevated choline: creatine ratios associated with various neurologic insults and disease states. The association observed between brain choline:creatine ratios and in utero ethanol exposure suggest a role for 1H-MRS in elucidating mechanisms of ethanol teratogenicity.

Analysis of Variance↗
PubMed1988

Magnetic resonance imaging: a noninvasive tool for fetal and placental physiology.

Nuclear magnetic resonance imaging (MRI), a technique that utilizes biochemical information reflected in nuclear magnetic moments, can be used to image the uterus, fetus, and placenta of the human and nonhuman primate. MRI studies during pregnancy in the human and nonhuman primate provide soft-tissue structural information of considerable detail. MRI also offers the opportunity for noninvasive pharmacokinetic and toxicokinetic studies during pregnancy. Paramagnetic ions (Cu, Ni, Gd, Fe, Mn) after spin-lattice (T1) and spin-spin (T2) relaxation times in reproductive tissues. Changes in T1 and T2 alter the MRI image, reflecting uptake of paramagnetic ions by the uterus, placenta, or fetus. MRI provides a noninvasive method of monitoring body burden of selected xenobiotics during gestation. The use of paramagnetic labels on endogenous substances may also allow noninvasive determination of physiological parameters such as intervillous blood flow, placental metabolism, and placental transport during gestation.

Animals↗
PubMed2001

Hemispheric and gender-related differences in the gross morphology of the anterior cingulate/paracingulate cortex in normal volunteers: an MRI morphometric study.

The sulci and gyri found within the anterior cingulate (AC), and across the cerebrum generally, have been found to vary in location and complexity from one individual to the next, making it difficult to analyze imaging data accurately and systematically. In this study, we examined the nature of morphometric variance in the AC of the left and right cerebral hemispheres using high-resolution structural magnetic resonance imaging (MRI) acquired from 176 healthy volunteers. Depending on the presence of a paracingulate sulcus (PCS) and its antero-posterior extent, three types of AC patterns were identified: 'prominent', 'present' and 'absent'. Hemispheric comparisons across the whole sample showed the PCS to be more commonly 'prominent' in the left hemisphere and more commonly 'absent' in the right hemisphere. There was a significant gender difference, such that males showed an asymmetric pattern characterized by increased fissurization of the left AC, while females showed greater symmetry, with less fissurization of the left AC. Overall cerebral morphology, namely hemispheric volume and hemispheric fissurization, were also measured and used as independent variables as well as covariates in the analyses in order to ascertain the specificity of the results regarding AC morphology. Results showed that cerebral volume for males was larger on the right than on the left while fissurization showed the reverse asymmetry of greater leftward fissurization. In contrast, females were symmetric in both respects. The findings regarding AC morphology could not be explained by differences in these overall cerebral measures or by differences in age and handedness within the population. The results suggest that in the normal male brain, there exist morphological asymmetries at both the global and local levels that are less apparent in the female brain. The findings have implications for future studies examining the organization, development and functional anatomy of the AC.

Adolescent↗
PubMed1996

Neurophysiologic evaluation of cyclosporine toxicity associated with bone marrow transplantation.

INTRODUCTION: Cortical blindness, a rare form of cyclosporine (CSA) neurotoxicity, has previously been described in only nine bone marrow transplant (BMT) recipients. METHODS: Our institution averages 35 allogeneic BMT's per year. In the past year we have seen two women with reversible cortical blindness secondary to CSA toxicity. RESULTS: Age (years) (Case 1; Case 2): 32; 22. Day post-BMT: 41; 50. Peak CSA level (ng/ml): 1159; 632. Both had a history of renal toxicity requiring adjustment of CSA dosage. MRI - both with diffuse while matter changes. EEG - both with moderate to severe generalized slowing. Visual evoked potentials were markedly prolonged in both. Auditory evoked potentials: minimally abnormal; normal. Somatosensory evoked potentials - both normal. Prompt improvement occurred with discontinuation of CSA. Followup neurophysiologic evaluations were normal, however structural changes remained on MRI. CONCLUSION: As neurophysiologic studies closely follow the clinical status they should be included in the evaluation and followup of CSA neurotoxicity.

Adult↗
PubMed2004

[Progressive structural abnormalities in the brain of the schizophrenic].

One hundred years ago, Kraepelin hypothesized that cerebral damage might cause dementia praecox. Many patients with schizophrenia show progressive clinical deterioration, although the evidence has remained unclear for the organic brain damage. Recently, brain abnormalities have been suggested, including enlargement of the lateral ventricles and reduction of the frontal and temporal lobes, due to the development of magnetic resonance imaging (MRI). Changes in brain structures have also been reported in the clinical course of schizophrenia. These structural brain studies have played important roles in clarifying the pathophysiology of schizophrenia and understanding the association of clinical symptoms with morphological brain change. However, there have been inconsistencies in the results on progressive structural changes. The selection of the patients, effects of medication, and social environmental factors may account for these inconsistencies. We have reviewed recent studies that found structural changes in the brain, including subcortical and ventricular of the schizophrenia.

Brain↗
PubMed1995

Neurophysiologic evaluation of cyclosporine toxicity associated with bone marrow transplantation.

INTRODUCTION: Cortical blindness, a rare form of cyclosporine (CSA) neurotoxicity, has previously been described in only nine bone marrow transplant (BMT) recipients. METHODS: Our institutions averages 35 allogeneic BMT's per year. In the past year we have seen two women with reversible cortical blindness secondary to CSA toxicity. RESULTS: Age (years) (Case 1; Case 2): 32; 22. Day post-BMT: 41: 50. Peak CSA level (ng/ml): 1159; 632. Both had a history of renal toxicity requiring adjustment of CSA dosage. MRI - both with diffuse white matter changes. EEG-both with moderate to severe generalized slowing. Visual evoked potentials were markedly prolonged in both. Auditory evoked potentials: minimally abnormal; normal. Somatosensory evoked potential - both normal. Prompt improvement occurred with discontinuation of CSA. Followup neurophysiologic evaluations were normal, however structural changes remain on MRI. CONCLUSION: As neurophysiologic studies closely follow the clinical status they should be included in the evaluation and followup of CSA neurotoxicity.

Adult↗
PubMed2000

Reduction of frontal neocortical grey matter associated with affective aggression in patients with temporal lobe epilepsy: an objective voxel by voxel analysis of automatically segmented MRI.

BACKGROUND: Interictal episodes of aggression are often reported in patients with epilepsy. Some have characteristics of what has been referred to as episodic dyscontrol or intermittent explosive disorder (IED). Although structural brain abnormalities are thought to play a part in the pathophysiology of aggression, there are few in vivo studies of structural cerebral changes in patients with epilepsy and aggression. Using quantitative MRI, subtle structural brain abnormalities can be investigated in subgroups of patients with both epilepsy and episodes of affective aggression. METHODS: After automated segmentation of cerebral grey matter from T1 weighted MRI, the objective technique of statistical parametric mapping (SPM) was applied to the analysis of 35 control subjects, 24 patients with temporal lobe epilepsy (TLE) with a history of repeated, interictal episodes of aggression, and 24 patients with TLE without episodes of aggression. Both TLE patient groups were compared with each other and with the control subjects on a voxel by voxel basis for increases and decreases of grey matter. RESULTS: The patients with TLE with aggressive episodes had a decrease of grey matter, most markedly in the left frontal lobe, compared with the control group and with patients with TLE without aggressive episodes. CONCLUSION: These findings suggest that a reduction of frontal neocortical grey matter might underly the pathophysiology of aggression in TLE. These voxel by voxel comparisons can guide further in vivo studies into aggression.

Adolescent↗
PubMed1985

Magnetic resonance imaging in the evaluation of urologic malignancies.

Although MRI has been available for clinical use for only a short time it has already proven its value in the diagnosis and staging of renal malignancies and has shown promise in evaluation of malignancies of the lower urinary tract. Its excellent tissue contrast discrimination, ease of evaluation of vascular structures and perivascular lymph nodes and its capability for multiplanar imaging contribute to this promise. Its dependence on multiple tissue and imaging parameters allows manipulation of images to permit evaluation of a variety of structures for anatomic and physiologic abnormalities. Its lack of ionizing radiation and the absence of requirement for intravenous contrast agents are attractive features in evaluation of genitourinary structures. Clinical experience with MRI in diagnosis and staging of urologic malignancies is growing in a number of academic centers, and MRI units are being installed in many private hospitals. It is anticipated that the importance of MRI in the evaluation of the genitourinary tract will increase rapidly as this technology becomes widely available.

Adenocarcinoma↗
PubMed1997

Imaging and epilepsy.

MRI has been applied to the investigation of epilepsy for 12 years. The principle role of MRI is in the definition of structural abnormalities that underly seizure disorders. Hippocampal sclerosis may be reliably identified, quantitative studies are useful for research and, in equivocal cases, for clinical purposes. A range of malformations of cortical development (MCD) may be determined. In patients with refractory partial seizures who are candidates for surgical treatment, a relevant abnormality is identifiable using MRI in 85%, it is likely that subtle MCD or gliosis accounts for the majority of the remainder. The proportion of cryptogenic cases will decrease with improvements in MRI hardware, signal acquisition techniques and post-processing methodologies. Functional MRI is used to identify the cerebral areas that are responsible for specific cognitive processes, and is of importance in planning resections close to eloquent cortical areas. Magnetic resonance spectroscopy (MRS) provides a means of investigating cerebral metabolites and some neurotransmitters, non-invasively. The concentrations of N-acetyl-aspartate (NAA), creatine and choline-containing compounds may be estimated using proton MRS. Reduction of the ratio of NAA/(creatine+choline) is a feature of cerebral regions that include epileptic foci. Cerebral concentrations of GABA and glutamate, and the effects of antiepileptic drugs on these, may be estimated. Concentrations of high energy phosphate compounds, inorganic phosphate and pH may be assessed using 31P-MRS. In general, epileptic foci are associated with an increase in pH, increased inorganic phosphate and decreased phosphate monoesters. Carbon-13 spectroscopy promises to be a useful method for investigating cerebral metabolism in vivo. PET may provide data on regional cerebral blood flow (rCBF), glucose metabolism and the binding of specific ligands to receptors. Correlation of functional and structural imaging data is necessary for adequate interpretation. The hallmark of an epileptic focus is an area of reduced glucose metabolism, identified using [18F]fluorodeoxyglucose (18FDG), that is commonly more extensive than the underlying anatomical abnormality. The clinical role of 18FDG-PET requires re-evaluation in the light of the advances in structural imaging with MRI. Specific ligands are used to investigate specific receptors. Benzodiazepine and opioid receptors have been studied most. Reduced benzodiazepine receptor binding is commonly seen at an epileptic focus, in a more restricted distribution than an area of hypometabolism. Focal increases and decreases in benzodiazepine receptor binding have been demonstrated in MCD in areas that appear normal on MRI, indicating the widespread nature of the abnormalities. It has been found that mu-opioid receptors are increased in temporal neocortex overlying mesial temporal epileptic foci. Dynamic studies of ligand-receptor binding are possible using PET, for example the release of cerebral endogenous opioids has been implied at the time of serial absences. The main use of single photon emission computed tomography (SPECT) is to produce images reflecting rCBF. Interictal studies alone are not reliable. A strength of SPECT is the ability to obtain images related to rCBF at the time of seizures. Concomitant video-EEG recording is necessary. Ictal scans need to be considered in comparison with an interictal scan and an MRI. Interpretation must be cautious, but may yield data that is useful in the investigation of patients for possible surgical treatment.

Cerebral Cortex↗
PubMed2006

In vitro MRI of brain development.

In this review, we demonstrate the developmental appearance, structural features, and reorganization of transient cerebral zones and structures in the human fetal brain using a correlative histological and MRI analysis. The analysis of postmortem aldehyde-fixed specimens (age range: 10 postovulatory weeks to term) revealed that, at 10 postovulatory weeks, the cerebral wall already has a trilaminar appearance and consists of: (1) a ventricular zone of high cell-packing density; (2) an intermediate zone; (3) the cortical plate (in a stage of primary consolidation) with high MRI signal intensity. The anlage of the hippocampus is present as a prominent bulging in the thin limbic telencephalon. The early fetal telencephalon impar also contains the first commissural fibers and fornix bundles in the septal area. The ganglionic eminence is clearly visible as an expanded continuation of the proliferative ventricular zone. The basal ganglia showed an initial aggregation of cells. The most massive fiber system is in the hemispheric stalk, which is in continuity with thalamocortical fibers. During the mid-fetal period (15-22 postovulatory weeks), the typical fetal lamination pattern develops and the cerebral wall consists of the following zones: (a) a marginal zone (visible on MRI exclusively in the hippocampus); (b) the cortical plate with high cell-packing density and high MRI signal intensity; (c) the subplate zone, which is the most prominent zone rich in extracellular matrix and with a very low MRI signal intensity; (d) the intermediate zone (fetal "white matter"); (e) the subventricular zone; (f) the periventricular fiber-rich zone; (g) the ventricular zone. The ganglionic eminence is still a very prominent structure with an intense proliferative activity. During the next period (22-26 postovulatory weeks), there is the developmental peak of transient MRI features, caused by the high content of hydrophyllic extracellular matrix in the subplate zone and the accumulation of waiting afferent axons. The period between 27 and 30 postovulatory weeks is characterized by gradual blurring of the laminar structure in parallel with the formation of cerebral convolutions. In near-term preterm infants, T2-weighted MR images showed better contrast resolution than T1-weighted images. We conclude that transient fetal zones and subcortical structures display characteristic MRI features due to the high content of extracellular matrix in the subplate zone, higher MRI signal intensity of zones with high cell-packing intensity, and the presence of growing fibers.

Brain↗
PubMed2002

Decreased left amygdala and hippocampal volumes in young offspring at risk for schizophrenia.

Abnormalities in the structural integrity and connectivity of the medial temporal and the prefrontal cortex are well documented in schizophrenia, but it is unclear if they represent premorbid indicators of neuropathology. Studies of young relatives at high-risk for schizophrenia (HR) provide an opportunity to clarify this question. We herein provide data from a magnetic resonance imaging (MRI) study of these structures in young offspring of schizophrenia patients. A series of 17 young HR offspring of schizophrenic patients were compared with 22 healthy comparison subjects (HC). Morphometric comparisons of the right and left dorsolateral prefrontal cortex (DLPFC), and the anterior and posterior amygdala-hippocampal (A-H) complex were conducted using high-resolution whole brain T(1) weighted brain images. Compared with the HC group, HR subjects had significant decreases in intracranial volume. The volumes of the left anterior and posterior A-H complex were reduced in the HR subjects after adjusting for intracranial volume. HR subjects also showed a significant leftward (Right>Left) asymmetry of the anterior A-H complex compared to the HC subjects. No significant changes were seen in the DLPFC. Thus, lateralized alterations in the volume of the left A-H complex are evident in unaffected young offspring of schizophrenia patients and may be of neurodevelopmental origin. Follow-up studies are needed to examine the predictive value of these measures for future emergence of schizophrenia in at-risk individuals.

Adolescent↗
PubMed1987

[Imaging of the Achilles tendon using magnetic resonance tomography].

The Achilles tendon and pre-achillean space of 30 patients was studied by MRI. A surface coil (Helmholtz' principle) was applied and all patients were examined with a superconducting magnet operating at 1.0 Tesla field strength. The purpose of the study was to illustrate pathological changes of the tendon and the surrounding soft tissue. In 3 cases MRI diagnosed a total rupture of the Achilles tendon. Furthermore, the strain of the tendon and side effects of an inflammatory process could be demonstrated. The use of a surface coil yields a high resolution of the normal anatomy of the region and of the pathological changes of the tendon and the surrounding soft tissue structures. The advantages of MRI for Achilles tendon diagnostics against competitive modalities are excellent soft tissue contrast, multiplanar imaging, as well as exact delineation and visualisation of the lesion.

Achilles Tendon↗
PubMed1992

CT and MRI in hydatid disease of cervical vertebrae.

Hydatid disease (HD) of the cervical spine is rare. A case investigated by computed tomography (CT) and magnetic resonance imaging (MRI) is presented. While CT shows the bone lesion better, MRI is superior in demonstrating compression of neural structures. The complementary use of CT and MRI in such cases is suggested.

Adult↗
PubMed2005

Development of an MRI/x-ray/ultrasound compatible marker for pre-operative breast tumour localization.

This paper describes an in vitro investigation into the composition, structure and development of an magnetic resonance imaging (MRI), ultrasound (US) and x-ray imaging compatible marker for breast tumour localization. The marker is composed of 0.4-0.6 mm glass and iron-containing aluminium microspheres suspended in a gelatin matrix. The final form of the marker is a cylindrical shape 7 mm long with 2.05 mm diameter to facilitate delivery through a 12 gauge biopsy needle. To get optimal reflectivity for the US contrast, the glass microsphere concentration was found to be 40% by weight. US contrast is independent of marker orientation and the cylindrical shape made its US signal appearance distinctive thus ensuring confident identification. To control the MRI contrast, iron content was varied to generate a clear and local susceptibility signal void to reflect the marker position. Optimal iron content was found to be 52 microg iron which produced a clear signal void in spoiled gradient recalled MR images. The appearance of the susceptibility artefact is determined by the marker's shape, orientation and echo time. The final marker produces a dark artefact in MRI while appears as a clear hyperintense structure with acoustic shadowing in US images. The x-ray image showed the marker as a radio-opaque structure. This in vitro study demonstrates that the marker forms an alternative to traditional wire localization currently used for breast surgical procedures and creates new opportunities for US guided surgical procedures.

Aluminum↗
PubMedDate not supplied

Magnetic resonance imaging studies in early-onset bipolar disorder: a critical review.

BACKGROUND: Neuroimaging studies of early-onset bipolar disorder (BD) are important in order to establish a fuller understanding of the underlying pathophysiology of the illness. The advantages of studying BD in children and adolescents include the relative absence of some confounds present in adult-onset research, such as lengthy duration of illness and exposure to treatments, greater number of mood episodes, and the presence of substance abuse or dependence. Finally, studying youths with the disorder may enhance our knowledge about the neural mechanisms of affective dysregulation and may specifically elucidate whether there are abnormalities that are unique to the early-onset form of the illness. METHODS: PubMed was used to identify peer-reviewed publications from the past 15 years (January 1990 to January 2005) that used brain-imaging techniques (anatomic, functional, and biochemical) to research early-onset BD. RESULTS: Eleven studies using anatomic magnetic resonance imaging (MRI), seven using magnetic resonance spectroscopy (MRS), and two using functional MRI (fMRI) were identified. Structural abnormalities were reported in total cerebral, white matter, superior temporal gyrus, putamen, thalamus, amygdala, and hippocampal volumes. Deficits in cortical gray matter were also reported. Using MRS, abnormalities were reported in the dorsolateral prefrontal cortex, anterior cingulate, and basal ganglia. One fMRI study found increased activation in the putamen and thalamus of BD youths compared to controls, and a second found abnormal prefrontal-subcortical activation in familial pediatric BD. CONCLUSION: Published MRI studies of early-onset BD are few. Nonetheless, extant data implicate abnormalities in brain regions thought to regulate mood and cognition. Synthesis of the findings into an overall model of anatomic and functional disruption is difficult due to the methodological variations among studies and the limitations of individual studies, such as the use of small sample sizes, the heterogeneity of sample characteristics, and the wide range of brain structures selected for analysis. Recommendations are offered to guide future research. It will be important for future studies to reproduce prior findings and determine which findings are unique to early-onset BD, relative to adult-onset illness. In addition, studies will need to establish the extent to which early-onset BD may overlap with comorbid disruptive, mood, anxiety, or psychotic disorders.

Age of Onset↗
PubMed2005

Anatomical analysis of an aye-aye brain (Daubentonia madagascariensis, primates: Prosimii) combining histology, structural magnetic resonance imaging, and diffusion-tensor imaging.

This report presents initial results of a multimodal analysis of tissue volume and microstructure in the brain of an aye-aye (Daubentonia madagascariensis). The left hemisphere of an aye-aye brain was scanned using T2-weighted structural magnetic resonance imaging (MRI) and diffusion-tensor imaging (DTI) prior to histological processing and staining for Nissl substance and myelinated fibers. The objectives of the experiment were to estimate the volume of gross brain regions for comparison with published data on other prosimians and to validate DTI data on fiber anisotropy with histological measurements of fiber spread. Measurements of brain structure volumes in the specimen are consistent with those reported in the literature: the aye-aye has a very large brain for its body size, a reduced volume of visual structures (V1 and LGN), and an increased volume of the olfactory lobe. This trade-off between visual and olfactory reliance is likely a reflection of the nocturnal extractive foraging behavior practiced by Daubentonia. Additionally, frontal cortex volume is large in the aye-aye, a feature that may also be related to its complex foraging behavior and sensorimotor demands. Analysis of DTI data in the anterior cingulum bundle demonstrates a strong correlation between fiber spread as measured from histological sections and fiber spread as measured from DTI. These results represent the first quantitative comparison of DTI data and fiber-stained histology in the brain.

Animals↗