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N Schuff

Publications and source records attributed to N Schuff.

53 records · Page 3Linked to original sources
PubMed1998

Alzheimer disease: quantitative H-1 MR spectroscopic imaging of frontoparietal brain.

PURPOSE: To replicate previous hydrogen-1 magnetic resonance (MR) spectroscopic imaging findings of metabolic abnormalities in patients with Alzheimer disease (AD), to verify that metabolic abnormalities are not an artifact of structural variations measured at MR imaging, to determine whether metabolic changes correlate with dementia severity, and to test whether MR imaging and MR spectroscopic imaging findings together improve ability to differentiate AD. MATERIALS AND METHODS: MR spectroscopic imaging and MR imaging were performed in 28 patients with AD and 22 healthy elderly subjects. Spectroscopic imaging data were coregistered with MR imaging segmentation data to obtain volume-corrected metabolite concentrations. RESULTS: Consistent with previous results, N-acetyl aspartate (NAA) levels were statistically significantly reduced in frontal and posterior mesial cortex of AD patients, presumably due to neuronal loss. NAA level reductions were independent of structural variations measured at MR imaging and, in parietal mesial cortex, were correlated mildly with dementia severity. Spectroscopic imaging findings of NAA level combined with MR imaging measures did not improve discrimination power for AD relative to that of MR imaging alone. CONCLUSION: Reduced NAA levels in frontoparietal brain are of limited use for diagnosis of AD. However, they are not an artifact of structural variations and thus may provide useful information for the understanding of the pathologic processes underlying AD.

Aged↗
PubMed1998

Decreased N-acetylaspartate in motor cortex and corticospinal tract in ALS.

The primary objectives of this study were to test whether 1) N-acetylaspartate (NAA), a neuronal marker, is reduced in motor cortex and corticospinal-tract (CST) brain regions of ALS patients; and 2) motor cortex NAA correlates to a clinical measurement of upper motor neuron function in ALS patients. Ten probable or definite ALS patients and nine neurologically normal control subjects were studied. Three axial planes of two-dimensional 1H MRSI data were collected, using a single spin-echo multislice sequence (TE140/TR2000). Two of the 1H MRSI planes were positioned superior to the lateral ventricles, and one plane was positioned at the level of the internal capsule. Spectroscopy voxels were selected from motor cortex, frontal cortex, parietal cortex, medial gray matter, centrum semiovale white matter, anterior internal capsule, and posterior internal capsule. Peak integrals were obtained for the three major 1H MRSI singlet resonances, NAA, creatine and phosphocreatine (Cr), and cholines (Cho). Maximum finger-tap rate was used as a clinical measurement of upper motor neuron function. In ALS, brain NAA/(Cho+Cr) was reduced 19% (p=0.024) in the motor cortex and 16% (p=0.021) in the CST (centrum semiovale and posterior internal capsule) regions. NAA/ (Cho+Cr) was not reduced in frontal cortex, parietal cortex, medial gray matter, or anterior internal capsule. There was a significant relation between ALS motor cortex NAA/(Cho+Cr) and maximum finger-tap rate (r=0.80; p=0.014). NAA/(Cho+Cr) was reduced in motor cortex and CST regions and unchanged in other brain regions of ALS patients when compared with controls. These findings are consistent with the known distribution of neuronal loss in ALS. The positive correlation between motor cortex NAA/(Cho+Cr) and maximum finger-tap rate suggests that reduced NAA/(Cho+Cr) is a surrogate marker of motor cortex neuron loss in ALS. These findings support the study of 1H MRSI NAA measurement as an objective and quantitative measurement of upper motor neuron dysfunction in ALS.

Adult↗
PubMed1997

Proton magnetic resonance spectroscopy of the anterior cingulate region in schizophrenia.

The authors measured N-acetylaspartate (NAA, a putative neuronal marker), choline and creatine in the anterior cingulate region of 26 schizophrenic patients and 16 control subjects using in vivo proton magnetic resonance spectroscopic imaging (1H MRSI). Relative to the control group, the patients with schizophrenia demonstrated significantly lower NAA in both the right and left anterior cingulate regions. There was no association between NAA and duration of illness or medication dosage. No group differences or lateralized asymmetries in choline or creatine were noted. The NAA findings provide support for either neuronal dysfunction or neuronal loss in the anterior cingulate region in schizophrenia. The absence of choline signal elevation does not support accelerated turnover of membrane phospholipids which might be expected if there were ongoing neuronal atrophy or neuronal necrosis.

Adult↗
PubMed1997

Temporal lobe epilepsy: bilateral hippocampal metabolite changes revealed at proton MR spectroscopic imaging.

PURPOSE: To determine which proton magnetic resonance (MR) spectroscopic imaging measures are best for lateralizing the seizure focus in patients who have temporal lobe epilepsy with and in those without hippocampal atrophy on MR images, the extent of contralateral abnormalities, and whether there is a correlation between MR spectroscopic imaging findings and surgical outcome. MATERIALS AND METHODS: MR spectroscopic imaging was performed in 16 adult patients with temporal lobe epilepsy and unilateral electroencephalographic findings and in 16 adult control subjects. Eleven patients underwent surgery; all patients underwent MR imaging. RESULTS: Nine patients had hippocampal atrophy on MR images. An ipsilateral decrease in the N-acetylaspartate concentration or the ratio of N-acetylaspartate to the sum of creatine and choline (N-acetylaspartate/ [creatine + choline]) was found in all patients. Decreased contralateral N-acetylaspartate concentration, N-acetylaspartate/(creatine + choline), or N-acetylaspartate concentration and N-acetylaspartate/(creatine + choline) were detected in eight patients (50%), which suggests bilateral abnormalities not detected with MR imaging. In the five patients who underwent surgery and did not show hippocampal atrophy on MR images, successful and unsuccessful outcomes were correctly predicted with N-acetylaspartate concentration. CONCLUSION: Decreased N-acetylaspartate concentration is not due solely to hippocampal atrophy. Contralateral abnormalities are much more frequent than expected. MR spectroscopic imaging is valuable in the presurgical evaluation of epilepsy.

Adult↗
PubMed1997

Volumetric method for evaluating magnetization transfer ratio of tissue categories: application to areas of white matter signal hyperintensity in the elderly.

An objective technique for analyzing magnetization transfer ratio of segmented tissues was used to evaluate differences between normal-appearing white matter and areas of white matter signal hyperintensity on T2-weighted magnetic resonance images in 23 healthy elderly subjects (mean age, 75 years). Segmented brain images (cerebrospinal fluid, gray matter, white matter, areas of white matter signal hyperintensity) computed from T1- and T2-weighted images were combined with magnetization-transfer-ratio images to produce magnetization-transfer-ratio histograms for each tissue. There was a significant 8.1% reduction in mean magnetization transfer ratio for areas of white matter signal hyperintensity compared with normal-appearing white matter (P < .001). The magnetization transfer ratio for all tissue categories was significantly negatively correlated with age (all, P < .05). This method of measuring magnetization transfer ratio was objective, independent of regional variations, and as reproducible as the segmentation procedure.

Aged↗
PubMed1997

1H MRSI of normal appearing white matter in multiple sclerosis.

The primary goal of this study was to determine if differences in proton magnetic resonance spectroscopy signals exist between normal appearing white matter (NAWM) of multiple sclerosis (MS) patients and white matter of control subjects. Water suppressed proton magnetic resonance spectroscopic imaging was used to determine the signal intensities of N-acetylated moieties (NA, predominantly N-acetylaspartate (NAA) the putative neuronal marker), creatine and phosphocreatine (Cr), and cholines (Ch) in 19 MS patients (15 relapsing-remitting and four secondary progressive) and 19 age matched control subjects. NA/Cr was significantly reduced (P < 0.001) in MS NAWM (1.8 +/- 0.2; x +/- s.d.) distant from MRI detected lesion areas compared to white matter of control subjects (2.1 +/- 0.2). This reduction was due to an increase in Cr from 0.39 +/- 0.04 (arbitrary units) in controls to 0.45 +/- 0.05 in MS patients. There was no significant change in NA or Ch in MS NAWM compared to controls. NA/Cr, distant from MRI lesion, was negatively correlated with total brain lesion volume as measured from T2-weighted MRI. We interpret the reduced NA/Cr in MS NAWM to indicate diffuse microscopic disease.

Adult↗
PubMed1997

Changes of hippocampal N-acetyl aspartate and volume in Alzheimer's disease. A proton MR spectroscopic imaging and MRI study.

Hippocampal atrophy detected by MRI is a prominent feature of early Alzheimer's disease (AD), but it is likely that MRI underestimates the degree of hippocampal neuron loss, because reactive gliosis attenuates atrophy. We tested the hypothesis that hippocampal N-acetyl aspartate (NAA: a neuronal marker) and volume used together provide greater discrimination between AD and normal elderly than does either measure alone. We used proton MR spectroscopic imaging (1H MRSI) and tissue segmented and volumetric MR images to measure atrophy-corrected hippocampal NAA and volumes in 12 AD patients (mild to moderate severity) and 17 control subjects of comparable age. In AD, atrophy-corrected NAA from the hippocampal region was reduced by 15.5% on the right and 16.2% on the left (both p < 0.003), and hippocampal volumes were smaller by 20.1% (p < 0.003) on the right and 21.8% (p < 0.001) on the left when compared with control subjects. The NAA reductions and volume losses made independent contributions to the discrimination of AD patients from control subjects. When used separately, neither hippocampal NAA nor volume achieved to classify correctly AD patients better than 80%. When used together, however, the two measures correctly classified 90% of AD patients and 94% of control subjects. In conclusion, hippocampal NAA measured by 1H MRSI combined with quantitative measurements of hippocampal atrophy by MRI may improve diagnosis of AD.

Aged↗
PubMed1997

Tissue segmentation of the brain in Alzheimer disease.

PURPOSE: To compare brain tissue in patients with Alzheimer disease with that in elderly control subjects by using high-resolution MR imaging and quantitative tissue-segmentation techniques. METHODS: MR imaging of the brain was performed in 21 patients with Alzheimer disease and 17 control subjects. A computerized segmentation program was used to quantify volumes of ventricular and sulcal cerebrospinal fluid (CSF), white matter, cortical gray matter, and white matter signal hyperintensity. Statistical analysis was performed using analysis of variance. RESULTS: We found a significant decrease in total brain tissue and cortical gray matter and an increase in the ventricular and sulcal CSF in Alzheimer patients compared with control subjects. There was no difference in the volume of white matter. More white matter signal hyperintensities were found in Alzheimer patients, and a significant interaction between age and group was noted. Neuropsychological test scores correlated significantly with sulcal CSF in patients with Alzheimer disease. CONCLUSION: Semiautomated segmentation of MR images of the brains of patients with Alzheimer disease reveals significant brain atrophy attributable to loss of cortical gray matter, which is compatible with the pathologic features of Alzheimer disease. There is also a significant increase in white matter signal hyperintensities. Tissue segmentation may increase our understanding of dementia but, as yet, when used alone, it does not play a role in the premorbid diagnosis of Alzheimer disease.

Aged↗
PubMed1996

Removal of lipid artifacts in 1H spectroscopic imaging by data extrapolation.

Proton MR spectroscopic imaging (MRSI) of human cerebral cortex is complicated by the presence of an intense signal from subcutaneous lipids, which, if not suppressed before Fourier reconstruction, causes ringing and signal contamination throughout the metabolite images as a result of limited k-space sampling. In this article, an improved reconstruction of the lipid region is obtained using the Papoulis-Gerchberg algorithm. This procedure makes use of the narrow-band-limited nature of the subcutaneous lipid signal to extrapolate to higher k-space values without alteration of the metabolite signal region. Using computer simulations and in vivo experimental studies, the implementation and performance of this algorithm were examined. This method was found to permit MRSI brain spectra to be obtained without applying any lipid suppression during data acquisition, at echo times of 50 ms and longer. When applied together with optimized acquisition methods, this provides an effective procedure for imaging metabolite distributions in cerebral cortical surface regions.

Algorithms↗
PubMed1992

Noninvasive imaging and spectroscopy--broad applications of magnetic resonance.

The present utility of nuclear magnetic resonance (NMR) spectroscopy in chemical analysis and magnetic resonance imaging (MRI) in the clinical environment has made this technology commonplace in the chemical industry, clinical medicine, and academic research. The attributes of nuclear magnetism that make the technique especially powerful in biology are discussed. This paper reviews the uses of NMR and MRI, with an emphasis on spatially resolved applications. These applications include imaging, localized spectroscopy, flow sensing, and diffusion mapping from using magnetic-field gradients. The limits of spatially resolved NMR and imaging will be examined in terms of both scientific principles and engineering practice. Block diagrams of both imaging and spectroscopy apparatus are presented and technical requirements of the critical components are discussed. Developing trends in sensing probes, magnets, and applications are highlighted.

Humans↗
PubMed1991

19F nuclear magnetic resonance spectroscopy of neuroleptics: the first in vivo pharmacokinetics of trifluoperazine in the rat brain and the first in vivo spectrum of fluphenazine in the human brain.

In vivo 19F nuclear magnetic resonance (19F-NMR) spectroscopy measurements of trifluorinated neuroleptics (fluphenazine--FL and trifluoperazine--TFP) were made in rat brain as well as in human brain. Animal studies were performed at 4.7 Tesla. Using rats that have been treated with FL over a period of 3 weeks, a NMR signal could be detected within 8-15 min. Following a single intravenous injection of TFP, brain levels could be monitored with a time resolution of 30 min. The first 19F-NMR examination of a patient was made at 3.0 Tesla 1 day after injection of FL decanoate (37.5 mg) in the course of which a signal could be detected within 30 min. It is expected that 19F-NMR will become an important tool in psychopharmacological research.

Adult↗
PubMed1990

Noninvasive in vivo detection of a fluorinated neuroleptic in the human brain by 19F nuclear magnetic resonance spectroscopy.

A fluorinated long-acting neuroleptic (fluphenazine decanoate) was detected in the human brain by fluorine nuclear magnetic resonance spectroscopy (MRS). The MRS system used had a 3 Tesla magnetic field, corresponding to a frequency of 118 MHz for the fluorine nucleus (Bruker Medspec 3 Tesla, 60-cm magnet bore width). The spectra were obtained with a surface coil having a 10-cm diameter, which was centered alternatively on the frontal lobe and basal ganglia, and on the occipital lobe. The impregnation and elimination kinetics of fluphenazine were monitored during three sessions (4 hours, 5 days, and 11 days after injection of the compound). This technique can be usefully applied to the in vivo study of the pharmacokinetics and site of action of psychiatric compounds in man.

Adult↗
PubMed1986

[MR-tomography and -spectroscopy of skeletal muscles using high magnetic field strengths].

Intact as well as neuromuscular affected skeletal muscles can be precisely analysed by MR tomography with high magnetic field strengths. The substitution of muscle by adipose tissue under atrophic conditions is seen most clearly in fat images, while the morphology of small structures is predominantly shown by water images. The aim of in-vivo spectroscopy is an identification and quantification of metabolites. A relative increase in the amount of adipose tissue within atrophic muscles was confirmed by the 1-H spectrum. As concluded from 13-C and 31-P spectra there was neither a change in adipose tissue composition nor a modification of energy metabolism.

Adenosine Triphosphate↗
PubMed1985

Structure of the barn owl's (Tyto alba) inner ear.

The basilar papilla of the Barn Owl's (Tyto alba) cochlea was found to be 9.5-11.5 mm long. Histological examination revealed that the sensory hair cells had a characteristic distribution: The proximal half contained mostly typical short cells; tall hair cells were present only on the distal half along with many short cells. Lenticular short cells occupied the proximal tip of the papilla. Another unusual feature of the proximal part was a dense fibrous mass in the basilar membrane. This was absent from the distal one-fourth.

Animals↗
PubMedDate not supplied

Comparison of methods for measuring longitudinal brain change in cognitive impairment and dementia.

PURPOSE: The goal of this project was to compare MRI measures of hippocampal, entorhinal cortex (ERC), and whole brain longitudinal change in cognitively normal elderly controls (C), non-demented subjects with cognitive impairment (CI), and demented (D) subjects. METHODS: 16 C, 6 CI, and 7 D subjects of comparable age were studied with MRI twice, at least 1 year apart. Longitudinal change in total brain size was measured by several methods, including computerized segmentation, non-linear warping, and change in the fluid/tissue boundaries between cerebrospinal fluid (CSF) and brain. Change in hippocampal volume was measured by semi-automated methods, and ERC volumes were manually measured. RESULTS: The annual rate of atrophy was greater in D versus C and D versus CI for cortical gray matter (cGM) (P=0.009 and 0.002), hippocampus (P=0.0001 and 0.002), and for the change in the fluid/tissue boundary (P=0.03 and 0.03). The annual rate of atrophy of ERC was greater in both CI and D versus C (P=0.01 and 0.0002). No significant differences between groups were found using non-linear warping. CONCLUSIONS: In CI, the greatest annual rates of atrophy were in ERC, while in D the greatest annual rates of atrophy were in hippocampus and cortex. Progressive ERC atrophy was observed with a greater degree of cognitive impairment, while hippocampal and cortical atrophy were only observed in demented subjects.

Aged↗
PubMedDate not supplied

Age-related metabolite changes and volume loss in the hippocampus by magnetic resonance spectroscopy and imaging.

Magnetic resonance imaging (MRI) studies have produced controversial results concerning the correlation of hippocampal volume loss with increasing age. The goals in this study were: 1) to test whether levels of N-acetyl aspartate (NAA, a neuron marker) change in the hippocampus during normal aging and 2) to determine the relationship between hippocampal NAA and volume changes. Proton magnetic resonance spectroscopic imaging (1H MRSI) and MRI were used to measure hippocampal metabolites and volumes in 24 healthy adults from 36 to 85 years of age. NAA/Cho decreased by 24% (r = 0.53, p = 0.01) and NAA/Cr by 26% (r = 0.61, p < 0.005) over the age range studied, whereas Cho/Cr remained stable, implying diminished NAA levels. Hippocampal volume shrank by 20% (r = 0.64, p < 0.05). In summary, aging effects must be considered in 1H MRSI brain studies. Furthermore, because NAA is considered a marker of neurons, these results provide stronger support for neuron loss in the aging hippocampus than volume measurements by MRI alone.

Adult↗