Biomedical subjects

R A Moats

Publications and source records attributed to R A Moats.

9 recordsLinked to original sources

PubMed1995

Probable Alzheimer disease: diagnosis with proton MR spectroscopy.

PURPOSE: To distinguish probable Alzheimer disease (AD) from other dementias (ODs) and normality in the elderly. MATERIALS AND METHODS: A double-blind trial of proton magnetic resonance (MR) spectroscopy was performed, principally in gray matter, in the occipital cortex of 114 patients with dementia (AD [n = 65], OD [n = 39], or frontal lobe dementia [FLD] [n = 10]), 98 patients without dementia, and 32 healthy control subjects. RESULTS: Reduced levels of N-acetylaspartate (NAA) (P < .0005) and increased levels of myo-inositol (MI) (P < .0005) characterize AD. Patients with OD had significantly reduced levels of NAA (P < .01) but normal levels of MI (P [vs AD] < .0005). When MI/NAA was used, AD was distinguished from normality with 83% sensitivity and 98% specificity. When MI/creatine was used, OD was distinguished from AD and FLD with a negative predictive rate of 80%, sensitivity of 82%, and specificity of 64%. CONCLUSION: Hydrogen-1 MR spectroscopy enables identification of mild to moderate AD with a specificity and sensitivity that suggest clinical utility.

Aged↗

PubMed1995

Evaluation of automated MR spectroscopy: application in Alzheimer disease.

In a trial involving 21 patients with dementia and 3 healthy control subjects, a comparison between the major cerebral metabolite ratios obtained with an established manually optimized proton MR spectroscopic examination and those obtained with an automated proton MR spectroscopic procedure shows that the two techniques provide very comparable results.

Adult↗

PubMed1994

Automated single-voxel proton MRS: technical development and multisite verification.

To improve clinical utility, an integrated method has been developed to automatically acquire and process single-voxel in vivo proton spectra on a 1.5 T clinical scanner. This method includes automated adjustment of linear shims using a very rapid modified simplex method, automated water suppression, and applies a water referencing scheme to correct for phase and residual eddy current effects. No operator intervention is required for the acquisition and processing of these pure-absorption spectra. This method was tested in a preliminary multisite trial to determine intersite and intrasite variability of metabolite ratio measurements. In a sample of over 100 examinations, the standard deviation of the ratios NAA:Cr, Cho:Cr, and ml:Cr were found to be under 15% when using this method, a substantially narrower range than has been found in studies relying on manual adjustment of the instrument and/or manual processing. This result indicates that automated setting of acquisition and processing parameters is of critical importance in the clinical application of in vivo spectroscopy.

Algorithms↗

PubMed1994

Abnormal cerebral metabolite concentrations in patients with probable Alzheimer disease.

To establish whether recently described abnormalities of peak ratios are the result of changes in metabolite concentrations, quantitative 1H magnetic resonance spectroscopy was performed in 10 patients with Alzheimer disease (AD) and seven normal elderly. CSF volumes, metabolite T1 and T2 relaxation rates, ratios and concentrations of N-acetyl residues, creatine, choline residues, myo-inositol, glutamine plus glutamate (Glx), and glucose were obtained. Difference spectroscopy and quantitative assays showed a 50% increase in myo-inositol (6.4-9.8 mM; P < 0.005) and a decrease in N-acetyl in occipital gray matter. A reduction in beta, gamma-Glx and a significant increase in intracerebral [glucose], greater than attributable to CSF, were defined. Choline concentration increased with age, but was not elevated above normal in AD patients. These findings indicate the need for quantitative 1H MRS to substantiate metabolite ratios. The increased myo-inositol concentration in AD is demonstrated by these studies.

Aged↗

PubMed1994

Scyllo-inositol depletion in hepatic encephalopathy.

Cerebral myo-inositol depletion is found in patients with hepatic encephalopathy and can be implicated in the pathogenesis of hepatic encephalopathy. We measured scyllo-inositol, a stereoisomer of myo-inositol, in brain extracts from patients dying in hepatic coma using HPLC and high resolution 1H MRS. The cerebral scyllo-inositol concentration, determined by both methods, in patients without hepatic encephalopathy was 0.41 +/- 0.11 mmol/kg wet weight. It decreased by 73% and 76%, respectively, as measured by HPLC and 1H MRS, in patients with hepatic encephalopathy. These findings indicate that myo-inositol depletion in patients with hepatic encephalopathy is not due to enhanced conversion of myo-inositol to scyllo-inositol or inhibition of myo-inositol transport by scyllo-inositol, but rather to the reduced biosynthesis or transport of both inositols.

Autopsy↗

PubMed1994

Subclinical hepatic encephalopathy: proton MR spectroscopic abnormalities.

PURPOSE: To determine whether hydrogen-1 magnetic resonance (MR) spectroscopy of the brain allows detection of subclinical hepatic encephalopathy (SCHE). MATERIALS AND METHODS: In a double-blind study, overt hepatic encephalopathy (HE) and SCHE (defined with clinical and neuropsychiatric tests) were compared by means of H-1 MR spectroscopic criteria--reduction in cerebral myo-inositol (< 2 standard deviations [SDs] from normal) and choline (< 2 SDs from normal) with or without increased cerebral glutamine (> 1 SD from normal)--in 20 patients with cirrhosis. RESULTS: Concordance between MR spectroscopic and neuropsychiatric test results was 94% (kappa = 0.84). MR spectroscopy allowed diagnosis of SCHE in nine of nine patients (100%) and of HE in seven of eight (88%). Myo-inositol depletion alone had 80%-85% sensitivity for detection of HE and SCHE. CONCLUSION: H-1 MR spectroscopy allows accurate diagnosis of SCHE, and the results suggest an important role for myo-inositol in psychomotor and visuopractic functions.

Adult↗

PubMed1993

Decrease in cerebral inositols in rats and humans.

Rats with portacaval shunts and humans with hepatic encephalopathy show severe myo-inositol depletion in the brain. The portacaval-shunted rat may therefore be a useful model for the investigation of neurochemical pathways containing myoinositol, which are modulated not only in hepatic encephalopathy but also in diabetes mellitus and Alzheimer's disease.

Animals↗

PubMed1993

Alzheimer disease: depiction of increased cerebral myo-inositol with proton MR spectroscopy.

To define altered metabolites in the brain of patients with probable Alzheimer disease (AD) of two brain regions, localized in vivo hydrogen-1 magnetic resonance (MR) spectroscopy was performed with a short echo time (30 msec) in 11 elderly patients and 10 healthy age-matched subjects. The patients had mild to moderate dementia, assessed with standard neuropsychological tests. Two abnormalities in the patients' cerebral cortex were defined: When compared with healthy subjects, the patients showed a 22% increase (P = .005) (approximately equal to 1.5 mmol/kg) in myo-inositol (MI) and an 11% decrease (P = .005) in residues of N-acetyl (NA), a putative neuronal marker. The elevation of MI in patients with mild to moderate AD suggests that abnormalities in the inositol polyphosphate messenger pathway occur early in the natural history of AD. The combination of high MI and low NA at examination with H-1 MR spectroscopy shows promise as an early diagnostic test for AD.

Aged↗

PubMedDate not supplied

Added value of automated clinical proton MR spectroscopy of the brain.

OBJECTIVE: A trial was conducted to establish the added diagnostic value of an automated proton MR spectroscopy (MRS) examination (PROBE). MATERIALS AND METHODS: The PROBE and MRS were compared for metabolite ratios of normal controls and 21 patients. In addition, PROBE was performed in either the occipital cortex (gray matter) or the parietal cortex (white matter) or, more rarely, within the confines of a focal lesion identified on MRI, using a GE Signa 1.5 T whole-body scanner, in 112 patients undergoing routine brain MRI. The trial was conducted in three different MR centers to establish percentage of positive findings with MRI vs. MRI plus MRS. RESULTS: Cerebral metabolite ratios (N-acetylaspartate/creatine, choline/creatine, myo-inositol/creatine) obtained by PROBE and MRS were similar. Metabolite profiles in dementia, head trauma, herpes encephalitis, hepatic and hypoxic encephalopathy, stroke, and tumor were identified using PROBE. The PROBE technique increased the number of positive findings ("added value") achieved by MRI; the added value was 28, 21, and 93% for the three trial sites. CONCLUSION: With only minor variations, PROBE reproduces the cerebral metabolite patterns obtained with MRS. It significantly increases the diagnostic yield of routine neuroimaging and might be incorporated as a standard sequence in a cost-effective manner.

Adult↗