Hydrogen-1 MR spectroscopy enables identification of mild to moderate AD with a specificity and sensitivity that suggest clinical utility.

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.

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.

H-1 MR spectroscopy allows accurate diagnosis of SCHE, and the results suggest an important role for myo-inositol in psychomotor and visuopractic functions.

The objective of this study was to demonstrate 1H MR spectroscopy (MRS) changes in cerebral metabolites after acute head trauma. Twenty-five patients (12 children, 13 adults) were examined with quantitative 1H MRS after closed head injury. Clinical grade (Glasgow Coma Scale [GCS]) and outcome (Rancho Los Amigos Medical Center Outcome Score [ROS]) were correlated with quantitative neurochemical findings. N-acetylaspartate (NAA), a neuronal and axonal marker, was reduced (P < .03-.001). In children, a reduced NAA/creatine plus phosphocreatine (Cr) level and the presence of detectable lipid/lactate predicted bad outcome (sensitivity, 89%; specificity, 89%). The first MRS examination of all patients correlated with ROS versus NAA (r = .65, P < .0001). Although most patients showed MRS abnormalities, striking heterogeneity of 1H MRS characterized the individual patients. 1H MRS identifies multiple patterns of diffuse brain injury after blunt head trauma. There was a strong correlation between MRS and outcome. Future prospective studies will be needed to determine the clinical usefulness of MRS in predicting outcome from closed head injury.