In vivo MR spectroscopy of human dementia.

Nuclear MR spectroscopy in low and medium magnetic fields yields well-resolved natural abundance proton and decoupled phosphorus spectra from small (1-10 mL) volumes of brain in vivo in minutes. With this tool, neurochemical research has advanced through identification and noninvasve assay of a specific neuronal-cf2Ncf1-acetylaspartate, glial (cf2myocf1-inositol)-markers, energetics and osmolutes, and neurotransmitters (glutamate, GABA). From these simple measurements, several dozen disease states are recognized, including birth injury, and white matter and Alzheimer disease.

Lack of effect of oral choline supplement on the concentrations of choline metabolites in human brain.

Recent reports suggest that oral choline supplement may alter the cerebral choline/creatine (Cho/Cr) ratio and might be used to treat neurodegenerative disorders of cholinergic transmission. Using both 1H and 31P MRS, we reexamined the Cho/Cr ratio and quantified cerebral choline and its major constituents: phosphoethanolamine (PE), phosphorylcholine (PC), glycerophosphorylethanolamine (GPE), and glycerophosphorylcholine (GPC). In the four brain locations examined, no significant increases in Cho/Cr, [Cho], or in its major constituents were found in response to an oral challenge of 50 mg/kg of choline bitartrate.

Quantitative proton-decoupled 31P MRS and 1H MRS in the evaluation of Huntington's and Parkinson's diseases.

Objective: To determine cerebral energy status in patients with Huntington's disease (HD) and Parkinson's disease (PD).

Methods: The study included 15 patients with DNA-proven, symptomatic HD and five patients with medically treated, idiopathic PD, all of whom were candidates for neurotransplant treatment, as well as 20 age-related normal subjects. Quantitative noninvasive, MRI-guided proton MRS was performed of single volumes in putamen of basal ganglia (BG), occipital gray matter, and posterior parietal white matter; in addition, quantitative phosphorus and proton-decoupled phosphorus MRS of superior biparietal white and gray matter was done.

Apoptosis in experimental myocardial infarction in situ and in the perfused heart in vitro.

We report the appearance of apoptotic cells in experimental myocardial infarction (rabbit heart) in in situ and in vitro preparations. Apoptosis was recognized by intravital staining with Hoechst 33342 (Ho342), by nick-end labeling (TUNEL) and by DNA laddering. A steady rise in the relative number of apoptotic cardiomyocytes (apoptotic index) was noted in in situ preparations.

Hypoxic encephalopathy after near-drowning studied by quantitative 1H-magnetic resonance spectroscopy.

Early prediction of outcome after global hypoxia of the brain requires accurate determination of the nature and extent of neurological injury and is cardinal for patient management. Cerebral metabolites of gray and white matter were determined sequentially after near-drowning using quantitative 1H nuclear magnetic resonance spectroscopy (MRS) in 16 children. Significant metabolite abnormalities were demonstrated in all patients compared with their age-matched normal controls.

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.

Quantitative P-31 MR spectroscopy of the liver in alcoholic cirrhosis.

To determine the cause of reduced urea synthesis in cirrhosis, absolute concentrations of phosphorus metabolites in the human liver have been measured in vivo with magnetic resonance (MR) spectroscopy. One-dimensional chemical shift imaging was used to obtain phosphorus-31 spectra from five healthy volunteers and five patients with alcoholic cirrhosis. A reference standard included in all studies enabled the calculation of absolute concentrations.

Damage in peripheral nerve from continuous electrical stimulation: comparison of two stimulus waveforms.

The propensity for two types of charge-balanced stimulus waveforms to induce injury during eight hours of continuous electrical stimulation of the cat sciatic nerve was investigated. One waveform was a biphasic, controlled-current pulse pair, each phase 50 microseconds in duration, with no delay between the phases ('short pulse', selected to excite primarily large axons), whereas in the second type each phase was 100 microseconds in duration, with a 400 microsecond delay between the phases (selected to excite axons of a broader spectrum of diameters). The sciatic nerve was examined for early axonal degeneration (EAD) seven days after the session of continuous stimulation.

Metabolic disorders of the brain in chronic hepatic encephalopathy detected with H-1 MR spectroscopy.

Proton magnetic resonance (MR) spectroscopy of the brain was performed in 11 patients with chronic hepatic encephalopathy (CHE), and the results were compared with those of patients with liver disease but without CHE; clinical control subjects with diabetes, uremia, or cortical atrophy; and healthy subjects. The technique of water-suppressed stimulated-echo hydrogen-1 MR spectroscopy for detection of cerebral glutamate, glutamine, glucose, N-acetylaspartate, choline metabolites, (phospho)creatine, and myo-inositol is described. Specific changes in the brain of CHE patients included the anticipated elevation in cerebral glutamine levels (P less than or equal to .

31P saturation transfer and phosphocreatine imaging in the monkey brain.

31P magnetic resonance imaging with chemical-shift discrimination by selective excitation has been employed to determine the phosphocreatine (PCr) distribution in the brains of three juvenile macaque monkeys. PCr images were also obtained while saturating the resonance of the gamma-phosphate of ATP, which allowed the investigation of the chemical exchange between PCr and the gamma-phosphate of ATP catalyzed by creatine kinase. Superposition of the PCr images over the proton image of the same monkey brain revealed topological variations in the distribution of PCr and creatine kinase activity.

Hydrocephalus: overdrainage by ventricular shunts. A review and recommendations.

Selected literature review of the clinical course of patients with ventricular shunts for hydrocephalus shows that the effects of cerebrospinal fluid overdrainage are subdural hematoma, craniosynostosis, slit ventricle syndrome, and low intracranial pressure syndrome. These occur sequentially at different age groups, but approximate averages of incidence and time of occurrence after first shunt reveal an overall incidence of 10%-12% for at least one of these appearing at 6.5 years after shunting.

Meninges: benign postoperative enhancement on MR images.

In a group of 20 postcraniotomy patients who underwent magnetic resonance imaging performed with gadopentetate dimeglumine, 16 (80%) had nonneoplastic meningeal enhancement. This was seen as either enhancement of a local dural membrane or generalized meningeal enhancement. In a control group of 23 patients, only three (13%) had similar findings.

Considerations for safety with chronically implanted nerve electrodes.

Electrical stimulation of cranial and peripheral nerves has been used to ameliorate a variety of neurologic disease states and neural injuries over the past 20 years. In this review, clinical applications and the histopathologic results of chronic implants in animals and humans are discussed, and the results of neural damage models developed at Huntington Medical Research Institutes are summarized. Chronically implanted electrode arrays may produce neural injury by either mechanical factors or by continuous, high-frequency electrical stimulation.

Low-artifact intravascular devices: MR imaging evaluation.

Flow-phantom magnetic resonance (MR) imaging, with use of both spin-echo (SE) and gradient-echo (GRE) techniques at 1.5 T, was performed on the percutaneous Greenfield (beta-III titanium alloy [TMA wire]), Amplatz (MP32-N alloy), and Simon nitinol filters and TMA wire facsimiles of the bird's nest, Gunther, new retrievable, and Amplatz vena caval filters. SE imaging allowed detection of thrombi as small as 5 X 5 mm trapped within the percutaneous Greenfield, Simon nitinol, and TMA-wire facsimile filters; with the MP32-N Amplatz filter, a larger volume of thrombus (10 X 20-mm clots) was necessary for clot detection.