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In vivo proton MR spectroscopy ( 1 H-MRS) is used extensively to study brain diseases and to add metabolic information to diagnostic MR examinations undertaken in routine clinical practice. The main central nervous system (CNS) metabolites detectable by 1 H-MRS are N-acetyl aspartate (NAA), creatine plus phosphocreatine (Cr), choline-containing compounds (Cho), and myoinositol (mI). Quantitative evaluation of these metabolites would be useful for the study of major spinal cord diseases, such as multiple sclerosis (MS), spinocerebellar ataxias, and intraaxial tumors, mainly because NAA may serve a neuronal marker function (1-4) in establishing axonal integrity (5-8), and mI signal change may be a marker of astrocytosis (9 -13).However, spinal cord proton spectroscopy is challenging because of technical difficulties that limit the quality of the spectroscopic data. The main drawbacks are the strong magnetic field inhomogeneities present in the spinal cord region, respiratory and cardiac movements, and the small size of the spinal cord. On a 3T system the increased signal-to-noise ratio (SNR) can help to find a good compromise between the size of the acquisition volume and the number of repetitions required to obtain a total acquisition time that is feasible in a clinical environment.Because of these technical challenges, few studies of spinal cord 1 H-MRS have been published to date. One study (14) quantified the main metabolites in six healthy volunteers using a 1.5T system (14). Another study involving MS patients and 12 healthy subjects was conducted (15), but the quantification data were not reported. A detailed study of the cervical spine proton spectroscopy protocol on a 2T system equipped with a purpose-built quadrature surface coil compared the concentrations of NAA, Cr, and mI on cervical spine and some brain areas in six healthy volunteers (16 -17). Two recent abstracts described studies on a 3T system: one involved a preliminary qualitative single-voxel comparison of the cervical and dorsal spine of a healthy volunteer and cervical spine tumor spectra (18), and one was a preliminary MR spectroscopic imaging (MRSI) quantification study (19).Our purpose was to devise an acquisition and postprocessing protocol to quantify the main CNS metabolites on the cervical spinal cord on a 3T system with standard equipment to include the spectroscopy study in routine clinical spinal cord imaging and define the normal metabolite concentrations in this location to use as a reference. This study presents a protocol for quantitative cervical spinal cord single-voxel MRS with the first mean relative concentrations for NAA, Cr, Cho, and mI in a group of 10 healthy volunteers using a clinical 3T system. These concentrations were also compared with brainstem metabolite contents in healthy subjects that were previously acquired with the same system. Statistical analysis confirmed a significant difference in metabolite concentrations between the spinal cord and the brainstem. MATERIALS AND METHODSSpinal cord 1 H-MRS examinatio...

BACKGROUND AND PURPOSE:Brain proton MR spectroscopy ( 1 H-MR spectroscopy) is a useful technique for evaluating neuronal/axonal damage and demyelization in multiple sclerosis (MS). Because MS disability is frequently related to spinal cord lesions, potential markers for MS stage differentiation and severity would require in vivo quantification of spinal integrity. However, few spectroscopy studies have investigated cervical disease due to technical difficulties. The present study used 3T 1 H-MR spectroscopy to measure the main metabolites in cervical spinal cord plaques of a group in patients with relapsing-remitting MS (RRMS) and compared them with metabolite measurements in healthy volunteers.

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Dominant optic atrophy has been associated with mutations in the OPA1 gene, which encodes for a dynamin-related GTPase, a mitochondrial protein implicated in the formation and maintenance of mitochondrial network and morphology. We used phosphorus magnetic resonance spectroscopy to assess calf muscle oxidative metabolism in six patients from two unrelated families carrying the c.2708-2711delTTAG deletion in exon 27 of the OPA1 gene. The rate of postexercise phosphocreatine resynthesis, a measure of mitochondrial adenosine triphosphate production rate, was significantly delayed in the patients. Our in vivo results show for the first time to our knowledge a deficit of oxidative phosphorylation in OPA1-related DOA.

Valeria Clementi was born in Ancona (1968) and graduated in physics (1994) and specialized in health physics (1996) at the University of Bologna. She then joined the Florence NMR laboratory with an industry research grant on relaxometry and MRI contrast agents, and is now working on the theory of water-biomolecules interaction.

A mathematical model is proposed showing that the mono-exponential recovery of phosphocreatine (PCr) after exercise is an approximation of a more complex pattern, which is identified by a second-order differential equation. The model predicts the possibility of three different patterns of PCr recovery: bi-exponential, oscillatory damped, and critically damped; the mono-exponential pattern being a particular case of the functions which are solutions of the differential equation. The model was tested on a sample of recovery data from 50 volunteers, checking whether the recovery patterns predicted by the model lead to a significant improvement of fit (IF) compared with the mono-exponential pattern. Results show that the IF is linked to pH. Bi-exponential solutions showed an IF in the pH range 6.65-6.85, and the oscillatory solutions at pH>6.9. Critically damped solutions displayed a poor IF. Oscillation frequencies found in the oscillatory recoveries increase at increasing pH. These results show that pH has a pivotal role on the pattern of PCr recovery and implications on the regulation of oxidative phosphorylation are discussed.