Quantitative Proton Magnetic Resonance Spectroscopy Research Articles

Identification of potential metabolic biomarkers in predicting esophageal varices needing treatment in patients with liver cirrhosis

The goal of this study was to determine the diagnostic performance of in vivo quantitative proton magnetic resonance spectroscopy (1H-MRS) to identify the presence of esophageal varices needing treatment (VNT), as well as investigate its correlation with clinical characteristics in patients with liver cirrhosis. Forty cirrhotic patients without VNT showing the negative red color sign, and 40 cirrhotic patients with VNT showing positive red color sign underwent laboratory tests, esophago-gastro-duodenoscopy, and 1H-MRS with single-voxel localization in the cirrhotic liver parenchyma. The levels of lactate + triglyceride (TG) and choline in cirrhotic patients with VNT were significantly higher than those in cirrhotic patients without VNT. In multivariate analysis, spleen diameter, platelet count, and platelet count/spleen diameter ratio, as well as lactate + TG, and choline were associated with the presence of VNT. Moreover, lactate + TG and choline levels were positively correlated with spleen diameter and negatively correlated with platelet count in the combined group of cirrhotic patients with and without VNT. Our study demonstrated that higher hepatic lactate + TG and choline levels in cirrhotic patients in conjunction with longer spleen diameter, lower platelet counts, and lower ratios of platelet count to spleen diameter were associated with the presence of esophageal VNT and the risk of developing variceal bleeding. Therefore, in vivo 1H-MRS might be an effective tool for diagnosing and predicting esophageal VNT in patients with liver cirrhosis.

Proton MR spectroscopic features of the cisternal segment of the trigeminal nerve in patients with trigeminal neuralgia: A pilot study

PurposeTo investigate normal quantitative proton magnetic resonance spectroscopy (MRS) features of the cisternal segment of the trigeminal nerve and evaluate possible metabolite concentration differences in the affected and unaffected nerves of trigeminal neuralgia patients. Material and methodsA total of 33 consecutive patients who underwent a MR study of the internal auditory canal/posterior fossa and dedicated trigeminal nerve multivoxel MRS were enrolled. Measurements of N-acetyl aspartate (NAA), creatine (Cr), choline (Cho), myoinositol (mI), glutamate-glutamine (Glx) concentrations, and ratios of NAA-to-Cr, Cho-to-Cr, and Cho-to-NAA were automatically calculated by the dedicated software. Vascular conflicts were also recorded. ResultsThe mean Cr concentration was significantly higher on the affected sides in all parts of the nerve (p < 0.05), while the mean NAA concentration was significantly higher in only the distal portion (p = 0.04). Mean mI concentration was significantly higher in the middle and distal parts (p < 0.05). NAA-to-Cr ratio was significantly higher in the proximal and middle parts (p < 0.05), while Cho-to-Cr ratio was significantly higher only in the middle portion (p = 0.028). Finally, the Cho-to-NAA ratio was significantly higher only in the distal portion (p = 0.04). Vascular conflicts were observed in 24 patients (72.7%), and in 20 of them (60.6%) the conflict was on the same side as the neuralgia symptoms. ConclusionAlthough the detected statistical relationships were variable in the spectroscopic measurements, metabolite concentrations and ratios were successfully exhibited in all patients. Features of a normal trigeminal nerve were able to determine by MRS. All calculated metabolite concentrations were higher in the affected nerves; however, only some of them were statistically significant. No statistically significant relationships were found between the MRS measurements and nerves with and without vascular compression.

Quantitative MR spectroscopy reveals metabolic changes in the dorsolateral prefrontal cortex of patients with temporal lobe epilepsy.

To characterize possible metabolic changes of the dorsolateral prefrontal cortex (DLPFC) in patients with temporal lobe epilepsy (TLE). Quantitative proton magnetic resonance spectroscopy (1H-MRS) studies were performed on 24 TLE patients and 22 healthy controls. Metabolite concentrations were calculated using a linear combination model (LCModel) and corrected for cerebrospinal fluid contamination. Comparisons were performed between the TLE patients and the controls and between the left DLPFC and right DLPFC in each group. Pearson correlation coefficients were calculated between the metabolite concentrations and epilepsy duration and between the metabolite concentrations and voxel tissue composition: [gray matter (GM)/(GM+white matter (WM))]. Metabolic asymmetry was found in controls between the left and right DLPFC, i.e., the NAA concentration of the left DLPFC was significantly higher than that of the right. However, such metabolic asymmetry was not observed in TLE patients. Compared with the controls, TLE patients showed significantly decreased NAA and Ins, and the reductions were greater in the left DLPFC. No significant correlation was found between the metabolite concentrations and epilepsy duration or between the metabolite concentrations and voxel tissue composition [GM/(GM+WM)]. This study suggests that TLE can produce metabolic changes to DLPFC that is remote from the seizure focus. • Magnetic resonance spectroscopy probes the brain metabolism noninvasively. • Dorsolateral prefrontal reductions in NAA (a neuronal marker) and Ins are observed in TLE. • Temporal lobe epilepsy can result in metabolic changes remote from the seizure focus.

ANTERIOR CINGULATE CORTEX EXHIBITS AGE-RELATED METABOLIC CHANGES: CORRELATION WITH BEHAVIORAL PERFORMANCE IN ATTENTION TASK

The anterior cingulate cortex(ACC) has become a focus for aging research because of its implicated role in cognition. Furthermore, a prior fMRI study in older adults had demonstrated an increase in blood oxygen level-dependent(BOLD) signal in the ACC compared to young adults during Stroop task, suggesting compensation. In this study, we investigated the metabolic changes during aging in the dorsal ACC of a local Chinese cohort using quantitative proton magnetic resonance spectroscopy(1H-MRS). In addition, relationship between metabolite concentrations and performance from an attention task (numerical Stroop) will be assessed. 36 cognitively normal (Mini-mental State Examination≥28; Montreal Cognitive Assessment≥26) subjects (mean=49.3±17.5years, age range 24–84years) underwent MR scan using 3.0T Philips scanner. A PRESS(TR/TE=2000/39 ms) single voxel of 2x2x2cm3 was placed in the dorsal ACC. Choline(Cho),creatine (Cr),N-acetyl aspartate(NAA), myo-inositol(mI), and summation of glutamate and glutamine complex(Glx), were measured and quantified using internal water as reference by QUEST in jMRUI 4.0(Figure 1). Cerebrospinal fluid(CSF) normalization, water content correction for grey matter, white matter and CSF, and correction factors for T1 and T2 relaxations were implemented. Also, the subjects took part in a numerical Stroop task (Figure 2) inside the scanner(fMRI data was currently undergoing analysis). Pearson correlation coefficient(r) was calculated to assess any correlation between 1) absolute metabolite concentrations ([met]abs) and age in the ACC, and 2) [met]abs and behavioral performance. SPSS version 20.0 was used for statistical analysis and level of significance was set at 0.05. Mean [met]abs and behavioral performance were shown in Tables 1 and 2, respectively. In the ACC, both [Cr]abs(r = 0.336; p = 0.045) and [NAA]abs(r = 0.354; p = 0.034) showed significant positive correlation with age. Only [Cho]abs showed significant positive correlation with both Stroop effect (incongruent-congruent)(r = 0.378; p = 0.023) and Stroop interference (incongruent-neutral)(r = 0.549, p = 0.001) after age-effect adjustment (Figure 3). Age-related increase in [Cr]abs might imply altered energy metabolism[1], while increase in [NAA]abs with age might indicate compensation activity[2]. For the positive correlation between [Cho]abs with Stroop effect, and Stroop interference, higher [Cho]abs could signify glial proliferation which might in turn lead to deficits on executive function[3]. [1]Charlton et al., 2007,[2]Milham et al., 2000,[3]Russell et al., 2006. (a) Position of voxel placed in the anterior cingulatecortex, (b) Simulated spectrum using QUEST in jMRUI, and (c) Simulated spectrum (blue) fitted on spectrum from subject (red). Trial conditions shown in numerical Stroop Task. Scatter plots of [Cho]abs with behavioral performance of (a) Stroop effect, and (b) Stroop Interference.

Direct Analysis of Free and Sulfite-Bound Carbonyl Compounds in Wine by Two-Dimensional Quantitative Proton and Carbon Nuclear Magnetic Resonance Spectroscopy.

Recent developments that have accelerated 2D NMR methods and improved quantitation have made these methods accessible analytical procedures, and the large signal dispersion allows for the analysis of complex samples. Few natural samples are as complex as wine, so the application to challenges in wine analysis look promising. The analysis of carbonyl compounds in wine, key oxidation products, is complicated by a multitude of kinetically reversible adducts, such as acetals and sulfonates, so that sample preparation steps can generate complex interferences. These challenges could be overcome if the compounds could be quantified in situ. Here, two-dimensional ((1)H-(1)H) homonuclear and heteronuclear ((13)C-(1)H) single quantum correlations (correlation spectroscopy, COSY, and heteronuclear single quantum coherence, HSQC) nuclear magnetic resonance spectra of undiluted wine samples were observed at natural abundance. These techniques achieve simultaneous direct identification and quantitation of acetaldehyde, pyruvic acid, acetoin, methylglyoxal, and α-ketoglutaric acid in wine with only a small addition of D2O. It was also possible to observe and sometimes quantify the sulfite, hydrate, and acetal forms of the carbonyl compounds. The accuracy of the method was tested in wine samples by spiking with a mixture of all analytes at different concentrations. The method was applied to 15 wine samples of various vintages and grape varieties. The application of this method could provide a powerful tool to better understand the development, evolution, and perception of wine oxidation and insight into the impact of these sulfite bound carbonyls on antimicrobial and antioxidant action by SO2.

1H Magnetic Resonance Spectroscopy Findings in Idiopathic Inflammatory Myopathies at 3 T

The aim of this study was to investigate the feasibility and potential use of quantitative proton magnetic resonance spectroscopy (MRS) for determining metabolite concentrations in patients with suspected inflammatory myopathies. In this institutional review board-approved, Health Insurance Portability and Accountability Act-compliant prospective study, 35 patients with a suspected inflammatory myopathy and 6 age-matched healthy volunteers underwent magnetic resonance imaging (MRI) (T1-weighted and short tau inversion recovery [STIR] sequences) and single-voxel MRS (point-resolved spectroscopy; repetition time/echo time, 2000/135 milliseconds; voxel size, 2.0 × 2.0 × 4.0 cm) at 3 T. The voxel was placed in a thigh muscle and targeted to one with abnormal STIR signal when possible. Absolute trimethylamine, creatine (Cr), and bulk lipid concentrations in each voxel were determined using the phantom replacement method. The MRS results of patients and healthy subjects were compared using the Wilcoxon rank sum test. Twenty-one patients were diagnosed with an active idiopathic inflammatory myopathy (IIM). In 20 of these patients, MRI showed increased intramuscular STIR signal; however, the muscle where the voxel was placed was normal in 9 patients. Patients with an IIM demonstrated higher mean intramuscular Cr concentration compared with controls (62.1 vs 35.3 IU; P = 0.01), but there were no differences in the mean trimethylamine or lipid concentrations. In IIM patients with no intravoxel signal abnormality (9/21), the mean Cr concentration was still higher than that in healthy subjects (63.2 vs 35.3 IU; P = 0.001). Quantitative 3-T MRS is feasible and may supplement the role of conventional MRI in the evaluation of patients with inflammatory myopathies, especially where MRI shows no obvious muscle abnormalities.

Metabolic changes in the anterior and posterior cingulate cortices of the normal aging brain: proton magnetic resonance spectroscopy study at 3 T

Magnetic resonance spectroscopy (MRS) can explore aging at a molecular level. In this study, we investigated the relationships between regional concentrations of metabolites (such as choline, creatine, myo-inositol, and N-acetyl-aspartate) and normal aging in 30 cognitively normal subjects (15 women and 15 men, age range 22-82, mean = 49.9 ± 18.3 years) using quantitative proton magnetic resonance spectroscopy. All MR scans were performed using a 3 T scanner. Point resolved spectroscopy was used as the volume selection method for the region-of-interest and the excitation method for water suppression. Single voxel spectroscopy with short echo time of 39 ms and repetition time of 2,000 ms was employed. Single voxels were placed in the limbic regions, i.e., anterior cingulate cortex (ACC), posterior cingulate cortex (PCC), and left and right hippocampi. Cerebrospinal fluid normalization and T1 and T2 correction factors were implemented in the calculation of absolute metabolite concentrations. A standardized T1W 3D volumetric fast field echo and axial T2-weighted fast spin-echo images were also acquired. Our results showed significant positive correlation of choline (r = 0.545, p = 0.002), creatine (r = 0.571, p = 0.001), and N-acetyl-aspartate (r = 0.674, p < 0.001) in the ACC; choline (r = 0.614, p < 0.001), creatine (r = 0.670, p < 0.001), and N-acetyl-aspartate (r = 0.528, p = 0.003) in the PCC; and NAA (r = 0.409, p = 0.025) in the left hippocampus, with age. No significant gender effect on metabolite concentrations was found. In aging, increases in choline and creatine might suggest glial proliferation, and an increase in N-acetyl-aspartate might indicate neuronal hypertrophy. Such findings highlight the metabolic changes of ACC and PCC with age, which could be compensatory to an increased energy demand coupled with a lower cerebral blood flow.

Biochemical correlates of neuropsychiatric illness in maple syrup urine disease

Maple syrup urine disease (MSUD) is an inherited disorder of branched chain amino acid metabolism presenting with neonatal encephalopathy, episodic metabolic decompensation, and chronic amino acid imbalances. Dietary management enables survival and reduces risk of acute crises. Liver transplantation has emerged as an effective way to eliminate acute decompensation risk. Psychiatric illness is a reported MSUD complication, but has not been well characterized and remains poorly understood. We report the prevalence and characteristics of neuropsychiatric problems among 37 classical MSUD patients (ages 5-35 years, 26 on dietary therapy, 11 after liver transplantation) and explore their underlying mechanisms. Compared with 26 age-matched controls, MSUD patients were at higher risk for disorders of cognition, attention, and mood. Using quantitative proton magnetic resonance spectroscopy, we found lower brain glutamate, N-acetylaspartate (NAA), and creatine concentrations in MSUD patients, which correlated with specific neuropsychiatric outcomes. Asymptomatic neonatal course and stringent longitudinal biochemical control proved fundamental to optimizing long-term mental health. Neuropsychiatric morbidity and neurochemistry were similar among transplanted and nontransplanted MSUD patients. In conclusion, amino acid dysregulation results in aberrant neural networks with neurochemical deficiencies that persist after transplant and correlate with neuropsychiatric morbidities. These findings may provide insight into general mechanisms of psychiatric illness.

Diagnostic Value of Breast Proton Magnetic Resonance Spectroscopy at 1.5T in Different Histopathological Types

The purpose of this study was to investigate the usefulness of quantitative proton magnetic resonance spectroscopy (1H-MRS) for characterizing breast lesions at 1.5T, and to evaluate the diagnostic performance of in vivo breast 1H-MRS using receiver operating characteristics (ROC) analysis. 112 patients (99 malignant and 13 benign tumors) who were scanned with the MRI/MRS protocol were included in this study. Choline-containing compounds (tCho) levels were measured and compared with histological findings. The measured tCho levels in this work had range of 0.08–9.99 mmol/kg from 65 (66%) of 99 patients with malignant tumors. Of the 13 benign lesions, 1H-MRS detected one as false positive, with tCho level of 0.66 mmol/kg. The optimal tCho level cutoff point that yielded the highest accuracy was found to be >0.0 mmol/kg. The resulting sensitivity was 66% and specificity 92% for distinguishing benign from malignant lesions. The tCho levels were found to be higher in invasive cancer compared to ductal carcinoma in situ or benign lesions, possibly associated with more aggressive behavior or faster cell replication in invasive cancer. Quantitative in vivo 1H-MRS may provide useful information for characterizing histopatholoigical types in breast cancer.

Quantitative Proton Magnetic Resonance Spectroscopy and Spectroscopic Imaging of the Brain

This article presents background information related to methodology for estimating brain metabolite concentration from magnetic resonance spectroscopy (MRS) and magnetic resonance spectroscopic imaging measurements of living human brain tissue. It reviews progress related to this methodology, with emphasis placed on progress reported during the past 10 years. It is written for a target audience composed of radiologists and magnetic resonance imaging technologists. It describes in general terms the relationship between MRS signal amplitude and concentration. It then presents an overview of the many practical problems associated with deriving concentration solely from absolute measured signal amplitudes and demonstrates how a various signal calibration approaches can be successfully used. The concept of integrated signal amplitude is presented with examples that are helpful for qualitative reading of MRS data as well as for understanding the methodology used for quantitative measurements. The problems associated with the accurate measurement of individual signal amplitudes in brain spectra having overlapping signals from other metabolites and overlapping nuisance signals from water and lipid are presented. Current approaches to obtaining accurate amplitude estimates with least-squares fitting software are summarized.

Region-specific effects on brain metabolites of hypoxia and hyperoxia overlaid on cerebral ischemia in young and old rats: a quantitative proton magnetic resonance spectroscopy study

BackgroundBoth hypoxia and hyperoxia, deregulating the oxidative balance, may play a role in the pathology of neurodegenerative disorders underlain by cerebral ischemia. In the present study, quantitative proton magnetic resonance spectroscopy was used to evaluate regional metabolic alterations, following a 24-hour hypoxic or hyperoxic exposure on the background of ischemic brain insult, in two contrasting age-groups of rats: young - 3 months old and aged - 24 months old.MethodsCerebral ischemia was induced by ligation of the right common carotid artery. Concentrations of eight metabolites (alanine, choline-containing compounds, total creatine, γ-aminobutyric acid, glutamate, lactate, myo-inositol and N-acetylaspartate) were quantified from extracts in three different brain regions (fronto-parietal and occipital cortices and the hippocampus) from both hemispheres.ResultsIn the control normoxic condition, there were significant increases in lactate and myo-inositol concentrations in the hippocampus of the aged rats, compared with the respective values in the young ones. In the ischemia-hypoxia condition, the most prevalent changes in the brain metabolites were found in the hippocampal regions of both young and aged rats; but the effects were more evident in the aged animals. The ischemia-hyperoxia procedure caused less dedicated changes in the brain metabolites, which may reflect more limited tissue damage.ConclusionsWe conclude that the hippocampus turns out to be particularly susceptible to hypoxia overlaid on cerebral ischemia and that old age further increases this susceptibility.

Quantitative proton magnetic resonance spectroscopy detects abnormalities in dorsolateral prefrontal cortex and motor cortex of patients with frontotemporal lobar degeneration

Frontotemporal lobar degeneration (FTLD) is a neurodegenerative disease of the frontal and temporal neocortex. The single most common pathology underlying FTLD is neuronal degeneration with ubiquitin-positive but tau-negative inclusions consisting of Tar DNA binding proteins (TDP-43). Inclusions containing TDP-43 in neurons are also the most common pathology underlying motor neuron disease (MND). The present study tested the hypothesis that abnormal metabolite patterns within the dorsolateral prefrontal cortex (DLPFC) as well as the motor cortex (MC) may be observed in FTLD patients without motor disorders, using proton magnetic resonance spectroscopy ((1)H MRS). Twenty-six FTLD patients with cognitive damage and ten controls underwent multivoxel (1)H MRS. Absolute concentrations of N-acetyl aspartate (NAA), creatine (Cr), choline (Cho) and myo-inositol (mI) were measured from the DLPFC, the MC and the parietal cortex (PC, an internal control). Statistical analyses were performed for group differences between FTLD patients and controls. Comparisons were also made across brain regions (PC and DLPFC; PC and MC) within FTLD patients. Significant reductions in NAA and Cr along with increased Cho and mI were observed in the DLPFC of FTLD patients compared to controls. Significantly lower NAA and higher Cho were also observed in the MCs of patients as compared to controls. Within the FTLD patients, both the MC and the DLPFC exhibited significantly decreased NAA and elevated Cho compared to the PC. However, only the DLPFC had significantly lower Cr and higher mI. Abnormal metabolite pattern from the MC supports the hypothesis that FTLD and MND may be closely linked.

Intrauterine hyperexposure to dexamethasone of the common marmoset monkey revealed normal cerebral metabolite concentrations in adulthood as assessed by quantitative proton magnetic resonance spectroscopy in vivo

Animal models of human brain disorders often have to rely on non-human primates because of their immunological, physiological, and cognitive similarities to humans. Localized proton magnetic resonance spectroscopy was performed to assess cerebral metabolite profiles of male common marmoset monkeys in vivo and to determine putative alterations of adult brain metabolism in response to intrauterine hyperexposure to the synthetic glucocorticoid hormone dexamethasone. Excellent spectral quality allowed for absolute quantification of the concentrations of major metabolites in predominantly white matter, gray matter, and thalamus. Marmoset monkeys intrauterinely hyperexposed to dexamethasone revealed normal neurochemical profiles at adulthood. Prenatally applied dexamethasone does not lead to persistent metabolic alterations affecting adult brain integrity.

Absolute choline concentration measured by quantitative proton MR spectroscopy correlates with cell density in meningioma

This study was aimed to investigate the relationship between quantitative proton magnetic resonance spectroscopy (1H-MRS) and pathological changes in meningioma. Twenty-two meningioma cases underwent single voxel 1H-MRS (point-resolved spectroscopy sequence, repetition time/echo time = 2,000 ms/68, 136, 272 ms). Absolute choline (Cho) concentration was calculated using tissue water as the internal reference and corrected according to intra-voxel cystic/necrotic parts. Pathological specimens were stained with MIB-1 antibody to measure cell density and proliferation index. Correlation analysis was performed between absolute Cho concentration and cell density and MIB-1 labeled proliferation index. Average Cho concentration of all meningiomas before correction was 2.95 +/- 0.86 mmol/kg wet weight. It was increased to 3.23 +/- 1.15 mmol/kg wet weight after correction. Average cell density of all meningiomas was 333 +/- 119 cells/HPF, and average proliferation index was 2.93 +/- 5.72%. A linear, positive correlation between cell density and Cho concentration was observed (r = 0.650, P = 0.001). After correction of Cho concentration, the correlation became more significant (r = 0.737, P < 0.001). However, no significant correlation between Cho concentration and proliferation index was found. There seemed to be a positive correlation trend after correction of Cho concentration but did not reach significant level. Absolute Cho concentration, especially Cho concentration corrected according to intra-voxel cystic/necrotic parts, reflects cell density of meningioma.

Evolutive Study of Relapsing-Remitting Multiple Sclerosis with Cervical Proton Magnetic Resonance Spectroscopy

We used quantitative proton magnetic resonance spectroscopy ((1)H-MRS) to evaluate mean relative concentrations ratios for NAA, Cr, Cho and mI during the study of cervical spinal cord plaques in a relapsing-remitting multiple sclerosis (RRMS). A cervical spine MR exam was repeated five times on the following days for two months starting from the onset of a relapse phase, using a 3T whole-body system, with the voxel placed along the demyelinazation lesion. The quantification results were compared with the healthy metabolites content. Quantitative cervical spectroscopy is a reliable tool and can offer important metabolic information as already used on the brain to evaluate the severity, progression and pathogenesis of multiple sclerosis.

The effect of epileptic seizures on proton MRS visible neurochemical concentrations

To investigate post-ictal changes in cerebral metabolites. We performed a longitudinal quantitative proton magnetic resonance spectroscopy (MRS) study in 10 patients with epilepsy and 10 control subjects. The patients were studied on two occasions: immediately following a seizure, and on a second occasion at least 7h after the most recent seizure. Each study measured N-acetyl aspartate plus N-acetyl aspartyl glutamate (NAAt), Creatine plus phosphocreatine (Cr), Choline containing compounds (Cho) and glutamate plus glutamine (GLX) concentrations using a short-echo time sequence (TE=30ms), and NAAt, Cr and lactate using a second sequence with longer echo time (TE=144ms). The control group was studied on two occasions using the same sequences. No inter-scan differences were observed for the control group. NAAt and NAAt/Cr levels were lower in the patient group at both measured TEs but did not change significantly between studies. The ratio of Cr at TE 144ms to TE 30ms (Cr(144)/Cr(30)) and GLX/Cr were higher and Cho lower in the post-ictal scan compared to the inter-ictal study. Change in Cr(144)/Cr(30) and NAAt(144)/Cr(144) correlated with the post-ictal interval. Lactate measurement at longer TE was not informative. Proton MRS is sensitive to metabolite changes following epileptic seizures within the immediate post-ictal period. The ratio Cr(144)/Cr(30) is the most sensitive measure of metabolic disturbance and is highest in the post-ictal period but appears to normalise within 2h of the most recent seizure.

P1-119 Effects of adverse prenatal conditions on rat cerebral development: a quantitative proton magnetic resonance spectroscopy (H-MRS) and histopathology analysis

Keywords: CIBM-AIT Reference EPFL-CONF-186252doi:10.1016/S0378-3782(07)70289-X Record created on 2013-04-28, modified on 2016-08-09

Quantitative proton magnetic resonance spectroscopy of the human cervical spinal cord at 3 tesla

Cervical spinal cord spectroscopy has the potential to add metabolic information to spinal cord MRI and improve the clinical evaluation and research investigation of spinal cord diseases, such as multiple sclerosis (MS) and intraspinal tumors. However, in vivo proton MR spectroscopy ((1)H-MRS) of the spinal cord is difficult to perform due to magnetic field inhomogeneities, physiological movements, and the size of the anatomical region of interest (ROI). For these reasons, few spinal cord (1)H-MRS studies have been undertaken and two preliminary studies on a 3T system were only recently presented as abstracts. In this work we demonstrate the feasibility of cervical spinal cord quantitative (1)H-MRS on a clinical 3T system, propose a study protocol, and report quantification results obtained from healthy volunteers. The main metabolite concentration ratios obtained in 10 healthy subjects, as provided by LCModel, were as follows: total N-acetyl aspartate/creatine (tNAA/Cr) 1.4 +/- 0.3, choline/creatine (Cho/Cr) 0.5 +/- 0.1, and myoinositol/creatine (mI/Cr) 1.7 +/- 0.2. A significant difference was found between spinal cord tNAA, Cr, Cho, and mI concentration ratios and brainstem concentrations previously acquired on the same system.

Comparative Prognostic Utilities of Early Quantitative Magnetic Resonance Imaging Spin-Spin Relaxometry and Proton Magnetic Resonance Spectroscopy in Neonatal Encephalopathy

We sought to compare the prognostic utilities of early MRI spin-spin relaxometry and proton magnetic resonance spectroscopy in neonatal encephalopathy. Twenty-one term infants with neonatal encephalopathy were studied at a mean age of 3.1 days (range: 1-5). Basal ganglia, thalamic and frontal, parietal, and occipital white matter spin-spin relaxation times were determined from images with echo times of 25 and 200 milliseconds. Metabolite ratios were determined from an 8-mL thalamic-region magnetic resonance spectroscopy voxel (1H point-resolved spectroscopy; echo time 270 milliseconds). Outcomes were assigned at age 1 year as follows: (1) normal, (2) moderate (neuromotor signs or Griffiths developmental quotient of 75-84), (3) severe (functional neuromotor deficit or developmental quotient <75 or died). Predictive efficacies for differentiation between normal and adverse (combined moderate and severe) outcomes were compared by receiver operating characteristic curve analysis and logistic regression. Thalamic and basal ganglia spin-spin relaxation times correlated positively with outcome and predicted adversity. Although thalamic and basal ganglia spin-spin relaxation times were prognostic of adversity, magnetic resonance spectroscopy metabolite ratios were better predictors, and, of these, lactate/N-acetylaspartate was most accurate. Deep gray matter spin-spin relaxation time was increased in the first few days after birth in infants with an adverse outcome. Proton magnetic resonance spectroscopy was more prognostic than spin-spin relaxation time, with lactate/N-acetylaspartate the best measure. Nevertheless, both techniques were useful for early prognosis, and the potential superior spatial resolution of spin-spin relaxometry may define better the precise anatomic pattern of injury in the early days after birth.

Regional brain metabolite abnormalities in inherited prion disease and asymptomatic gene carriers demonstrated in vivo by quantitative proton magnetic resonance spectroscopy

Inherited prion diseases are caused by mutations in the gene which codes for prion protein (PrP), leading to proliferation of abnormal PrP isomers in the brain and neurodegeneration; they include Gerstmann-Sträussler-Scheinker disease (GSS), fatal familial insomnia (FFI) and familial Creutzfeldt-Jakob disease (fCJD). We studied two patients with symptomatic inherited prion disease (P102L) and two pre-symptomatic P102L gene carriers using quantitative magnetic resonance spectroscopy (MRS). Short echo time spectra were acquired from the thalamus, caudate region and frontal white matter, metabolite levels and ratios were measured and z-scores calculated for individual patients relative to age-matched normal controls. MRS data were compared with structural magnetic resonance imaging. One fCJD case had generalised atrophy and showed increased levels of myo-inositol (MI) in the thalamus (z=3.7). The other had decreased levels of N-acetylaspartate (z=4) and diffuse signal abnormality in the frontal white matter. Both asymptomatic gene carriers had normal imaging, but increased frontal white matter MI (z=4.3, 4.1), and one also had increased MI in the caudate (z=5.3). Isolated MI abnormalities in asymptomatic gene carriers are a novel finding and may reflect early glial proliferation, prior to significant neuronal damage. MRS provides potential non-invasive surrogate markers of early disease and progression in inherited prion disease.