Point-resolved Spectroscopy Sequence Research Articles

Uncertainty assessment of gamma-aminobutyric acid concentration of different brain regions in individual and group using residual bootstrap analysis.

The aim of this work is to quantify individual and regional differences in the relative concentration of gamma-aminobutyric acid (GABA) in human brain with in vivo magnetic resonance spectroscopy. Spectral editing Mescher-Garwood point resolved spectroscopy (MEGA-PRESS) sequence and GABA analysis toolkit (Gannet) were used to detect and quantify GABA in anterior cingulate cortex (ACC) and occipital cortex (OCC) of healthy volunteers. Residual bootstrap, a model-based statistical analysis technique, was applied to resample the fitting residuals of GABA from the Gaussian fitting model (referred to as GABA+ thereafter) in both individual and group data of ACC and OCC. The inter-subject coefficient of variation (CV) of GABA+ in OCC (20.66%) and ACC (12.55%) with residual bootstrap was lower than that of a standard Gaussian model analysis (21.58% and 16.73% for OCC and ACC, respectively). The intra-subject uncertainty and CV of OCC were lower than that of ACC in both analyses. The residual bootstrap analysis thus provides a more robust uncertainty estimation of individual and group GABA+ detection in different brain regions, which may be useful in our understanding of GABA biochemistry in brain and its use for the diagnosis of related neuropsychiatric diseases.

GABA+ levels in postmenopausal women with mild-to-moderate depression: A preliminary study.

Background:It is increasingly being recognized that alterations of the GABAergic system are implicated in the pathophysiology of depression. This study aimed to explore in vivo gamma-aminobutyric acid (GABA) levels in the anterior cingulate cortex/medial prefrontal cortex (ACC/mPFC) and posterior-cingulate cortex (PCC) of postmenopausal women with depression using magnetic resonance spectroscopy (1H-MRS).Methods:Nineteen postmenopausal women with depression and thirteen healthy controls were enrolled in the study. All subjects underwent 1H-MRS of the ACC/mPFC and PCC using the “MEGA Point Resolved Spectroscopy Sequence” (MEGA-PRESS) technique. The severity of depression was assessed by 17-item Hamilton Depression Scale (HAMD). Quantification of MRS data was performed using Gannet program. Differences of GABA+ levels from patients and controls were tested using one-way analysis of variance. Spearman correlation coefficients were used to evaluate the linear associations between GABA+ levels and HAMD scores, as well as estrogen levels.Results:Significantly lower GABA+ levels were detected in the ACC/mPFC of postmenopausal women with depression compared to healthy controls (P = 0.002). No significant correlations were found between 17-HAMD/14-HAMA and GABA+ levels, either in ACC/mPFC (P = 0.486; r = 0.170/P = 0.814; r = −0.058) or PCC (P = 0.887; r = 0.035/ P = 0.987; r = −0.004) in the patients; there is also no significant correlation between GABA+ levels and estrogen levels in patients group (ACC/mPFC: P = 0.629, r = −0.018; PCC: P = 0.861, r = 0.043).Conclusion:Significantly lower GABA+ levels were found in the ACC/mPFC of postmenopausal women with depression, suggesting that the dysfunction of the GABAergic system may also be involved in the pathogenesis of depression in postmenopausal women.

P6. Comparison of water signal T2 biexponential fitting and image segmentation to determine voxel CSF fraction in magnetic resonance spectroscopy

Introduction For partial volume correction in 1H MMR spectroscopy the voxel fraction of brain matter (BM) and cerebrospinal fluid (CSF) can be calculated via biexponential fitting of T2 relaxation of the unsuppressed water signal or via segmentation of a high-resolution structural image. To determine their equivalence, we compared CSF percentages obtained using these two methods in 3 brain regions. Material and methods 113 children were scanned on a 3T Siemens Allegra. The protocol included a T1-weighted 3D EPI-navigated multiecho magnetisation prepared rapid gradient echo (MEMPRAGE) and single voxel spectroscopy (SVS) in the basal ganglia (BG), midfrontal gray matter (MFGM) and peritrigonal white matter (PWM) using an EPI-navigated point-resolved spectroscopy (PRESS) sequence. Water unsuppressed SVS measurements were acquired at TE’s 30 ms, 50 ms, 75 ms, 100 ms, 144 ms, 500 ms and 1000 ms. The voxel water signal S(TE) was quantified using LCModel and modeled as a biexponential function of TE. Percentage CSF ( PV CSF ) in the voxel was estimated according to (1), where S CSF and S BM are the signals from CSF and BM at TE = 0 (1) PV CSF = S CSF S CSF + 0.75 × S BM × 100 The T1-weighted image was used to segment the SVS voxel into GM, WM and CSF in SPM12. Results BG: PV CSF from segmentation was PV CSF was zero in more than half the subjects. A paired t-test showed a significant difference between methods (t = −2.9, p = 0.004). PWM: PV CSF from the segmentation method was PV CSF using the relaxation method was larger (t = −7.4, p = 2e−11). MFGM: in the MFGM many points fell around the y = x line. A paired t-test showed no significant difference between methods (t = 0.9, p = 0.4). Conclusion There is most consistency between methods where the PV CSF is small, and less consistency in voxels with larger amounts of CSF.

MRS of pilocytic astrocytoma: The peak at 2 ppm may not be NAA.

To determine whether the chemical shift of residual N-acetylaspartate (NAA) signal in pilocytic astrocytomas (PA) is consistent with the position of the NAA peak in controls. MR spectra from 27 pediatric World Health Organization (WHO) grade I pilocytic astrocytoma patients, fifteen patients with WHO grade II and high-grade (III-IV) astrocytomas, and 36 controls were analyzed. All spectra were acquired with a short echo time (35 ms), single voxel point-resolved spectroscopy sequence on clinical 3 tesla scanners. Fully automated LCModel software was used for processing, which included the fitting of peak positions for NAA and creatine (Cr). The chemical shift difference between the NAA and Cr peaks was significantly smaller (by 0.016 ± 0.005 parts per million, P < 1e-10) in PAs than in controls and was also smaller than what was observed in infiltrative astrocytomas. The chemical shift position of the residual NAA peak in PAs is not consistent with NAA. The signal likely originates from an N-acetyl group of one or more other chemicals such as N-acetylated sugars. Magn Reson Med 78:452-456, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Poster - 04: Resolving the Glutamine Resonance with an Optimized Magnetic Resonance Spectroscopy PRESS Sequence at 9.4T

Purpose: To optimize the timings of the magnetic resonance spectroscopy technique, Point RESolved Spectroscopy (PRESS), to resolve glutamine (Gln; ∼2.45ppm) in vivo at 9.4T. The Gln resonance is contaminated by N-acetylaspartate (NAA; ∼2.49ppm) and to a lesser extent by glutathione (GSH; ∼2.51ppm). Methods: Signals of glutamate (Glu; ∼2.35ppm), Gln, and NAA at 9.4T in response to TE (echo time) values of a PRESS sequence were investigated numerically, and the {TE1, TE2} combination that best resolved Gln while retaining Glu was considered optimal. The timings were verified on phantom solutions and in vivo on four Sprague Dawley rat brains. In-vivo spectra were analyzed with LCmodel. Results: An optimal {TE1, TE2} combination was determined to be {106ms, 16ms}, which resulted in simulated peak areas for Glu, Gln, and NAA, of 54%, 42%, and −2%, respectively, of the corresponding shortest {2ms, 2ms} values. Experimentally, the Gln yield with the optimal TE values was found to be ∼54% of that obtained with a short-TE of {TE1, TE2} = {12ms, 9ms}. The yield changed by <10% with the addition of NAA and GSH. The rat brain spectra showed well resolved peaks for Glu and Gln at ∼2.35ppm and ∼2.45ppm, respectively. LCModel Cramer-Rao Lower Bound values for all rats were <8% and <20% for Glu and Gln, respectively. Conclusions: A PRESS sequence with {TE1, TE2} = {106ms, 16ms} is suitable for resolving Gln in vivo at 9.4T.

Gaussian signal relaxation around spin echoes: Implications for precise reversible transverse relaxation quantification of pulmonary tissue at 1.5 and 3 Tesla.

To characterize the reversible transverse relaxation in pulmonary tissue and to study the benefit of a quadratic exponential (Gaussian) model over the commonly used linear exponential model for increased quantification precision. A point-resolved spectroscopy sequence was used for comprehensive sampling of the relaxation around spin echoes. Measurements were performed in an ex vivo tissue sample and in healthy volunteers at 1.5 Tesla (T) and 3 T. The goodness of fit using χred2 and the precision of the fitted relaxation time by means of its confidence interval were compared between the two relaxation models. The Gaussian model provides enhanced descriptions of pulmonary relaxation with lower χred2 by average factors of 4 ex vivo and 3 in volunteers. The Gaussian model indicates higher sensitivity to tissue structure alteration with increased precision of reversible transverse relaxation time measurements also by average factors of 4 ex vivo and 3 in volunteers. The mean relaxation times of the Gaussian model in volunteers are T2,G' = (1.97 ± 0.27) msec at 1.5 T and T2,G' = (0.83 ± 0.21) msec at 3 T. Pulmonary signal relaxation was found to be accurately modeled as Gaussian, providing a potential biomarker T2,G' with high sensitivity. Magn Reson Med 77:1938-1945, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

SU‐F‐I‐64: Comparison of Lipid Contents Using STEAM and PRESS with in Vivo High‐Resolution Spectra at 9.4 T

Purpose:The objective of this study is to compare lipid contents using localized point‐resolved spectroscopy (PRESS) and stimulated echo acquisition mode (STEAM) sequences to assess lipid resonances in the liver, using in vivo high‐resolution spectra at 9.4 T.Methods:The examinations were performed on a Bruker 9.4T scanner using 4‐channel animal coil for higher resolution. We used PRESS (repetition time [TR]/ TE = 3500/20 ms; number of signal averages [NSA] = 128; acquisition data points = 2048) and STEAM (TR/TM/TE = 3500/10/20 ms; NSA = 128; acquisition data points = 2048). Lipid relaxations in HF diet mice were estimated at a fixed TR of 5000 ms, and TEs of 20–70 ms. All spectra acquired were processed using the Advanced Method for Accurate, Robust, and Efficient Spectral (AMARES) fitting algorithm including in the Java‐based Magnetic Resonance User Interface (jMRUI) software package. Preprocessing was performed using an automatic frequency shift and the Hankel‐Lanczos Singular Value Decomposition (HLSVD) filter with subtraction of water peak (4.70 ppm).Results:To accurately quantify lipid content, a sequence was selected. The total lipid and total saturated fatty acid were differently changed in HF diet mice that underwent PRESS compared with those that underwent STEAM (total lipid, p &lt; 0.05; total saturated fatty acid, p &lt; 0.001). Compared with PRESS, STEAM showed different total unsaturated fatty acid value (p &lt; 0.001). Compared with PRESS, STEAM showed different total unsaturated and poly unsaturated bonds (total unsaturated bond, p&lt;0.001; poly unsaturated bond, p &lt; 0.001).Conclusion:Due to stronger J‐coupling effects on the PRESS sequence, the accurate estimation could not be obtained. STEAM is less sensitive to J‐coupling and gives a theoretically more accurate estimate at 9.4T.

Improved localisation for 2-hydroxyglutarate detection at 3T using long-TE semi-LASER.

2-hydroxyglutarate (2-HG) has emerged as a biomarker of tumor cell isocitrate dehydrogenase mutations that may enable the differential diagnosis of patients with glioma. At 3 T, detection of 2-HG with magnetic resonance spectroscopy is challenging because of metabolite signal overlap and spectral pattern modulation by slice selection and chemical shift displacement. Using density matrix simulations and phantom experiments, an optimized semi-LASER scheme (echo time = 110 milliseconds) considerably improves localization of the 2-HG spin system compared with that of an existing point-resolved spectroscopy sequence. This results in a visible 2-HG peak in the in vivo spectra at 1.9 ppm in the majority of isocitrate dehydrogenase-mutated tumors. Detected concentrations of 2-HG were similar using both sequences, although the use of semi-LASER generated narrower confidence intervals. Signal overlap with glutamate and glutamine, as measured by pairwise fitting correlation, was reduced. Lactate was readily detectable across patients with glioma using the method presented here (mean Cramér–Rao lower bound: 10% ± 2%). Together with more robust 2-HG detection, long-echo time semi-LASER offers the potential to investigate tumor metabolism and stratify patients in vivo at 3 T.

Alterations in brain metabolism and function following administration of low-dose codeine phosphate: 1H-magnetic resonance spectroscopy and resting-state functional magnetic resonance imaging studies.

The aim of the present study was to identify alterations in brain function following administration of a single, low-dose of codeine phosphate in healthy volunteers using resting-state functional magnetic resonance imaging (fMRI). In addition, the metabolic changes in the two sides of the frontal lobe were identified using 1H-magnetic resonance spectroscopy (1H-MRS). A total of 20 right-handed healthy participants (10 males, 10 females) were evaluated, and a Signa HDx 1.5T MRI scanner was used for data acquisition. An echo planar imaging sequence was used for resting-state fMRI, whereas a point resolved spectroscopy sequence was used for 1H-MRS. Regional Saturation Technique, Data Processing Assistant for Resting-State fMRI, and Statistical Parameter Mapping 8 were used to analyze the fMRI data. The 1H-MRS data were analyzed using LCModel software. At 1 h after oral administration of codeine phosphate (1.0 mg/kg), the amplitude of low-frequency fluctuation (ALFF) and regional homogeneity were altered in different brain areas. The choline content was significantly increased in the right and left frontal lobes following codeine phosphate administration (P=0.02 and P=0.03, respectively), whereas the inositol content was significantly decreased in the left frontal lobe (P=0.02). There was no change in the glutamic acid content in the frontal lobes. In conclusion, the functions of different brain regions can be affected by a single, low-dose administration of codeine phosphate. The alterations in metabolite content in the two frontal lobes may be associated with changes in brain function, whereas the ALFF in the globus pallidus may have an effect on codeine phosphate addiction. Finally, glutamic acid may be useful in the estimation of codeine dependence.

Measurement of the metabolites in the cortical masticatory area of patients with sleep bruxism: a magnetic resonance spectroscopy study

To determine whether there are in vivo differences of metabolites levels in bilateral cortical masticatory area(CMA) of patients with sleep bruxism, compared with healthy controls using proton magnetic resonance spectroscopy(1H-MRS). Accordingly to explore if cortical control of the central jaw motor system is abnormal in sleep bruxism patients. Fifteen sleep bruxism patients and fifteen age- and gender-matched healthy controls underwent 1H-MRS of bilateral CMA using J-difference edited point-resolved spectroscopy sequence(MEGA-PRESS) technique. Levels of metabolites were quantified from the ratio of the metabolite integral to the unsuppressed water signal. Differences of levels of γ-aminobutyric acid(GABA), glutmate(Glu) and N-acetyl aspartate(NAA) in bilateral CMA between sleep bruxism patients and healthy controls were tested using two-way ANOVA. Edited spectra were successfully obtained from the bilateral CMA in all of the participants. Levels of GABA+, glutmate and NAA in right and left CMA in sleep bruxism patients were (2.45±0.48)×10(-3), (2.35±0.62)×10(-3), (10.65±1.84)×10(-3), (10.49±2.37)×10(-3), (10.70±3.61)×10(-3), and (11.26±4.01)×10(-3) respectively. In contrast, levels of GABA+, glutmate and NAA in right and left CMA in healthy controls were (2.63±0.68)×10(-3), (2.65±0.97)×10(-3), (11.19± 1.34)×10(-3), (10.58±3.14)×10(-3), (11.82±1.80)×10(-3), and (11.95±3.23)×10(-3). There were no differences in levels of GABA+(P=0.196), Glu(P=0.590), and NAA(P=0.292) between sleep bruxism patients and healthy controls, nor in inbilateral CMA(GABA+: P=0.837; Glu: P=0.510; NAA: P=0.628). The results indicate the absence of any alteration of the cortical control of the central jaw motor system in the levels of GABA, Glu and NAA in patients with sleep bruxism.

Optimized PRESS sequence timings for measuring glycine at 9.4 T: demonstration in vivo in rat brain

The objective of this work is to optimize the Point Resolved Spectroscopy (PRESS) sequence echo times, TE1 and TE2, for glycine (Gly) detection at 9.4 T, a common field strength at which animal magnetic resonance studies are conducted. The two uncoupled protons of Gly resonate at about 3.55 ppm and their peak is largely overwhelmed by signal from the strongly coupled protons of myo-inositol (mI) which resonate in the Gly spectral region (3.52–3.57 ppm). J-coupling evolution of the mI protons was characterized at 9.4 T by numerical calculations and by acquiring PRESS spectra with various {TE1, TE2} combinations from a 50 mM mI phantom. A {TE1, TE2} combination of {60 ms, 100 ms} minimized mI signal in the Gly spectral region and its efficacy was verified on mI and Gly phantom solutions and on rat brain in vivo. LCModel was employed to analyse in vivo spectra. The average Gly concentration from three rat brains was found to be 1.35 mM assuming a creatine (Cr) concentration of 8 mM. LCModel Cramér-Rao Lower Bound values for Gly ranged between 15% and 20%.

MP78-08 DIAGNOSTIC POTENTIAL OF PROTON MAGNETIC RESONANCE SPECTROSCOPY ON RENAL TUMORS.

You have accessJournal of UrologyKidney Cancer: Epidemiology & Evaluation/Staging II1 Apr 2016MP78-08 DIAGNOSTIC POTENTIAL OF PROTON MAGNETIC RESONANCE SPECTROSCOPY ON RENAL TUMORS. Masahiro Sumura, Naoko Arichi, Shigenobu Nakamura, Hiroaki Yasumoto, Takeshi Yoshizako, Hajime Kitagaki, and Hiroaki Shiina Masahiro SumuraMasahiro Sumura More articles by this author , Naoko ArichiNaoko Arichi More articles by this author , Shigenobu NakamuraShigenobu Nakamura More articles by this author , Hiroaki YasumotoHiroaki Yasumoto More articles by this author , Takeshi YoshizakoTakeshi Yoshizako More articles by this author , Hajime KitagakiHajime Kitagaki More articles by this author , and Hiroaki ShiinaHiroaki Shiina More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2016.02.1964AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Magnetic resonance spectroscopy (MRS) is a noninvasive method for assessment of biochemical tissue characteristics in vivo and has proven its value for differentiation of tumors in brain, breast, and prostate. However, there are few reports of MRS on kidney, because of respiratory displacement of kidney. This problem could be solved with respiratory-triggered examination in our institution. We evaluate the diagnostic potential of MRS on renal tumors. METHODS 28 renal tumors in 28 patients were enrolled in this study (age 60-82 years-old (median 62 years-old), and clinical stage T1a 15 cases, T1b 5cases, T2a 1 case, T3a 6 cases and T4 1 cases). All patients underwent MRS with 1.5 T MR device and phased array type external surface coil, pre-operatively. A respiratory-triggered single voxel MRS was performed with the point-resolved spectroscopy sequence (TR 2000 ms, TE 135 ms). The spectra were analyzed for choline resonances at 3.2 ppm, that were normalized using the noise outside the diagnostic range of the spectra. The spectra obtained from both tumor and benign tumors were compared. Histological results were defined as the standard of reference. RESULTS 26 tumors in 28 tumors were histologically malignant. Two tumors were histologically diagnosed angiomyolipoma (AML). In all cases, spectrum had sufficient quality to diagnose. Mean choline SNR in malignant lesions was 3.4 and 1.01 in AML. Higher choline SNR were observed in tumors with higher grade. CONCLUSIONS We recognized that further studies were essential, but MRS might have the potential to differentiate the malignant renal tumor from benign. Furthermore, choline could be a biomarker of aggressiveness in malignant renal tumors. © 2016FiguresReferencesRelatedDetails Volume 195Issue 4SApril 2016Page: e1027 Advertisement Copyright & Permissions© 2016MetricsAuthor Information Masahiro Sumura More articles by this author Naoko Arichi More articles by this author Shigenobu Nakamura More articles by this author Hiroaki Yasumoto More articles by this author Takeshi Yoshizako More articles by this author Hajime Kitagaki More articles by this author Hiroaki Shiina More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Flexible proton 3D MR spectroscopic imaging of the prostate with low-power adiabatic pulses for volume selection and spiral readout.

Cartesian k-space sampling in three-dimensional magnetic resonance spectroscopic imaging (MRSI) of the prostate limits the selection of voxel size and acquisition time. Therefore, large prostates are often scanned at reduced spatial resolutions to stay within clinically acceptable measurement times. Here we present a semilocalized adiabatic selective refocusing (sLASER) sequence with gradient-modulated offset-independent adiabatic (GOIA) refocusing pulses and spiral k-space acquisition (GOIA-sLASER-Spiral) for fast prostate MRSI with enhanced resolution and extended matrix sizes. MR was performed at 3 tesla with an endorectal receive coil. GOIA-sLASER-Spiral at an echo time (TE) of 90 ms was compared to a point-resolved spectroscopy sequence (PRESS) with weighted, elliptical phase encoding at an TE of 145 ms using simulations and measurements of phantoms and patients (n = 9). GOIA-sLASER-Spiral acquisition allows prostate MR spectra to be obtained in ∼5 min with a quality comparable to those acquired with a common Cartesian PRESS protocol in ∼9 min, or at an enhanced spatial resolution showing more precise tissue allocation of metabolites. Extended field of views (FOVs) and matrix sizes for large prostates are possible without compromising spatial resolution or measurement time. The flexibility of spiral sampling enables prostate MRSI with a wide range of resolutions and FOVs without undesirable increases in acquisition times, as in Cartesian encoding. This approach is suitable for routine clinical exams of prostate metabolites. Magn Reson Med 77:928-935, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Associations Between Recent Heavy Drinking and Dorsal Anterior Cingulate N-Acetylaspartate and Glutamate Concentrations in Non-Treatment-Seeking Individuals with Alcohol Dependence.

Proton magnetic resonance spectroscopy ((1) H-MRS) studies have consistently found abnormal brain concentrations of N-acetylaspartate (NAA) and glutamate in individuals with alcohol use disorders (AUD) relative to light drinkers. However, most such studies have focused on individuals in treatment for severe alcohol dependence (AD), and few studies have investigated associations between neurochemical concentrations and recent alcohol consumption. This study focused on associations between recent drinking and prefrontal neurometabolite concentrations in nonsevere, non-treatment-seeking individuals with AUD. Nineteen treatment-naïve alcohol-dependent individuals aged 21 to 40 completed a (1) H-MRS scan. Single-voxel (1) H-MRS spectra were acquired in dorsal anterior cingulate cortex (dACC) using a 2-dimensional J-resolved point resolved spectroscopy sequence. Associations between recent heavy drinking, assessed using the Timeline FollowBack, and dACC metabolite concentrations were estimated via regression controlling for within-voxel tissue composition. Participants provided a negative breathalyzer reading and reported between 1 and 5days (M=2.45, SD=1.23) since their last drink. Number of heavy drinking days in the 14days preceding the scan (M=4.84, SD=3.32) was significantly inversely associated with both glutamate/water (β=-0.63, t(17)=-3.37, p=0.004) and NAA/water concentrations (β=-0.59, t(17)=-2.98, p=0.008). This study extends the literature by demonstrating inverse associations between recent heavy drinking and dACC glutamate and NAA concentrations in a sample of nonsevere, non-treatment-seeking individuals with AD. These findings may support the hypothesis that amount of recent alcohol consumption may account for differences in neuronal metabolism, even in nonsevere, non-treatment-seeking alcoholics.

Second-order motion compensated PRESS for cardiac spectroscopy.

Second-order motion compensation for point-resolved spectroscopy (PRESS) is proposed to allow for robust single-voxel cardiac spectroscopy throughout the entire cardiac cycle and at various heart rates. Bipolar FID spoiling gradient pairs compensating for first and second-order motion were designed and implemented into a cardiac-triggered PRESS sequence on a clinical MR system. A numerical three-dimensional model of cardiac motion was used to optimize and validate the gradient waveforms. In vivo measurements in healthy volunteers were obtained to assess the signal-to-noise ratio (SNR) and triglyceride-to-water ratio (TG/W). SNR gains and variability of TG/W of the proposed approach were evaluated against a conventional PRESS sequence with optimized gradients. The proposed sequence increases the mean SNR by 32% (W) and 23% (TG) on average with significantly lower variability for different trigger delays. The variability of TG/W quantification over the cardiac cycle is significantly decreased with second-order motion compensated PRESS when compared with conventional PRESS with reduced-spoiler gradients (coefficient of variation: 0.1 ± 0.02 versus 0.37 ± 0.26). Second-order motion compensated PRESS effectively reduces cardiac motion-induced signal degradation during FID spoiling, providing higher SNR and less variability for TG/W quantification. The sequence is considered promising to assess the TG/W modulation during various interventions including pharmacologically induced stress. Magn Reson Med 77:57-64, 2017. © 2016 Wiley Periodicals, Inc.

Cingulate GABA levels inversely correlate with the intensity of ongoing chronic knee osteoarthritis pain.

BackgroundThis study aims to investigate the role of the mid-anterior cingulate cortex γ-aminobutyric acid levels in chronic nociceptive pain. The molecular mechanisms of pain chronification are not well understood. In fibromyalgia, low mid-anterior cingulate cortex γ-aminobutyric acid was associated with high pain suggesting a role of prefrontal disinhibition. We hypothesize that mid-anterior cingulate cortex GABAergic disinhibition may underpin chronic pain independent of the pain etiology and comorbid negative affect. Proton magnetic resonance spectra were acquired at 3T from the mid-anterior cingulate cortex in 20 patients with chronic painful knee osteoarthritis, and 19 healthy pain-free individuals using a point resolved spectroscopy sequence optimized for detection of γ-aminobutyric acid. Participants underwent questionnaires for negative affect (depression and anxiety) and psychophysical pain phenotyping.ResultsNo differences in mid-anterior cingulate cortex γ-aminobutyric acid or other metabolite levels were detected between groups. Ratings of perceived intensity of ongoing osteoarthritis pain were inversely correlated with γ-aminobutyric acid (r = −0.758, p < 0.001), but no correlations were seen for negative affect or pain thresholds. The pain γ-aminobutyric acid interrelation remained strong when controlling for depression (r = −0.820, p < 0.001). Combined levels of glutamine and glutamate were unrelated to psychometric or to pain thresholds.ConclusionOur study supports mid-anterior cingulate cortex γ-aminobutyric acid as a potential marker of pain severity in chronic nociceptive pain states independent of negative affect. The findings suggest that GABAergic disinhibition of the salience network may underlie sensitization to averse stimuli as a mechanism contributing to pain chronification.

MR Spectra of Normal Adult Testes and Variations with Age: Preliminary Observations.

The aim was to determine the proton MR (1H-MR) spectra of normal adult testes and variations with age. Forty-one MR spectra of normal testes, including 16 testes from men aged 20-39years (group I) and 25 testes from men aged 40-69years (group II), were analyzed. A single-voxel point-resolved spectroscopy sequence (PRESS), with TR/TE: 2000/25ms was used. The volume of interest was placed to include the majority of normal testicular parenchyma. Association between normalized metabolite concentrations, defined as ratios of the calculated metabolite concentrations relative to creatine concentration, and age was assessed. Quantified metabolites of the spectra were choline (Cho), creatine (Cr), myo-inositol (mI), scyllo-inositol, taurine, lactate, GLx compound, glucose, lipids, and macromolecules resonating at 0.9ppm (LM09), around 20ppm (LM20), and at 13ppm (LM13). Most prominent peaks were Cho, Cr, mI, and lipids. A weak negative correlation between mI and age (P = 0.015) was observed. Higher normalized concentrations of Cho (P = 0.03), mI (P = 0.08), and LM13 (P = 0.05) were found in group I than in group II. 1H-MR spectra of a normal adult testis showed several metabolite peaks. A decrease of levels of Cho, mI, and LM13 was observed with advancing age. • Single-voxel PRESS MRS of a normal testis is feasible. • 1H-MR spectra of a normal testis showed several metabolite peaks. • Most prominent peaks were Cho, Cr, mI, and lipids. • A decrease of Cho, mI, and LM13 was seen with advancing age.

Nonalcoholic Fatty Liver Disease: Correlation of the Liver Parenchyma Fatty Acid with Intravoxel Incoherent Motion MR Imaging-An Experimental Study in a Rat Model.

PurposeTo prospectively evaluate the changes in fatty acid concentration after administrating a 60% high-fat diet to a non-alcoholic fatty liver disease rat model and to perform a correlation analysis between fatty acid with molecular diffusion (Dtrue), perfusion-related diffusion (Dfast), and perfusion fraction (Pfraction).Material and MethodsThis prospective study was approved by the appropriate ethics committee. Ten male Sprague-Dawley rats were fed a 60% high-fat diet until the study was finished. Point-resolved spectroscopy sequence 1H-MRS with TR = 1,500 msec, TE = 35 msec, NEX = 64, and 8×8×8 mm3 voxel was used to acquire magnetic resonance spectroscopy (MRS) data. Diffusion-weighted imaging was performed on a two-dimensional multi-b value spin echo planar image with the following parameters: repetition time msec/echo time msec, 4500 /63; field of view, 120×120 msec2; matrix, 128×128; section thickness, 3 mm; number of repetition, 8; and multiple b value, 0, 25, 50, 75, 100, 200, 500, 1000 sec/mm2. Baseline magnetic resonance imaging and magnetic resonance spectroscopy data (control) were acquired. 1H proton MRS and diffusion-weighted imaging were obtained every 2 weeks for 8 weeks. The individual contributions of the true molecular diffusion and the incoherent motions of water molecules in the capillary network to the apparent diffusion changes were estimated using a least-square nonlinear fitting in MatLab. A Wilcoxon signed-rank test with the Kruskal-Wallis test was used to compare each week’s fatty acid mean quantification. Spearman’s correlation coefficient was used to evaluate the correlation between each fatty acid (e.g., total lipid (TL), total saturated fatty acid (TSFA), total unsaturated fatty acid (TUSFA), total unsaturated bond (TUSB), and polyunsaturated bond (PUSB)) and intravoxel incoherent motion (IVIM) mapping images (e.g., Dtrue, Dfast, and Pfraction).ResultsThe highest mean TL value was at week 8 (0.278 ± 0.10) after the administration of the 60% high-fat diet, followed by weeks 6, 4, 2, and 0. The concentration level (16.99±2.29) of TSFA at week 4 was the highest. No significant differences in the concentrations of TUSFA, TUSB, or PUSB were observed in different weeks.ConclusionAfter the administration of the 60% high-fat diet in nonalcoholic fatty liver disease model, TL and TSFA depositions had significant changes. The mean concentrations of TUSFA, TUSB, PUSB did not significantly change. Total unsaturated fatty acid and polyunsaturated bond showed positive correlations with Dtrue and Pfraction.

Effect of J coupling on 1.3-ppm lipid methylene signal acquired with localised proton MRS at 3 T.

The purpose of this work was to investigate the effect of J-coupling interactions on the quantification and T2 determination of 1.3-ppm lipid methylene protons at 3 T. The response of the 1.3-ppm protons of hexanoic, heptanoic, octanoic, linoleic and oleic acid was measured as a function of point-resolved spectroscopy (PRESS) and stimulated echo acquisition mode (STEAM) TE. In addition, a narrow-bandwidth refocusing PRESS sequence designed to rewind J-coupling evolution of the 1.3-ppm protons was applied to the five fatty acids, to corn oil and to tibial bone marrow of six healthy volunteers. Peak areas were plotted as a function of TE, and data were fitted to monoexponentially decaying functions to determine Mo (the extrapolated area for TE = 0 ms) and T2 values. In phantoms, rewinding J-coupling evolution resulted in 198%, 64%, 44%, 20% and 15% higher T2 values for heptanoic, octanoic, linoleic and oleic acid, and corn oil, respectively, compared with those obtained with standard PRESS. The narrow-bandwidth PRESS sequence also resulted in significant changes in Mo , namely -77%, -22%, 28%, 23% and 28% for heptanoic, octanoic, linoleic and oleic acid, and corn oil, respectively. T2 values obtained with STEAM were closer to the values measured with narrow-bandwidth PRESS. On average, in tibial bone marrow (six volunteers) rewinding J-coupling evolution resulted in 21% ± 3% and 9 % ± 1% higher Mo and T2 values, respectively. This work demonstrates that the consequence of neglecting to consider scalar coupling effects on the quantification of 1.3-ppm lipid methylene protons and their T2 values is not negligible. The linoleic and oleic acid T2 results indicate that T2 measures of lipids with standard MRS techniques are dependent on lipid composition.

Myocardial Metabolic Abnormality in a Primary Left Atrial Rhabdomyosarcoma: Localized 1H MR Spectroscopy

We report a 73-year-old woman with primary left atrial rhabdomyosarcoma and its 1H MR spectroscopy (MRS) findings. The tumor showed a 2.8 cm sized lesion in the posteroinferior atrial wall on MRI. 1H MR spectra were acquired using a point-resolved spectroscopy (PRESS) sequence with electrocardiographic (ECG) gating and respiratory motion. The use of 1H-MRS allowed the quantification of triglyceride (TG) peak groups at 0.9 and 1.3 ppm, and unsaturated group of lipids at 2.1 ppm, creatine (Cr) at 3.0 ppm, and choline (Cho) at 3.2 ppm. The percentages of the myocardial metabolites based on water-peak in the interventricular septum were TG 18.4%, Cr 1.6%, Cho 3.3% and unsaturated group 4.0%, whereas the rhabdomyosarcoma showed TG 118.8%, unsaturated group 5.1%, Cr 1.3%, Cho 3.5% and the olefinic components of fatty acid at 5.4 ppm 24.5%. This case demonstrates that 1H-MRS is potentially useful to diagnose the rhabdomyosarcoma by quantifying the myocardial metabolites which are important biomarkers for heart function and diseases.