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MR spectroscopy (MRS) is a unique and useful method for noninvasively evaluating biochemical metabolism in human organs and tissues, but its clinical dissemination has been slow and often limited to specialized institutions or hospitals with experts in MRS technology. The number of 3-T clinical MR scanners is now increasing, representing a major opportunity to promote the use of clinical MRS. In this review, we summarize the theoretical background and basic knowledge required to understand the results obtained with MRS and introduce the general consensus on the clinical utility of proton MRS in routine clinical practice. In addition, we present updates to the consensus guidelines on proton MRS published by the members of a working committee of the Japan Society of Magnetic Resonance in Medicine in 2013. Recent research into multinuclear MRS equipped in clinical MR scanners is explained with an eye toward future development. This article seeks to provide an overview of the current status of clinical MRS and to promote the understanding of when it can be useful. In the coming years, MRS-mediated biochemical evaluation is expected to become available for even routine clinical practice.

Objective: To determine the optimal quantitative magnetic resonance (MR) biomarker in neonatal encephalopathy following therapeutic hypothermia based on scan timing. Study design: This retrospective study included 98 neonates (35-41 weeks of gestation) with neonatal encephalopathy, who underwent therapeutic hypothermia; diffusion-weighted imaging and proton MR spectroscopy were performed at 24-96 hours (n = 56) and 7-14 days (n = 92) after birth, respectively, to estimate apparent diffusion coefficient (ADC) values, N-acetylaspartate and N-acetylaspartylglutamate (tNAA), lactate, and choline concentrations, and lactate/tNAA, tNAA/choline ratios in the deep gray matter. Adverse outcomes included death or neurodevelopmental impairment at 18-22 months of age. We used receiver operating characteristic curves to examine the prognostic accuracy of each MR biomarker. Results: Deep gray matter tNAA concentrations showed the best prognostic value, with an area under the curve (AUC) of 0.97 and 1.00 at 24-96 hours and 7-14 days after birth, respectively. At 24-96 hours of age, ADC values, lactate concentrations, and lactate/tNAA ratios showed prognostic value with AUCs of 0.90, 0.95, and 0.97, respectively. At 7-14 days of age, the AUCs of ADC values, lactate, and lactate/tNAA ratios were 0.61, 0.67, and 0.80, respectively; these were lower than those at 24-96 hours of age. Conclusions: During the first 2 weeks of life, the deep gray matter tNAA concentration was the most accurate quantitative MR biomarker. Although ADC values, lactate levels, and lactate/tNAA ratios also showed high prognostic value during 24-96 hours of life, only tNAA retained high prognostic value in the second week of life.

このスライドは、日本磁気共鳴医学会大会（2019年9月、熊本）で行った教育講演「MRSI」の内容をPDFで見やすいように改変したものです． 説明は、1. MRSIの基礎、2. 臨床MR装置 (3T) でのMRSI、3. 高磁場MR装置 (7T, 9.4T) でのMRSI、の3つの内容に分け、MRSIとは？から研究ベースでの高磁場 (7T～) による高分解能 (～128x128) MRSIデータ収集法について述べています．

Background A very-low-birth-weight (VLBW) preterm infants is associated with an increased risk of impaired neurodevelopmental outcomes. In this study, we investigated how neonatal brain metabolite concentrations changed with postmenstrual age and examined the relationship between changes in concentration (slopes) and neurodevelopmental level at 3–4 years. Methods We retrospectively examined 108 VLBW preterm infants who had brain single-voxel magnetic resonance spectroscopy at 34–42 weeks’ postmenstrual age. Neurodevelopment was assessed using a developmental test, and subjects were classified into four groups: developmental quotient 100. One-way analyses of covariance and multiple-comparison post hoc tests were used to compare slopes. Results We observed correlations between postmenstrual age and the concentrations of N-acetylaspartate and N-acetylaspartylglutamate (tNAA) (p p p p = 0.049) in the deep gray matter; and tNAA (p p = 0.022), and we found a significant difference between the p = 0.024). Conclusions In VLBW preterm infants, the slopes of tNAA concentrations (adjusted for postmenstrual age) were associated with lower developmental quotients at 3–4 years. Impact In very-low-birth-weight preterm-born infants, a slower increase in tNAA brain concentration at term-equivalent age was associated with poorer developmental outcomes at 3–4 years. The increase in tNAA concentration in very-low-birth-weight infants was slower in poorer developmental outcomes, and changes in tNAA concentration appeared to be more critical than changes in tCho for predicting developmental delays. While tNAA/tCho ratios were previously used to examine the correlation with neurodevelopment at 1–2 years, we used brain metabolite concentrations.

A very-low-birth-weight (VLBW) preterm infants is associated with an increased risk of impaired neurodevelopmental outcomes. In this study, we investigated how neonatal brain metabolite concentrations changed with postmenstrual age and examined the relationship between changes in concentration (slopes) and neurodevelopmental level at 3-4 years.

BackgroundVisualization of aqueous humor flow in the human eye is difficult because gadolinium, a magnetic resonance imaging (MRI) contrast agent, does not readily cross the blood-retinal and blood-aqueous barriers of capillaries that supply water to the eye. The proton (1H) of oxygen-17 water (H217O) has a very short transverse relaxation time (T2), and the T2-weighted (T2W) 1H-MRI signal intensity of a region with H217O is lower than that with only H216O.PurposeTo observe the distribution of H217O in the human eye, and the flow into and out of the anterior chamber of H217O, using dynamic T2W 1H-MRI.Materials and MethodsSeven ophthalmologically normal adult volunteers under 40 years old participated in this study. During dynamic imaging, the subject self-administered 10 mol% H217O saline (0.92–1.37 mL) to their right eye for 1 min. Time-series images were created by subtracting the image before the eye drops from each of the images obtained after the eye drops. The “normalized signal intensity of the right anterior chamber” (rAC) in each image was obtained by dividing the signal intensity of the right anterior chamber region-of-interest by that of the left. Changes in transverse relaxation rate and H217O concentration (PO17) were calculated from the rAC. The inflow and outflow constants of H217O in the right anterior chamber were also determined.ResultsDecreased signal intensity after the H217O eye drops was observed in the anterior and posterior chambers, but not in the vitreous body. The rAC signal intensity decreased after the eye drops, and then recovered to close to rAC(0) at 40 min. The inflow and outflow constants were 0.53 ± 0.19 and 0.055 ± 0.019 min-1, respectively, and the peak value of PO17 was 0.19 ± 0.04% (mean ± SD).ConclusionH217O saline eye drops distributed in the human anterior and posterior chambers. Further, the eye drops smoothly flowed into, and slowly out of, the anterior chamber.SummaryO-17 water dropped into human eyes as a T2-weighted MRI contrast agent was distributed in the anterior and posterior chambers, with smooth flow into, and slow outflow from, the anterior chamber.Key findingsIn seven healthy volunteers, dynamic T2-weighted 1H-MRI showed that the signal intensity in the anterior chamber decreased smoothly after H217O eye drops and then slowly recovered, reaching a value close to that observed before the eye drops, after 40 minutes, with inflow and outflow constants of H217O of 0.53 ± 0.19 min-1 and 0.055 ± 0.019 min-1, respectively. The signal changes were limited to the anterior and posterior chambers and were not observed in the vitreous body.

Objective To determine the optimal quantitative magnetic resonance (MR) biomarker in neonatal encephalopathy following therapeutic hypothermia based on scan timing. Study design This retrospective study included 98 neonates (35-41 weeks of gestation) with neonatal encephalopathy, who underwent therapeutic hypothermia; diffusion-weighted imaging and proton MR spectroscopy were performed at 24-96 hours (n = 56) and 7-14 days (n = 92) after birth, respectively, to estimate apparent diffusion coefficient (ADC) values, N-acetylaspartate and N-acetylaspartylglutamate (tNAA), lactate, and choline concentrations, and lactate/tNAA, tNAA/choline ratios in the deep gray matter. Adverse outcomes included death or neurodevelopmental impairment at 18-22 months of age. We used receiver operating characteristic curves to examine the prognostic accuracy of each MR biomarker. Results Deep gray matter tNAA concentrations showed the best prognostic value, with an area under the curve (AUC) of 0.97 and 1.00 at 24-96 hours and 7-14 days after birth, respectively. At 24-96 hours of age, ADC values, lactate concentrations, and lactate/tNAA ratios showed prognostic value with AUCs of 0.90, 0.95, and 0.97, respectively. At 7-14 days of age, the AUCs of ADC values, lactate, and lactate/tNAA ratios were 0.61, 0.67, and 0.80, respectively; these were lower than those at 24-96 hours of age. Conclusions During the first 2 weeks of life, the deep gray matter tNAA concentration was the most accurate quantitative MR biomarker. Although ADC values, lactate levels, and lactate/tNAA ratios also showed high prognostic value during 24-96 hours of life, only tNAA retained high prognostic value in the second week of life.

Vigabatrin (VGB) is an effective antiseizure medication for West syndrome. It works by irreversibly inhibiting gamma-aminobutyric acid (GABA) transaminase and increasing central GABA levels. Vigabatrin-associated brain abnormalities on magnetic resonance imaging (VABAM) are an adverse effect of VGB that has only been reported in children, but the pathophysiology of this effect is unknown. In this study, we evaluated the relationship of VGB and brain GABA levels as well as the association between VABAM and GABA.For the 15 consecutive pediatric patients treated with VGB, free GABA, glutamine, and glutamate in cerebrospinal fluid (CSF) and plasma, GABA to creatine and phosphocreatine (Cr) peak ratio (GABA/Cr), glutamine (Gln)/Cr, and glutamate (Glu)/Cr as quantified by proton MR spectroscopy (Thirteen of the included subjects underwent magnetic resonance imaging (MRI) andElevated brain GABA levels were observed in VABAM patients, suggesting its involvement in the pathogenesis of this condition. In particular, a marked increase in CSF-free GABA was characteristic. Although the elevation of the GABA/Cr is mild, it may be useful for early identification of patients with risk of VABAM.

Both glutamine (Gln) and glutamate (Glu) are known to exist in plasma and brain. However, despite the assumed relationship between brain and plasma, no studies have clarified the association between them. Proton magnetic resonance spectroscopy (MRS) was sequentially performed twice, with a 60-min interval, on 10 males and 10 females using a 3T scanner. Blood samples for liquid chromatography&ndash, mass spectrometry (LC/MS) to measure Gln and Glu concentrations in plasma were collected during the time interval between the two MRS sessions. MRS voxels of interest were localized at the posterior cingulate cortex (PCC) and cerebellum (Cbll) and measured by the SPECIAL sequence. Spearman&rsquo, s correlation coefficient was used to examine the association between brain and plasma metabolites. The Gln concentrations in PCC (mean of two measurements) were positively correlated with Gln concentrations in plasma (p &lt, 0.01, r = 0.72). However, the Glu concentrations in the two regions were not correlated with those in plasma. Consideration of the different dynamics of Gln and Glu between plasma and brain is crucial when addressing the pathomechanism and therapeutic strategies for brain disorders such as Alzheimer&rsquo, s disease and hepatic encephalopathy.

Purpose To investigate the time-course changes and predictive utility of brain metabolite concentrations in neonatal hypoxic-ischemic encephalopathy (HIE). Materials and Methods Sixty-eight neonates (age, 35-41 gestational weeks) with HIE were admitted to a neonatal intensive care unit between September 2009 and March 2016 and examined by using proton MR spectroscopy at 18-96 hours (n = 25) and 7-14 days (n = 64) after birth (35-43 postmenstrual weeks) to estimate metabolite concentrations in the deep gray matter. Adverse outcome was defined as death or neurodevelopmental impairment at 18-22 months of age. Areas under the receiver operating characteristic curves were calculated to evaluate the prognostic values of metabolites. Results At 18-96 hours, N-acetylaspartate and creatine concentrations were lower, whereas lactate, and glutamate and glutamine (Glx) concentrations were higher in neonates with adverse outcomes than in those with favorable outcomes. Metabolite concentrations at 18-96 hours decreased during days 7-14 in neonates with adverse outcomes but did not change in those with favorable outcomes. For N-acetylaspartate, creatine, lactate, and Glx concentrations measured at 18-96 hours to predict adverse outcomes, areas under the receiver operating characteristic curve were 0.98, 0.89, 0.96, and 0.88, respectively, whereas at 7-14 days, the areas under the receiver operating characteristic curve were 0.97, 0.97, 0.59, and 0.36, respectively. Conclusion Time-dependent reductions in N-acetylaspartate and creatine concentrations at both 18-96 hours and 7-14 days accurately predicted adverse outcomes. However, higher lactate and glutamate and glutamine concentrations were often transient.

Gamma-aminobutyric acid transaminase (GABA-T) deficiency is a rare, autosomal recessive disorder characterized by severe psychomotor retardation, early-onset epileptic encephalopathy, intractable seizures, hypotonia, and hyperreflexia. The disease is caused by mutation in the 4-aminobutyrate aminotransferase (ABAT) gene, which encodes an enzyme involved in GABA catabolism. In this chapter, a 10-year follow-up of GABA-T deficiency in a rare case of a long-term survivor patient is discussed. The patient showed a progression of clinical phases with increasing age. In infancy, the patient developed psychomotor retardation and recurrent encephalopathic episodes associated with febrile illness. In early childhood, the patient presented with refractory involuntary and hyperkinetic movements and dystonic hypertonicity. In childhood, the patient gradually progressed into the chronic stable phase of the condition. Magnetic resonance imaging demonstrated high signal intensity on diffusion-weighted images involving the internal and external capsules and cerebral white matter in infancy which disappeared gradually by the age of 3 years, and showed subsequently diffuse brain atrophy in childhood. Using proton magnetic resonance spectroscopy, GABA levels in the basal ganglia were shown to be markedly elevated at the age of 1-2 years, and subsequently decreased with increasing age (toward 5 years). These findings suggest that the encephalopathic episodes in infancy and clinical severity of involuntary and hyperkinetic movements may be correlated with levels of GABA in the basal ganglia. The high levels of GABA in the cerebrospinal fluid remained unaltered, whereas levels of GABA in the serum decreased during childhood. Further investigation of long-term clinical surveillance may improve the understanding of GABA-T deficiency.

We describe a male neonate with classic maple syrup urine disease (MSUD) in metabolic crisis. On day 7 of life, he was referred to hospital because of coma and metabolic acidosis with maple syrup odor. On day 4 after admission, brain magnetic resonance imaging findings were consistent with encephalopathy due to MSUD. Proton magnetic resonance spectroscopy ((1) H-MRS) showed a large methyl resonance peak at 0.9 p.p.m. The diagnosis of MSUD was confirmed on low branched-chain α-keto acid dehydrogenase complex activity in lymphocyte. (1) H-MR spectra were obtained in 10 min, while it took at least several days to obtain the results of other diagnostic examinations. In convalescence, the peak at 0.9 p.p.m. decreased. The large methyl resonance peak at 0.9 p.p.m. in brain (1) H-MRS would be one of the earliest clues to the diagnosis of classic MSUD in the neonatal period, especially in metabolic crisis.

A stroke-like episode is a core symptom in mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS). Proton magnetic resonance spectroscopy (1H-MRS) is useful in the diagnosis of mitochondrial diseases. We report an 8-year-old girl with MELAS, presenting with a seizure and blindness. 1H-MRS showed a strikingly elevated lactate peak in the right occipital region, where no abnormal signals appeared on either T2-W or diffusion-weighted MRI. She recovered completely within a day. We describe this mild clinical condition with abnormal lactate peak in normal-appearing gray matter as a transient ischemic attack-like episode in MELAS.

Lactate peaks are occasionally observed during in vivo magnetic resonance spectroscopy (MRS) scans of the neonatal brain, even in healthy patients. The purpose of this study was to investigate the normal range of neonatal brain lactate concentration, as a definitive normal range would be clinically valuable.Using a clinical 3T scanner (echo/repetition times, 30/5000ms), single-voxel MRS data were obtained from the basal ganglia (BG) and centrum semiovale (CS) in 48 healthy neonates (postconceptional age (PCA), 30-43weeks), nine infants (age, 1-12months old), and 20 children (age, 4-15years). Lactate concentrations were calculated using an MRS signal quantification program, LCModel. Correlations between regional lactate concentration and PCA (neonates), or age (all subjects) were investigated.Absolute lactate concentrations of the BG and CS were as follows: neonates, 0.77mM (0-2.02) [median (range)] and 0.77 (0-1.42), respectively; infants, 0.38 (0-0.79) and 0.49 (0.17-1.17); and children, 0.17 (0-0.76) and 0.22 (0-0.80). Overall, subjects' lactate concentrations decreased significantly with age (Spearman: BG, n=61, ρ=-0.38, p=0.003; CS, n=68, ρ=-0.57, p0.001). However, during the neonatal period no correlations were detected between lactate concentration in either region and PCA.We determined normal ranges of neonatal lactate concentration, which may prove useful for diagnostic purposes. Further studies regarding changes in brain lactate concentration during development would help clarify the reasons for higher concentrations observed during the neonatal period, and contribute to improvements in diagnoses.

In order to improve the fat suppression performance of in vivo (13)C-MRS operating at 3.0 Tesla, a phantom model study was conducted using a combination of two fat suppression techniques; a set of pulses for frequency (chemical shift) selective suppression (CHESS), and spatial saturation (SAT). By optimizing the slab thickness for SAT and the irradiation bandwidth for CHESS, the signals of the -(13)CH(3) peak at 49 ppm and the -(13)CH(2)- peak at 26 ppm simulating fat components were suppressed to 5% and 19%, respectively. Combination of these two fat suppression pulses achieved a 53% increase of the height ratio of the glucose C1β peak compared with the sum of all other peaks, indicating better sensitivity for glucose signal detection. This method will be applicable for in vivo (13)C-MRS by additional adjustment with the in vivo relaxation times of the metabolites.

To investigate the relationship between liver glucose, glycogen, and plasma glucose in diabetic patients, in vivo liver carbon-13 magnetic resonance spectroscopy ((13)C MRS) with a clinical 3.0T MR system was performed. Subjects were healthy male volunteers (n=5) and male type-2 diabetic patients (n=5). Pre- and during oral glucose tolerance tests (OGTT), (13)C MR spectra without proton decoupling were acquired in a monitoring period of over 6h, and in total seven spectra were obtained from each subject. For OGTT, 75g of glucose, including 5g of [1-(13)C]glucose, was administered. The MR signals of liver [1-(13)C]glucose and glycogen were detected and their time-course changes were assessed in comparison with the plasma data obtained at screening. The correlations between the fasting plasma glucose level and liver glycogen/glucose rate (Spearman: rho=-0.68, p

Rationale and Objectives A phantom set was devised to evaluate capability of independent component analysis (ICA) as an image filter for magnetic resonance (MR) images to segregate components. Materials and Methods Four components (free water [FW], olive oil [OL], 2% and 4% agar gels [2A and 4A, respectively]) were arranged in a phantom set. Seven MR images were obtained with different echo time and repetition time. ICA was performed on 23 combinations of four components. A segregation rate higher than 70% was defined as effective. Results Four-component segregation was obtained in 5 of 23 combinations. The best result showed a mean of 87% across the four components. For each component, there were 20 of 23 for FW, 22 for OL, 9 for 2A, and 16 for 4A. Conclusions The results demonstrated ICA works as an image filter and provides new contrast images that unambiguously segregate components in MR images. For practical application, the best performance should be obtained when T 1 W, T 2 W, and proton density images are included in the dataset for ICA.

A new interpretation is proposed for stimulus-induced signal changes in diffusion-weighted functional MRI. T2-weighted spin-echo echo-planar images were acquired at different diffusion-weightings while visual stimulation was presented to human volunteers. The amplitudes of the positive stimulus-correlated response and post-stimulus undershoot (PSU) in the functional time-courses were found to follow different trends as a function of b-value. Data were analysed using a three-compartment signal model, with one compartment being purely vascular and the other two dominated by fast- and slow-diffusing molecules in the brain tissue. The diffusion coefficients of the tissue were assumed to be constant throughout the experiments. It is shown that the stimulus-induced signal changes can be decomposed into independent contributions originating from each of the three compartments. After decomposition, the fast-diffusion phase displays a substantial PSU, while the slow-diffusion phase demonstrates a highly reproducible and stimulus-correlated time-course with minimal undershoot. The decomposed responses are interpreted in terms of the spin-echo blood oxygenation level dependent (SE-BOLD) effect, and it is proposed that the signal produced by fast- and slow-diffusing molecules reflect a sensitivity to susceptibility changes in arteriole/venule- and capillary-sized vessels, respectively. This interpretation suggests that diffusion-weighted SE-BOLD imaging may provide subtle information about the haemodynamic and neuronal responses. Copyright © 2009 John Wiley & Sons, Ltd.

To evaluate the contamination of glycogen signal synthesized in skeletal muscle by that in the liver, long-term monitoring of over 7 h of in vivo [1- 13 C] glycogen synthesis/degradation at the right abdomen and left shoulder was achieved using a 3.0-T clinical MR system. 13 C MR spectra without localization were obtained from five healthy volunteers before and after oral administration of 85 g of d -glucose, including 10 g of 99% [1- 13 C] glucose. In all volunteers, the relative signal intensities at the abdomen to those at shoulder were about two- to fivefold, and those of time-course changes at the abdomen and shoulder were dissimilar. It is considered that the quantity of muscle-synthesized glycogen signal at the abdomen is less than that at the shoulder because of the lesser muscle volume at the abdomen, and it may be less affected for evaluating glycogen synthesis/degradation in the liver even without localization pulses.

Brain metabolite concentrations change dynamically throughout development, especially during early childhood. The purpose of this study was to investigate the brain metabolite concentrations of neonates (postconceptional age (PCA): 30 to 43 weeks) using single-voxel magnetic resonance spectroscopy (MRS) and to discuss the relationships between the changes in the concentrations of such metabolites and brain development during the neonatal period. A total of 83 neonatal subjects were included using the following criteria: the neonates had to be free of radiological abnormalities, organic illness, and neurological symptoms; the MR spectra had to have signal-to-noise ratios ≥ 4; and the estimated metabolite concentrations had to display Cramér-Rao lower bounds of ≤ 30%. MRS data (echo time/repetition time, 30/5000 ms; 3T) were acquired from the basal ganglia (BG), centrum semiovale (CS), and the cerebellum. The concentrations of five metabolites were measured: creatine, choline, N-acetylaspartate, myo-inositol, and glutamate/glutamine complex (Glx). One hundred and eighty-four MR spectra were obtained (83 BG, 77 CS, and 24 cerebellum spectra). Creatine, N-acetylaspartate, and Glx displayed increases in their concentrations with PCA. Choline was not correlated with PCA in any region. As for myo-inositol, its concentration decreased with PCA in the BG, whereas it increased with PCA in the cerebellum. Quantitative brain metabolite concentrations and their changes during the neonatal period were assessed. Although the observed changes were partly similar to those detected in previous reports, our results are with more subjects (n = 83), and higher magnetic field (3T). The metabolite concentrations examined in this study and their changes are clinically useful indices of neonatal brain development.

We describe a male neonate with classic maple syrup urine disease (MSUD) in metabolic crisis. On day 7 of life, he was referred to hospital because of coma and metabolic acidosis with maple syrup odor. On day 4 after admission, brain magnetic resonance imaging findings were consistent with encephalopathy due to MSUD. Proton magnetic resonance spectroscopy ((1) H-MRS) showed a large methyl resonance peak at 0.9 p.p.m. The diagnosis of MSUD was confirmed on low branched-chain α-keto acid dehydrogenase complex activity in lymphocyte. (1) H-MR spectra were obtained in 10 min, while it took at least several days to obtain the results of other diagnostic examinations. In convalescence, the peak at 0.9 p.p.m. decreased. The large methyl resonance peak at 0.9 p.p.m. in brain (1) H-MRS would be one of the earliest clues to the diagnosis of classic MSUD in the neonatal period, especially in metabolic crisis.

Gamma‐aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the brain, and plays a key role in brain development. However, the in vivo levels of brain GABA in early life are unknown. Using edited MRS, in vivo GABA can be detected as GABA+ signal with contamination of macromolecule signals. GABA+ is evaluated as the peak ratio of GABA+/reference compound, for which creatine (Cr) or water is typically used. However, the concentrations and T 1 and T 2 relaxation times of these references change during development. Thus, the peak ratio comparison between neonates and children may be inaccurate. The aim of this study was to measure in vivo neonatal brain GABA+ levels, and to investigate the dependency of GABA levels on brain region and age. The basal ganglia and cerebellum of 38 neonates and 12 children were measured using GABA‐edited MRS. Two different approaches were used to obtain GABA+ levels: (i) multiplying the GABA/water ratio by the water concentration; and (ii) multiplying the GABA+/Cr by the Cr concentration. Neonates exhibited significantly lower GABA+ levels compared with children in both regions, regardless of the approach employed, consistent with previous ex vivo data. A similar finding of lower GABA+/water and GABA+/Cr in neonates compared with children was observed, except for GABA+/Cr in the cerebellum. This contrasting finding resulted from significantly lower Cr concentrations in the neonate cerebellum, which were approximately 52% of those of children. In conclusion, care should be taken to consider Cr concentrations when comparing GABA+/Cr levels between different‐aged subjects.

The changes in the signals for brain metabolites in the left cerebellum of a 14-year-old boy with acute hemicerebellitis were monitored using proton magnetic resonance spectroscopy (MRS). From the onset of disease treatment to long-term follow-up, MRS data were serially acquired from the left and right cerebella, basal ganglia (BG), and centrum semiovale (CS). Large fluctuations in his MRS signals were observed in the left cerebellum. At onset (first day), his glutamate/glutamine complex signals were increased (>mean ± 2 standard deviations [SD] of the control), and those for N-acetylaspartate/N-acetylaspartylglutamate and myo-inositol were decreased (

A new interpretation is proposed for stimulus-induced signal changes in diffusion-weighted functional MRI. T(2)-weighted spin-echo echo-planar images were acquired at different diffusion-weightings while visual stimulation was presented to human volunteers. The amplitudes of the positive stimulus-correlated response and post-stimulus undershoot (PSU) in the functional time-courses were found to follow different trends as a function of b-value. Data were analysed using a three-compartment signal model, with one compartment being purely vascular and the other two dominated by fast- and slow-diffusing molecules in the brain tissue. The diffusion coefficients of the tissue were assumed to be constant throughout the experiments. It is shown that the stimulus-induced signal changes can be decomposed into independent contributions originating from each of the three compartments. After decomposition, the fast-diffusion phase displays a substantial PSU, while the slow-diffusion phase demonstrates a highly reproducible and stimulus-correlated time-course with minimal undershoot. The decomposed responses are interpreted in terms of the spin-echo blood oxygenation level dependent (SE-BOLD) effect, and it is proposed that the signal produced by fast- and slow-diffusing molecules reflect a sensitivity to susceptibility changes in arteriole/venule- and capillary-sized vessels, respectively. This interpretation suggests that diffusion-weighted SE-BOLD imaging may provide subtle information about the haemodynamic and neuronal responses.