Measurement of brain glutamate using TE-averaged PRESS at 3T.

A method is introduced that provides improved in vivo spectroscopic measurements of glutamate (Glu), glutamine (Gln), choline (Cho), creatine (Cre), N-acetyl compounds (NAtot, NAA + NAAG), and the inositols (mI and sI). It was found that at 3T, TE averaging, the f1 = 0 slice of a 2D J-resolved spectrum, yielded unobstructed signals for Glu, Glu + Gln (Glx), mI, NA(tot), Cre, and Cho. The C4 protons of Glu at 2.35 ppm, and the C2 protons of Glx at 3.75 ppm were well resolved and yielded reliable measures of Glu/Gln stasis. Apparent T1/T2 values were obtained from the raw data, and metabolite tissue levels were determined relative to a readily available standard. A repeatibility error of <5%, and a coefficient of variation (CV) of <10% were observed for brain Glu levels in a study of six normal volunteers.     

MR imaging and (1)H spectroscopy of brain metabolites in hepatic encephalopathy: time-course of renormalization after liver transplantation

PURPOSE: To evaluate changes in hydrogen 1 magnetic resonance (MR) spectroscopic findings in overt or subclinical hepatic encephalopathy (HE) after liver transplantation and to compare these changes with clinical outcomes and basal ganglia high signal intensity (BGH). MATERIALS AND METHODS: Twenty-two patients scheduled for liver transplantation and 17 healthy control subjects were examined with (1)H MR spectroscopy and standard nonenhanced MR imaging. Eight patients underwent complete MR imaging and (1)H spectroscopic examinations before liver transplantation and at 3-4-week, 12-28-week, and 10-12-month follow-up after liver transplantation. RESULTS: Before liver transplantation, typical (1)H spectroscopic changes-decreased myo-inositol (mI)/creatine (Cr) and choline (Cho)/Cr ratios and an elevated glutamine and glutamate (Glx)/Cr ratio-were found in 21 patients. Eighteen patients had BGH at T1-weighted imaging. Three to 7 months after liver transplantation, the mI/Cr and Glx/Cr ratios were within the normal range in five of eight and eight of eight patients, respectively, without any residual signs of subclinical or overt HE; however, at MR imaging, seven patients still had BGH. CONCLUSION: After successful liver transplantation, renormalization of HE-specific brain metabolite changes is detected at (1)H spectroscopy and precedes the disappearance of BGH. The neuropsychologic signs of subclinical or overt HE follow the changes seen at (1)H spectroscopy rather than those seen at MR imaging.     

轻微肝性脑病的氢质子MR波谱研究

目的 应用氢质子MR波谱(~1H-MRS)检测肝硬化患者脑内代谢物改变,评价其异常变化是否能鉴别轻微肝性脑病(MHE),并与临床神经心理测试进行相关性分析.方法 选取54例肝硬化患者(肝硬化组)和13名健康志愿者(正常对照组)完成神经心理测试,包括数字连接试验A(NCT-A)和数码-符号试验(DST),54例肝硬化患者中包括肝性脑病(HE)9例(HE组)、MHE 23例(MHE组)、无HE和MHE者22例(无HE组).所有患者和志愿者均进行常规头颅MR扫描以及枕叶皮质、左侧顶叶白质的~1H-MRS扫描,分别计算各代谢物包括N-乙酰天冬氨酸(NAA)、胆碱化合物(Cho)、肌醇(mI)和谷氨酰胺复合物(Glx)与肌酸(Cr)的比值.正常对照组与肝硬化组的代谢物比值比较采用独立样本t检验,正常对照组和肝硬化各分组间代谢物比值的比较采用单因素方差分析,组间两两比较采用非参数Mann-Whitney U检验,并用Bonferroni法进行校正.~1H-MRS代谢物比值与HE分级、神经心理测试结果、静脉血氨的相关性分析采用Spearman等级相关分析.结果 肝硬化组枕叶皮质和左顶叶白质的代谢物比值NAA/Cr、Cho/Cr/、mI/Cr、Glx/Cr值分别为1.55±0.12、0.48±0.10、0.42±0.14、2.52±0.48和1.73±0.17、0.75±0.16、0.42±0.16、2.75±0.59,其中无HE组为1.53±0.10、0.48±0.09、0.51±0.11、2.20±0.39和1.69±0.15、0.82±0.14、0.53±0.12、2.40±0.40,MHE组为1.58±0.13、0.48±0.08、0.38±0.13、2.62±0.39和1.78±0.18、0.74±0.14、0.38±0.15、2.84±0.58,HE组分别为1.54±0.12、0.50±0.13、0.29±0.07、3.04±0.31和1.70±0.19、0.62±0.16、0.29±0.07、3.37±0.38.正常对照组相应部位代谢物比值分别为1.61±0.06、0.60±0.10、0.63±0.04、2.05±0.11和1.78±0.07、1.01±0.14、0.70±0.07、1.93±0.34.与正常对照组比较,肝硬化组及肝硬化各分组的Cho/Cr、mI/Cr值均降低,Glx/Cr值均升高,差异均有统计学意义(肝硬化组与对照组比较,枕叶皮质:t值分别为3.196、9.394、-6.527,肝硬化各分组与对照组比较,F值分别为5.097、25.896、20.204,P值均＜0.01.左顶叶白质:t值分别为5.592、9.717、-6.681,F值分别为16.435、28.660、21.283,P值均＜0.01＝.枕叶皮质和左顶叶白质的Glx/Cr值在无HE组、MHE组和HE组间的差异均有统计学意义(P值均＜0.0084＝,mI/Cr值在无HE组和MHE组间比较差异也有统计学意义(P＜0.0084＝.Cho/Cr、mI/Cr值与肝硬化患者HE的严重程度成负相关(枕叶皮质Cho/Cr和mI/Cr的r值分别为-0.316和-0.740,P值均＜0.01;左顶叶白质Cho/Cr和mI/Cr的r值分别为-0.620和-0.749,P值均＜0.01＝,Glx/Cr值与其呈正相关(枕叶皮质和左顶叶白质的r值分别为0.709、0.720,P值均＜0.01＝.正常对照组NCT-A值为(49±8)s,DST值为39 ±6,肝硬化组HE、MHE、无HE组患者NCT-A值分别为(134±37)、(83±26)、(64 ±22)s,DST值分别为15±2、25±9、35±8.正常对照组和肝硬化组67例的代谢物比值Cho/Cr、mI/Cr、Clx/Cr的改变与神经心理测试有很好相关性(P＜0.01＝,其中Glx/Cr值与NCT-A为正相关(枕叶皮质r=0.570,左顶叶白质r=0.541),与DST值为负相关(枕叶皮质r=-0.642,左顶叶白质r=-0.632).各代谢物比值与静脉血氨值之间无相关性.结论 ~1H-MRS研究能显示肝硬化患者大脑皮质与白质区代谢物异常改变,以mI/Cr值和Glx/Cr值明显,并且与神经心理测试之间存在相关性,可以作为HE分级的参考,对MHE有提示作用.     

MR spectroscopy: predicting long-term neuropsychological outcome following pediatric TBI

PURPOSE: To identify useful acute indicators of long-term neurocognitive outcome beyond clinical variables for children and adolescents treated for a traumatic brain injury (TBI). MATERIALS AND METHODS: The efficacy of magnetic resonance spectroscopy (MRS) acquired 6+/-4 days after TBI in 20 children/adolescents in predicting intellectual and neuropsychological functioning one to four years post injury was assessed. Short echo-time single voxel MRS (SVS) from normal-appearing brain was compared to intermediate echo-time multivoxel MR spectroscopic imaging (MRSI) from normal-appearing and visibly-injured brain acquired through the level of the corpus callosum (CC). RESULTS: N-acetyl aspartate (NAA) was moderate to strongly correlated with cognitive scores. Mean NAA/creatine (Cre) from MRSI alone explained over 40% of the variance in cognitive scores and 18% of the variance above and beyond demographic and clinical variables alone. Mild to moderate associations were noted between SVS metabolites (glutamate/glutamine [Glx] and myoinositol [mI]) and cognitive scores, with no such associations apparent for choline (Cho) or Cre. Exploratory analyses revealed trends for regional neuroimaging data and specific cognitive abilities. CONCLUSION: Acute MR spectroscopy of the pediatric brain injury patient improves prognostic ability and may provide valuable information for early treatment and intervention planning.     

Reproducibility of short echo time proton magnetic resonance spectroscopy using point-resolved spatially localized spectroscopy sequence in normal human brains.

The reproducibility of short echo time proton MR spectroscopy (1H-MRS) in normal human brains was examined. Thirteen healthy volunteers were studied, and each underwent three MRS examinations. Second and third measurements were done on the same day, about two months after the first measurement, and interday and intraday reproducibility were evaluated. MRS was performed with proton brain examination/single voxel (PROBE/SV) and point-resolved spatially localized spectroscopy (PRESS) (repetition time = 2000 ms, echo time = 30 ms). Five metabolite ratios were computed; N-acetyl-aspartate (NAA)/creatine (Cr), choline (Cho)/Cr, myo-inositol (mI)/Cr, NAA/(NAA + Cr + Cho), and NAA/Cho. Their normal range and reproducibility were measured. For each metabolite ratio, there was no significant difference between interday difference and intraday difference, suggesting that the interval of two months has minimal effect on MRS measurements. MRS may be utilized for the observation of central nervous system diseases.     

Noninvasive evaluation of malignancy of brain tumors with proton MR spectroscopy.

PURPOSETo test clinical proton MR spectroscopy as a noninvasive method for predicting tumor malignancy.METHODSWater-suppressed single-voxel point resolved spectroscopy in the frontal white matter of 17 healthy volunteers and 25 patients with brain tumors yielded spectra with peaks of N-acetyl aspartate (NAA), choline-containing compounds (Cho), creatine/phosphocreatine (Cre), and lactate. These peak intensities were semiquantitated as a ratio to that of the external reference. The validity of the semiquantitation was first evaluated through phantom and volunteer experiments.RESULTSThe variation in measurements of the designated region in the volunteers was less than 10%. Normal ranges of NAA/reference, Cho/reference, and Cre/reference were 3.59 +/- 0.68, 1.96 +/- 0.66, and 1.53 +/- 0.64 (mean +/- SD), respectively. In 17 gliomas, the Cho/reference value in high-grade gliomas was significantly higher than in low-grade gliomas. Levels of NAA/reference were also significantly different in low-grade and high-grade malignancy. In eight meningiomas (four newly diagnosed and four recurrent), the level of Cho/reference was significantly higher in recurrent meningiomas than in normal white matter or in newly diagnosed meningiomas.CONCLUSIONSHigher grades of brain tumors in this study were associated with higher Cho/reference and lower NAA/reference values. These results suggest that clinical proton MR spectroscopy may help predict tumor malignancy.     

Proton MR spectroscopy in Wilson disease: analysis of 36 cases

BACKGROUND AND PURPOSE: Wilson disease (WD) is rare but one of the few metabolic disorders that can possibly benefit from effective available treatments. The literature regarding proton MR spectroscopy (MRS) in WD is scarce and controversial. The purpose of this study was to determine the brain metabolic changes due to WD by using MRS. To our knowledge, this is the first time that MRS was performed in such a large sample of patients with WD. METHODS: Thirty-six patients with WD and 37 healthy volunteers were examined with MRS in the parieto-occipital cortex, frontal white matter, and basal ganglia (BG). Ratios of the following metabolites were calculated in relation to creatine (Cr): N-acetylaspartate (NAA), choline (Cho), myo-inositol (mI), and glutamine/glutamate (Glx). The mean peak line width was measured on each spectrum. RESULTS: Compared with control subjects, patients with WD had significantly decreased NAA/Cr ratios in the three studied areas (P < .005) and an increased mI/Cr ratio in the BG (P < .001). Cho/Cr and Glx/Cr did not differ between the groups. The mean peak line in the BG was wider in patients than in control subjects. CONCLUSION: WD is unequivocally associated with MRS changes that could possibly be assigned to neuronal loss (in the three studied areas), to gliosis, and to iron and/or copper deposition in the BG.     

肝硬化患者脑代谢的磁共振波谱成像研究

目的 利用磁共振波谱成像(MRS)评价肝硬化患者脑内代谢物的异常改变及其与临床静脉血氨值和神经心理学测试结果 之间的相关性. 资料与方法 52例经病理学和/或临床检查证实的肝硬化患者和30例健康志愿者纳入本研究.所有研究对象在MRI检查前进行数字连接试验-A(NCT-A)、数字符号试验(DST)以及符号数字试验(SDT).均行扣带回和右侧基底节的单体素氢质子波谱扫描,给出各代谢物曲线下面积与Cr的比值.记录肝硬化患者的静脉血氨值. 结果 患者组扣带回和基底节出现Cho/Cr降低、(Cho mIns)/NAA降低、Glx/Cr升高、mIns/Cr降低.扣带回的mIns/Cr与Child分级(r＝-0.496,P<0.001)及HE分级(r＝-0.313,P<0.05)之间均存在相关性;而基底节的Cho/Cr(r＝-0.497,P<0.001)、mIns/Cr(r＝-0.341,P<0.05)和(Cho mIns)/NAA(r＝-0.276,P<0.05)与Child分级之间有显著负相关,Glx/Cr与HE分级之间有正相关性(r＝0.385,P<0.05).扣带回与右侧基底节的MRS指标与血氨之间存在负相关关系.扣带回的Glx/Cr与NCT-A有正相关关系(r＝0.366,P＝0.028). 结论 肝硬化患者扣带回和基底节存在生化代谢的异常改变,扣带回可作为检测肝硬化患者脑改变的一个敏感部位.     

Brain metabolite alterations in Eisenmenger syndrome: Evaluation with MR proton spectroscopy

ObjectiveEisenmenger syndrome (ES) is a life-threatening disease characterized by pulmonary hypertension and cyanosis in patients with congenital heart diseases. The aim of this study was to determine the brain metabolite changes in Eisenmenger syndrome compared with a control group using MR proton spectroscopy.Methods and MaterialsThe study included 10 children (3 male, 7 female) with congenital heart diseases and a diagnosis of Eisenmenger syndrome. The control group consisted of 10 healthy volunteer children. All were examined with a 1.5 T MRI scanner and single voxel spectroscopy was performed to obtain spectra from three different regions; left frontal subcortical white matter, left lentiform nucleus and left thalamus. Peak integral values obtained from the spectra were used as quantitative data.ResultsThe ages of the children with ES were between 5 and 16 years, and between 5 and 15 years in the control group. Periventricular white matter hyperintensities were observed in 3 patients. On MR spectroscopy study, significantly lower levels of Choline metabolite (Cho) were detected in the frontal subcortical region and thalamus regions of the patients compared with the control group. There was no statistically significant difference between the levels of other metabolites (NAA, Cr, mI and Glx). In the lentiform nucleus, although the average value of Cho in ES patients was lower than that of the control group, it was not statistically significant.ConclusionCho metabolite was determined to have an important role in brain metabolism in Eisenmenger syndrome patients. Oral Cho treatment may help to extend survival.     

Proton MR spectroscopy in Rett syndrome.

Seven patients (mean age 7.7yr) with Rett syndrome, a condition with progressive regression of psychomotor development are included in this study. Proton MR spectroscopy images were obtained with the multivoxel chemical-shift imaging mode (TR=1500ms, TE=40ms). Spectra from 224 voxels in the brain parenchyma were studied. N-acetyl aspartate (NAA), creatine (Cr), choline (Cho), and myoinositol (mI) peaks were quantitatively evaluated, and NAA/Cr, NAA/Cho, and Cho/Cr, mI/Cr ratios were calculated. Five age-matched normal cases were available as controls. In three patients with Rett syndrome spectroscopy findings were normal, and the metabolite ratios were similar to control cases. In the remaining four patients with the syndrome prominent decrease of the NAA peak was the main finding resulting in decreases in NAA/Cr (1.14+/-17), and NAA/Cho (1.08+/-27) ratios (p<0.0001). Cho/Cr ratios (0.93+/-26), and mI/Cr ratios (0.88+/-36) were normal compared to controls. There was no correlation between spectroscopic changes and clinical status of the patients. The findings suggested that not only reduced neuronal-dendritic arborizations but also decreased neuronal function could contribute to spectroscopy changes in Rett syndrome.     

Accelerated proton echo planar spectroscopic imaging (PEPSI) using GRAPPA with a 32-channel phased-array coil.

Parallel imaging has been demonstrated to reduce the encoding time of MR spectroscopic imaging (MRSI). Here we investigate up to 5-fold acceleration of 2D proton echo planar spectroscopic imaging (PEPSI) at 3T using generalized autocalibrating partial parallel acquisition (GRAPPA) with a 32-channel coil array, 1.5 cm(3) voxel size, TR/TE of 15/2000 ms, and 2.1 Hz spectral resolution. Compared to an 8-channel array, the smaller RF coil elements in this 32-channel array provided a 3.1-fold and 2.8-fold increase in signal-to-noise ratio (SNR) in the peripheral region and the central region, respectively, and more spatial modulated information. Comparison of sensitivity-encoding (SENSE) and GRAPPA reconstruction using an 8-channel array showed that both methods yielded similar quantitative metabolite measures (P > 0.1). Concentration values of N-acetyl-aspartate (NAA), total creatine (tCr), choline (Cho), myo-inositol (mI), and the sum of glutamate and glutamine (Glx) for both methods were consistent with previous studies. Using the 32-channel array coil the mean Cramer-Rao lower bounds (CRLB) were less than 8% for NAA, tCr, and Cho and less than 15% for mI and Glx at 2-fold acceleration. At 4-fold acceleration the mean CRLB for NAA, tCr, and Cho was less than 11%. In conclusion, the use of a 32-channel coil array and GRAPPA reconstruction can significantly reduce the measurement time for mapping brain metabolites.     

Cerebral MR spectroscopy in neurologically asymptomatic HIV-infected patients

PURPOSE: To detect early metabolic changes in the brain of neurologically asymptomatic HIV-infected patients with normal MR imaging and to find the correlation between 1H MR results and immune status. MATERIAL AND METHODS: Twenty neurologically asymptomatic HIV seropositive patients underwent MR imaging and single-voxel 1H MR spectroscopy (MRS) using a PRESS sequence. For all patients, the signals from N-acetyl-aspartate (NAA), choline-containing compounds (Cho), creatine-phosphocreatine (Cr) and myoinositol (mI) were compared with 32 healthy volunteers as metabolite ratios and metabolite areas to non-suppressed water area ratios. RESULTS: In HIV patients, the NAA/Cho ratio was significantly lower ( p < 0.01), but there were no changes in NAA/Cr ratio. A statistically significant reduction in NAA/H2O and Cr/H2O (both p < 0.05) was observed. For the immune status there was a statistically significant correlation (r=0.47, p<0.05) between CD4 counts and NAA/H2O ratio. A significant increase in Cho/Cr ( p<0.001) and mI/Cr ( p<0.01) ratios in HIV patients was found, but Cho/H2O and mI/H2O concentrations were non-significantly increased. CONCLUSION: These results indicate that neuronal loss and gliosis in HIV-infected patients may be associated with impairment of energy metabolism. The spectral changes found suggest that 1H MRS can be used for early detection of brain damage induced by HIV.     

重复时间对MR氢质子波谱定量脑组织代谢物浓度的影响

目的 探讨在体单体素氢质子MR波谱(1H-MRS)重复时间(TR)对定位测量脑组织代谢物绝对和相对浓度的影响.方法 正常志愿者30名采用1.5 T超导型MR成像系统行点分辨自旋回波(PRESS)序列单体素1H-MRS扫描,取左侧大脑半球顶枕部白质,体素8 cm3,TR分别为1500和5000 ms.采用线性拟合模型(LCModel)处理原始数据,测量肌酸和磷酸肌酸(tCr)、谷氨酸(Glu)、肌醇(mI)、N-乙酰天冬氨酸(NAA)、甘油磷酸胆碱(GPC)和谷氨酸和谷氨酰胺(Glx)等的绝对浓度和相对浓度,并采用配对t检验对不同TR下各代谢物的浓度进行比较.结果 大脑左顶枕部白质代谢物tCr、Clu、mI、NAA、GPC和Glx在TR为1500 ms时绝对浓度分别为(3.0±0.2)、(4.4±0.7)、(3.0±0.3)、(5.0±0.4)、(1.1±0.1)和(5.9±0.6)mmol/L;TR为5000 ms时分别为(4.2±0.4)、(5.3±0.5)、(3.7±0.5)、(6.7±0.7)、(1.4±0.1)和(6.6±0.6)mmol/L.TR为1500 ms时,Gh、mI、NAA、GPC和Glx的相对浓度分别为1.47±0.27、1.00±0.11、1.69±0.17、0.36±0.05和1.95±0.22;TR为5000 ms时分别为1.25±0.12、0.89±0.09、1.60±0.16、0.33±0.04和1.58±0.17.不同TR时,各代谢物绝对浓度和相对浓度差异均有统计学意义(P值均＜0.05).结论1H-MRS可有效地进行脐组织代谢物绝对浓度和相对浓度的测量,PRESS序列中不同的TR所获得的代谢物绝对和相对浓度均有较大差异,较短的TR可低估代谢物的绝对浓度.     

MR spectroscopy in post-treatment follow up of brain tumors

PurposeTo detect the role of MR spectroscopy in evaluating the whole area of signal alteration within the irradiated volume aiming to differentiate recurrent/residual tumors from radiation injury and to detect the tumor margin and extent.Materials and methodsThis prospective study included 25 patients with previously treated primary intracranial tumors. All patients received radiotherapy. MRI and multivoxel MRS were performed. The volume of interest was placed over the whole area of signal alteration. The spectra were analyzed for the signal intensity of choline (Cho), creatine (Cr), and N-acetyl aspartate (NAA), lipid (Lip), lactate (Lac), and myo-inositol (mI). Metabolite ratios for Cho/NAA, Cho/Cr, and NAA/Cr were calculated.ResultsCho/NAA and Cho/Cr were significantly higher while NAA/Cr ratios were significantly lower in tumors than radiation injury (p = 0.001 for all ratios). The Cho/NAA and Cho/Cr ratios were significantly higher in radiation injury than in normal-appearing brain tissue (p = 0.032 and p = 0.008, respectively), whereas NAA/Cr was insignificantly lower in radiation injury than normal-appearing brain tissue (p = 0.051). Value >1.8 for Cho/NAA ratio was considered as indicator for tumor.ConclusionMR spectroscopy can differentiate recurrent/residual tumor from radiation injury and delineate the tumor margin and extent.     

Congenital muscular dystrophy with merosin deficiency: 1H MR spectroscopy and diffusion-weighted MR imaging

PURPOSE: To prospectively use hydrogen 1 ((1)H) magnetic resonance (MR) spectroscopy and apparent diffusion coefficient (ADC) maps to try to explain the discrepancy between the extensive white matter (WM) abnormalities observed at MR imaging and the relatively mild neurocognitive decline in patients with merosin-deficient congenital muscular dystrophy (CMD). MATERIALS AND METHODS: The hospital ethics committee approved this study, and informed consent was obtained. Nine patients (five boys, four girls; age range, 3-9 years; mean, 6 years +/- 2 [standard deviation]) with merosin-deficient CMD underwent T1-weighted, T2-weighted, fluid-attenuated inversion recovery, and diffusion-weighted MR imaging and (1)H MR spectroscopy, which was performed in the parieto-occipital WM (POWM) and frontal WM (FWM) by using stimulated-echo acquisition mode. Metabolite (N-acetylaspartate [NAA], choline-containing compounds [Cho], and myo-inositol [mI]) ratios were calculated in relation to creatine/phosphocreatine (Cr) and water (H(2)O). NAA/Cho was also calculated. ADCs were calculated in approximately the same locations that were studied with spectroscopy. For comparison, (1)H MR spectroscopy (n = 10) and ADC mapping (n = 7) were also performed in 10 healthy age- and sex-matched control subjects (three boys, seven girls; age range, 4-9 years; mean, 6 years +/- 1). Statistical analysis involved the t test for comparison between different groups; correlation between ADC and spectroscopy results was studied with the Pearson test. RESULTS: MR imaging revealed evidence of bilateral WM involvement in all patients. Whereas their NAA/Cr and Cho/Cr were normal, their mI/Cr was slightly increased compared with that in control subjects (P = .03 in FWM and P = .07 in POWM), and their NAA/Cho was decreased in POWM (P = .03). NAA/H(2)O, Cr/H(2)O, Cho/H(2)O, and mI/H(2)O were considerably decreased (P < .05 for all) and ADC values were increased (P < .001) in WM in all patients versus these values in WM in control subjects. There was significant correlation between ADC values and metabolite/water ratios (r = -0.777 to -0.967, P < .05). CONCLUSION: ADC mapping and (1)H MR spectroscopy reveal abnormally high free-water concentrations in the WM of patients with merosin-deficient CMD.     

青年抑郁症患者基底节和丘脑3D 1H-MRS研究

目的:探讨青年抑郁症患者基底节和丘脑可能存在的神经生化异常.方法:对44例青年抑郁症患者(抑郁症组)和40例年龄和性别匹配的健康志愿者(对照组)进行常规MRI扫描和三维氢质子MR波谱(3D 1H-MRS)检查,测量双侧基底节和丘脑的 N-乙酰天门冬氨酸(NAA)、胆碱复合物(Cho)、肌醇(mI)和肌酸(Cr)的绝对值,并计算它们与Cr的比值.对两组实验对象各代谢物及其比值进行统计学分析.结果:①抑郁症组双侧豆状核和尾状核头部Cho/Cr、mI/Cr明显高于对照组,差异有显著性意义(P＜0.05),而NAA/Cr在两组间差异无统计学意义(P＞0.05);②抑郁症组丘脑NAA/Cr、Cho/Cr和mI/Cr与对照组相比,差异无统计学意义(P＞0.05).结论:青年抑郁症患者基底节区豆状核和尾状核头部的Cho/Cr、mI/Cr增高,可能构成该病的神经生物学基础.     

Single-voxel proton MR spectroscopy and positron emission tomography for lateralization of refractory temporal lobe epilepsy.

PURPOSEWe compared the metabolic information obtained from single-voxel proton MR spectroscopy and positron emission tomography (PET) in patients with temporal lobe epilepsy.METHODSTwenty-nine patients with temporal lobe epilepsy were screened for metabolic abnormalities with both proton MR spectroscopy and PET. Lateralization with MR spectroscopy was possible by using NAA/(Cho+Cr) and an asymmetry index. Hypometabolism as determined by PET was classified as typical or complex.RESULTSTwenty-four (96%) of 25 patients whose seizure onset could be lateralized to one temporal lobe showed ipsilateral lateralization with either MR spectroscopy or PET, whereas concordant lateralization with both techniques was possible only in 14 (56%) of the 25 patients. MR spectroscopy showed 42 abnormal temporal lobes whereas PET showed only 25 lobes with decreased metabolism. All temporal lobes with hypometabolism at PET also had a low NAA/(Cho+Cr). Five patients (20%) with negative PET studies had seizures lateralized correctly with MR spectroscopy.CONCLUSIONProton MR spectroscopy is more sensitive in depicting metabolic abnormalities than is PET in patients with temporal lobe epilepsy. Patients with negative PET studies will benefit from MR spectroscopy for the purpose of lateralization.     

阿尔茨海默病的高场氢质子磁共振波谱研究

目的:探讨阿尔茨海默病(Alzheimer's disease,AD)双侧海马的高场氢质子磁共振波谱(proton magnetic resonance spectroscopy,1H-MRS)的特点.方法:对AD组14例及正常对照组(normal control,NC)10例受试者行T_1WI-3D薄层扫描并进行海马三平面MPR重建,在所得MPR图像上定位双侧海马.采用MRS测定双侧海马N-乙酰天门冬氨酸(N-acetyl aspartate,NAA)、胆碱(choline,Cho)、肌醇(myo-lnositol,mI)和谷氨酸-谷氨酰胺复合物(Glx)与肌酸(ereatine,Cr)的比值.采用SPSS 17.0软件进行统计分析,观察AD组与NC组双侧海马各代谢物比值的差异.结果:AD组双侧海马的NAA/Cr、Glx/Cr比值较NC组降低,其差异具有统计学意义,AD组右侧海马ml/Cr比值较NC组升高具有统计学意义(P<0.05),左侧海马mI/Cr比值有升高趋势.但未达到统计学意义水平,AD组双侧海马Cho/Cr比值与NC组的差异无统计学意义.结论:双侧海马的高场MRS能够检测到AD特征性的代谢物改变.T_1WI-3D扫描行海马三平面MPR重建有助于海马MRS的准确定位,提高图像质量及可信度.     

Diagnostic value of proton MR spectroscopy and diffusion-weighted MR imaging in childhood inherited neurometabolic brain diseases and review of the literature

The purpose of this study is to evaluate parenchymal diffusion properties and metabolite ratios in affected brain tissues of inherited neurometabolic brain diseases with an overview of the current literature about the diagnostic data of both techniques in childhood inherited metabolic brain diseases. The study group was consisting, 19 patients (15 males, 4 females; mean age, 54 months (4.5 years); age range, 1-171 months (14.25 years)) diagnosed with inherited neurometabolic brain disease. Single- and multivoxel proton MRS was carried out and NAA/Cr, Cho/Cr, mI/Cr, Glx/Cr ratios were calculated. Presence of lactate peak and abnormal different peaks were noted. ADC values were calculated from brain lesions. Results are compared with age and sex matched normal subjects. Elevated NAA/Cr ratio (Canavan disease), galactitol peak (galactosemia) at 3.7 ppm, branched chain amino acids (Maple syrup urine disease—MSUD) at 0.9 ppm were seen on different diseases. In Leigh disease and MSUD restricted diffusion was detected. Different diffusion properties were seen only in one Glutaric aciduria lesions. NAA/Cr ratios and calculated ADC values were significantly different from normal subjects (p < 0.05). DWI combined with MRS are complementary methods to routine cranial MRI for evaluating neurometabolic diseases which can give detailed information about neurochemistry of affected brain areas.     

Early- and late-state subacute sclerosing panencephalitis: chemical shift imaging and single-voxel MR spectroscopy

BACKGROUND AND PURPOSE: Subacute sclerosing panencephalitis (SSPE) is a rare, progressive, inflammatory neurodegenerative disease. Our aim was to determine the metabolic abnormalities of brain in early- and late-stage SSPE by using MR spectroscopy and to assess areas of involvement in the early stages when MR imaging findings were normal. METHODS: Children with stage II (n = 3) or III (n = 3) SSPE and 10 healthy, age-matched children underwent MR imaging, multivoxel MR spectroscopy, and short-echo single-voxel MR spectroscopy (SVS). Areas of involvement in the brain were determined with chemical shift imaging. For SVS, 2 x 2 x 2-cm voxels were placed in the frontal subcortical white matter (FSWM) and parieto-occipital white matter (POWM). N-acetylaspartate (NAA)/creatine (Cr), choline (Cho)/Cr, myo-inositol (Ins)/Cr, and NAA/Cho ratios were calculated. RESULTS: Comparisons of NAA/Cr, Cho/Cr, Ins/Cr and NAA/Cho ratios between patients and control subjects showed significant differences in FSWM and POWM (P <.01). In patients with SSPE, NAA/Cr ratios in POWM were significantly less than those in FSWM (P <.01). NAA/Cr ratios in patients with stage II SSPE and those in the control group were not significantly different; this may reflect the absence of neuronal loss. Decreased NAA/Cr, increased Cho/Cr and Ins/Cr ratios, and increased lactate and lipid peaks were found in patients with stage III SSPE. CONCLUSION: MR spectroscopy showed findings suggestive of inflammation in stage II and findings of demyelination, gliosis, cellular necrosis, and anaerobic metabolism in stage III. MR spectroscopy could be a promising technique for early diagnosis and treatment planning in cases of SSPE.