高场强头颅柔性线圈的颅脑成像质量的应用价值研究

【摘要】目的：通过与头颅16通道硬质线圈（HC16）比较，评价头颅12通道柔性磁共振线圈（AHC12）的颅脑成像效果。方法：首先对二个线圈进行物理测试，之后招募20例健康志愿者，分别采用同一磁共振仪、同一成像序列，先后采用AHC12和HC16线圈进行头颅成像，成像序列包括横轴面T2WI 、矢状面3D T1WI及扩散加权成像。对两组中各序列图像质量进行主观评分，测量及计算图像信噪比，并进行统计学分析。结果：AHC12线圈组中T2WI、3D-T1WI、DWI图像的信噪比均高于HC16线圈组，组间差异均具有统计学意义（P<0.05）。AHC12线圈组T2WI图像质量的主观评分明显高于HC16线圈（4.77±0.43 vs. 4.41±0.50，P<0.05)；两个线圈组中T1WI和DWI图像质量的主观评分差异君无统计学意义（4.82±0.39 vs. 4.64±0.49，4.70±0.47 vs. 4.40±0.50；P均>0.05）。结论：高场强下AHC12 柔性线圈可获得优于HC16硬质线圈的图像质量，可应用于临床常规头颅MRI检查中。     

肩关节MRI硬质线圈与柔性线圈的成像质量比较

目的：对比12通道硬质线圈与柔性线圈对肩关节MRI图像质量的影响。方法：分别采用肩关节硬质线圈和柔性线圈对33例健康志愿者行肩关节MRI扫描,对比冈上肌(三角肌)、肱骨头、肱二头肌长头肌腱在PDWI-FSE-COR-FS、T₁WI-FSE-COR、PDWI-FSE-TRA-FS、T₂WI-FSE-SAG-FS序列中的SNR与对比噪声比(CNR)。由2名医师对图像质量进行主观评分,采用2种线圈对联影专用水模行T₁WI-FSE序列扫描,采集每层的SNR。符合正态性分布的计量资料,组间比较行配对t检验。结果：客观评价方面,冈上肌PDWI-FSE-COR-FS、冈上肌T₁WI-FSE-COR、肱骨头PDWI-FSE-TRA-FS和肱骨头T₂WI-FSE-SAG-FS序列柔性线圈获得图像的SNR均优于硬质线圈,差异均有统计学意义(均P<0.05);冈上肌PDWI-FSE-COR-FS序列柔性线圈获得图像的CNR优于硬质线圈,差异有统计学意义(P<0.05);其余各序列SNR及...     

4通道与16通道相控阵乳腺专用线圈在乳腺MRI成像的应用比较

目的探讨4通道相控阵乳腺专用线圈与16通道相控阵乳腺专用线圈在乳腺MRI成像中的应用比较。方法回顾性分析54例在我科完成乳腺MRI扫描的被检者影像资料,其中使用4通道相控阵乳腺专用线圈作为射频线圈的27例;使用16通道相控阵乳腺专用线圈作为射频线圈的27例。MR影像序列主要包括:Tirm、T1WI、DWI、动态增强、单体数MRS。在Tirm、T1WI、DWI、动态增强图像上选择经乳头平面相同位置乳腺腺体测量其信噪比;两名高年资影像诊断医师根据Tirm、T1WI、DWI、动态增强、单体数MRS图像质量,对每例检查者图像进行双盲评价:优、良、中、差;同时根据手术或者活检结果,比较两种射频线圈MR图像对乳腺癌诊断的敏感性、特异性和准确性。结果 1)经4通道相控阵乳腺专用线圈作为射频线圈的Tirm、T1WI、DWI、动态增强影像的平均信噪比分别为13.96±4.02、44.50±24.01、2.34±0.90、25.77±9.20;经16通道相控阵乳腺专用线圈作为射频线圈的相应MRI影像的平均信噪比分别为8.28±3.89、175.71±147.28、2.32±0.80、36.77±14.54。T1WI及动态增强序列差异均有统计学意义(P值0.05),Tirm及DWI序列差异无统计学意义(P值0.05);2)经16通道相控阵乳腺专用线圈作为射频线圈的MRI影像的优良率(70.37%)高于4通道相控阵乳腺专用线圈(40.74%),差异有统计学意义(P值0.05);3)经16通道相控阵乳腺专用线圈作为射频线圈的MRI影像乳腺癌诊断的敏感性为87.50%(14/16),特异性为81.82%(9/11),准确性为85.19%(23/27),经4通道相控阵乳腺专用线圈作为射频线圈的MRI影像乳腺癌诊断的敏感性为84.62%(11/13),特异性为71.43%(10/14),准确性为77.78%(21/27)。结论 1)乳腺MRI检查对乳腺癌的诊断具有较高的敏感性和特异性;2)以4通道相控阵乳腺专用线圈作为射频线圈得到的MRI影像能较好的满足临床需求;3)16通道相控阵乳腺专用线圈优于4通道相控阵乳腺专用线圈。     

3.0T MRI胸椎扫描中联合线圈单元开放对图像质量的影响

目的:探讨不同的联合线圈单元开放方法在3.0T MRI胸椎扫描中对图像质量的影响,筛选最佳扫描方案。方法:应用3.0T MR机联合线圈(NV线圈及SPINE线圈)对20例患者行胸椎扫描,分别获得不同线圈单元开放的T1WI压脂增强(SPIR)序列图像,测量图像的信噪比(SNR)及对比度噪声(CNR),比较其图像质量是否存在差异。结果:20例中使用NV线圈开放NPC单元结合SPINE线圈开放ABC单元(即NPC-ABC,A组)图像的SNR-Ⅰ(上段胸椎)及CNR-Ⅰ均高于使用NV线圈开放PC单元结合SPINE线圈开放ABCD单元(即PC-ABCD,B组),SNR-Ⅰ分别为70.11±5.38和16.37±4.76(P<0.05),CNR-Ⅰ分别为15.11±4.62和7.90±4.48,两组间差异有统计学意义(P<0.05);而NPC-ABC与PC-ABCD的SNR-Ⅱ(即中段胸椎)及NPC-ABC与PC-ABCD的SNR-Ⅲ(即下段胸椎)间差异均无统计学意义。A组序列上段胸椎图像的主观评分为3.6±0.4,B组为2.7±0.5。结论:使用NV线圈开放NPC单元结合SPINE线圈开放ABC单元得出的上段胸椎图像质量最好,可作为常规扫描方案。     

3.0 T MR扫描仪联合8通道相控阵眼表面线圈提高眼部肿块显示能力的多中心研究

目的探讨在3.0 T MR扫描仪上联合使用8通道相控阵眼表面线圈提高眼部图像质量及眼部肿块显示能力的价值。方法前瞻性收集2018年7月至2020年1月6个中心的692例拟行眼部MRI的眼部肿块初诊患者, 均采用3.0 T MR扫描仪, 以简单随机法分为2组, 表面线圈组413例, 使用8通道相控阵眼表面线圈进行扫描;头线圈组279例, 使用8通道相控阵头线圈行相同序列扫描。评价2组图像的图像质量, 客观评价为计算眼眶正常结构(眼睑、玻璃体、泪腺和视神经眶内段)和各部位肿块(眼睑肿块、眼球内肿块、泪腺窝肿块及眼眶肿块)图像的信噪比(SNR)和对比噪声比(CNR);主观评价为主观评分, 指标包括运动伪影、肿块边缘及肿块与邻近结构关系的显示情况, 并计算图像质量总体评分。采用独立样本t检验或Wilcoxon秩和检验比较2组图像间客观指标和主观评分的差异。结果表面线圈组所有图像的SNR、CNR高于头线圈组, 差异有统计学意义(P<0.05), 运动伪影评分低于头线圈组, 差异有统计学意义(P<0.05)。表面线圈组眼球内肿块边缘、肿块与邻近结构关系评分及图像总体质量评分高于头线圈组...     

不同线圈接收信号的三维前列腺磁共振波谱

目的：比较不同线圈接收信号的前列腺磁共振波谱（MRS）,研究单纯采用体表线圈进行三维前列腺MRS检查的可行性和可靠性。材料和方法：以水模研究不同接收线圈的信号曲线。志愿者以相同参数按仅选择直肠内线圈（E组）、仅选择体表线圈（S组）和直肠内线圈与体表线圈均选择（C组）三种条件连续进行前列腺MRS检查,计算各谱线Cho与Cr的积分之和,Cho与Ci、Cr与Ci的积分之比及波峰高度之比,并对各谱线数据进行相关分析和配对资料t检验。结果：直肠内线圈信号曲线为距线圈越远,信号越低;体表线圈信号曲线基本与距离无关;直肠内线圈加体表线圈,距直肠内线圈3cm内,距线圈越远,信号越低,3cm外,信号与距离无关。Ci、Cho的积分,波峰高度,Cr的波峰高度及Cho与Cr积分之和在不同线圈组之间具有相关性（P〈0.05）;Cho与Ci、Cr与Ci积分之比在E组与S组之间有显著差异（P〈0.05）,在C组与E组距直肠内线圈3cm以外的体素之间、C组与S组距直肠内线圈3cm以内的体素之间有显著差异（P〈0.05）。结论：单纯采用体表线圈接收信号进行前列腺MRS检查是切实可行的,其结果也是可靠的,但定量诊断标准不能简单套用直肠内线圈MRS的研究结果。     

非专用线圈在MRI乳腺检查中的应用研究

目的:探讨非专用线圈在乳腺MRI检查中的应用价值。方法:运用乳腺专用线圈、SPINE matrix线圈两种检查方法扫描乳腺健康志愿者126例,Wilcoxon检验对126例健康志愿者扫描所得两组图像质量进行比较分析;利用t检验分析两组图像SNR;采用卡方检验分析两组横轴位扫描图像范围(腋窝淋巴组织)。结果:运用乳腺专用线圈和SPINEmatrix线圈两种检查方法图像质量、SNR比较差异无显著意义,SPINE matrix线圈横轴位显示双侧腋窝淋巴组织优于专用线圈,差异有显著意义。结论:SPINE matrix线圈可以达到等同乳腺专用线圈的应用效果,同时可以较好显示双侧腋窝组织。     

高场强MR仪结合小动物线圈在小鼠神经系统疾病中的应用

【摘要】目的：研究临床常规高场强MR仪结合8通道小孔径专用线圈用于小鼠神经系统常见疾病成像的可行性。方法：采用3.0T MR仪结合8通道横向放置小孔径线圈及小柔线圈扫描小鼠脑组织，调整T1WI、 T2WI冠状面及横轴面参数，优化各个序列图像质量，最终确定扫描参数。取15只C57小鼠，采用8通道横向放置线圈和小柔线圈依次扫描。扫描结束对图像质量行主观评分，测量并计算大脑皮层及中心区域信噪比（SNR）及对比噪声比（CNR），并采用配对t检验法比较两种线圈各个序列的主观评分及SNR、CNR值。采用8通道横向放置小孔径线圈扫描永久性脑缺血模型及脑胶质瘤模型并观察病灶显示情况。结果：8通道横向放置线圈T1WI及T2WI冠状面及横轴面图像主观评分均高于小柔线圈（P均<0.001）。8通道横向线圈T1WI及T2WI冠状面图像（皮层及中心）SNR高于小柔线圈（P均<0.01）。8通道横向线圈T1WI及T2WI冠状面图像（皮层及中心）CNR高于小柔线圈，差异不具有统计学意义（P均>0.05）。8通道横向线圈T1WI及T2WI横轴面图像（皮层及中心）SNR和CNR高于小柔线圈（P均<0.01）。使用8通道横向放置线圈结合高场强MR仪能清晰显示缺血灶及胶质瘤部位及范围，增强后可见肿瘤明显强化。结论：使用8通道横向放置线圈结合高场强MR仪能很好的进行小鼠脑部MR成像，T1WI、T2WI图像成像质量佳，图像质量明显优于小柔线圈，对脑卒中及脑胶质瘤病灶显示清晰，可以用于小鼠脑缺血疾病及肿瘤疾病的成像。     

7.0TMR配置3种多通道发射/接收射频线圈在心脏解剖和功能成像的比较

目的 7TMR配置3种多通道发射/接收射频线圈实行心脏MR(CMR)的比较。方法使用3种射频发射/接收(TX/RX)线圈,分别是4、8和16通道线圈。10名健康志愿者[7名男性,年龄(28±4)岁]采用7TMR设备进行了CMR,这三种RX/TX线圈均得到了心脏的二维的CINEFLASH影像。进行心腔定量分析、信噪比(SNR)分析,并行成像性能评估及影像质量评分。结果平均总的检查时间为(29±5)min。8通道、16通道线圈获得的所有影像是可以诊断的,观察射血分数(EF)(P>0.09)、左室质量(LVM)(P>0.31),这两种线圈间的差异无统计学意义。8通道和16通道线圈比4通道线圈产生了较高的SNR,16通道线圈的影响因素最低(平均值±标准差为2.3±0.5,R=4),16通道线圈的影像质量明显高于8通道和4通道线圈(P<0.04)。结论 7.0T配置3种线圈适合常规的CMR,较大数目的线圈提高了影像质量和并行成像性能,但不会影响心腔定量的准确性。     

两种不同磁共振线圈对肘部正常尺神经扩散张量成像的影响

目的:探讨使用膝关节专用线圈(Ex)和表面阵列线圈(Fl)对肘部正常尺神经扩散张量(DTI)成像的影响.方法:分别使用Ex线圈和Fl线圈采集31名志愿者肘部尺神经图像并建立扩散示踪图(DTT).比较两种线圈成像时,尺神经各向异性分数(FA值)、表观扩散系数(ADC值)、神经纤维束长度和DTI图像质量的差异.结果:共分析了50例尺神经.使用Ex线圈和Fl线圈时,肘部尺神经的FA值、ADC值均无明显统计学差异(P值分别为0.482、0.263),且两者尺神经DTT评分相当(P值分别为0.615、0.704),而Ex线圈采集的DTI图像质量优于F1线圈(P=0.004),DTT尺神经纤维束较长(P=0.000).结论:使用Ex线圈和Fl线圈对肘部尺神经DTI成像时均能获得稳定可靠的扩散测量参数,但Ex线圈得到的图像质量更高.     

Field, coil, and echo-time influence on sensitivity and reproducibility of brain proton MR spectroscopy

BACKGROUND AND PURPOSE: Clinical MR imaging scanners now offer many choices of hardware configurations that were not available in the first 25 years of their existence. Our goal was to assess the influence of coil technology, magnetic field strength, and echo time (TE) on the sensitivity, reflected by the signal intensity-to-noise-ratio (SNR) and reproducibility of proton MR spectroscopy (1H-MR spectroscopy). MATERIAL AND METHODS: The SNR, the intersubject reproducibility, and the intrasubject reproducibility of N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) levels were compared at the common TEs of 30, 144, and 288 ms, by using 1H-MR spectroscopy in 6 volunteers at (1) 3T with a single-element quadrature (SEQ); (2) 1.5T with SEQ; and (3) 1.5T with a 12-channel phased-array (PA) head coil. RESULTS: In terms of sensitivity, the best SNR for all metabolites was obtained at the shortest TE (30 ms). It was comparable between the 3 and 1.5T with the PA, but approximately 35% better than the 1.5T with SEQ. This SNR difference declined <25% at TE of 144 ms and to equity among all imagers at TE of 288 ms. Reproducibility, reflected in the coefficient of variation (CV), was best for NAA at TE of 288 ms, 15%-50% better than at TE of 30 ms in either gray (GM) or white matter (WM). The CV for Cr was best, at TE of 288 ms for GM, but its WM results were independent of TE. Metabolite level reproducibility did not depend on coil technology or magnetic field strength. CONCLUSIONS: For the same coil type, the SNR of all major metabolites was approximately 35% better at 3T than at 1.5T. This advantage, however, was offset at 1.5T with a PA coil, making it a cost-effective upgrade for existing scanners. Surprisingly and counterintuitively, despite the lowest SNR, the best reproducibility was obtained at the longest TE (288 ms), regardless of field or coil.     

1H MRS in acute traumatic brain injury

The objective of this study was to demonstrate ¹H MR spectroscopy (MRS) changes in cerebral metabolites after acute head trauma. Twenty-five patients (12 children, 13 adults) were examined with quantitative ¹H MRS after closed head injury. Clinical grade (Glasgow Coma Scale [GCS]) and outcome (Rancho Los Amigos Medical Center Outcome Score [ROS]) were correlated with quantitative neurochemical findings. N-acetylas-partate (NAA), a neuronal and axonal marker, was reduced (P < .03?.001). In children, a reduced NAA/creatine plus phosphocreatine (Cr) level and the presence of detectable lipid/lactate predicted bad outcome (sensitivity, 89%; specificity, 89%). The first MRS examination of all patients correlated with ROS versus NAA (r = .65, P < .0001). Although most patients showed MRS abnormalities, striking heterogeneity of ¹H MRS characterized the individual patients. ¹H MRS identifies multiple patterns of diffuse brain injury after blunt head trauma. There was a strong correlation between MRS and outcome. Future prospective studies will be needed to determine the clinical usefulness of MRS in predicting outcome from closed head injury.     

Signal-to-noise ratio enhancement of intermolecular double-quantum coherence MR spectroscopy in inhomogeneous fields with phased array coils on a 3 Tesla whole-body scanner

Purpose

To improve signal‐to‐noise ratio (SNR) of intermolecular double‐quantum coherence (iDQC) MRS on a 3 Tesla (T) whole‐body scanner.

Materials and Methods

A 32‐channel phased array coil was used to acquire iDQC signal of a MRS phantom in the presence of large field inhomogeneity. The obtained individual spectra from the array elements were combined together in the time domain using a multichannel nonparametric singular value decomposition algorithm. The results were compared quantitatively with those acquired with a circularly polarized (CP) head coil.

Results

The achieved gain in SNR ranges from 1.63 to 2.10 relative to the CP coil, mainly depending on the relative position between the surface of the phased array coil and the voxel of acquisition.

Conclusion

SNR enhancement of iDQC MRS in inhomogeneous fields on a 3T whole‐body scanner is feasible with phased array coils. This can facilitate iDQC applications of high‐resolution in vivo spectroscopy in the presence of field inhomogeneity for potential disease diagnosis in humans. J. Magn. Reson. Imaging 2011;33:698–703. © 2011 Wiley‐Liss, Inc.     

Signal-to-noise ratio and spectral linewidth improvements between 1.5 and 7 Tesla in proton echo-planar spectroscopic imaging.

This study characterizes gains in sensitivity and spectral resolution of proton echo-planar spectroscopic imaging (PEPSI) with increasing magnetic field strength (B(0)). Signal-to-noise ratio (SNR) per unit volume and unit time, and intrinsic linewidth (LW) of N-acetyl-aspartate (NAA), creatine (Cr), and choline (Cho) were measured with PEPSI at 1.5, 3, 4, and 7 Tesla on scanners that shared a similar software and hardware platform, using circularly polarized (CP) and eight-channel phased-array (PA) head coils. Data were corrected for relaxation effects and processed with a time-domain matched filter (MF) adapted to each B(0). The SNR and LW measured with PEPSI were very similar to those measured with conventional point-resolved spectroscopy (PRESS) SI. Measurements with the CP coil demonstrated a nearly linear SNR gain with respect to B(0) in central brain regions. For the PA coil, the SNR-B(0) relationship was less than linear, but there was a substantial SNR increase in comparison to the CP coil. The LW in units of ppm decreased with B(0), resulting in improved spectral resolution. These studies using PEPSI demonstrated linear gains in SNR with respect to B(0), consistent with theoretical expectations, and a decrease in ppm LW with increasing B(0).     

96‐Channel receive‐only head coil for 3 Tesla: Design optimization and evaluation

The benefits and challenges of highly parallel array coils for head imaging were investigated through the development of a 3T receive‐only phased‐array head coil with 96 receive elements constructed on a close‐fitting helmet‐shaped former. We evaluated several designs for the coil elements and matching circuitry, with particular attention to sources of signal‐to‐noise ratio (SNR) loss, including various sources of coil loading and coupling between the array elements. The SNR and noise amplification (g‐factor) in accelerated imaging were quantitatively evaluated in phantom and human imaging and compared to a 32‐channel array built on an identical helmet‐shaped former and to a larger commercial 12‐channel head coil. The 96‐channel coil provided substantial SNR gains in the distal cortex compared to the 12‐ and 32‐channel coils. The central SNR for the 96‐channel coil was similar to the 32‐channel coil for optimum SNR combination and 20% lower for root‐sum‐of‐squares combination. There was a significant reduction in the maximum g‐factor for 96 channels compared to 32; for example, the 96‐channel maximum g‐factor was 65% of the 32‐channel value for acceleration rate 4. The performance of the array is demonstrated in highly accelerated brain images. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.     

磁共振波谱定量分析脑内代谢产物鉴别诊断早老痴呆和血管性痴呆

目的:探讨1HMRS鉴别早老痴呆(AD)和血管性痴呆(VD)。材料和方法:61名被试者,AD组20例,VD组20例,健康对照组(HC)21例,均用GESigna1.5T超导磁共振扫描仪,采用PRESS序列对兴趣区内脑代谢产物浓度采集并计算比值;并行统计学处理。结果:AD和VD患者的额叶NAA浓度及NAA/Cr、NAA/MI的比值较HC组明显降低;AD患者颞叶和海马区MI浓度明显高于VD和HC组;而AD患者海马区的NAA浓度以及NAA/Cr和NAA/MI的比值降低。结论:AD组海马区的NAA浓度和NAA/Cr明显降低而MI浓度和MI/Cr明显升高,与VD之间具有鉴别诊断意义。     

脑星形细胞肿瘤多体素1H-MRS代谢物含量变化及其与Ki-67的相关性

目的:探讨脑星形细胞肿瘤中多体素1H-MRS代谢物含量的变化及其与Ki-67间的相关性。方法:应用SiemensSonata 1.5T超导型MR成像系统对41例脑星形细胞肿瘤患者进行常规MR扫描及MRS检查,其中28例进行了Ki-67抗原指标的免疫组化染色。磁共振波谱分析采用四通道正交头部专用线圈3D-CSI序列扫描,比较分析不同级别星形细胞肿瘤间代谢物情况。用兔抗人Ki-67单克隆抗体测定肿瘤标本的Ki-67抗原标记指数。应用SPSS统计软件进行统计学相关性分析。结果:低级别组脑星形细胞肿瘤多体素?1H-MRS均表现为Cho峰不同程度增高和NAA峰不同程度的降低,5例出现Lac峰,无出现Lip峰。高级别组脑星形细胞肿瘤均表现为Cho峰明显增高,NAA不同程度的明显降低,21例出现Lac峰,11例出现Lip峰。高低级别肿瘤间Cho/Cr,Cho/NAA和Lac/Cr比值有统计学意义的差别。Cho/Cr、Cho/NAA比值与Ki-67指数间均存在明显的相关关系(其相关系数分别为0.640、0.694)。结论:多体素1H-MRS代谢物含量与Ki-67间有良好的相关性,磁共振波谱分析能够为星形细胞肿瘤治疗方案的制定提供更多信息。     

Comparison of volume, four- and eight-channel head coils using standard and parallel imaging

Array coils can potentially offer increased signal-to-noise ratio (SNR) over standard coils adjacent to the array elements, while preserving the SNR at the center of the volume. The SNR advantage should theoretically increase with the number of array elements. Parallel acquisition techniques (PAT), on the other hand, can benefit acquisition times or spatial resolution at a cost to SNR as well as image quality. This study examines the question of whether SNR and image quality are still acceptable with two different array coils (four and eight channels) in conjunction with PAT when compared to standard imaging with a volume coil. All imaging was on a 1.5 T MR scanner. T2-weighted, FLAIR, diffusion-weighted, and time of flight (TOF) angiography images were performed with and without PAT in a phantom and in ten healthy volunteers. The phantom measurements demonstrated superior SNR for the eight-channel coil versus the four-channel and standard head coils. Using the eight-channel head coil for in vivo imaging, image quality with PAT (acceleration factor=2) was scored similar to images without PAT using the volume coil. The four-channel head coil suffered from inhomogeneity, lower SNR and poorer image quality when using PAT compared to standard imaging with the volume head coil. Both the in vivo and the phantom results indicate that the eight-channel head coil should be used for the highest quality brain images; this coil can be combined with PAT sequences for shorter acquisition time without a significant decrease in image quality relative to a volume coil without PAT.     

对比正交鸟笼线圈与CTL脊柱线圈颅脑MR图像质量

目的 探讨正交鸟笼线圈与CTL脊柱线圈在颅脑扫描中的应用价值.方法 采用MRI所配备的正交鸟笼头线圈和CTL脊柱线圈对标准ACR水模行轴位T1FLAIR序列扫描,对每层图像的信噪比(SNR)及均匀度百分比(PIU)进行测量计算,并对其结果进行配对t检验.随机抽取使用头颅正交鸟笼线圈和CTL脊柱线圈进行颅脑检查的100例...     

Observation of coupled 1H metabolite resonances at long TE.

A PRESS localization (1)H MRS acquisition sequence with a Carr-Purcell train of refocusing pulses (CP-PRESS) has been implemented using global refocusing "sandwich" pulses. The CP pulse train minimized the effects of J-coupled dephasing in metabolites with strongly coupled, multiplet resonance groups as demonstrated in both phantom data and in vivo single-voxel spectroscopy in normal volunteers. Metabolites with multiplet resonance patterns were maintained with greater signal to noise and a simpler resonance pattern at long echo times. T(2) decay times for metabolites with singlet and multiplet resonances were similar to published values, except for the NAA multiplet at 2.5 ppm, which had a significantly shorter T(2) value (147 ms) than that typically reported for the singlet at 2.01 ppm. Metabolite-nulled spectra were acquired in normal volunteers to evaluate the effects of CP-PRESS on baseline signal contributions from residual water, lipids, and macromolecules. The T(2) decay times in four baseline regions in data acquired with the CP-PRESS sequence showed longer decays than corresponding regions in metabolite-nulled spectra from a standard PRESS sequence, but were significantly diminished long before the metabolites of interest were gone. The spectral analysis for spectra with longer TE times also showed less variability due the higher metabolite SNR, simpler spectral patterns, and the decreased baseline contributions.