Detection of intrahepatic lipids by 1H-MRS--studies by breath-holding & 1 cm3 VOI]

The authors performed 1H-MR spectroscopy (MRS) to depict lipids in the liver of 10 healthy volunteers. Spectra were obtained by a 1.5 T-MR unit, with STEAM from 1 x 1 x 1 cm3 VOI. Lipid peaks were depicted in 7 of the 10 volunteers by breath-holding 1H-MRS study, while in only 4 on normal breathing. The existence of lipids could not be depicted through chemical shift imaging adopting in-phase & opposed images. This suggests a clinical utility of 1H-MRS, particularly through breath-holding studies, in depicting lipids from 1 x 1 x 1 cm3 VOI in the liver in vivo.     

难治性颞叶癫痫的分子影像学研究与病理对照

目的:对照难治性颞叶癫痫(TLE)手术病理资料,探讨联合单光子发射计算机断层(SPECT)和质子磁共振波谱(1 H-MRS)两种分子影像学技术对TLE定位的临床价值。方法:选择29例经手术病理证实的单侧TLE。所有患者术前均行SPECT发作间期脑血流(CBF)灌注显像、常规磁共振(MRI)扫描和1 H-MRS成像。将两种分子影像学技术,发作间期CBF灌注显像和1 H-MRS,对TLE的定位表现与病理结果进行对比分析。结果:病理改变最常见的是海马硬化和皮质发育不良,共27例(93.10%),此两种改变伴随出现于16例中(55.17%)。对于双重病理TLE,MRI、SPECT定位阳性率均为100%(16/16),MRS为87.50%(14/16)。对于单纯性海马硬化,MRI为阴性,SPECT仅为14.29%(1/7),而MRS高达57.14%(4/7)。对于单纯性皮质发育不全,MRS为阴性,MRI为50.00%(2/4),而SPECT高达75.00%(3/4)。联合应用SPECT和MRS对TLE定位率高达86.20%(25/29),尤其是对MRI阴性的患者,两种技术联合能发现54.55%(6/11)TLE的致痫灶。结论:联合SPECT发作间期脑血流灌注显像和1 H-MRS两种分子影像学技术能为难治性TLE提供更为全面和准确的定位诊断信息,可进一步提高定位MRI阴性TLE患者致痫灶的比例。     

Combination of free-breathing and breathhold steady-state free precession magnetic resonance angiography for detection of coronary artery stenoses

PURPOSE: To analyze the incremental diagnostic value of a combination of two approaches (free-breathing and breathhold) vs. the sole free-breathing approach to coronary magnetic resonance angiography (CMRA) for detection of significant stenoses. MATERIALS AND METHODS: Thirty patients were consecutively included in this prospective trial. CMRA was performed on a 1.5-T MR scanner (Magnetom Sonata, Siemens) using a balanced steady-state free precession (SSFP) sequence during free-breathing (2.4 x 0.9 x 0.7 mm3). Breathholding acquisitions (3.0 x 1.5 x 0.7 mm3) were only performed in cases in which the quality of free-breathing CMRA precluded assessment. Patients with contraindications to CMRA, claustrophobia, or nonassessable images were not excluded from the assessment of diagnostic accuracy (intention-to-diagnose design). RESULTS: In 60% of all free-breathing coronary acquisitions the image quality was adequate for diagnostic assessment. For the remaining 40% of the cases, breathhold acquisitions were obtained. The sensitivity, specificity, nonassessable rate, and accuracy in identifying main coronary branches with significant stenoses using the combination of both breathing approaches and the free-breathing approach alone were 65% vs. 32%, 73% vs. 53%, 24% vs. 52%, and 71% vs. 46%, respectively (P < 0.001). CONCLUSION: In this consecutive cohort of patients, the combination of free-breathing and breathhold CMRA significantly improved diagnostic accuracy. Nevertheless, even this combination did not reach accuracies sufficient for routine clinical application.     

1H-MR波谱评价骨骼肌细胞内脂肪含量的在体和模型研究

目的 解释骨骼肌1H-MRS中的脂峰形态及其影响因素,建立利用骨骼肌1H-MRS评价肌细胞内脂肪的方法 .方法 取5名健康志愿者的小腿胫骨前肌和比目鱼肌区域行1H-MRS检查,改变小腿纵轴与主磁场(B0)之间的角度,观察0.80～1.80 ppm(×10-6)处脂峰形态的变化.体外模型研究采用毛细玻璃管束中灌注大豆油和脂肪乳液,分别模拟肌纤维细胞外、细胞内脂肪,比较脂峰随模璎与B0角度变化的特征.结果小腿骨骼肌在0.80～1.80 ppm处可以观察到3～4个峰,各峰相差约0.20～0.30 ppm;当小腿纵轴与B0所成角度增大时,胫骨前肌肌纤维间隙内的脂肪(EMCL)的亚甲基峰逐渐向右侧移位.体外模型很好地模拟了在体骨骼肌1H-MRS脂峰形态,在0.80～1.80 ppm处出现2组甘油三酸酯亚甲基峰和甲基峰,其中心频率相差0.20～0.30 ppm,分别代表肌细胞内、外脂肪.由于骨骼肌组织肌纤维走行的高度有序性及肌细胞内、外脂肪的分子分布状态不同,两者感应的化学位移不同而表现出波峰的分离.这种肌细胞内外脂肪峰的分离在肌束与B0一致时最大,在两者夹角接近魔角(54.7°)时无法分离.结论骨骼肌1H-MRS中肌细胞内、外脂肪发生分离,是一种无创性评价肌细胞内脂肪含量的有效方法 ;胫骨前肌是进行1H-MRS检查的理想部位.     

Radiation dose from volumetric helical perfusion CT of the thorax, abdomen or pelvis

Purpose

To evaluate the radiation doses delivered during volumetric helical perfusion CT of the thorax, abdomen or pelvis.

Materials and methods

The dose-length product (DLP) and CT dose index (CTDIvol) were recorded and effective dose (E) determined for patients undergoing CT (4D adaptive spiral) for tumour evaluation. Image noise and contrast to noise (CNR) at peak enhancement were also assessed for quality.

Results

Forty two consecutive examinations were included: thorax (16), abdomen (10), pelvis (16). Z-axis coverage ranged from 11.4 to 15.7?cm. Mean DLP was 1288.8?mGy.cm (range: 648 to 2456?mGy.cm). Mean CTDIvol was 96.2?mGy (range: 32.3 to 169.4?mGy). Mean effective dose was 19.6?mSv (range: 12.3?mSv to 36.7?mSv). In comparison mean DLP and effective dose was 885.2?mGy.cm (range: 504 to 1633?mGy.cm) and 13.3 mSV (range: 7.8 to 24.5?mSv) respectively for the standard staging CT thorax, abdomen and pelvis. Mean tumour CNR at peak enhancement was 1.87.

Conclusion

The radiation dose imposed by perfusion CT was on average 1.5 times that of a CT thorax, abdomen and pelvis. The dose is not insubstantial, and must be balanced by the potential clinical utility of additional physiologic data. Further efforts towards dose reduction should be encouraged.     

Colonography using multislice CT

Computed tomography (CT) represents the preferred imaging modality for imaging the large bowel when virtual endoscopic reconstructions are desired. Using the spiral acquisition technique, it has become possible to scan the entire abdomen within a single breathhold, however, slice thicknesses of 5 mm or more are necessary should the breathhold not last longer than 30-40 s. With the advent of multislice CT, contiguous 1-mm slices can be obtained through the entire abdomen while even shortening the breathhold to 25-30 s. The improved speed and spatial resolution of multislice CT results in remarkably sharp virtual reconstructions allowing detection of polyps with sizes less than 3 mm. The disadvantages must still be considered including a dataset consisting of up to 800 images representing a new challenge for postprocessing hard- and software.     

顺磁性对比剂Gd-DTPA对短暂性脑缺血发作1H MRS的影响

目的:分析短暂性脑缺血发作(TIA)患者MR脑灌注成像(PWI)后顺磁性对比剂钆喷酸葡甲胺(Gd DTPA)对质子磁共振波谱(1H MRS)的影响,探讨用PWI检查指导1H MRS定位的可行性.方法:对20例临床诊断为TIA的患者行PWI检查,分别在PWI检查前后于双侧半卵圆中心行1H MRS检查,扫描参数及兴趣区(VOI)均相同.对比分析注射Gd-DTPA前后两次1H MRS主要代谢产物氮-乙酰天门冬氨酸(NAA)、胆碱复合物(Cho)和肌酸复合物(Cr)谱线的形态(峰高和半高宽)及相对浓度值(峰下面积比值).结果:注射Gd-DTPA前后两次1H MRS检查NAA、Cho和Cr谱线的形态未发现明显改变,同一区域代谢物谱线的各项参数差异均无显著性意义(P＞0.05).结论:TIA患者PWI检查注射顺磁性对比剂Gd-DTPA对1H MRS没有明显影响,可以通过PWI显示的灌注异常,指导TIA患者的1H MRS定位.     

Magnetic resonance spectroscopy in the evaluation of neurotoxicity following cranial irradiation for childhood cancer

In order to evaluate the role of proton MR spectroscopy (1H-MRS) in the diagnosis and assessment of long-term radiation-related neurotoxicity, 14 children who had received cranial irradiation for the treatment of childhood leukaemia (n = 6) or brain tumours (n = 8) underwent 1H-MRS, MRI and neuropsychological assessment. Short-term effects at 2 months following treatment were studied in a further three patients. MRI abnormalities were observed in nine patients. No statistically significant differences between patients and controls (n = 17) were seen in any of the calculated 1H-MRS metabolite ratios, in any of the three patient groups. On multivariate logistic regression analysis there was a correlation between the choline/water ratio and a low IQ. It is concluded that any systematic radiation-induced changes in the 1H MRS metabolites must be below the detection threshold of this study.     

Reduced (1)H-NMR visibility of creatine in isolated rat hearts.

The aim of this study was to measure the concentration of creatine in Langendorff perfused rat hearts, both by quantitative (1)H-MRS and by high-pressure liquid chromatography (HPLC). First, the relaxation times and other parameters affecting absolute quantification by MRS were determined. At 11.75 T, the relaxation times of myocardial creatine were T(1) = 1.1+/-0.29 sec (mean +/- SD, n = 5) and T(2) = 56.4+/-6.2 ms (n = 9). In phantom experiments the MRS measurements gave accurate values for the known relative concentrations of the detected substances. In glucose-perfused rat hearts, the creatine concentration measured by HPLC was 14.2+/-1.9 mmol/kg wet weight (n = 8), in good agreement with literature values. The (1)H-MRS measurements, however, resulted in creatine concentrations of only approximately 60% of this value. The application of CHESS-pulses for water suppression led to a further 30% reduction of the creatine MRS signal. These results indicate a reduced (1)H-NMR visibility of creatine in the myocardium, which suggests a compartmentation of myocardial creatine into various pools.     

MRS对胼胝体病变的鉴别诊断价值

目的 探讨多体素氢质子磁共振波谱(1H-MRS)对胼胝体病变的鉴别诊断价值.方法 选取17例经临床或病理证实的胼胝体病变患者,其中胼胝体淋巴瘤2例、胼胝体变性4例、胼胝体胶质瘤3例、胼胝体梗死7例、胼胝体多发性硬化1例,研究其病灶MRS特点.结果 2例胼胝体淋巴瘤病灶胆碱(Cho)峰明显升高,肌酸(Cr)及N-乙酰天门冬氨酸(NAA)峰明显降低,并出现高耸的脂质(Lip)峰;4例胼胝体变性患者中2例示Cho/Cr升高,NAA/Cr下降,1例示正常,1例探测到倒置的乳酸(Lac)峰;3例胼胝体胶质瘤病灶NAA峰下降或消失、Cho峰不同程度升高;7例胼胝体梗死均出现明显倒置的Lac峰,NAA不同程度下降;1例多发性硬化患者活动期病灶强化且Cho峰升高,NAA峰降低,并出现倒置的Lac峰,非活动期病灶不强化且MRS基本恢复正常.结论 多体素1H-MRS对胼胝体病变的鉴别诊断有重要的临床应用价值.     

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。     

Magnetic resonance spectroscopy in schizophrenia. Possibilities and limitations

Magnetic resonance spectroscopy is a noninvasive investigative technique for in vivo detection of biochemical changes in neuropsychiatric disorders for which especially proton (1H-MRS) and phosphorus (31P-MRS) magnetic resonance spectroscopy have been used. In this review we explain the principles of MRS and summarize the studies in schizophrenia. A systematic literature review was carried out for 1H-MRS studies investigating schizophrenic patients compared to controls. The inconsistent results in the cited studies may be due to different study population, specific neuroimaging technique, and selected brain regions. Frequent findings are decreased PME and increased PDE concentrations (31P-MRS) linked to altered metabolism of membrane phospholipids and decreased N-acetylaspartate (NAA) or NAA/choline ratio (1H-MRS) linked to neuronal damage in frontal (DLPFC) or temporal regions in patients with schizophrenia. These results contribute to the disturbed frontotemporal-thalamic network assumed in schizophrenia and are supported by additional functional neuroimaging, MRI morphometry, and neuropsychological evaluation. The combination of the described investigative techniques with MRS in follow-up studies may provide more specific clues for understanding the pathogenesis and disease course in schizophrenia.     

Proton MR spectroscopy in clinical routine

In vivo magnetic resonance spectroscopy (MRS) addresses metabolic pathways and their steady states in different tissue types. The brain has by tradition, and due to technical limitations in other organs, been one of the tissues most studied by MRS, and both 1H- and 31P-MRS have been used. Although 31P-MRS is outstanding for the evaluation of sources of metabolic energy in the brain, 1H-MRS has become the major clinically applied method in neurospectroscopy, as it provides information on markers of neuronal function, myelin, cell membranes, and metabolic active compounds. Furthermore, MR sensitivity is much greater for protons than it is for phosphorus and 1H-MRS, therefore allowing better spatial resolution. This review focuses on neurospectroscopy and diagnostic insights into diverse neurological problems provided by 1H-MRS applied as a clinical tool.     

肝细胞癌1.5T~1H-MRS波峰形态特征分析

目的:磁共振波谱(MRS)是目前唯一能从分子水平上非侵入性检测在体组织和器官代谢情况的磁共振功能成像技术。本研究采用单体素氢质子磁共振波谱(1H-MRS),观察、总结肝细胞癌(HCC)的波峰形态特征,探讨其在HCC诊断及鉴别诊断中的价值。资料和方法:对病理确诊的24例HCC和21例肝良性病变(6例肝腺瘤、3例FNH及12例血管瘤)患者行1H-MRS扫描,观察谱线的形态特征,并对结果进行记录和比较。结果:45例患者中有42例得到了可分析的谱线,波谱的成功率为93.3%(42/45)。15例HCC和2例肝良性病变获得宽大的Ⅱ型波峰(含"M"型波峰)。HCC组Ⅱ型波型的发生率高于肝良性病变组,差异有显著的统计学意义(P<0.01)。结论:HCC宽大的"M"型波峰具有一定的特征,对HCC的诊断具有一定参考价值。     

肝脏肿瘤的活体氢质子MR波谱和病理分析

目的 研究活体肝脏氢质子MRS(1H-MRS)评价肝脏局灶性病变的价值.方法 对53例肝肿瘤患者(54个直径＞4 cm的肿瘤)和19名正常志愿者进行1H-MRS检查,分别测量满足诊断需要的正常对照组(17名)和经病理证实的良性肝脏肿瘤组(8例)和肝细胞癌(HCC)组(25例)胆碱I唪/甘油三酯亚甲基峰(Cho/Lip)比值,对结果进行方差分析和两样本间Dunnett-t检验,并通过受试者工作特征(ROC)曲线评价1H-MRS诊断HCC的敏感性和特异性.结果 正常肝脏、良性肿瘤及HCC组的Cho/Lip比值分别为0.07±0.04、0.11±0.06和0.55±0.17(F=6.58,P＜0.05),HCC组高于正常对照组和良性肝脏肿瘤组(t值分别为2.99和2.32,P值均＜0.05),正常肝脏组和良性肿瘤组Cho/Lip比值差异无统计学意义(t=1.53,P＞0.05).ROC曲线下面积为0.77,1H-MRS对诊断HCC有较高诊断价值,当Cho峰与Lip峰比值界值点为0.1时,诊断HCC的敏感性和特异性分别为80.0%和62.5%.结论肝脏局灶性病变1H-MRS分析是可行的,对于鉴别IHCC和良性肝脏肿瘤有一定的临床参考价值.     

氢质子磁共振波谱成像在脑肿瘤中的临床应用

磁共振波谱(magnetic resonance spectroscopy,MRS)是可以无损伤性检测活体器官的组织代谢及化合物定量显示的技术,在形态成像的基础上,通过代谢成像提供被检测组织代谢物的化学信息,广泛的应用在脑肿瘤诊断中,技术也较为成熟,本文将1H-MRS的研究进展介绍如下。     

颞叶癫痫定位诊断的磁共振波谱研究

目的:探讨氢质子磁共振波谱(1H-MRS)对颞叶癫痫(TLE)定位诊断的应用价值.方法:选择15例经手术和病理证实的TLE患者和15例性别、年龄与之相匹配的健康志愿者为研究对象,分别作双侧颞叶内侧的1H-MRS,并对双侧海马区域进行精确定位,通过计算峰下面积,对代谢产物氮-乙酰天门冬氨酸(NAA)、肌酸(Cr)及胆碱复合物(Cho)的浓度进行相对定量分析.结果:采用Kappa检验,两位医师对海马硬化诊断的一致性K值=0.80(P＜0.05),表明一致性很好,MRI可对10例患者作出术前定位.MRS示TLE患侧组NAA/(Cho Cr)为0.37±0.07,对照组和TLE对侧组则分别为0.65±0.07和0.62±0.18,差异有显著性意义(F值为23.170,P＜0.05);MRS定位准确12例,另3例为阴性,结合MRI可对13例准确定位.结论:1H-MRS能敏感地探测到神经元的异常改变,为颞叶癫痫的术前定位提供了一种新的检查方法,其与MRI相结合可提高术前定位的准确率.     

Magnetresonanzspektroskopie bei Schizophrenie

Magnetic resonance spectroscopy is a noninvasive investigative technique for in vivo detection of biochemical changes in neuropsychiatric disorders for which especially proton (¹H-MRS) and phosphorus (³¹P-MRS) magnetic resonance spectroscopy have been used. In this review we explain the principles of MRS and summarize the studies in schizophrenia. A systematic literature review was carried out for ¹H-MRS studies investigating schizophrenic patients compared to controls. The inconsistent results in the cited studies may be due to different study population, specific neuroimaging technique, and selected brain regions. Frequent findings are decreased PME and increased PDE concentrations (³¹P-MRS) linked to altered metabolism of membrane phospholipids and decreased N-acetylaspartate (NAA) or NAA/choline ratio (¹H-MRS) linked to neuronal damage in frontal (DLPFC) or temporal regions in patients with schizophrenia. These results contribute to the disturbed frontotemporal-thalamic network assumed in schizophrenia and are supported by additional functional neuroimaging, MRI morphometry, and neuropsychological evaluation. The combination of the described investigative techniques with MRS in follow-up studies may provide more specific clues for understanding the pathogenesis and disease course in schizophrenia.     

大鼠弥漫性颅脑损伤磁共振波谱初步研究

目的 探讨磁共振波谱(MRS)揭示弥漫性颅脑损伤(DBI)的细胞代谢改变及早期动态演变的价值。材料与方法 以SD雄性大鼠为对象，自由落体法复制DBI动物模型，于损伤后4、8、24、48h行MRS检查(其中各鼠均于损伤前行MRS检查以作对照)，观察氮-乙酰天门冬氨酸(NAA)／肌酸(Cr)、胆碱(Ch♂)／Cr、NAA在DBI中随时间发展的演变过程。结果 与损伤前相比，DBI后4h下降显著，8、24h轻度回升；48h复又回落。各个观察时段Cho／Cr、NAA变化无统计学意义。结论 DBI^1H-MRS各项指标中，NAA／Cr较敏感。通过观测NAK／Cr的变化，可早期诊断DBI，且对病情的发展作出准确的估测。     

MR spectrsocopy of head and neck cancer

The aim of this review is to discuss the technique and potential applications of magnetic resonance spectroscopy (MRS) in head and neck cancer. We illustrate the technical issues related to data acquisition, post processing and interpretation of MRS of head and neck lesions. MRS has been used for differentiation of squamous cell carcinoma from normal tissue. The main potential clinical application of proton MRS (¹H-MRS) is monitoring patients with head and neck cancer undergoing therapy. Pretreatment prediction of response to therapy can be done with phosphorus MRS (³¹P-MRS). Although performance of MRS of head and neck is challenging, technological advances in both software and hardware has the potential to impact on the clinical management of patients with head and neck cancer.