对比剂对3T氢质子MR波谱的影响

目的 用高场MR仪研究对比剂是否会影响氢质子MR波谱(1H-MRS)的结果.方法 对22例颅内肿瘤患者分别于增强扫描前后行1H-MRS检查,比较扫描前后2次胆碱复合物(Cho)、肌酸(Cr)、N-乙酰天门冬氨酸(NAA)的峰下面积及Cho/Cr、Cho/NAA比值.结果 增强后Cho、Cr、NAA峰下面积分别为增强前的(86.7±27.3)%、(94.6±40.8)%、(113.8±74.5)%,NAA、Cr峰下面积增强前后差异无统计学意义(Z值分别为-0.601、-1.640,P值均＞0.05),Cho峰下面积较增强前明显缩小,差异有统计学意义(Z值为-2.520,P值＜0.05).Cho/Cr增强前为2.4±1.6、增强后为2.3±1.3,Cho/NAA增强前为2.5±1.8、增强后为2.1±1.5,增强前后差异均无统计学意义(Z值分别为-0.179、-1.408,P值均＞0.05).结论 对比剂不会影响1H-MRS的结果分析.     

3.0T MRI BOLD成像技术在评价正常大鼠肾脏氧含量的实验研究

目的 探讨3.0T MRI BOLD成像技术在评估正常大鼠肾脏氧代谢的价值.方法 29只SD大鼠麻醉后行3.0T MRI 常规及BOLD序列扫描,分别测量大鼠左右肾脏皮质、外髓及内髓的T2*值,从而计算R2*值(=1/ T2*值).结果 正常大鼠左右肾脏皮质R2*值分别为(28.84±3.11)s-1及(30.20±3.48) s-1;外髓R2*值分别为(32.77±3.07) s-1及(31.76±2.73) s-1;内髓R2*值分别为(28.37±2.80) s-1及(29.54±2.42) s-1.结论 磁共振BOLD成像技术可监测肾脏皮髓质氧代谢变化情况,从而评估肾脏疾病的功能损害程度.     

MRI DTI联合血氧水平依赖功能成像在星形细胞瘤术前的研究

目的探讨3.0T磁共振弥散张量成像(DTI)技术联合功能磁共振成像(fMRI)在星形细胞瘤与邻近脑白质纤维束解剖关系术前计划中的作用。方法对22例星形细胞瘤患者术前行常规MRI平扫,增强扫描及DTI技术fMRI检查,原始数据采集后进行图像分析处理,分别获得各项异性图(FA图),彩色编码张量图及脑白质纤维束图,并测定肿瘤的病灶区表观弥散系数(ADC值)及灶周水肿区各项异性分数(FA值)。分析肿瘤与相邻脑白质解剖关系,并对患者手术前后的临床症状进行评价。结果不同级别星形细胞瘤的肿瘤病灶区和灶周水肿区与正常白质区的ADC值和FA值存在差异,有统计学意义(P0.05﹚。白质纤维束可见受压、移位、浸润及破坏三种改变。4例Ⅰ~Ⅱ级星形细胞瘤推移相邻脑白质纤维束;8例Ⅱ~Ⅲ级星形细胞瘤侵润脑白质;10例Ⅲ~Ⅳ级星形细胞瘤破坏相邻脑白质纤维束。DTI图可以清晰显示运动区锥体束形态变化及与肿瘤之间的关系,在此基础上指导手术,效果满意。结论磁共振DTI技术联合fMRI是目前唯一在活体无创、三维清晰星形细胞瘤与周围白质纤维束的关系,由于二者的联合应用不仅能够显示大脑重要功能激活区在病理情况下的移位和改变,同时还能显示肿瘤与重要功能区和白质纤维束结构的关系,具有重要意义。     

功能MRI在评价对比剂诱导急性肾损伤中的研究进展

对比剂诱导急性肾损伤（CI-AKI）是注射碘对比剂后严重的并发症之一,早期诊断和治疗可以改善或延缓肾损伤。目前多种功能MRI（fMRI）技术可用于肾损伤后肾脏微循环和病理生理学的评估,包括扩散加权成像（DWI）、体素内不相干运动（IVIM）成像、扩散张量成像（DTI）、扩散峰度成像（DKI）、血氧水平依赖（BOLD）成像、动脉自旋标记（ASL）成像等。这些技术不但可以对肾功能损害进行定量分析,还可以在肾损伤的早期诊断和监测方面提供更多信息。就CI-AKI的发病机制及fMRI评价CI-AKI的研究现状做一综述。     

3.0T MR单源与多源发射技术对肝脏成像质量影响的对比研究

目的 探讨3.0T MR单源与多源发射技术对肝脏成像质量的影响.方法 回顾性分析107例行3.0 T MR肝脏扫描受试者的图像,检查序列包括频谱选择性衰减反转恢复T2WI( SPAIRT2WI序列、DWI以及平衡式快速场回波(Balanced FFE)序列.每一序列均在单源和多源的激发模式下进行双重采集,采用Student＇st检验比较单多源图像的均匀性与对比度,采用Wilcoxon秩和检验比较单多源图像质量的评分.2名放射科医师独立进行阅片,采用Kappa检验比较读片者之间的诊断一致性.结果 采用单源和多源发射技术测量图像的均匀性分别为418.40±66.75和416.26±50.61,多源发射技术图像均匀性优于单源发射技术,差异有统计学意义(=2.524,P＜0.05).单源和多源发射技术测得的信噪比(SNR)分别为20.36±11.21和22.03±12.16,对比噪声比(CNR)分别为15.22±8.95和18.33±10.01,差异均有统计学意义(t值分别为- 2.630和- 4.238,P值均＜0.05).多源发射技术图像对比度优于单源发射技术图像.SPAIR T2WI序列单源和多源发射技术图像质量评分分别为(1.40±0.42)和(1.81±0.27)分,DWI序列分别为(1.08±0.46)和(1.63±0.36)分,Balanced FFE序列分别为(0.95±0.45)和(1.65±0.37)分,多源发射技术图像质量在上述3个序列中均优于单源发射技术图像(Z值分别为-5.894、-5.801和-6.985,P值均＜0.01).2名评判医师之间的诊断一致性好(Kappa值均＞0.8,P值均＜0.05).结论 相对于单源发射技术来说,多源发射技术能够消除电解质阴影,提供更好的图像均匀性、更高的图像对比度和更佳的图像质量,3.0T多源技术在腹部成像上具有很明显的优势.     

MRI血氧水平依赖成像评价正常大鼠肾脏氧合水平的重复性研究

目的 探讨用MR血氧水平依赖(BOLD)成像评价大鼠肾脏氧合水平的重复性和科学性.方法5只健康雄性Wistar大鼠,扫描前称量大鼠体重,在3.0 T MR扫描仪上分别在第1天(d1)、第5天(d5)、第10天(d10)、第30天(d30)和第50天(dS0)行BOLD成像,测量表观自旋-自旋弛豫率(R2*).在d30和d50扫描完成后,注射呋塞米10 min后再次扫描,计算注药前后R2*的差值(△R2*).对5次扫描的R2*进行重复测量方差分析,对d30和d50注射呋塞米前后的皮、髓质R2*和皮、髓质△R2*进行配对t检验,观察呋塞米对皮、髓质R2*的影响并评价△R2*的重复性.结果d1、d5、d10、d30和d50大鼠体重分别为(150.4±3.7)、(170.2±7.0)、(201.0±5.8)、(306.2±17.0)和(352.0±12.2)g,差异有统计学意义(F=422.103,P＜0.01);肾脏皮、髓质R2*值差异均无统计学意义(P＞0.05).d30皮、髓质R2*在注射呋塞米前分别为(25.2±1.2)和(32.8±2.2)Hz,注射后分别为(21.1±2.2)和(25.9±3.0)Hz,皮、髓质R2*在注射呋塞米后均降低(P＜0.01);d50皮、髓质R2*在注射呋塞米前分别为(25.9±0.8)和(34.3±3.9)Hz,注射后分别为(20.2±1.5)和(27.0±3.2)Hz,皮、髓质R2*在注射呋塞米后均降低(P＜0.01).d30皮、髓质△R2*值分别为(4.1±1.7)和(6.9±2.8)Hz,d50皮、髓质△R2*值分别为(5.8±1.1)和(7.3±2.8)Hz,2次检查皮、髓质的AR2*差异均无统计学意义(P＞0.05).结论 大鼠肾脏皮、髓质基础R2*值在50 d内稳定,不受体重影响;在3.0 T MR上,应用呋塞米后大鼠肾脏皮、髓质R2*值均降低.     

血氧水平依赖磁共振成像评价肾脏铁过载的初步研究

目的:通过MR血氧水平依赖成像(BOLD)初步评价兔肾脏铁过载病理变化的可行性.方法:将24只纯种健康新西兰大白兔随机分为对照组(n=12)和铁过载组(n=12).铁过载组兔经后腿肌内注射右旋糖酐铁(60mg/kg),对照组后腿肌内注射同等剂量0.9％生理盐水,分别于建模后即刻(0周)及第12周对2组兔行左肾MR扫描,...     

乙二胺四乙酸铁钠作为MRI口服胃肠道对比剂的实验研究

目的:研究乙二胺四乙酸铁钠溶液作为MRI口服胃肠道对比剂的可行性.方法:以乙二胺四乙酸铁钠溶液作为对比剂进行体外试验,根据浓度不同分10个等级进行T1 WI、T2 WI、PDWI和单次激发厚层水成像扫描,所得图像与水为对比剂时得到的图像作对比研究.结果:乙二胺四乙酸铁钠溶液浓度在7.5～10 mmol/l时各个序列增强效果均较佳,在T1 WI、PDWI表现为高信号,在T2 WI表现为低信号.结论:乙二胺四乙酸铁钠溶液可以作为MRI口服胃肠道对比剂.     

肾脏MR血氧水平依赖成像的研究进展

MR血氧水平依赖成像主要用于中枢神经系统,近年来其在肾脏方面的研究逐渐成为热点,就血氧水平依赖在肾脏方面的应用技术、试验研究及临床应用方面的成果作一综述.     

肾脏MR血氧水平依赖成像的研究进展

MR血氧水平依赖成像主要用于中枢神经系统,近年来其在肾脏方面的研究逐渐成为热点,就血氧水平依赖在肾脏方面的应用技术、试验研究及临床应用方面的成果作一综述。     

MRI T-staging of laryngeal tumours: role of contrast medium

Our aim was to evaluate the relative diagnostic accuracy of MRI without contrast medium and MRI before and after contrast medium in the assessment of T-staging of laryngeal tumours. We studied 25 men (mean age 51.8, range 41–61) with laryngeal squamous cell carcinomas, using Spin-echo (SE) T1-weighted and fast SE T2-weighted sequences. The T1-weighted sequences were then repeated after gadolinium-diethylene-triaminepenta-acetic acid (Gd DTPA) 0.1 ml/kg. All patients then underwent biopsy and surgery. Two radiologists independently assessed the anonymised images by filling-out two multiple-choice forms, one for each technique, at a 2 week interval. The forms included a judgement concerning tumour identification and infiltration of the anterior commissure, supraglottic region, arytenoid cartilage, Morgagni's ventricle, paraglottic space, thyroid and cricoid cartilages, thyro-hyo-epiglottic space, vocal cords, subglottic region, and epiglottis. Similar forms were filled out by the surgeon and the pathologist after surgery. The sensitivity, specificity and diagnostic accuracy of MRI were unaffected by the use of contrast medium. Since it did not provide additional staging information, its continued routine use in these cases is not justified. Received: 13 November 1998/Accepted: 6 April 1999     

Gadodiamide injection as a contrast medium for MRI of the central nervous system: a comparison with gadolinium-DOTA

The tolerance and diagnostic efficacy of a new nonionic, intravenous MRI contrast medium, gadodiamide injection (Omniscan^®) are reported and compared with those of gadolinium-DOTA after completion of a double-blind, randomized, parallel study in 60 patients using a dose of 0.1 mmol/kg. Two patients were excluded from the statistical analysis after trial entrance since no contrast medium was injected. The indications for the MRI examination were known or suspected CNS lesions. Vital signs, chemical and haematological parameters were monitored. No significant abnormalities were observed, confirming the excellent tolerance of both contrast media. The usefulness of gadolinium-containing contrast media was again documented, since in 8.6% (5/58) of the patients the lesion(s) could be seen only after injection. Contrast enhancement was seen in 87.8% (43/49) of the patients with abnormal findings, and provided additional diagnostic information in 24.5% (12/49). Lack of contrast enhancement in 12.2% (6/49) of patients with abnormal findings was a significant negative finding.     

大剂量对比剂团注在MRI检查中应用

目的：探讨大剂量对比剂注射器团注在脑转移瘤及其血管成像中的临床意义。方法：对35例脑转移瘤患者行MR平扫和增强扫描作为对照，其中26例脑转移瘤患者增强扫描分别采用单剂量手推方式注射(10ml和大剂量注射器团注，并对图像做对比分析。对22例体部血管病变患者和15例肝、肾移植患者及供体行常规扫描后的增强血管成像(enhancedMRA)。快速大剂量团注(20～40ml扫描以1．5～3ml／s流率经上肢大静脉注射造影，造影前根据病灶和血管大小，首先预设置流率、流量及注射时间，再对所选择的病变区域或血管行快速动态扫描和延迟扫描。结果：35例均已确诊有原发病灶的脑转移瘤忠者中23例经手术病理证实，12例经活检病理证实。19例体部血管病变经DSA证实。所有检查均获成功，且大剂量注射器团注组对病变显示优于小剂量手推组。结论：大剂量的注射冕团注能更清晰显示病灶数目和病灶大小、数目和病灶内钙化、坏死以及供给血管情况，为临床提供精确的诊断。     

Gd-EOB-DTPA与Gd-DTPA增强MR对肝硬化患者肝血管和肝实质增强效果的自身对照研究

【摘要】目的：自身对照比较Gd-EOB-DTPA与Gd-DTPA增强MR对肝硬化患者的肝动脉、门静脉和肝实质强化效果的差异。方法：回顾性分析35例肝硬化患者的Gd-EOB-DTPA与Gd-DTPA增强MR图像,计算肝总动脉、门静脉和肝实质的强化比率（PE）和肝总动脉、门静脉与肝实质的相对对比度（RC）,并统计是否存在差异。结果：Gd-EOB-DTPA增强MR肝总动脉、门静脉的平均PE明显低于Gd-DTPA（P<0.05）。Gd-EOB-DTPA的门脉期肝实质的平均PE明显低于Gd DTPA（P<0.05）而动脉期肝实质的PE值无明显差异（P=0.1010）。肝总动脉、门静脉与肝实质的RC值Gd-DTPA增强MR略高于Gd-EOB-DTPA,但是无明显统计学差异（P分别为0.3421和0.2389）。结论：肝硬化患者Gd-EOB-DTPA增强MR的肝血管和肝实质效果低于Gd-DTPA, Gd-EOB-DTPA的剂量需要进一步调整。     

BOLD-fMRI技术在心肌缺血中的研究进展

血氧水平依赖功能MRI成像(BOLD-f MRI)技术已经成为心肌无创检查的重要方法之一。已有研究证实其评估心肌缺血具有较高的准确性和可靠性。随着MRI设备的发展及扫描序列的优化,BOLD-f MRI技术不仅实现了对心肌缺血的定量评估,而且可以对存活心肌进行无创检出。     

CO2 as a distending medium for gastric and small bowel MRI: a feasibility study

This work evaluates carbon dioxide as a contrast medium for magnetic resonance imaging of the stomach and small bowel. Twelve healthy volunteers underwent rapid magnetic resonance imaging after oral administration of a carbon dioxide generating agent using a combination of breath-hold and interactive fluoroscopic imaging during breathing. Diagnostic-quality images were obtained in 100% of cases for the stomach and in 92, 75, 67 and 42% of cases for the duodenal segments 1–4, respectively. Visualisation of the jejunum and ileum proved unacceptable for clinical use and anti-peristaltic agents did not significantly influence the results. Further development of fast imaging and magnetic resonance interactive fluoroscopic methods may allow the use of carbon dioxide as a contrast medium for clinical imaging of the stomach and duodenum.     

Low-field interventional MRI in neurosurgery: finding the right dose of contrast medium

MRI is increasingly being used as an interventional tool in neurosurgery. The field strength of “intraoperative” MR systems is usually lower than that of imagers commonly used for diagnostic purposes. However, lesion enhancement and apparent lesion extent depend on field strength. The aim of this study was to compare the contrast between intracranial, contrast-enhancing space-occupying lesions and the surrounding white matter obtained with low-field (0.2 T) and high-field (1.5 T) MR imaging and to find the contrast medium dosage for low-field MRI that produces the same lesion-to-white-matter contrast as the one obtained with high-field MRI after the administration of a standard dose of the contrast medium. A total of 38 patients with intracranial metastases or high-grade glioma were enrolled in this study. T1-weighted spin-echo sequences were acquired. High-field (1.5 T) studies were performed after the i. v. administration of 0.1 mmol gadolinium-DTPA /kg body weight. For low-field MRI (0.2 T) a dose escalation technique was used. T1-weighted sequences were repeated after each of three i. v. injections of 0.1 mmol gadolinium-DTPA/kg body weight. Thus, at the low-field examinations three T1-weighted sequences with a contrast medium dosage of 0.1, 0.2 and 0.3 mmol gadolinium-DTPA /kg body weight were obtained. Lesion-to-white-matter contrasts were calculated and compared. The average lesion-to-white-matter contrast obtained with high-field MR examinations was 1.63 (standard deviation 0.32). In the low-field MR examinations the average lesion-to-white-matter contrast was 1.34 (0.2) after a single dose, 1.57 (0.2) after a double dose, and 1.71 (.19) after a triple dose of contrast medium. The lesion-to-white-matter contrast of the high-field MR examination after a single dose of contrast medium was significantly higher than that of the low-field study after a single dose (P < 0.0001), but did not differ significantly from the low-field studies after a double (P = 0.28) or a triple dose (P = 0.17) of contrast medium. In a series of patients with contrast-enhancing space occupying brain lesions low-field MRI (0.2 T) after a double dose of contrast medium yielded the same lesion-to-white-matter contrasts as high-field MRI (1.5 T) after a standard dose. This is an important finding to avoid errors in intraoperative MRI due to the immanently lower degree of lesion enhancement in low-field MR imaging. Received: 14 September 1999 Accepted: 15 February 2000