New Directions in NMR Imaging

Spectroscopic NMR imaging, microscopic NMR imaging, and the NMR imaging of gases are under development and may have significant applications in biomedical research and clinical investigations.     

Electronics and Instrumentation for NMR Imaging

The development of Nuclear Magnetic Resonance (NMR) imaging has brought together the experimental techniques of NMR spectroscopy and image processing with the consequence that new experimental requirements and apparatus are currently being developed. Examples of these requirements include the large amounts of data which can be generated and the effect on data processing and storage requirements. Also, the increased size of objects under investigation necessitate some major changes in the magnet and r.f. system. A discussion of these specific requirements is presented together with an overview of all components of the NMR imaging system.     

Zeugmatography by Reconstruction from Projections

Nuclear magnetic resonance (NMR) zeugmatographic imaging may be accomplished in a number of ways. Reconstruction from projections offers several advantages when compared with those techniques that depend upon transient perturbations of the NMR response. The generation of either two- or three-dimensional images is possible, and the effects of differences in relaxation times and spectroscopic properties may be incorporated into the experiment. Complete three-dimensional reconstruction is an especially efficient imaging method, and some examples of such images are shown.     

Study of R.f., Gradient Pulse and Magnet Instability Effect in NMR Tomography

Newly emerged NMR imaging requires careful studies on r. f. pulse shapes and sequencing for the selection of the region, gradient pulsing for the 2- or 3-D spatial coding, and suitable signal handling technique for the compensation of the inherent instability of the system, especially fluctuation of the static magnetic field. Above subjects are discussed in detail and a new method which would be useful for the line integral projection reconstruction is proposed. The method could equally be applied to other 3-D NMR imaging techniques such as KWE (Kumar-Welti-Ernst) direct Fourier reconstruction or planar integral projection type reconstruction.     

Physical Basis of Nuclear Magnetic Resonance Imaging

NMR imaging is based on the ability to induce and monitor resonance of the magnetic moment of nuclei in the presence of magnetic fields. By the use of magnetic fields whose strength varies with position, it is possible to define both the location and concentration of resonant nuclei, and, thereby to create images that reflect their distribution in tissue. Hydrogen, because it is the most sensitive of the stable nuclei to NMR and because it is also the most abundant nucleus in the body, is ideally suited for NMR imaging.     

Limited Angular View Planar-Integral Projection Reconstruction in NMR Imaging

Limited angular view planar-integral projection reconstruction for fast multislice imaging in NMR is proposed and its efficacy is studied. Alghough it is known that the planar-integral projection reconstruction (PPR) method has advantages in signal to noise ratio improvement in NMR imaging, necessary data acquisition time is too long to be of practical value. In this paper, a study is undertaken on the variations of the PPR method which would lead to a shorter data acquisition time than the orginal PPR method. Also a new method which provides high quality multislice images through the use of limited angular view data acquisition mode is introduced. Computer simulation results and experimentally obtained images are presented for the demonstration of the potential of the method for clinical applications.     

N_2S_2或N_3S型配体的合成、~(99)Tc~m标记及生物分布研究

以MAG3为基本分子骨架，根据构效关系，分别引入合适的天然氨基酸，设计合成了4种N2S2或N3S型小分子多肽新配体，并通过了IR，^1H NMR,^13C NMR,MS谱学鉴定和元素分析表征。采用葡庚糖酸钙（GH）交换法对4个配体进行了^99Tc^m标记，研究了配合物在小鼠体内的生物分布特征。结果表明，^99Tc^m-MVGG肾摄取较高，滞留时间较长，血清除快，且肾与其它组织的活度比值高，具备成为肾功能显像剂的条件；^99Tc^m-MPGG肾初始摄取较高，R（肾／血）活度比值高，但肾清除较快，R（肾／肝）活度比值较低；^99Tc^m-MVTC和^99Tc^m－MPTC心肌初始摄取均较高，但在心肌和血中的清除速度较快。     

99Tcm-MAG2-Ade肿瘤显像剂的合成及其生物活性研究

为了制备肿瘤显像剂^99Tc^m标记肽,合成并表征了新的碱基修饰的小肽配体9-[N-(S-三苯甲基巯基乙酰)二甘氨酰氨基乙基]腺嘌呤(Tr—MAG2-Ade)。通过直接标记法得到了水溶性配合物^99Tc^m-MAGz—Ade,并对其体外稳定性进行了检测。在荷瘤小鼠体内的生物分布结果表明,^99Tc^m-MAGz—Ade在肿瘤中有较高的摄取,肿瘤与肌肉的摄取比为5．7,肿瘤与血液的摄取比为1．55。血液清除较快,有望用于非腹部肿瘤的显像。     

四(2-甲氧基异丁基异腈)络铜(Ⅰ)氟硼酸盐的合成和~(99)Tc~m-2-甲氧基异丁基异腈制备研究

本文报道了四[2-甲氧基异丁基异腈]络铜(Ⅰ)氟硼酸盐(Cu(MIBl)_4BF_4)的合成和心肌灌注显像剂~(99)Tc~m-2-甲氧基异丁基异腈(~(99)Tc~m-MIBl)的制备研究及初步动物实验结果。Cu(MIBI)_4BF_4是一白色晶体,经IR,NMR,MS和元素分析等测定,结果与结构完全一致。讨论了pH值、Cu(MIBI)_4BF_4用量、FSA用量及~(99)Tc~mO_4~-洗脱液体积、加热时间对~(99)Tc~m-MIBI标记率的影响。以Cu(MIBI)_4BF_4为原料制成的一步法冻干药盒,标记率大于90％,经动物实验和初步临床应用,证明该药盒使用简单方便,稳定性好,是很有前途的心肌灌注显像剂。     

单轴载荷下岩石核磁共振特征的实验研究

对岩石在单轴载荷下的核磁共振(NMR)特征进行了实验研究.选取两组砂岩和一组人工烧结陶瓷实验样品,在轴向施加压力作用改变岩石的孔隙结构,然后进行核磁共振谱测量,分析岩石在加压前后核磁共振谱和谱面积的变化特征.实验结果表明,由于外加载荷改变了岩石的孔隙结构,岩石的核磁共振谱产生明显的变化,其中横向弛豫时间T2谱面积是反映岩石孔隙结构变化的一个重要参数.     

核磁共振测井与核磁共振录井对比分析

石油工程中的核磁共振技术是利用油和水中的氢原子在磁场中具有共振并产生信号的特征来探测和评价岩石特性。核磁共振测井是在井筒中测量井周地层的物性参数,核磁共振录井是在地面（钻井现场）分析岩心、岩屑和井壁取心的物性参数（随钻分析）。对同一深度13口井中的核磁共振测井孔隙度、渗透率参数与核磁共振录井分析岩心、岩屑和井壁取心样品得到的孔隙度、渗透率参数进行对比分析表明,两者虽存在一定差异,但整体有较好的趋势一致性。     

三种核磁共振测井仪器的比较

目前国内商业应用的核磁共振测井仪器主要有三种:Schlumberger公司的CMR仪器,Baker hughs公司的MREx仪器,Halliburton公司的MRIL-P仪器.在文献调研的基础上,对这三种核磁共振测井仪器的结构、信息采集的特点、主要性能指标以及在主要储层参数计算方面的不同进行了对比,得出了三种仪器的优势应用条件.     

致密砂岩气藏核磁共振测井与常规测井的孔与渗透模型关系

为建立良好的测井物性解释模型,以更准确地评价塔巴庙地区上古生界盒3段致密砂岩气藏产能,对比了14块岩样的核磁孔隙度与其岩心孔隙度,发现它们有线性相关性;对比核磁渗透率与岩心渗透率,也获相同结果.这表明核磁孔渗与常规孔渗线性相关.以此为依据,以核磁共振测井的孔渗为桥梁,以常规测井数据为基础,建立了常规测井的孔、渗计算模型.所建模型既避免了取心位置与常规测井之间深度的不一致性,又不会存在因岩心数据的不连续而带来的岩心孔渗模型计算值应有的误差,所以它更适合于盒3段储层孔渗的评价.     

Experimental investigation of natural circulation instability in a BWR-type small modular reactor

The Purdue NMR (Novel Modular Reactor) represents a BWR-type small modular reactor with a significantly reduced reactor pressure vessel (RPV). Specifically, the NMR is one third the height and area of a conventional BWR RPV with an electrical output of 50 MWe. Experiments are performed in a well-scaled test facility to investigate the thermal hydraulic flow instabilities during the startup transients for the NMR. The scaling analysis for the design of natural circulation test facility uses a three-level scaling methodology. Scaling criteria are derived from non-dimensional field and constitutive equations. Important thermal hydraulic parameters, e.g. system pressure, inlet coolant flow velocity and local void fraction, are analyzed for slow and fast normal startup transients. Flashing instability and density wave oscillation are the main flow instabilities observed when system pressure is below 0.5 MPa. And the flashing instability and density wave oscillation show different type of oscillations in void fraction profile. Finally, the pressurized startup procedure is recommended and tested in current research to effectively eliminate the flow instabilities during the NMR startup transients.     

石油工程中的核磁共振技术

石油工程中的核磁共振技术包括核磁共振测井技术、核磁共振录井技术、随钻核磁共振技术以及利用核磁共振技术进行流体识别的模块式地层测试技术等.限于篇幅,本文仅从核磁共振(NMR)测井与录井技术在储层物性评价、储层流体识别、完井方案选取、试油层位确定、地层压力预测等方面的成功案例进行分析,说明NMR技术在石油工程中的地位和作用越来越重要.     

核磁共振测定皮质醇等八种氚标记化合物中氚的位置及其相对含量

本文阐述了核磁共振测定皮质醇等八种氚标记化合物中氘在分子中的位置及相对含量。用氚核磁共振(~5H-NMR)测定具有无损、快速、准确的特点,可用于化学反应过程中催化剂的选择及反应机理的研究。采用JEOL的FX-100型核磁共振波谱仪测定氚标记化合物样品,一般取样置10～30mCi可获得满意的图谱。     

多靶分子影像学及其研究进展

多靶分子影像学是分子影像学极其重要的研究领域和发展方向.多靶分子影像学技术(多靶分子显像)包括多种显像剂-多靶分子显像、融合分子多靶显像、偶合分子多靶显像、多靶多功能分子显像.对多靶分子显像及其显像模式进行了较详尽阐述,尤其是对多靶正电子发射断层(PET)显像进行了较深入的探讨与研究.     

99m显像剂的研究

成了一种新的含有SNN结构的三齿配体N'-(2巯基-2-甲基异丙基)-N,N-二乙基乙二胺(MDEDA)。用99 mTc-葡庚糖配体交换法与不同的单齿硫醇制备了4种99mTc的3+1混配配合物,标记率均大于90%。对标记率的影响因素如pH、温度等作了探讨,并作了小鼠体内的分布实 验和家兔的SPECT显像。实验表明这些配合物在血中的摄取和滞留远远超过了其他脏器,其中以配合物5c的血滞留最好,有望达到血池显像剂的要求。     

~(99m)Tc标记“3 1”混合配体心血池显像剂的研究

合成了一种新的含有ＳＮＮ结构的三齿配体Ｎ＇－（２巯基－２－甲基异丙基）－Ｎ,Ｎ－二乙基乙二胺（ＭＤＥＤＡ）。用９９ｍＴｃ－葡庚糖配体交换法与不同的单齿硫酸制备了４种９９ｍＴｃ的“３＋１”混配配合物,标记率均大于９０％。对标记率的影响因素如ｐＨ、温度等作了探讨,并作了小鼠体内的分布实验和家兔的ＳＰＥＣＴ显像。实验表明这些配合物在血中的摄取和滞留远远超过了其他脏器,其中以配合物５ｃ的血滞留最好,有望达到血池显像剂的要求。     

肿瘤核素诊治现状与进展

对近年来肿瘤核素诊治现状及进展进行了论述，着重介绍了放射性核素非特异性亲肿瘤显像，肿瘤代谢显像、乏氧显像、多耐药显像，肿瘤前哨淋巴结显像和肿瘤放射免疫显像与放射免疫治疗、肿瘤受体显像与受体介导靶向治疗、基因表达显像与基因治疗及肿瘤分子显像探针等应用研究的进展。