16层螺旋CT及其三维重建与多平面重组在胫骨平台骨折诊断中的应用

目的探讨16层螺旋CT(16层SCT)及其三维重建(3-D)与多平面重组(MPR)在胫骨平台骨折诊断中的应用价值。方法39例胫骨平台骨折病例经膝关节常规X线平片检查后，采用16层SCT进行膝关节的多层面螺旋CT扫描，在工作站上作3D及MPR影像后处理，就胫骨平台骨折的平片与16层SCT影像进行比较及综合分析。结果39例胫骨平台骨折中，X线平片漏诊1例髁间隆突骨折、1例内髁骨折及1例双髁骨折，此3例(7．69％)平片漏诊的骨折均为16层SCT予以诊断。16层SCT的3-D影像可清晰显示胫骨平台骨折的立体形态；MPR影像则可明确显示胫骨平台内部的骨质损伤情况如骨折的具体部位、关节面碎裂及塌陷程度、骨折移位距离。结论16层SCT能够显示X线平片难于诊断的胫骨平台隐匿性骨折；3-D及MPR成像技术十分有利于全面观察胫骨平台骨折的形态变化，是16层SCT横轴位扫描的重要补充。     

Cardiac metabolism: A technical spectrum of modalities including positron emission tomography,single-photon emission computed tomography,and magnetic resonance spectroscopy

Noninvasive techniques for the assessment of cardiac metabolism are important for the detection of potentially salvageable tissue in jeopardized areas of the myocardium. The correct identification of hibernating and stunned myocardium in patients with severely depressed cardiac function can have vital therapeutic consequences for the patient. Changes in myocardial fatty acid and glucose metabolism during acute and prolonged ischemia can be traced by positron-emitting or gamma-emitting radiopharmaceuticals. Alternatively,³¹P-labeled magnetic resonance spectroscopy can be used for the assessment of high-energy phosphate metabolism. It is not yet clear which modality will emerge as the most useful in the clinical setting. Positron emission tomography (PET) that uses combinations of flow tracers and metabolic tracers offers unique opportunities for quantification and high-resolution static and rapid dynamic studies. Currently, assessment of glucose metabolism with¹⁸F-fluorodeoxyglucose is regarded as the gold standard for myocardial viability and prediction of improvement of impaired contractile function after revascularization. However, preserved oxidative metabolism may be required for potential functional improvement, and therefore assessment of residual oxidative metabolism by¹¹C-labeled acetate PET may prove to be more accurate than¹⁸F-fluorodeoxyglucose PET, which reflects both anaerobic and oxidative metabolism. Moreover, because fatty acids are metabolized only aerobically, they are excellent candidates for the clinical assessment of myocardial viability and prediction of functional improvement after revascularization. Especially derivatives of fatty acids that are not metabolized but accumulate in the myocyte are attractive for myocardial imaging. Examples are¹²³I-beta-methyl-p-iodophenyl pentadecanoic acid and 15-(o-¹²³I-phenyl)-pentadecanoic acid. These tracers can be detected by planar scintigraphy and single-photon emission computed tomography, which are more economical and widely available than PET. In addition, 511 keV collimators have been developed recently, making the detection of positron emitters by planar scintigraphy and single-photon emission computed tomography feasible. The experience with³¹P-labeled magnetic resonance spectroscopy in humans is still limited. With current magnetic resonance spectroscopic techniques, insufficient spatial resolution is achieved for clinical purposes, but the possibility of serial measurements to monitor rapid changes of phosphate-containing molecules in time makes magnetic resonance spectroscopy very valuable for the research of myocardial metabolism.     

Early embryonic expression patterns of the mouse Flamingo and Prickle orthologues.

The Drosophila melanogaster proteins Flamingo and Prickle act in the planar cell polarity (PCP) pathway, which is required for acquisition of epithelial polarity in the wing, eye, and epidermis. In mammals, PCP signaling has been shown to regulate cell movements and polarity in a variety of tissues. Here, we show that the murine Flamingo orthologues Celsr1-3 and the Prickle orthologues Prickle1, Prickle2, and Testin have dynamic patterns of expression during pregastrulation and gastrulation stages. Celsr1 is expressed in the anterior visceral endoderm and nascent mesoderm, Celsr2 and Celsr3 mark the prospective neuroectoderm, Prickle1 is expressed in the primitive streak and mesoderm, Prickle2 in the node, and Testin in the anterior visceral endoderm, the extraembryonic ectoderm, primitive streak, and mesoderm. Analysis of a gene-trap mutation in Testin indicates that this gene is not required for embryogenesis; therefore, other Prickle homologues may compensate for its function during development.     

pH modulates conducting and gating behaviour of single calcium release channels

Intracellular pH changes affect excitation-contraction coupling in skeletal, and cardiac muscles. However the proton implication in modulating the sarcoplasmic reticulum Ca²⁺ release channel activity has never been visualized at single channel level. A large conducting Ca²⁺ release pathway has previously been characterized after incorporation of skeletal and cardiac sarcoplasmic reticulum vesicles into planar lipid bilayers. This channel has been activated by micromolar and millimolar concentrations of Ca²⁺ and ATP, respectively. The pH was independently varied on each side of the channels. Acidification of the cis-chamber (7.4 to 6.6) induced a modification of the gating behaviour, resulting in a decrease of the open probability. This effect was completely reversible. On the other hand, acidification of the trans-chamber (7.4 to 6.8) induced a reduction of the unitary conductance of the sarcoplasmic reticulum Ca²⁺ release channel.     

基于图像域的Ghost伪影自动相位校正

回波平面成像过程中会产生Ghost伪影.抑制Ghost伪影的常用方法是利用参考扫描对实际扫描图像进行校正.本研究提出了一种无须参考扫描且基于图像域的自动相位校正方法.这种方法是对含伪影的图像作二维傅里叶变换,利用变换后的奇偶行数据分别重建图像以求取成像过程中奇偶回波之间的相位偏移.利用线性拟合或Marquardt-Levenber非线性拟合得到的无卷褶相位值对伪影图像进行校正,能有效抑制Ghost伪影.     

A survey of different high resolution visualization modes of a volumetric object with applications

Summary In view of the variety of 3D representation techniques, a clinical study was carried out in order to evaluate their respective usefulness. It appears that a single technique cannot be claimed to be valid for all clinical situations and that a combination of representations brings more relevant information. Among the different techniques a clear delineation must be established between those which allow the accurate definition of landmarks (multiplanar reformation, surface representation), and those which do not (integral shading, reconstructed radiology). The main point is the possibility to recognize anatomical landmarks on these latter modes and to choose oblique cut planes in relation to them. Visualization quality is strongly dependent upon the acquisition protocol which must provide a spatial resolution as isotropic as possible.

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Une revue de différents modes de visualisation en haute résolution d'un objet volumique avec des applications

Résumé Face à la variété des techniques de représentation 3D une étude clinique a été conduite pour évaluer leurs utilités respectives. Il apparait qu'une technique unique ne peut pas convenir à toutes les situations cliniques et qu'une combinaison de différents modes de présentation apporte une information plus pertinente. Parmi les différentes techniques une distinction claire doit être établie entre celles qui autorisent la prise de repères précis (reformatage multiplanaire, représentation de surface), et celles qui ne le permettent pas (ombrage intégral, radiologie reconstruite). Le point principal est la possibilité de reconnaître des repères anatomiques sur ces derniers modes et de choisir des plans de coupe en relation avec eux. La qualité de la visualisation dépend étroitement du protocole d'acquisition qui doit fournir une résolution aussi isotrope que possible.

     

肝外胆管梗阻病变MSCT曲面重建胆管成像与MRCP的比较研究

目的比较多层螺旋CT（MSCT）曲面重建（CPR）胆管成像与磁共振胰胆管成像（MRCP）对肝外胆管梗阻病变的诊断价值。方法66例经B超检查提示有肝外胆管梗阻病变的患者，采用单次激发快速自旋回波（SSFSE）序列，行MRCP检查，同期采用10mm层厚层距，使用血管对比剂，行MSCT增强扫描，将门静脉期图像采用2．5mm层厚、1．25mm层距重建，获得轴面源像（ASI），数据传输至图像工作站，作CPR胆管成像。比较CPR胆管成像、MRCP对肝外胆管梗阻病变的定位、定性诊断价值。结果CPR胆管成像、MRCP成功率为100％；CPR胆管成像、MRCP均对肝外胆管梗阻部位做出明确诊断，定位诊断率为100％；CPR胆管成像、MRCP定性诊断率分别为95．5％和80．9％。结论CPR胆管成像、MRCP对肝外胆管梗阻病变均能明确定位，CPR胆管成像定性诊断率明显高于MRCP，CPR胆管成像显示胆管及其周围病变与扩张胆管的关系更直观。     

关于我国医疗卫生改革的思考和建议

本文总结了当前我国医疗卫生系统存在的问题,并对其产生原因进行了分析,从而针对这些问题提出了对我国医疗卫生改革的建议.     

中山大学药学院药学专业课程体系的改革

介绍了中山大学药学院在药学专业培养目标与教学计划、教学内容与课程体系等方面进行的改革,为综合性大学药学专业的课程体系改革提供了一定的思路和借鉴。     

Webquest样式的医学伦理学课程教学改革试验

网络时代的高速发展和建构主义学习理论的兴起引发了以Webquest样式为主的网络教学改革。Webquest样式的网络教学实践离不开网络教学目标的精心分析，网站学习内容的合理设计以及网菇教学模块的科学编排。Webquest样式的采用是对网络环境下探究式学习的有益尝试；有利于提高医学生的综合素质；有利于师生关系的重塑。