衍射增强成像与成像应用实验

目的:目前的常规X线医学成像是通过吸收衬度成像,但分辨率不够高,由于DEI采用相位衬度机制而不是依赖于物体的吸收,故适合弱吸收组织尤其是软组织成像。本实验旨在评价DEI在生物医学样品成像中的诊断价值。材料和方法:大鼠脏器样品切片,在BSRF的4W1A束线上进行DEI方法成像。首先扫描获得摇摆曲线,再选择摇摆曲线上不同位置进行成像,成像结果与常规吸收像进行对照,分辨率通过显微放大法获得。结果:图像能显示常规医学X成像方法无法显示的肝脏微细结构,分辨率达到微米。结论:DEI的优良分辨率和衬度将有望改进生物医学组织的影像诊断水平。     

应用类同轴技术开展肾脏相位成像的实验研究

目的:应用同步辐射光源的相干性,进行肾脏组织的类同轴成像研究,旨在评价相位衬度成像技术在软组织成像方面的意义.方法:在北京同步辐射装置形貌站4W1A束线上,取经过4%甲醛溶液固定后的人体肾脏组织样品,置于类同轴光路的样品架上进行成像,以空间分辨率和组织衬度作为评价标准.结果:在样品与成像板距离Z为150mm获得的肾脏成像,具有较高的组织衬度,包括肾小囊在内的结构均能较好显示,通过显微放大法获得的空间分辨率达到30μm.结论:类同轴技术能较好显示肾脏的微细解剖结构,对于以轻元素为主的脏器成像有较好的应用价值.     

同步辐射衍射增强成像技术应用于小鼠肾脏的成像实验

目的:不同于常规的吸收成像,相位衬度成像可以获得更高的衬度分辨率、显示更多的微细结构信息,尤其适合于轻元素(含氮、氢成分较高的组织)显示,本实验通过对小鼠肾脏组织的成像研究,旨在评价应用同步辐射相位衬度成像技术在软组织成像诊断上的价值。方法:在北京同步辐射装置形貌站4W1A束线上,设计衍射增强成像实验(DEI)光路,取经过福尔马林固定后的小鼠肾脏组织样品(根据光斑尺寸做适度切除),置于光路的样品架上进行成像,以空间分辨率和组织衬度作为评价标准。结果:在衍射增强(DEI)中腰位成像获得较好的对比度及图像衬度,可以显示包括肾小球结构在内的肾脏微细结构;采用333Si分析晶体要比111Si衬度明显提高。结论:衍射增强成像技术能较好显示肾脏的微细解剖结构,对于以轻元素为主的脏器成像有较好的应用价值,而对于适龄和老龄的肾脏之间存在着的血管模式、形态上的差异在某种程度上有一定的诊断价值。     

同步辐射装置X线位相对比成像的初探

目的研究同步辐射光源X射线位相对比成像的方法，并观察其图像特点，分析其图像质量。方法在北京同步辐射装置上对几种不同的生物样品进行X射线位相对比成像及传统的吸收对比成像，然后比较分析其图像。结果几种生物样品均获得了满意的位相对比图像，其分辨率显著高于吸收对比成像，清晰地显示出生物样品中约30～40μm的精细结构，并且能够显示吸收对比成像无法显示的一些组织结构。结论利用同步辐射光源可进行X射线位相对比成像，与吸收对比成像相比，其图像质量有显著的提高。这种成像技术对于低吸收物体或吸收差异小的物体有着很高的应用价值。     

肝脏同步辐射相位衬度成像的实验研究

目的 :利用同步辐射光源的特性,对大鼠肝脏组织分别行类同轴成像、衍射增强成像、干涉法成像及光栅成像实验,通过4种相位衬度技术不同成像效果的比较、分析,评价同步辐射相位衬度成像的意义及临床应用前景。方法:在同步辐射光源装置上,分别根据成像机制设计4种不同的光路进行成像,均采用经35%～40%甲醛水溶液固定的大鼠离体肝脏样品,根据光路及成像方法分别调节曝光参数以达到最佳成像效果。结果:4种成像技术各具优势,且分辨率均能达到微米(μm)量级,可显示肝脏样品远端(8级)血管。类同轴成像技术显示肝脏实质结构上优势较明显,能够清晰显示肝小叶结构(包括小叶间结构及窦状间隙血管),可见肝细胞在围绕窦状间隙中呈板状排列。结论:相位衬度成像具有较高的组织衬度及较好的图像分辨力,能够显示包括肝小叶在内的微小结构或多级血管分支结构,有助于观察肝脏肿瘤生长过程中新生血管的形态、分布,以及肝脏组织细胞微观层面的研究,有望在肝脏的生理、病理及病变机制的可视化研究上发挥重要作用。     

同步辐射相位对比X线成像技术的初步研究

目的 探讨同步辐射相位对比X线成像技术进行小鼠肝血管成像的试验研究。方法C57BL/6 小鼠6只, 3只开腹,直接结扎所有的进出肝脏的血管和胆管等结构,其余3只则通过门静脉灌注碘造影剂置换小鼠肝内的全部血液后,结扎肝脏的血管和胆总管,然后取出肝脏,所有制成的肝脏标本均放置在4%的甲醛溶液中。标本在北京高能物理研究所的同步辐射国家级实验室进行成像,主要使用同步辐射X线衍射增强成像技术。结果 同步辐射X线衍射增强成像技术在不使用造影剂的情况下即可以显示40μm左右直径的肝脏血管,可以显示血管主干及其8级以上的血管分支。结论 同步辐射X 线衍射增强成像技术具有很高的衬度分辨率和空间分辨率,而且其采用的折射成像机制,可以有效的减少X射线对人体的辐射损伤。     

显微CT应用于正畸微种植体的研究进展

微种植体支抗技术是正畸治疗中一种有效和理想的办法,而其稳定性是获得可靠支抗的必要条件。显微CT是一种新型的采用X线成像原理进行超高分辨率三维成像技术,可以在不破坏样品的情况下对微种植体周围的骨质进行超高分辨率X线成像,获得高精度三维图像,并进行结构、密度和力学的定量分析,是研究硬组织材料的强大工具。本文对显微CT目前在正畸微种植体领域方面的应用予以综述。     

相位对比成像对冠状动脉粥样硬化斑块体外定量与定性诊断的准确性

<正>摘要目的探讨X射线光栅干涉法相位对比(PC)成像显示冠状动脉斑块特征的准确性。材料与方法经机构伦理委员会批准后,使用同步辐射光源对40段人冠状动脉节段     

16排40层螺旋CT冠状动脉血管造影的应用技术探讨简

目的：探讨16排40层螺旋CT冠状动脉血管造影的应用技术。方法使用东芝公司16排螺旋CT进行冠状动脉血管成像检查,采用多平面重建（MPR）、最大密度投影（MIP）、曲面重建（CPR）和容积再现技术（VR）进行图像后处理,可清晰显示冠状动脉主干及主要分支。结果心率平稳为53~66次/min,冠状动脉节段图像质量可准确地显示冠状动脉通畅情况及管壁病变。心率＞68次/min时,冠状动脉的主要分支显示不规整。结论16排CT冠状动脉成像可比较准确诊断冠状动脉病变,具有较高的临床应用价值。     

双源CT冠状动脉成像的初步研究

目的初步探讨无需口服控制心率药物准备的双源CT冠状动脉成像的扫描技术和图像质量。方法对215例临床怀疑冠心病或冠状动脉早期病变患者进行无需口服控制心率药物准备的双源CT冠状动脉成像。扫描步骤包括平扫和增强扫描。用平扫图像行冠状动脉钙化积分，用增强扫描图像行多平面重组（MPR）、最大密度投影（MIP）及容积再现技术（VRT）重组。总结双源CT冠状动脉成像的扫描技术和后处理方法。将图像质量分为3级，按冠状动脉分段标准评价各个节段的图像质量。结果215例患者钙化积分值中位数为82．2（2．3～1827．9）。增强扫描平均心率为（80．6±15．3）（57～139）次／min，尽可能使冠状动脉良好显示的后处理方法有：（1）多个时相筛选法；（2）2个或多个时相补充法；（3）早搏去除法和心律不齐移位法。共评价3026个冠状动脉节段，其中图像质量为1级者占97．5％（2951／3026），2级者占2．0％（62／3026），为3级者占0．5％（13／3026）；图像质量为2级和3级的节段多由于呼吸伪影所致。215例患者共91例冠状动脉各节段均未见斑块或狭窄，共诊断〈50％冠状动脉狭窄节段112个，≥50％冠状动脉狭窄节段213个。结论双源CT冠状动脉成像在无需口服控制心率药物准备的情况下可获得非常好的冠状动脉各节段图像，心率不再是影响图像质量的关键因素，通过单时相或多时相重组可良好显示冠状动脉主干及分支。     

多层螺旋CT冠状动脉成像临床应用价值探讨

目的 探讨冠状动脉多层螺旋CT成像的临床应用价值。资料与方法 38例冠状动脉进行多层螺旋CT血管造影,利用多种重建方法进行重建,分析冠状动脉的成像质量及其显示率,以及冠状动脉疾病的影像特点。结果 图像质量的优良率：优28．9％(11／38),良60．5％(23／38),差10．5％(4／38),优良率为89．5％(34／38);冠状动脉分段显示率为：右冠状动脉近段100％(38／38),中段76．3％(29／38),远段60．5％(23／38);左冠状动脉前降支近中段100％(38／38),远段81．6％(31／38),左回旋支近段100％(38／38),远段55．3％(21／38)。发现冠状动脉管壁欠光滑18例,钙化8例,管腔充盈缺损2例,冠状动脉仿真内镜发现冠状动脉夹层1例,管腔狭窄3例。结论 多层螺旋CT冠状动脉成像可以作为冠心病的一种筛选手段。     

Impact of bulk cardiac motion on right coronary MR angiography and vessel wall imaging

The purpose of this study was to investigate the impact of in-plane coronary artery motion on coronary magnetic resonance angiography (MRA) and coronary MR vessel wall imaging. Free-breathing, navigator-gated, 3D-segmented k-space turbo field echo ((TFE)/echo-planar imaging (EPI)) coronary MRA and 2D fast spin-echo coronary vessel wall imaging of the right coronary artery (RCA) were performed in 15 healthy adult subjects. Images were acquired at two different diastolic time periods in each subject: 1) during a subject-specific diastasis period (in-plane velocity <4 cm/second) identified from analysis of in-plane coronary artery motion, and 2) using a diastolic trigger delay based on a previously implemented heart-rate-dependent empirical formula. RCA vessel wall imaging was only feasible with subject-specific middiastolic acquisition, while the coronary wall could not be identified with the heart-rate-dependent formula. For coronary MRA, RCA border definition was improved by 13% (P < 0.001) with the use of subject-specific trigger delay (vs. heart-rate-dependent delay). Subject-specific middiastolic image acquisition improves 3D TFE/EPI coronary MRA, and is critical for RCA vessel wall imaging.     

High-resolution steady-state free precession coronary magnetic resonance angiography within a breath-hold: parallel imaging with extended cardiac data acquisition.

Coronary artery imaging data are conventionally acquired in a single imaging frame during mid-diastole. The data acquisition window must be sufficiently short to avoid cardiac motion artifacts. A short data acquisition window results in decreased imaging efficiency and limited spatial resolution. Parallel imaging may lessen these limitations, but requires highly accurate coil sensitivity. The purpose of this work was to increase the imaging efficiency and spatial resolution in coronary artery imaging using parallel imaging with an extended acquisition window. External coil calibration data were acquired before and after a short mid-diastolic period of accelerated imaging data acquisition. It was assumed that residual cardiac motion in the extended acquisition window would not impede accurate estimation of coil sensitivity since only low spatial frequency signals were acquired for coil calibration. Experimental studies were performed in five healthy volunteers at 3 T using steady-state free precession sequence. Statistical comparison was made between the proposed method and conventional data acquisition for visual quality of image and vessel sharpness. The proposed technique demonstrated higher visual grading and improved vessel sharpness. The proposed method is a new approach to enhance the imaging efficiency and spatial resolution in coronary artery imaging.     

CT冠状动脉成像在冠心病诊断中的应用

目的:研究CT冠状动脉成像在冠心病早期诊断冠状动脉狭窄定性定量判读的作用。方法:对34例临床未发生急性冠脉综合征的冠心病患者,先后进行冠状动脉造影、128排双源CT冠状动脉成像。以冠状动脉造影为"金标准",计算CT冠状动脉成像敏感性、特异性、阳性预测值、阴性预测值。结果:①与冠状动脉造影相比,CT冠状动脉成像的敏感性为68%,特异性为97%,阳性预测值为89%,阴性预测值为90%。②CT冠状动脉成像有65个血管段图像质量差,约占12%,造成图像质量差的原因主要为钙化,心跳、呼吸伪影,少部分为管腔显示不良。结论:冠心病早期诊断中,CT冠状动脉成像可用作冠状动脉造影前筛选,CT冠状动脉成像阴性的患者不必行冠状动脉造影检查;CT冠状动脉成像阳性的患者,可行冠状动脉造影进一步确认病变。     

Coronary MR angiography with steady-state free precession: individually adapted breath-hold technique versus free-breathing technique

PURPOSE: To compare image quality and coronary artery stenosis detection with breath-hold (BH) and free-breathing navigator-gated (NAV) coronary magnetic resonance (MR) angiography performed with the same imaging sequence (steady-state free precession) and identical spatial resolution in patients suspected of having coronary artery disease. MATERIALS AND METHODS: Forty consecutive patients suspected of having coronary artery disease underwent steady-state free precession MR imaging of the left or the right coronary artery twice. Correction of breathing motion was performed once with NAV and again with BH. Maximal BH duration and coronary artery rest period were individually determined, and duration of data acquisition was adapted (parallel imaging with different sensitivity encoding factors was used). Quantitative analysis of coronary MR angiography data was performed with multiplanar reformatting software to determine visual score for image quality, vessel sharpness, visible vessel length, and number of visible side branches. Diagnostic accuracy for detection of coronary stenosis of 50% or greater was determined in comparison with results of conventional invasive angiography. The two techniques were compared regarding differences in angiographic parameters with paired Student t testing. chi(2) or Fisher exact testing was used when appropriate. RESULTS: More coronary artery segments were assessable with NAV than with BH MR angiography (254 [79.4%] vs 143 [44.7%] of 320 segments). Overall sensitivity and specificity with NAV were 72% (26 of 36 segments) and 91.7% (200 of 218 segments), versus 63% (12 of 19 segments) and 82.3% (102 of 124 segments) with BH; NAV enabled correct diagnosis in 13% more segments. BH yielded nondiagnostic images in 14 patients, while NAV yielded diagnostic images in all patients. When these 14 patients were excluded, there was a significant increase in visual score for left (3.0 vs 2.4, P <.01) and right (3.3 vs 3.0, P <.05) coronary arteries and no significant difference in vessel sharpness but significant improvement in visible vessel length in left coronary artery (85.9 vs 71.4 mm, P =.003) and number of visible side branches in left (4.9 vs 3.9, P =.04) and right (2.8 vs 2.4, P =.04) coronary arteries on NAV images as compared with BH images. CONCLUSION: Free-breathing NAV was superior to BH coronary MR angiography in terms of image quality and diagnostic accuracy of stenosis detection.     

Comparison of cardiac to hepatic uptake of 99mTc-tetrofosmin with and without adenosine infusion to predict the presence of haemodynamically significant coronary artery disease

BACKGROUND: Coronary artery disease impairs cardiac vasodilatory reserve. A low ratio of cardiac to hepatic vasodilatory reserve may be diagnostic for coronary artery disease. AIM: To compare the ratio of cardiac to hepatic uptake of 99mTc-tetrofosmin during adenosine infusion and at rest in patients with and without coronary artery disease in order to determine whether the ratio was significantly different between the two groups. METHODS: Fifty-one patients who underwent coronary angiography and adenosine stress myocardial perfusion imaging using 99mTc-tetrofosmin were studied retrospectively. Anterior planar images from the single photon emission computed tomography (SPECT) raw data were used to draw regions of interest around the heart and liver. The counts per pixel in each region were used to calculate the stress ratio (SR) and the rest ratio (RR) as follows: SR = (cardiac counts per pixel)at stress/(hepatic counts per pixel)at stress; RR = (cardiac counts per pixel)at rest/(hepatic counts per pixel)at rest. The SR and SR/RR ratios were compared in patients with and without significant coronary artery disease. Receiver operating characteristic curves were drawn for SR and SR/RR. RESULTS: The SR and SR/RR ratios were significantly lower in patients with significant coronary artery disease than in patients without (P<0.001). A cut-off ratio of SR/RR = 1.00 yielded 87% sensitivity and 74% specificity for the detection of significant coronary artery disease. Combining SR/RR with standard SPECT image interpretation increased the sensitivity without substantially changing the specificity in comparison with standard SPECT image interpretation only. CONCLUSION: Comparison of cardiac to hepatic 99mTc-tetrofosmin concentration at rest and under adenosine stress provides useful diagnostic information for the assessment of the presence of significant coronary artery disease.     

64排容积CT对成人冠状动脉起源异常的诊断价值

 目的 探讨64排容积CT对成人冠状动脉起源异常的诊断价值.方法 回顾分析3 030例成人冠状动脉CTA检查资料. 结果 3 030例冠脉CTA中,检查出冠状动脉起源异常70例,检出率为2.3%,其中冠状动脉起源于对侧冠状窦及窦外27例(38.5%);冠状动脉高位开口23例(32.8%);前降支、回旋支均开口于左冠状窦17例(24.3%);单一冠脉2例(均为单一左冠,其中1例合并左主干高开口,2.8%),回旋支开口于对角支及窦房结支开口于右冠状窦各1例(1.4%).结论 64排容积CT诊断冠状动脉起源异常是一种无创、安全、准确、经济的检查方法 .     

64层螺旋CT诊断成人冠状动脉起源异常

目的 探讨64层螺旋CT诊断成人冠状动脉起源异常的价值。方法 对978例成人冠状动脉CT血管成像（CTA）资料进行回顾性分析、总结，并与国内外文献比较。结果 978例完整冠状动脉CTA结果中，共检出成人冠状动脉起源异常30例，检出率为3．07％，包括右冠状动脉起源异常9例（30．00％），左冠状动脉起源异常7例（23.33％），左、右冠状动脉均起源异常2例（6.67％），回旋支缺如1例（3.33％）和冠状动脉其他分支起源异常11例（36．67％）。结论 64层螺旋CT诊断成人冠状动脉起源异常是一种无创、安全和有效的方法。