衍射增强成像(DEI)动物实验研究

目的通过动物样品的衍射增强成像(DEI),获得衬度及分辨率,并与常规吸收成像比较,对DEI方法进行分析和评价。方法在北京高能物理研究所同步辐射装置(BSRF)形貌站(4W1A束线)上,取大鼠脏器在摇摆曲线上进行扫描,并与常规吸收像进行比较,通过放大法获得分辨率。结果大鼠的肝脏、肾脏样本的DEI均显示较好的衬度和分辨率,并且扫描位置对图像显示具有较大影响。结论DEI从相位衬度角度进行成像,是一种有望开发运用于临床的先进成像技术。     

同步辐射装置(BSRF)上的衍射增强医学成像实验

目的：利用衍射增强成像（DEI）技术成像机制的特异性，进行医学样品的成像研究，并进行分析评价。方法：使用衍射增强成像（DEI）技术对肝、肾样本进行成像，通过显微放大法获得图像分辨率，并对摇摆曲线上的不同位置成像结果进行分析，与病理和常规吸收像图像进行比较。结果：获得的成像具有较高的分辨率、可以显示更多的微细结构，摇摆曲线上的不同位置对成像具有较大的影响。结论：DEI对样品，尤其是弱吸收组织（软组织）显示具有较强的特异性，可望在临床上具有广阔的应用前景。     

同步辐射技术应用于冠状动脉成像的实验初探

目的比较衍射增强成像（DEI）和单色光成像两种方法冠状动脉成像效果,评价同步辐射方法在冠状动脉成像上的意义。方法DEI装置及白光成像装置下,分别对大鼠心脏进行成像,在DEI成像时,采用离体心脏样品;在单色光成像时,采用活体大鼠,并静注60%碘造影剂1ml,迅速采集图像,以图像衬度和空间分辨率作为评价指标。结果两种方法均能显示大鼠的冠状动脉。虽然DEI不用造影剂,从成像效果上来说稍差于单色光技术效果,但两种成像方法获得的图像没有显著性差异。结论DEI用于冠状动脉成像是可行的,但受成像条件和方法的限制,同步辐射的优良特性尚未得到充分利用。     

比较同步辐射衍射增强与同轴技术小鼠肾脏成像

目的 通过评价同步辐射相位衬度成像技术在小鼠肾脏微细结构的成像过程,比较同轴成像技术(IOXI)与衍射增强成像(DEI)的差异,探索相位成像技术的应用价值。方法 在北京同步辐射装置(BSRF)形貌站4W1A和上海光源(SSRF)成像线站BL13W上,分别对小鼠肾脏进行成像,以组织衬度与空间分辨力作为评价指标。结果 肾脏微细结构在IOXI与DEI中均得以显示,尤其是IOXI可显示肾小球。通过显微放大法获得的图像空间分辨力达10 μm。结论 包括IOXI与DEI在内的相位衬度成像技术在软组织及血管结构的显示中均具有较高的应用价值。IOXI由于获得成像信息更多,且光路较为简单、图像可直接获得,在生物医学应用研究中的价值可能更高。     

同轴X射线位相衬度成像实验研究

目的研究利用类点光源的同轴X射线位相衬度成像技术。方法在北京同步光源4W1A光束线上,分别利用白光束X射线和14keV单色X射线,采用同轴方式开展生物样品的位相衬度成像实验。结果位相衬度图像比吸收衬度的图像分辨率更高、衬度更好。结论对于X射线吸收很弱的样品,位相衬度成像能够得到更好衬度和更高分辨率的图像。利用类点源X射线同轴相位衬度成像技术相对比较容易地被用于临床。     

大鼠肾X线衍射增强成像

目的探讨高衬度成像技术--同步辐射衍射增强成像(DEI)对肾脏成像的可能性.方法在北京同步辐射装置(BSRF)采用X线衍射增强成像法对离体的大鼠肾样品进行成像,成像样品的厚度分别为2 mm和120 μm.成像后的样品进行组织学切片,其结果和DEI结果进行对比分析.结果离体大鼠肾衍射增强成像可清晰显示常规成像方法无法观察到的走向清晰的髓质区直集合管和乳头管,以及常规需经造影处理才可见的小叶间动、静脉,最细可分辨直径为30μm的管道结构.结论同步辐射衍射增强成像法具有早期观察肾脏髓质病变及血管微细病变的潜力,该方法为目前影像学尚不能观察到的生物样品结构的成像提供了一种新的研究手段.     

磁共振胰胆管成像与常规扫描诊断胆系结石的对照研究

目的：对比探讨磁共振胰胆管成像及其原始图像与磁共振常规扫描诊断胆系结石的价值。方法：应用1．0T超导MRI扫描仪对55例患者（36例胆囊结石和19例胆总管结石）行重T2加权多次激发FSE序列（HT2-FSE）磁共振胰胆管成像扫描及常规轴面FSE序列MRI T1WI及T2WI扫描。结果：磁共振胰胆管成像的最大强度投影图像能清晰显示肝内、外胆管及扩张胰管的形态结构。多数较大的胆系结石在磁共振胰胆管成像原始图像及MRI常规T2WI图像上可很好地显示，但常在最大强度投影图像被掩盖；较小的胆系结石在磁共振胰胆管成像的最大强度投影图像及MRI常规T2WI图像均难以准确显示，而仅在磁共振胰胆管成像原始图像上显示。结论：磁共振胰胆管成像原始图和最大强度投影图像以及磁共振常规扫描是分析、诊断胆系结石的一个有机整体，不能仅仅依靠某一种成像技术作出诊断。     

MR三维颅脑容积成像增强扫描序列在舌下神经管区病变中的应用

目的 探讨三维MR颅脑容积成像（3D-BRAVO）增强扫描序列在舌下神经管区病变中的应用价值。方法 对14例舌下神经管区病变患者的MR资料进行回顾性分析,所有病例均行常规MR平扫、增强及3D-BRAVO增强扫描。结果 14例患者于常规平扫序列上可发现病灶,常规增强序列上不能清晰显示舌下神经及舌下神经管,三维颅脑容积成像增强扫描序列上所有病例均能显示舌下神经及舌下神经管,并可进行MPR多方位清楚显示舌下神经管、舌下神经及病灶。结论 3D-颅脑容积成像增强扫描序列较常规扫描提供更多信息,是诊断舌下神经管区病变准确、可靠的扫描序列。     

同步辐射类同轴技术应用于肾脏成像的实验研究

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150 mm时获得的肾脏成像,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30 μm.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.     

胸部T1WI成像自由呼吸StarVIBE序列与常规VIBE序列图像质量对比研究

目的 对比分析StarVIBE序列自由呼吸扫描与常规三维容积内插屏气检查（VIBE）序列屏气扫描的图像质量，探讨自由呼吸StarVIBE序列在胸部MR成像中的临床价值。方法 前瞻性收集CT检查提示胸部病变的患者37例，根据患者能否配合屏气20 s，分为无法屏气组17例及配合屏气组20例，所有患者均在平扫及增强延迟期行StarVIBE序列及常规VIBE序列成像。两名影像医师采用“5分法”对两序列图像的病变清晰度、伪影、肺血管清晰度、纵膈结构清晰度及总体图像质量进行盲法评分，并比较两序列间图像质量评分差异。结果 无法屏气组，StarVIBE序列平扫及增强图像的各项评分均高于常规VIBE序列（P均＜0.05）。配合屏气组，StarVIBE序列平扫图像的病灶清晰度、肺血管清晰度评分低于常规VIBE序列（P均＜0.05），但增强后以上评分无统计学差异（P均＞0.05），同时两序列图像的伪影及图像总体质量评分亦无统计学差异（P均＞0.05），而在纵膈清晰度评分中StarVIBE序列增强前后均具有更高的评分（P＜0.05）。结论 在胸部T1WI中，对能配合屏气患者，自由呼吸StarVIBE序列可获得与常规VIBE序列相近的图像质量；而对无法屏气患者，自由呼吸StarVIBE序列可提供更好的图像质量。     

Diffraction-enhanced Synchrotron Imaging of Bovine Ovaries Ex Vivo

ObjectivesThe objective of this study was to test the hypothesis that diffraction-enhanced imaging (DEI), a synchrotron x-ray imaging technique, would provide greater contrast for evaluating bovine ovaries compared with conventional diagnostic ultrasonography.Materials and MethodsBovine ovaries were evaluated ex vivo as follows: fresh without radiographic arterial contrast (n = 2), fresh with contrast (n = 1), preserved in 10% formalin without contrast (n = 2), and preserved with contrast (n = 1). Each ovary was imaged with DEI and subsequently with ultrasonography and histology. The ability to visualize and differentiate preantral and antral follicles, corpora lutea (CL), and cumulus oocyte complexes (COCs) were compared using DEI, ultrasonography, and histology. The diameter of follicles and CL were measured and compared using ultrasonography, DEI, and histology. The diameter of the smallest follicle detected was reported using each of the three imaging methods. The number of antral follicles (antral follicle count ≥2 mm) was compared between ultrasonography and DEI.ResultsDEI enabled the detection of 71% of follicles and 67% of CL that were detected ultrasonographically. However, DEI did not allow the detection of COCs and cell layers of the follicle wall that were visualized histologically. Luteal tissues were not easily distinguished using DEI, and DEI was inferior for differentiating follicles and CL compared with ultrasonography. The mean follicle diameter was similar between DEI (4.00 ± 0.35 mm, fresh with contrast; 9.62 ± 2.43 mm, fresh without contrast) and ultrasonography (3.85 ± 0.28 mm, fresh with contrast; 8.97 ± 2.60 mm, fresh without contrast) (P > .05). However, the mean follicle diameter was greater using both DEI (4.00 ± 0.35 mm) and ultrasonography (3.85 ± 0.28 mm) compared with histology (2.21 ± 0.38 mm; P = .01, fresh ovaries with contrast). The mean CL diameter was similar between DEI (11.64 ± 1.67 mm), ultrasonography (9.34 ± 0.35 mm), and histology (9.59 ± 0.36 mm) (P > .05). The mean diameter of the smallest follicle detected was similar between DEI (3.06 ± 0.45 mm) and ultrasonography (2.95 ± 0.74 mm); both DEI and ultrasonographic measurements were greater than histology (0.39 ± 0.04 mm, P < .0001). The mean antral follicle count was similar between ultrasonography (6.50 ± 0.71 mm, fresh with no contrast; 6.50 ± 2.50 mm, preserved with no contrast) and DEI (4.50 ± 0.50 mm, fresh with no contrast; 6.50 ± 0.50 mm, preserved with no contrast) (P > .05).ConclusionsThe contrast resolution of antral follicles, CL, and COCs in bovine ovaries was inferior using DEI compared with ultrasonography and histology. Alternative synchrotron techniques, such as phase-contrast computed tomography and DEI computed tomography, may prove more effective than DEI for imaging ovaries ex vivo.     

Computed tomography of amyloid plaques in a mouse model of Alzheimer's disease using diffraction enhanced imaging

Our understanding of early development in Alzheimer's disease (AD) is clouded by the scale at which the disease progresses; amyloid beta (Aβ) plaques, a hallmark feature of AD, are small (~ 50 μm) and low contrast in diagnostic clinical imaging techniques. Diffraction enhanced imaging (DEI), a phase contrast x-ray imaging technique, has greater soft tissue contrast than conventional radiography and generates higher resolution images than magnetic resonance microimaging. Thus, in this proof of principle study, DEI in micro-CT mode was performed on the brains of AD-model mice to determine if DEI can visualize Aβ plaques. Results revealed small nodules in the cortex and hippocampus of the brain. Histology confirmed that the features seen in the DEI images of the brain were Aβ plaques. Several anatomical structures, including hippocampal subregions and white matter tracks, were also observed. Thus, DEI has strong promise in early diagnosis of AD, as well as general studies of the mouse brain.     

In-vivo evaluation of convex array synthetic aperture imaging

This paper presents an in-vivo study of synthetic transmit aperture (STA) imaging in comparison with conventional imaging, evaluating whether STA imaging is feasible in-vivo and whether the image quality obtained is comparable with traditional scanned imaging in terms of penetration depth, spatial resolution, contrast resolution and artifacts. Acquisition was performed using our research scanner RASMUS and a 5.5 MHz convex array transducer. STA imaging was acquired using circular wave emulation by 33-element subapertures and a 20 micros linear FM signal as excitation pulse. For conventional imaging, a 64 element aperture was used in transmit and receive with a 1.5 cycle sinusoid excitation pulse. Conventional and STA images were acquired interleaved, ensuring that the exact same anatomical location was scanned. Image sequences were recorded in real time and processed off-line. Seven male volunteers were scanned abdominally and the resulting images were compared by three medical doctors using randomized blinded presentation. Penetration and image quality were scored and evaluated statistically. Results showed slightly but significantly (0.48 cm, p = 0.008) increased penetration using STA. Image quality was also highly significantly (p < 0.001) increased. Results show that in-vivo ultrasound imaging using STA is feasible for abdominal imaging without severe motion artifacts.     

Investigation of the effect of subcutaneous fat on image quality performance of 2D conventional imaging and tissue harmonic imaging

Tissue harmonic imaging (THI) has been reported to improve contrast resolution, tissue differentiation and overall image quality in clinical examinations. However, a study carried out previously by the authors (Brown et al. 2004) found improvements only in spatial resolution and not in contrast resolution or anechoic target detection. This result may have been due to the homogeneity of the phantom. Biologic tissues are generally inhomogeneous and THI has been reported to improve image quality in the presence of large amounts of subcutaneous fat. The aims of the study were to simulate the distortion caused by subcutaneous fat to image quality and thus investigate further the improvements reported in anechoic target detection and contrast resolution performance with THI compared with 2D conventional imaging. In addition, the effect of three different types of fat-mimicking layer on image quality was examined. The abdominal transducer of two ultrasound scanners with 2D conventional imaging and THI were tested, the 4C1 (Aspen-Acuson, Siemens Co., CA, USA) and the C5-2 (ATL HDI 5000, ATL/Philips, Amsterdam, The Netherlands). An ex vivo subcutaneous pig fat layer was used to replicate beam distortion and phase aberration seen clinically in the presence of subcutaneous fat. Three different types of fat-mimicking layers (olive oil, lard and lard with fish oil capsules) were evaluated. The subcutaneous pig fat layer demonstrated an improvement in anechoic target detection with THI compared with 2D conventional imaging, but no improvement was demonstrated in contrast resolution performance; a similar result was found in a previous study conducted by this research group (Brown et al. 2004) while using this tissue-mimicking phantom without a fat layer. Similarly, while using the layers of olive oil, lard and lard with fish oil capsules, improvements due to THI were found in anechoic target detection but, again, no improvements were found for contrast resolution for any of the layer combinations. Therefore, it was felt that the lack of improvement in contrast resolution performance may be due to the test phantom design and not to whether a layer was present that caused beam distortion and phase aberrations.     

敏感性编码技术在腹部磁共振快速成像中的应用

目的　研究敏感性编码 (SENSE)技术在腹部快速MRI检查中的临床应用。方法　对 15例患者的腹部进行常规快速自旋回波 (TSE)序列T2 加权成像 (T2 WI)、选择性部分反转恢复 (SPIR)序列T2 WI、快速场回波 (FFE)序列T1加权成像 (T1WI)以及在保持参数不变时联合应用SENSE成像。观察应用SENSE后 ,扫描时间的缩短情况以及图像的对比度变化情况。结果　应用SENSE成像当缩减因子为 2 .0时 ,腹部每个序列扫描时间缩短约 43 %～ 5 0 % ,而图像的对比度不变。结论　联合应用SENSE技术能显著缩短扫描时间 ,而保持图像对比度基本不变。SENSE技术在磁共振快速成像中的应用前景广阔。     

编码谐频超声成像在检查甲状腺占位性病变中的应用价值

目的：探讨编码谐频成像技术在甲状腺占位性病变中的应用价值。方法：对病变处同一切面分别用基频和谐频成像进行分析对比。结果：编码谐频较基频成像表现出全场图像清晰，病变周围和内部回声细致。结论：编码高频谐频在图像均匀度、细微分辨力和对比度方面具有特点，能够提高图像质量。