股骨头挖除后螺旋CT三维重建在髋臼粉碎性骨折中的应用

目的 探讨股骨头挖除后螺旋CT三维重建在髋臼粉碎性骨折中的应用价值。资料与方法 对27例经普通X线诊断的髋关节骨折患者,应用螺旋CT扫描获得原始轴面图像,在工作站对兴趣区进行染色显影,通过关节解体技术去除股骨头,然后对髋臼采用多平面重建（MPR）及表面遮盖法（SSD）和容积漫游技术（VRT）三维重建。结果 股骨头挖除后三维重建图像能直观显示髋臼骨折的全貌及关节腔内的游离碎骨片及相互之间的解剖关系。结论 股骨头挖除后SSD和VRT三维重建对外科手术前充分了解髋臼损伤情况、手术方案的制定及内固定器械的选择,均有重要的指导作甩。     

多普勒血流超声医学图像的动态三维重建

目的：将超声医学图像三维重建技术与多普勒血流成像技术结合起来，实现超声血流图的动态三维重建。方法：通过对多普勒血流图的彩色编码方式的研究，利用多普勒血流图中Color Bar的信息，解决了从原始多普勒血流图中分离解剖结构和功能信息的问题，实现了心腔内血流的动态三维重建及与心脏解剖结构的三维融合显像。结果：对临床人体实验获取的超声血流图像进行三维重建，所得重建图中，血流信息与解剖结构之间的相互关系正确，与心脏解剖生理情况相符，证明了方法的可行性和有效性。结论：结合超声医学图像三维重建技术和多普勒成像技术，实现超声医学图像功能三维重建，提供更多的医学信息，是超声医学成像技术的发展方向，具有巨大的应用前景。     

基于PC机的医学图像三维表面重建

目的：利用CT，MR等获得的图像，重构出器官、骨骼或组织的三维形体，帮助医生诊断、治疗或制订手术方案。方法：Shear-Warp算法通过将三维数据场的投影分解为错切变换（shear)和变形变换（warp)两步来实现三维重建，显著减少了计算量，先对体数据进行错切变换，然后在错切空间根据阈值法获取三维表面，根据光照模型得到三维表面的亮度，最后通过变形变换得到最终的结果图像，结果：提出了一种基于Shear-Warp投影原理快速显示三维表面的直接重建算法。结论：与其他表面重建算法比较，这种算法不需要预处理，重建过程中不必生成中间数据，在无硬件加速的条件下，能在普通微机上实现医学图像的快速三维表面重建。     

Advances in three-dimensional reconstruction of the experimental spinal cord injury

Three-dimensional (3D) computer reconstruction is an ideal tool for evaluating the centralized pathology of mammalian spinal cord injury (SCI) where multiple anatomical features are embedded within each other. Here, we evaluate three different reconstruction algorithms to three-dimensionally visualize SCIs. We also show for the first time, that determination of the volume and surface area of pathological features is possible using the reconstructed 3D images themselves. We compare these measurements to those calculated by older morphometric approaches. Finally, we demonstrate dynamic navigation into a 3D spinal cord reconstruction.     

The use of 3-dimensional CT reconstruction in childhood. Technics and dosimetry

A new computer method has been developed that allows the reprocessing of standard CT scans to produce 3D surface images. We employed the 3D reconstruction program developed by Hitachi Medical System using an Ansaldo A-TOM XR 1200 scanner. The process requires only standard CT scanner hardware, and reconstruction time is comparable to that of sagittal and coronal reconstructions. The applications of this technique and methodology to pediatric patients are discussed. In order to assess the relationship between image quality and radiation dose, we performed many CT scans with different protocols. A skull was employed for phantom, and plunged into a physiological solution, which helped us to determine the radiation exposure dose from every single CT scan. The measurements were taken with film and thermoluminescent crystal dosimeters (TLD). The results confirm that low-dose techniques allow a significant reduction in the total exposure. The authors discuss the clinical indications and the eventual applications of these techniques.     

Myocardial perfusion visualized with SPECT: three-dimensional representation

A recently developed computer program for three-dimensional (3D) reconstruction of SPECT images has been employed to study myocardial perfusion in coronaropathic patients using MIBI-99mTc or 201Tl chloride. By subtracting after-stress from at-rest 3D reconstructed images, even small ischemic lesions could be located in the myocardium, with good morphological definition. The general characteristics of the method and some clinical results are here presented.     

超高速CT三维重建在颌面部髁状突骨折中的应用研究

目的：探讨超高速CT三维重建在颌面部髁状突骨折中应用价值。方法：对21例外伤病人进行常规X线检查及电子束CT扫描和三维重建检查．研究骨折的类型、骨折移位程度，提供合适的治疗方案。结果：超高速CT具有扫描速度快，层次薄，图像清晰的特点，其三维影像可任意旋转和切割，从不同角度观察(骨折)病变情况，准确显示骨折类型。结论：超高速CT平扫及三维重建在颌面部髁状突骨折中，能客观地提供骨折的所有特征，将二维和三维重建方法互相弥补。可以更清晰地显示骨折线碎骨的移位，提示颌面部髁状突骨折诊断的正确率、显示率、降低漏诊和误诊率，为临床提供准确诊断信息。     

Quantitative comparison of analytic and iterative reconstruction methods in 2- and 3-dimensional dynamic cardiac 18F-FDG PET.

The aim of this work was to compare the quantitative accuracy of iteratively reconstructed cardiac (18)F-FDG PET with that of filtered backprojection for both 2-dimensional (2D) and 3-dimensional (3D) acquisitions and to establish an optimal procedure for imaging myocardial viability with (18)F-FDG PET. METHODS: Eight patients underwent dynamic cardiac (18)F-FDG PET using an interleaved 2D/3D scan protocol, enabling comparison of 2D and 3D acquisitions within the same patient and study. A 10-min transmission scan was followed by a 10-min, 25-frame dynamic 3D scan and then by a series of 10 alternating 5-min 3D and 2D scans. Images were reconstructed with filtered backprojection (FBP) or attenuation-weighted ordered-subsets expectation maximization (OSEM), combined with Fourier rebinning (FORE) for 3D acquisitions, applying all usual corrections. Regions of interest (ROIs) were drawn in the myocardium, left ventricle, and ascending aorta, with the last 2 being used to define image-derived input functions (IDIFs). Patlak graphical analysis was used to compare net (18)F-FDG uptake in the myocardium, calculated from either 2D or 3D data, after reconstruction with FBP or OSEM. Either IDIFs or arterial sampling was used as the input function. The same analysis was performed on parametric images. RESULTS: A good correlation (r(2) > 0.99) was found between net (18)F-FDG uptake values for a myocardium ROI determined using each acquisition and reconstruction method and blood-sampling input functions. A similar result was found for parametric images. The ascending aorta was the best choice for IDIF definition. CONCLUSION: Good correlation and no bias of net (18)F-FDG uptake in relation to that based on FBP images, combined with less image noise, make 3D acquisition with FORE plus attenuation-weighted OSEM reconstruction the preferred choice for cardiac (18)F-FDG PET studies.     

HYPR TOF: time-resolved contrast-enhanced intracranial MR angiography using time-of-flight as the spatial constraint

Purpose

To investigate the feasibility of using time‐of‐flight (TOF) images as a constraint in the reconstruction of a series of highly undersampled time‐resolved contrast‐enhanced MR images (HYPR TOF), to allow simultaneously high temporal and spatial resolution and increased SNR.

Materials and Methods

Ten healthy volunteers and three patients with aneurysms underwent a HYPR TOF study, which includes a clinical routine TOF scan followed by a first pass time‐resolved contrast‐enhanced exam using an undersampled three‐dimensional (3D) projection trajectory (VIPR). Image quality, waveform fidelity and signal to background variation ratio measurements were compared between HYPR TOF images and VIPR images without HYPR reconstruction.

Results

Volunteer results demonstrated the feasibility of using the clinical routine TOF as the spatial constraint to reconstruct the first pass time‐resolved contrast‐enhanced MRA acquired using highly undersampled 3D projection trajectory (VIPR). All the HYPR TOF images are superior to the corresponding VIPR images with the same temporal reconstruction window on both spatial resolution and SNR.

Conclusion

HYPR TOF improves the spatial resolution and SNR of the rapidly acquired dynamic images without losing the temporal information. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.     

Reduction of truncation artifacts in rapid 3D articular cartilage imaging

PURPOSE: To reduce Gibbs ringing artifact in three-dimensional (3D) articular knee cartilage imaging with linear prediction (LP). MATERIALS AND METHODS: A reconstruction method using LP in 3D was applied to truncated data sets of six healthy knees. The technique first linearizes the data before applying the prediction algorithm. Three radiologists blindly reviewed and ranked images of the full, truncated, and predicted data sets. Statistical analysis of the radiologists' reviews was performed for image quality, clinical acceptability of the images, and equivalence with the gold standard. RESULTS: LP applied to 3D knee cartilage imaging allows for 40% decreased scan time while providing image quality with statistical equivalence to a full data set. CONCLUSION: 3D spoiled gradient echo imaging (SPGR) knee cartilage imaging requires significant scan time. This 40% reduction in scan time will allow such scans to be more feasible without sacrificing clinical acceptability.     

构建国人头颈三维有限元模型

目的研究构建国人头颈三维有限元模型。方法依据正常国人头颅CT、MRI断层扫描图像，识别确定重建对象，对皮肤、颅骨采用灰度阈值法、轮廓跟踪算法及B样条曲线拟合法进行自动重建；对其他结构采用人机对话方式提取边界关键点，进行重建实体。定义结构材料参数后划分网格。筛选相邻体积交接面节点，粘连节点完成建模。结果完成包含皮肤、颅骨、硬膜、静脉窦、脑灰白质、脑干、小脑、脑室系统、颈椎及颈髓的国人头颈三维有限元模型。模型单元及节点数分别为168733，80535，总质量约5．14kg。结论利用医学影像资料，采用轮廓跟踪算法等数字图像技术可半自动实现人颅脑复杂结构的三维重建。     

Evaluation of the resolving power of different angles in MPR images of 16DAS-MDCT

In this study, we evaluated the resolving power of three-dimensional (3D) multiplanar reformation (MPR) images with various angles by using 16 data acquisition system multi detector row computed tomography (16DAS-MDCT) . We reconstructed the MPR images using data with a 0.75 mm slice thickness of the axial image in this examination. To evaluate resolving power, we used an original new phantom (RC phantom) that can be positioned at any slice angle in MPR images. We measured the modulation transfer function (MTF) by using the methods of measuring pre-sampling MTF, and used Fourier transform of image data of the square wave chart. The scan condition and image reconstruction condition that were adopted in this study correspond to the condition that we use for three-dimensional computed tomographic angiography (3D-CTA) examination of the head in our hospital. The MTF of MPR images showed minimum values at slice angles in parallel with the axial slice, and showed maximum values at the sagittal slice and coronal slice angles that are parallel to the Z-axis. With an oblique MPR image, MTF did not change with angle changes in the oblique sagittal slice plane, but in the oblique coronal slice plane, MTF increased as the tilt angle increased from the axial plane to the Z plane. As a result, we could evaluate the resolving power of a head 3D image by measuring the MTF of the axial image and sagittal image or the coronal image.     

MSCT非增强扫描三维重建技术在诊断动静脉畸形中的应用

目的 评价MSCT非增强扫描三维重建技术在诊断肺动静脉畸形(PAVM)中的临床应用.方法 回顾性分析12例经DSA证实的PAVM患者的临床和影像学资料.采用16层螺旋CT扫描仪,非增强薄层扫描后,在后处理工作站行肺血管三维重建,重建方法包括多平面重建(MPR)、最大密度投影(MIP)、容积再现(VR).结果 全部病例均能正确诊断,并能充分显示供血动脉、引流静脉、瘤囊的空间构造及关系.结论 非增强MSCT扫描后处理技术对PAVM能做出明确的诊断,清晰显示PAVM的构型,无对比剂的应用,减低辐射剂量.     

正常人膝关节软骨MR成像和软骨重建

目的　研究正常人膝关节软骨的MR成像和软骨三维重建方法 ,为临床诊治关节软骨病变提供科学依据。材料与方法　使用Philips 1.0T磁共振成像仪对 2 0例志愿者行软骨序列扫描 ,然后进行三维软骨重建。 结果　软骨序列及软骨重建技术可以清晰显示软骨的结构 ,关节软骨在SE序列上显示为 3层结构 ,在SPIR/ 3D/FFE/T1WI上最多显示为 4层结构 ,重建后的软骨像具有立体直观的效果 ,并具有良好的空间分辨率。结论　软骨MR成像和软骨重建能清晰显示膝关节的软骨结构 ,可为临床对骨关节病变的诊断和治疗提供帮助。     

Dosimetry of the cone beam computed tomography Veraviewepocs 3D compared with the 3D Accuitomo in different fields of view

OBJECTIVES: This study compares tissue-absorbed and effective doses of the cone beam CT (CBCT) units, the Veraviewepocs 3D and the 3D Accuitomo, in different protocols. METHODS: The absorbed organ doses were measured using an anthropomorphic phantom loaded with thermoluminescent dosemeters (TLDs) in 16 sensitive organ sites. Both CBCT units were deployed with different fields of view (FOVs): 3D Accuitomo using two protocols (anterior 4 x 4 cm scan and anterior 6 x 6 cm scan) and Veraviewepocs 3D using three protocols (anterior 4 x 4 cm scan, anterior 8 x 4 cm scan and panoramic + anterior 4 x 4 cm). Equivalent and effective doses were then calculated, the latter based on the International Commission on Radiological Protection's (ICRP) 2005 recommendations. RESULTS: The lowest effective dose was observed for the 3D Accuitomo 4 x 4 cm (20.02 microSv), the highest for the 3D Accuitomo 6 x 6 cm (43.27 microSv). The effective dose recorded for Veraviewepocs 3D was 39.92 microSv for the 8 x 4 cm scan, 30.92 microSv for the 4 x 4 cm scan and 29.78 microSv for the panoramic + 4 x 4 cm scan protocol. CONCLUSIONS: The radiation doses delivered by both machines were in comparable ranges when using 4 x 4 cm FOV. A smaller FOV should be used for dental images, whereas a larger FOV should be restricted to cases in which a wider view is required.     

Diagnostic radiograph based 3D bone reconstruction framework: Application to the femur

Three dimensional (3D) visualization of anatomy plays an important role in image guided orthopedic surgery and ultimately motivates minimally invasive procedures. However, direct 3D imaging modalities such as Computed Tomography (CT) are restricted to a minority of complex orthopedic procedures. Thus the diagnostics and planning of many interventions still rely on two dimensional (2D) radiographic images, where the surgeon has to mentally visualize the anatomy of interest. The purpose of this paper is to apply and validate a bi-planar 3D reconstruction methodology driven by prominent bony anatomy edges and contours identified on orthogonal radiographs. The results obtained through the proposed methodology are benchmarked against 3D CT scan data to assess the accuracy of reconstruction. The human femur has been used as the anatomy of interest throughout the paper. The novelty of this methodology is that it not only involves the outer contours of the bony anatomy in the reconstruction but also several key interior edges identifiable on radiographic images. Hence, this framework is not simply limited to long bones, but is generally applicable to a multitude of other bony anatomies as illustrated in the results section.     

Patient dose from 3D rotational neurovascular studies

The use of image-guided interventional radiological techniques is increasing in prevalence and complexity. Imaging system developments have helped improve the information available to interventionalists to plan and guide procedures. Information on doses to patients resulting from alternative imaging techniques or protocols is useful for both the process of justifying particular procedures and in optimizing the resultant exposures. Such information is not always available, especially for new or developing imaging techniques. We have undertaken a study of doses to patients associated with two alternative imaging methods for pre-intervention assessment of intracranial aneurysms. In the first technique the aneurysm is assessed from a series of digital subtraction angiography (DSA) runs taken at different imaging projections. The second technique involved acquiring images from one single image run while the imaging system rotated 180 degrees around the patient's head. In this technique, the aneurysm was then evaluated from a 3D reconstruction of the projection images. Effective doses were calculated using a computer model to simulate the exposure geometry and parameters. The mean dose from the DSA protocol used at our centre was 3.4 mSv and from the 3D rotational angiography (RA) technique was 0.20 mSv.     

MRI和CT图像融合构建头面部分层网格模型的研究

目的:分层构建头面部软、硬组织三维网格模型,探讨其在计算机辅助手术中的应用价值.方法:依据正常人头面部MRI和三维CT断层扫描图像,进行MRI与CT图像的融合,识别确定重建对象,对皮肤、皮下组织及骨组织采用灰度阈值法进行自动重建;采用MIMICS软件对获取的医学信息进行分层网格划分,完成建模.结果:完成了包含皮肤、皮下组织和骨组织的正常人头面部三维网格模型.模型单元及节点数分别为皮肤层36524个单元,18263个节点;皮下层38954个单元,19247个节点;头颅68722个单元,33689个节点.结论:利用医学影像资料的图像融合,采用MIMICS软件等数字图像技术可实现人头面部复杂结构的精确三维重建和分层网格划分.     

电子束CT血管造影及三维重建在主动脉病变诊断中的临床应用

目的建立电子束ＣＴ血管造影（ＥＢＣＴ－Ａｎｇｉｏｇｒａｐｈｙ）常规扫描及三维重建方法，探讨其临床应用价值。材料与方法回顾分析了自１９９５年７月至１９９６年１２月经ＥＢＣＴ诊断的各种主动脉病变共１８９例，男１５２例，女３７例，其中６８例与手术结果作了对照。胸主动脉扫描采用单层增强扫描方法（ＳＳＭ），心电门控采像；腹主动脉扫描采用连续容积扫描方法（ＣＶＳ），无心电门控。三维重建方法采用表面阴影显示法（ＳＳＤ）、多层面或曲面重建法（ＭＰＲ／ＣＰＲ）及最大密度投影法（ＭＩＰ）。结果１８９例主动脉病变包括各型夹层动脉瘤９７例，真性动脉瘤２６例，假性动脉瘤８例，马凡综合征３９例，大动脉炎５例，各种先天性主动脉发育异常１４例。６８例与手术对照，ＥＢＣＴ诊断符合率为９７％。结论ＥＢＣＴ血管造影图像时间分辨率高，消除了呼吸及运动伪影，可以明确诊断各种主动脉病变；三维重建图像利于整体直观地显示病变，帮助明确诊断并指导手术；在主动脉病变的诊断方面，可望取代有创的常规血管造影。     

无框架立体定向机器人引导颈椎弓根螺钉植入的实验研究

目的探讨基于虚拟现实可视化技术的无框架立体定向机器人（CRAS-2型）引导颈椎弓根螺钉植入的可行性。方法 3例成人颅-颈椎标本,以不同单一椎体作为独立目标分别进行1 mm的薄层扫描,不同的椎体图像序列分组在手术规划工作站进行三维重建。然后对标本的颅颈和上位颈椎切开暴露,以完全暴露同一椎体表面突出的、细小的、唯一的（CT上能清晰显示的）骨性标志为准;在目标椎体的薄层CT图像上,选择突出的、容易在标本上识别的唯一性骨性标志作为空间位置注册点,用5个自由度的CRAS-2型无框架立体定向机械臂进行靶点的注册。将目标椎弓根和侧块作为一个容积块对待,在每一个断层平面上对其进行轮廓的逐层标记。在计算机软件的辅助下进行椎弓根的三维容积重建,确定钉头预达点为靶点后,将可能的路径显示在重建的三维模型上,并在容积块内调整选择合适的路径。利用机械臂对骨性注册点在手术空间和图像空间的测量结果,计算机辅助直接将手术空间中实物结构坐标映射变换到图像空间中去;在手术空间中移动机械臂末端的手术导引探针;当手术导引针图像的轴向与预先设计的轨迹重合时锁定机械臂;在机械臂末端的操作把持平台上,严格按照导引方向细钻钻孔后,插入导向钢针,最后CT复查验证导向植入螺钉的准确性。结果无框架立体定向机器人辅助椎弓根螺钉植入25枚（部分标本因为下颈椎缺失,未行椎弓根钢钉植入）,钢钉完全与规划路径吻合,准确率达到100%。结论无框架立体定向机器人引导的颈椎弓根螺钉植入具有精确度高、操作简便、图像引导直观清晰、经济实用等特点,有十分广阔的应用前景。