Techniques for efficient, real-time, 3D visualization of multi-modality cardiac data using consumer graphics hardware.

We exploit consumer graphics hardware to perform real-time processing and visualization of high-resolution, 4D cardiac data. We have implemented real-time, realistic volume rendering, interactive 4D motion segmentation of cardiac data, visualization of multi-modality cardiac data and 3D display of multiple series cardiac MRI. We show that an ATI Radeon 9700 Pro can render a 512x512x128 cardiac Computed Tomography (CT) study at 0.9 to 60 frames per second (fps) depending on rendering parameters and that 4D motion based segmentation can be performed in real-time. We conclude that real-time rendering and processing of cardiac data can be implemented on consumer graphics cards.     

激光共聚焦显微镜数据的交互体绘制算法

目的在PC机上实现激光共聚焦显微镜数据的实时交互体绘制 ,以满足用户对数据场的不同观察要求。方法通过分析激光共聚焦显微镜数据光学属性 ,得到交互传递函数 ,使用户可以改变绘制参数来参与对激光共聚焦显微镜数据场的数据挖掘 ;同时采用了纹理映射体绘制技术进行实时三维重建。结果在普通PC上实现了本算法。对一空间分辨率为 2 5 6× 2 5 6× 40的激光共聚焦显微镜数据场进行了三维重建实验 ,得到一组满足用户不同观察目的的重建结果。重建过程中 ,在用户更改绘制参数时 ,可以 1 0帧 /s的速度进行重绘制。结论与传统算法不同 ,本算法可在PC上提供给用户实时交互环境 ,更方便地获得符合观察要求的重建结果。     

Synchronized 2D/3D optical mapping for interactive exploration and real-time visualization of multi-function neurological images

Efficient software with the ability to display multiple neurological image datasets simultaneously with full real-time interactivity is critical for brain disease diagnosis and image-guided planning. In this paper, we describe the creation and function of a new comprehensive software platform that integrates novel algorithms and functions for multiple medical image visualization, processing, and manipulation. We implement an opacity-adjustment algorithm to build 2D lookup tables for multiple slice image display and fusion, which achieves a better visual result than those of using VTK-based methods. We also develop a new real-time 2D and 3D data synchronization scheme for multi-function MR volume and slice image optical mapping and rendering simultaneously through using the same adjustment operation. All these methodologies are integrated into our software framework to provide users with an efficient tool for flexibly, intuitively, and rapidly exploring and analyzing the functional and anatomical MR neurological data. Finally, we validate our new techniques and software platform with visual analysis and task-specific user studies.     

Three-dimensional volume rendering of spiral CT data: theory and method.

Three-dimensional (3D) medical images of computed tomographic (CT) data sets can be generated with a variety of computer algorithms. The three most commonly used techniques are shaded surface display, maximum intensity projection, and, more recently, 3D volume rendering. Implementation of 3D volume rendering involves volume data management, which relates to operations including acquisition, resampling, and editing of the data set; rendering parameters including window width and level, opacity, brightness, and percentage classification; and image display, which comprises techniques such as "fly-through" and "fly-around," multiple-view display, obscured structure and shading depth cues, and kinetic and stereo depth cues. An understanding of both the theory and method of 3D volume rendering is essential for accurate evaluation of the resulting images. Three-dimensional volume rendering is useful in a wide variety of applications but is just now being incorporated into commercially available software packages for medical imaging. Although further research is needed to determine the efficacy of 3D volume rendering in clinical applications, with wider availability and improved cost-to-performance ratios in computing, 3D volume rendering is likely to enjoy widespread acceptance in the medical community.     

New method for 3D parametric visualization of contrast-enhanced pulmonary perfusion MRI data

Three-dimensional (3D) dynamic contrast-enhanced magnetic resonance imaging (3D DCE-MRI) has been proposed for the assessment of regional perfusion. The aim of this work was the implementation of an algorithm for a 3D parametric visualization of lung perfusion using different cutting planes and volume rendering. Our implementation was based on 3D DCE-MRI data of the lungs of five patients and five healthy volunteers. Using the indicator dilution theory, the regional perfusion parameters, tissue blood flow, blood volume and mean transit time were calculated. Due to the required temporal resolution, the volume elements of dynamic MR data sets show a reduced spatial resolution in the z-direction. Therefore, perfusion parameter volumes were interpolated. Linear interpolation and a combination of linear and nearest-neighbor interpolation were evaluated. Additionally, ray tracing was applied for 3D visualization. The linear interpolation algorithm caused interpolation errors at the lung borders. Using the combined interpolation, visualization of perfusion information in arbitrary cutting planes and in 3D using volume rendering was possible. This facilitated the localization of perfusion deficits compared with the coronal orientated source data. The 3D visualization of perfusion parameters using a combined interpolation algorithm is feasible. Further studies are required to evaluate the additional benefit from the 3D visualization.     

Effects of ECG gating and postprocessing techniques on 3D MDCT of the bronchial tree

OBJECTIVE: Our goal was to determine the impact of ECG gating and different postprocessing techniques on 3D imaging of the bronchial tree. SUBJECTS AND METHODS. Retrospective ECG-gated MDCT and non-ECG-gated MDCT of the chest were performed in 25 patients. ECG-gated MDCT data were reconstructed mid diastole using a fixed interval of -400 msec in 25 patients and then additionally at -200, -300, and -500 msec in 10 of those patients. Shaded surface display and volume rendering of the bronchial tree combined with virtual bronchoscopy were performed using all data sets. The extent of bronchial tree visualization in shaded surface display-virtual bronchoscopy and volume rendering-virtual bronchoscopy and the presence of artifacts in volume-rendered images were scored by three blinded reviewers. The effective radiation doses of the ECG-gated and nongated acquisitions were compared. RESULTS: The summary scores of all bronchial segments for gated shaded surface display-virtual bronchoscopy and gated volume rendering-virtual bronchoscopy did not differ significantly. The summary scores for nongated shaded surface display-virtual bronchoscopy and nongated volume rendering-virtual bronchoscopy were not significantly different. Non-gated acquisition yielded significantly better visualization of the bronchial tree for both post-processing techniques, regardless of the time interval used for reconstruction of the ECG-gated series. Artifact scores in volume-rendered images were significantly higher for ECG-gated MDCT compared with nongated MDCT. Effective radiation dose was significantly higher for the ECG-gated acquisition. CONCLUSION: Given the advantage of volume rendering for representing the entire data set and given the lower radiation dose and better 3D image quality of nongated acquisition, volume rendering performed on nongated MDCT data is the method of choice for 3D visualization of the bronchial tree.     

医学图像三维可视化

本文详细综述了在医学图像三维可视化领域应用广泛的各种体绘制技术,进一步展示了在可视化领域结合因特网技术的最新发展方向。在比较各种体绘制技术的基础上,提出了适合在高档PC上开发用于计算机辅助手术导航系统的三维可视化方法。     

Cinematic rendering of cardiac CT volumetric data: Principles and initial observations

BackgroundCinematic rendering (CR) a new method of 3D computed tomography (CT) volumetric visualization that produces photorealistic images. As with traditional 3D visualization methods, CR may prove to be of value in providing important information when evaluating regions of complex anatomy such as the heart.MethodsThe gated, IV contrast-enhanced chest CT angiogram data from three recent patients were evaluated with CR. Image comparision demonstrates the difference between CR and traditional volume rendering (VR), owing to a more complex lighting model that enhances surface detail and produces realistic shadows to add depth to 3D visualizations.ResultsRepresentative examples of normal cardiac anatomy, a coronary artery stenosis, and an intracardiac malignant neoplasm are presented with 2D multiplanar reconstruction, traditional VR and CR. A potential pitfall in CR utilization, namely the possibility of obscuring important pathology, is demonstrated and discussed.ConclusionsCR is a promising method to enhance display volumetric CT data and should prove useful in diagnosis, treatment planning, surgical navigation, trainee education, and patient engagement. However, further study is needed to establish the advantaged and disadvantages of CR in comparison to other 3D methods.     

基于有序体数据的体绘制方法

目的 体绘制是三维可视化的有效方法，但是它处理的数据量巨大。本文提出一种称为有序体数据的空间数据结构，它可以有效地加速体绘制而对图像质量没有影响。方法 在体绘制前，将每个体数据的每个层片编码成以体素值为序的有序数组。依据不透明度函数可确定出不透明体素所对应的体素值范围。通过对有序数组的截取，可快速地定位不透明体素，而跳过所有透明的体素。该算法的优点是在不透明度函数改变后无需重新生成有序体数据，方便体绘制中的交互，快速地绘制出结果图片。结果 在典型的PC机上验证了上述算法，对于CT头部体数据，绘制时间不大于1s，绘制速度达到了临床诊断的要求。结论 基于有序体数据的体绘制方法思路简洁，易于实现，不受透明度变换函数的约束，显著提高了绘制速度，而且不影响图象的质量。     

Dynamic imaging of the compliant perfusion of the lungs

A method for the study of the dynamics of the perfusion of the compliant vascular tree of the lungs using in vivo labelled 99mTc red cells and ECG gating is presented. Following blood pool labelling, posterior, ECG gated gamma camera images were acquired in time intervals of about 40 ms for 1,000-2,000 cardiac cycles. The images show the lungs plus the heart and great vessels. The image sequence containing the periodic variation of the blood activity in the lungs during the cardiac cycle is analyzed to obtain volume curves and functional images of the amplitude and phase of the lung perfusion. The interference of the heart and great vessels with the left lung can be avoided by excluding the superimposed areas in the ROIs with the sacrifice of part of the left lung. This technique allows dynamic visualization of the perfusion process in the compliant arterial and venous vascular trees of the lungs. The results obtained with this method in normals and some pathologies are discussed.     

Advances in cardiac imaging with 16-section CT systems

RATIONALE AND OBJECTIVES: The authors present advances in electrocardiographically (ECG) gated cardiac spiral scanning with recently introduced 16-section computed tomographic (CT) equipment. MATERIALS AND METHODS: The authors discuss the technical principles of ECG-gated cardiac scanning. They give an overview on system properties and on the detector design. They describe ECG-gated scan- and image-reconstruction techniques and ECG-controlled dose modulation ("ECG pulsing") for a reduction of the patient dose. They discuss key parameters for image quality and present simulation and phantom studies and they give preliminary values for the patient dose. RESULTS: An extension of the adaptive cardiac volume reconstruction for ECG-gated spiral CT provides adequate image quality for up to 16 sections. With the smallest reconstructed section width (about 0.83 mm) and overlapping image reconstruction, cylindrical holes 0.6-0.7 mm in diameter can be resolved in a transverse resolution phantom independent of the heart rate. For coronary CT angiography, the influence of transverse resolution is most pronounced for coronary segments that are only slightly tilted relative to the scan plane. In this case, visualization of stents and plaques is considerably improved with 1.0-mm or smaller section width. For 0.42-second gantry rotation time, temporal resolution reaches its optimum (105 msec) at a heart rate of 81 beats per minute. Effective patient dose for the standard protocols recommended by the manufacturer ranges from 0.45 mSv (male) for ECG-triggered calcium scoring to 7.1 mSv (male) for high-resolution ECG-gated coronary CT angiography. With ECG pulsing, the dose is reduced by 30%-50% depending on the patient's heart rate. CONCLUSION: Clinical experience will be needed to evaluate fully the potential of 16-section technology for cardiac imaging.     

螺旋CT三维成像在诊断面颅骨骨折中的作用

目的　评价螺旋CT三维成像技术在诊断面颅骨骨折中的作用。方法　总结利用螺旋CT三维成像技术处理 2 6例面颅骨骨折患者的影像学资料 ,分析其多平面重建 (MPR) ,三维表面遮盖法重建 (SSD) ,容积重建 (VRT)等多种重建技术的影像学表现。结果　MPR、SSD、VRT可清晰显示面颅骨骨折的位置、形态、大小 ,叠加成像能清楚显示面颅骨骨折与邻近结构关系。结论　 3D重建能立体地显示面颅骨骨折 ,结合轴位图像能提高诊断面颅骨骨折的准确性 ,对临床治疗方案有较大帮助     

采用半透明效果实现医学三维整体可视化

目的通过改进直接体绘制技术（DVR）算法中的关键步骤，绘制能表达数据场中不同层次组织的内部结构。方法根据界面对光线的反射和物质本身对光线的衰减，将数据场划分为边界不丰富的简单数据场和边界丰富的复杂数据场，从而采用分段线性函数来构造阻光度传递函数（TF）；将数据场中低灰度体素点看为一种不发光但会导致采样光线衰减的物质；根据采样结束时采样光线的阻光度分布来调整TF，完成三维绘制。结果绘制出了不同层次组织的内部结构。结论本算法有效地解决了体素点相互遮挡的问题，实现了医学三维整体可视化。     

Skeletal 3-D CT: advantages of volume rendering over surface rendering

 Both surface rendering and volume rendering have been extensively applied to CT data for 3-D visualization of skeletal pathology. This review illustrates potential limitations of each technique by directly comparing 3-D images of bone pathology created using volume rendering and surface rendering. Surface renderings show gross 3-D relationships most effectively, but suffer from more stairstep artifacts and fail to effectively display lesions hidden behind overlying bone or located beneath the bone cortex. Volume-rendering algorithms effectively show subcortical lesions, minimally displaced fractures, and hidden areas of interest with few artifacts. Volume algorithms show 3-D relationships with varying degrees of success depending on the degree of surface shading and opacity. While surface rendering creates more three-dimensionally realistic images of the bone surface, it may be of limited clinical utility due to numerous artifacts and the inability to show subcortical pathology. Volume rendering is a flexible 3-D technique that effectively displays a variety of skeletal pathology with few artifacts.     

心率对64层螺旋CT冠状动脉成像图像质量的影响

目的:评价心率对64层螺旋CT冠状动脉成像图像质量的影响.方法:采用GE Light speed 64层螺旋VCT,以心脏扫描模式对心脏动态体模进行扫描.心脏动态体模由3个部分组成:动力部分、解剖结构模拟部分和控制部分.心脏动态体模的心率设置为40、45、50、55、60、65、70、75、80、85、90、95、100、105、110和115次/min,心律齐.以球管转速0.35 s对不同心率下的心脏动态体模进行冠状动脉成像扫描.所有扫描数据在R-R间期90%时相分别进行单扇区和多扇区重建.重建数据传至工作站后处理成像.后处理方法采用VR、MPR重组模式.分别对重建图像进行评分.结果:①心率与图像质量呈负相关(P＜0.01);随着心率的增加,图像质量评分呈下降趋势;②在同一条件下多扇区重建算法较单扇区重建算法提高了图像质量评分.结论:采用心脏动态体模评价心率对64层螺旋CT冠状动脉成像图像质量的影响,对临床研究和应用有着重要价值.     

A fantastic journey: 3D cardiac ultrasound goes live

With a recent product introduction, live 3D echo is now clinically practical. It is already beginning to have a profound impact on the way we care for patients at The University of Chicago Medical Center. In the past, dynamic cardiac 3D rendered images were possible by sequentially acquiring 2D images and then using a workstation to input 2D images for Cartesian coordinate conversion and volume rendering. Outside research settings, this time-consuming process proved cumbersome and was simply impractical. Now that these technical and practical issues have been addressed, real-time 3D cardiac sonography has great potential to impact both patient care and throughput in a number of ways, including better pre- and post-surgical planning, improved measurement of heart function, decreased exam times, and enhanced communication between clinicians and their patients. With real-time 3D cardiac ultrasound images, clinicians will be able to better quantify size, shape and function of the heart. However, the most important contribution of real-time 3D sonography in cardiology may be improvement in locating abnormalities for surgical planning. The new technology will also provide important information regarding surgical outcomes. A great benefit to obtaining more diagnostic information and higher diagnostic confidence from real-time 3D cardiac ultrasound images is that it could lead to more rapid exam times and the reduction of patient wait times. Being able to see the whole heart makes examinations more simple and rapid, benefitting the staff and patient. The utility of this technology is unusually broad, as it is able to move beyond diagnostics into a key role in therapeutic procedures. As with any new technology, there will be a learning curve to understanding 3D imaging. Though the matrix transducer is somewhat larger than a standard 2D probe, the ergonomics are quite similar. The interface of the ultrasound unit is also very user friendly. Because real-time 3D cardiac ultrasound involves looking at the heart as if you are holding it in your hands, with the additional ability to turn it any way you want, we expect that the transition from 2D to 3D will be easily achieved.     

Improving coronary artery imaging quality in the high heart rate region and on MDCT using a pulsating cardiac phantom

The multi-sector reconstruction (MSR) algorithm and cardiac half-reconstruction (CHR) algorithm are the main algorithms used in cardiac reconstruction. Analysis of effective temporal resolution (TR) confirmed that optimal rotation speed depends on different heart rates when using MSR. During visualization (3D/MPR image) and quantitative (EF: ejection fraction) evaluations, it was found that image quality and measurement accuracy are well correlated with effective temporal resolution (TR) by the different algorithms. The CHR algorithm resulted in less desirable image quality at TR 250 ms than that from MSR at high heart rates (>75 bpm) in the phantom experiment. We determined that the combination of the MSR algorithm and the optimal selection of gantry rotation speed is important for obtaining high-quality cardiac imaging in the high heart rate region.     

Real-Time Four-dimensional Imaging of the Heart with Multi-Detector Row CT.

An interactive four-dimensional (4D) visualizing system for the heart was developed by the authors. The system realizes high-resolution three-dimensional (3D) imaging with temporal resolution in a beating heart by using eight or more data sets reconstructed from multi-detector row computed tomography (MDCT) with a retrospective electrocardiograph-gated reconstruction algorithm. The motion of heart walls, papillary muscles, septa, and valves can now be observed in 4D multiplanar reformations (MPRs), as with sonography, while coronary arteries, coronary sinuses, and cardiac veins can be analyzed during the optimal phase in 4D volume-rendering images, as with angiography. All parameters such as window width, window level, field of view, panning, tilt, thresholds, opacity, color, and segmentation function are completely interactive in 4D imaging. Two longitudinal views and one latitudinal view of a heart can be simultaneously visualized in the three relative 4D MPR views. These newly developed capabilities in viewing both 3D volume and temporal resolution data, functional data, and even multiphase data with registration add considerable diagnostic potential. The advent of this real-time 4D visualizing system has enhanced the capabilities of MDCT. Copyright RSNA, 2003     

Multi-detector row CT of thoracic disease with emphasis on 3D volume rendering and CT angiography.

Multi-detector row computed tomography (CT) with three-dimensional (3D) volume rendering provides a unique perspective on thoracic anatomy and disease. Multi-detector row CT allows shorter acquisition times, greater coverage, and superior image resolution. Three-dimensional volume rendering now permits real-time, interactive modification of relative pixel attenuation in an infinite number of planes and projections. In vascular imaging, this technique provides image quality that equals or surpasses that of conventional angiography. Its use has expanded to aid in diagnosis and surgical planning, often obviating conventional or digital angiography and reducing costs. It is reliable in depicting clot and the pulmonary vasculature and may also be used to evaluate thoracic venous anomalies (eg, pulmonary arteriovenous malformations) and to plan therapy. Airway imaging with multi-detector row CT with 3D volume rendering is particularly useful in the planning and follow-up of stent placement. In diffuse lung disease, this technique can increase nodule detection and help differentiate between small nodules and vessels. It is also helpful in imaging the musculoskeletal system and the thoracic cage. Multi-detector row CT with 3D volume rendering has enhanced the conventional roles of thoracic CT and challenged the supremacy of other imaging modalities. It will likely play a leading role in future radiologic research and practice.     

Computer system for four-dimensional transesophageal echocardiographic image reconstruction.

This paper presents a system for reconstructing a four-dimensional (4D) heart-beating image from transesophageal echocardiographic (TEE) data acquired with a rotational approach. The system consists of the necessary processing modules for two-dimensional (2D) echocardiogram reformation and 3D/4D-image reconstruction. These include the modules of image decoding, image re-coordinating, and three-dimensional (3D) volume rendering. The system is implemented under PC platform with Windows 95 operating system (with Intel Pentium-166 CPU, 64 MB RAM on board, and 2.0 GB hard disk capacity). It takes 6 min to reconstruct a 4D echocardiographic data set. The resultant 2D/3D/4D echocardiographic image provide the tools for investigating the phenomenon of heart beating, exploring the heart structure, and reformatting the 2D echocardiograms in an arbitrary plane. The functions provided by the system can be applied for further studies, such as 3D cardiac shape analysis, cardiac function measurement, and so forth.