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1、Visualization of 3D Ultrasound Data Thomas R. Nelson University of California, San Diego T. Todd Elvins San Diego Supercomputer Center Ultrasound imaging plays a vital role in diagnosis. Future systems will acquire 30 data directly into the imager, where physicians can immediately examine, visualize
2、, and interpret the patients 30 anatomy ltrasound data acquisition will play an increasing role in U the future of medical imaging. Unlike magnetic resonance imaging (MRI) and computerized tomography (a), ultrasound offers interactive visualization of underlying anatomy in real time. Additionally, u
3、ltrasound equipment costs far less and does not use ionizing radiation or require specialized facilities. Most ultrasound imaging procedures are noninvasive com- pared to radiologic or laparoscopic procedures. As outpatient procedures become more common in health care delivery, spe- cialized cathete
4、rs will further expand the role of ultrasound ex- amination. Sonographic image quality has benefitted from increasingly sophisticated computer technology, with systems integration ensuring better data acquisition, analysis, and display in future systems. The inherent flexibility and cost advantages
5、of ultra- sound imaging will ultimately play a large role in increasing ef- ficiency and reducing health care costs. Multidimensional medical imaging Three-dimensional display of data, while available for some time in CT, single photon emission computed tomography (SPECT), positron emission tomograp
6、hy (PET), and MRI, has not achieved widespread clinical use for two reasons: the time required to obtain high-resolution image data and the often slow postprocessing, which requires significant operator in- volvement. Unlike other tomographic imaging techniques, ul- trasound offers interactive visua
7、lization of underlying anatomy while providing flexibility in viewing images from different ori- entations in real time. Currently, much pathology is readily di- agnosed with conventional 2D ultrasound equipment. However, complex cases often make it difficult even for specialists to vi- sualize 3D a
8、natomy. While ultrasound imaging facilitates following the path of a tortuous vessel or complex underlying anatomy with consider- able freedom, patient orientation might limit the image projec- tion angle, making critical views unavailable. Also, although ultrasounds flexibility offers significant i
9、maging advantages, it requires the physician to completely understand the underlying anatomy and to integrate multiple images to obtain a 3D im- pression of the anatomy. While such practice is routine, the physician often needs significant time to completely understand the patients anatomy. Occasion
10、ally, the limitations of 2D ultrasound imaging (such as suboptimal projection angle or large patient size) make it 50 0272 17-16/Y3/1100-0050$03 000 1993 IEEE IEEE Computer Graphics the bumpy or erratic surface significantly distorts features used in arriving at the correct diagnosis, which poten- t
11、ially limits use in ultrasound imaging except in specialized ap- plications such as vascular imaging. Images created with ray casting and splatting appear similar to the viewer. The differences are primarily in the algorithmic methods of production. These approaches produce high-qual- ity images tha
12、t are relatively tolerant of noise in the ultrasound data. Filtering can improve results as long as it does not ob- scure fine detail. Careful selection of opacity values helps pro- vide an accurate rendition of the structure being studied. Transparency permits viewing surface and subsurface feature
13、s, which can help in establishing spatial relationships. For specific applications, maximum intensity methods give a clear view of structures such as bones in the hands, spine, or ribs, although they are often best applied to selected regions of the volume. Spatially aligning two data sets sampled f
14、rom the same pa- tient (such as soft tissue and blood flow) can create hybrid im- sampled from the same patient (such as soft tissue and blood flow) can create hybrid images that improve the diagnostic process. ages that improve the diagnostic process. You can do this by us- ing an algorithm that we
15、ights the display based on values from the two data sets at every grid point, either during rendering or as a postprocess compositing step. Keep in mind that, although not specifically discussed, ani- mation sequences can greatly assist volume visualization. With- out the animation display of render
16、ed volumetric images offered by real-time processing or precalculation, the physician often has a difficult time extracting 3D information from 2D dis- plays. Animation is often a straightforward extension to the topics covered here. Summary Clinical applications of 3D ultrasound visualization are in- creasing. Real-time review of patient volume data by the physi- cian can potentially enhance the diagnostic process. However, researchers must address specialized problems before widespread cli
