|
Presenting three-dimensional information in the form of 3D solid models rather than as a sequence of two-dimensional intensity images provides many benefits in presurgical planning and diagnostic radiography. Although the model generation process does not add information to the sequential slice data, it does present images of organs and bony structures in a form more like the expected view of solid objects in natural scenes. Surface shapes and details of surface variations, which would require practiced observation of two-dimensional intensity data, are readily visible in the solid model displays making this information immediately available to a broad cross section of medical personnel. After a year of experience with a commercially available system, a Contour Medical Systems CEMAX-l000, which accepts input from several CT or MR scanner models and provides basic solid model displays, additional types of solid model viewing have been made available to clinical personnel for preliminary evaluation. The advantages and disadvantages in terms of subjective display quality, information content, and computational cost of several display methods have been investigated. Display of solid models by range encoding, heuristic mappings of intensity levels, and complete reflectance models have been compared for black-and-white and monochromatic color images. The option of displaying multiple objects in contrasting colors both as opaque and transparent objects has also been tested. Methods of surface acquisition from the two-dimensional data have been varied to match the material of interest and the characteristics of the original intensity data allowing improved representation of soft tissue. Finally, the utility of several types of time varying imagery is discussed, including the advantages of viewing rotating solid objects compared to viewing a collage of still pictures in many orientations. Some clinical examples of these experimental image display techniques are presented. The advantages of each are discussed in the context of the computational burden of display generation.
|
