Improved techniques for fast sliding thin-slab volume visualization

High-resolution three-dimensional (3D) volumetric images obtained by today's radiologic imaging scanners are rich in detailed diagnostic information. Despite the many visualization techniques available to assess such images, there remains information that is challenging to uncover, such as the location of small structures (e.g., mediastinal lymph nodes, narrowed-airway regions). Recently, sliding thin-slab (STS) visualization was proposed to improve the visualization of interior structures. These STS techniques and the other existing techniques, involve considerable computation, significant memory, extra processing, and dependence on user specifications. Further, other effective rendering approaches are conceivable using the general STS mechanism. We introduce two fast direct techniques for STS volume visualization. The first, a depth (perspective) rendering process, produces an unobstructed, high-contrast 3D view of the information within a thin volume of image data. Results are a function of relative planar locations, not individual voxel values. Thus, rendered views accurately depict the internal properties that were initially captured as position and intensity. The second method produces a gradient-like view of the intensity changes in a thin volume. Results can effectively detect the occurrence and location of dramatic tissue variations, often not visually recognized otherwise. Both STS techniques exploit the concept of temporal coherence to form sequences of consecutive slabs, using information from previously computed slabs. This permits rapid real-time computation on a general-purpose computer. Further, these techniques require minimal processing and memory, require no pre-processing, and results are not dependent on user knowledge. Results show the computational efficiency and visual efficacy of these new STS techniques.