But the goal here is not really technology-it's to obtain better visualization of particular entities. Nelson predicts a merger of 3-D technology with harmonic and pulse inversion approaches for contrast media. Pulse inversion harmonics with contrast produces spectacular results when coupled with 3-D, he said. Yet the current of clinical medicine is hampered by clinical and economic realities. While the technologies necessary to make volumetric imaging a reality are almost at hand, the perceived clinical value of volumetric imaging has not resulted in widespread adoption of the technology.
Some kinks remain to be worked out, such as exactly demonstrating blood flow.
Because flow consists of motion, it can occur in any direction, depending on the vascular tree. Flow, therefore, must be plotted according to its velocity. Success at this promises enormous benefits, as the information can be translated into images, as well as into quantifying a host of cardiovascular indicators. Most appealing is the possibility of characterizing complex flow events, such as regurgitant flow jets that are hard to visualize in two dimensions. Researchers at Thomas Jefferson University in Philadelphia have been exploring ways to get around some of the limitations of harmonic imaging, especially the problems caused by second harmonic generation and harmonic frequency accumulation within the tissue itself.