Getting a high-resolution picture of the interior of a coronary artery is difficult: to take a scan using existing technology, the heart has to be kept free of blood for 30 seconds. A new approach could dramatically reduce the time required for imaging, making it safer and easier for doctors to check stents for stability and keep track of new scar tissue.The new method builds on a technique called optical coherence tomography (OCT). This high-resolution medical imaging system has been in use in ophthalmology for more than a decade and is occasionally used to scan coronary arteries. OCT is problematic because it cannot see through blood, so any area being scanned has to be flushed with saline. During the procedure, a special balloon blocks incoming blood, which can cause damage to the tissue.Two U.S. companies are working individually on a scanning method that would take a fraction of the time, greatly reducing the risk of damage to the heart, and a number of companies are working on improving OCT using a formula known as the Fourier domain.This mathematical formula is used to process a complex signal so that it can be differentiated into its component parts and analyzed. For OCT, this means that multiple wavelengths of data can be gathered simultaneously rather than sequentially, an improvement on previous generations of the technology. Sometimes called optical Fourier-domain imaging, this method substantially reduces the time required to perform a scan. Traditional OCT scanning requires multiple exposures of light aimed at specific points to make a full image. Fourier domain OCT exposes the entire area at once, reducing the time required to obtain a section from 30 seconds to two seconds. This reduction dramatically reduces the associated risks of the procedure. In two seconds, an area of artery 40 millimeters to 50 millimeters in size can be scanned, with an accompanying improvement in scanning resolution down to 10 microns.Optical Fourier domain imaging is “a fairly well-established approach in principle,” says Thomas Milner, associate professor in the Department of Biomedical Engineering at the University of Texas, “and it's just starting to work its way into instruments that will be on the market soon.”An initial application for this technology will be to image stents after insertion to ensure they haven't shifted. A stent is an artificial buttress placed in an artery to keep it open, allowing the blood to flow freely. Research from Harvard University Medical School has shown that stent prolapsing can occur with shifts of less than 100 microns. The increased accuracy of OCT technology allows doctors to observe how well the stent is adhering to the arterial walls and to track small amounts of endothelial regrowth. It could also be used postoperatively to check healing. The resolution of this scan is fine enough to allow doctors to identify small but significant plaque deposits that existing technology might overlook. The technology could also be used to carefully target biopsies, as cancerous cells could be identified in much smaller quantities than currently possible.