Coronary atherosclerosis could someday be more easily diagnosed and treated, thanks to a new version of the intravascular imaging technology optical coherence tomography that provides a resolution 10 times greater than that of standard OCT. The new version, developed at the Wellman Center for Photomedicine at Massachusetts General Hospital, is called microOCT, and it provides the contrast and resolution required to show individual arterial and inflammatory cells within coronary artery samples, including subcellular features that may identify vulnerable plaques. These are images of a coronary artery plaque (Ca in image c) produced by (a) standard OCT, (b) microOCT and (c) tissue histology. Courtesy of Nature Medicine and the Wellman Center for Photomedicine at Massachusetts General Hospital. OCT, a catheter-based technology, uses reflected near-infrared light to create detailed images of a blood vessel’s internal surfaces. Standard OCT is used to identify arterial plaques that are likely to rupture, but it can only clearly image structures larger than 10 μm. Now, using new types of lenses and advanced imaging components, microOCT can image structures as small as 1 μm. The technique reveals an intact tissue’s detailed information in three dimensions – and does so much more quickly than with the prepared tissue slides of traditional pathology. Using microOCT, researchers were able to image human and animal coronary artery tissue, revealing inflammatory cells that contribute to the formation of coronary plaques, endothelial cells that line coronary arteries, smooth muscle cells that produce collagen in response to inflammation, and fibrin proteins and platelets that are involved in the formation of blood clots. The technology also can distinguish between bare-metal stents and drug-eluting stents placed in coronary arteries. During the study, defects in the drug-eluting coating were identifiable using the technology. The researchers anticipate that observation of cells with microOCT could be performed in humans in roughly three to five years. They are hopeful that, with the ability to follow and track cells in 3-D, they can prove or disprove many theories of coronary artery disease, as well as better understand how clots form on a microscopic level. In addition, improved definitions of high-risk plaques could lead to greater accuracy in identifying those that could rupture or block coronary arteries. The researchers also said that being able to monitor the healing of implanted stents could reduce the number of patients who must be on anticlotting medications, which have major side effects and are very costly. Findings were described in the July 10 online edition of Nature Medicine (doi: 10.1038/nm.2409).