Thomas Frederick Boltz BS, Presenter: Nothing to Disclose

Prasad Mukund Panse MD, Abstract Co-Author: Nothing to Disclose

William Pavlicek PhD, Abstract Co-Author: Nothing to Disclose

Robert Gene Paden, Abstract Co-Author: Nothing to Disclose

Didem Yamak, Abstract Co-Author: Nothing to Disclose

Sandeep Dutta PhD, Abstract Co-Author: Nothing to Disclose

Single energy reconstructions can accurately assess vessel stenosis in CCTA exams but are unable to provide diagnostic confidence in arteries with high levels of calcium. Dual energy reconstructions provide better visualization of vessel stenosis by reducing calcium blurring.

Coronary Computed Tomography Angiography (CCTA) uses iodine to identify possible stenosis in an artery. Stenosis occurring as a result of soft plaques can be confidently visualized and quantified. The presence of dense calcified plaques can cause blurring that hinders the ability to diagnose stenosis and/or assess surrounding soft plaque composition.

The proposed work evaluates the use of single energy CCTA to visualize and quantify soft plaque stenosis. There is also discussion on the use of monochromatic energy images and two material basis images for improved visualization of iodine patency with reduced calcium blur in coronary angiograms.

Measurements were taken of 19 machined soft plaques with densities of 0.91g/cm3, 0.97 g/cm3, and 1.18 g/cm3. Each density plaque had known stenosis of 40%, 60%, and 80%. Single energy 100kVp acquisitions were performed on the plaques while inserted in a beating heart phantom at 60bpm. After 7 independent observers took measurements of the plaques, it was found that single energy images had 0.63 correlation to known stenoses. The presence of calcium increases the perceived stenosis, causing concern for stenosis confidence in single energy image. Monochromatic images acquired from dual energy CT scans cause a reduction in the population of calcium pixels present in an artery. As monochromatic energy increases, calcium pixels decrease in value but iodine pixels also decrease in value. The result is that monochromatic images either eliminate needed iodine enhancement or suffer from calcium blurring. Two material basis (MB) images have a single reconstruction that is independent of energy level and able to selectively visualize calcium or iodine. MB images like Calcium(Water) or Iodine(Water) provide visual calcium blurring reduction while maintaining sufficient iodine enhancement.

Boltz, T, Panse, P, Pavlicek, W, Paden, R, Yamak, D, Dutta, S, Accurate Coronary Artery Stenosis Evaluation with and without the Presence of Calcified Plaques.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9013074.html