K-edge subtraction imaging for coronary angiography with a compact synchrotron X-ray source - Fig 4

K-edge subtraction imaging of the left anterior descending artery of a porcine heart with injected iodine contrast agent and inhomogeneous background structures: First row: In both, the unfiltered (a) and the iodine-filtered (b) image, air artefacts and inhomogeneous absorption make the identification of small blood vessels difficult. In the KES image (c), only the contrast agent remains visible; Second row: The overlying bone structures make the identification of the small blood vessel (marked by the red arrow) impossible in images (d) and (e). Only KES imaging, combined with an energy correction, restores contrast for these blood vessels. Although in areas of lower counting statistics the image quality is compromised in the KES image (f) by noise, the visibility of the small vessels is increased. The ROIs for the calculation on the CNR of the blood vessel (1) and the bone (2) are shown in the unfiltered (d) and difference (f) image. The gray scales of the images were chosen such that the contrast for the coronary arteries is optimized. The gray scales for the unfiltered and filtered images show the relative intensity of the X-ray beam, while the gray values in the KES images show the negative differences in the absorption.