Contrast-to-Noise determination in the aortic arch.

<p>Region of interest (ROI) placement in the MR images were used to determine the contrast to noise ratios (CNR) in the atherosclerotic plaques in black blood images of a cross section of the aortic arch. ROI1 is placed in the atherosclerotic plaque in the vessel wall (Iwall). ROI2 is positioned in a muscle and used for normalization purposes (Imuscle). Noise levels were determined in ROI 3, placed in a region without signal. The standard deviation of the noise (stdevnoise) was used for normalization purposes.