Description of contrast-to-noise ratio (CNR) measurement for deep medullary veins (DMV) in a combined multi-echo susceptibility weighted image.

<p>A, Each red region of interest (ROI) for periventricular DMV was drawn with one pixel width along the center of vein. Each blue ROI for neighboring white matter tissues was drawn surrounding the vein by the same pixel size of red ROI. Three different regions of DMV and adjacent white matter tissues (yellow rectangle in A) were shown (B to D, magnification of the three regions in A). CNR was calculated based on values obtained from the two ROIs.