Fig. 1

Use of a low dose CT image (a) to derive active (b) and manual (c) contours in one CT slice which are then projected onto the coregistered PET image to determine radioactivity concentration of the enclosed volumes of interest. In each CT slice, a loose region (c₁—blue), enclosing the LV segment, was defined as the starting point of the active contour algorithm. In the next step, the active contour method was applied so as to identify the outer bone contour (c₂—green) of the LV. Lastly, erosion of c₂ was performed by sampling three pixels (vertically and horizontally) so as to exclude the compact bone from the LV segment, allowing for the creation of a contour that encompasses only the bone marrow component (c₃—red)