Abstract: Systems and methods for deriving a cardiac cycle signal by selecting images of a portion of a cardiovascular system include receiving a plurality of images from a scanner that have been recorded over a period of time. The images represent one or more locations along the extent of the cardiovascular system. The images are then selected based on common criteria determined from the plurality of images and without reference to an external signal. The common criteria comprises changes in the size of a cross section of the aorta, changes in the volume of the heart, changes in the area of a cross section of the heart. In addition, the criteria can include the mean pixel difference between adjacent images.

Abstract: This document discusses, among other things, systems and methods for segmenting and displaying blood vessels or other tubular structures in volumetric imaging data. The vessel of interest is specified by user input, such as by using a single point-and-click of a mouse or using a menu to select the desired vessel. A central vessel axis (CVA) or centerline path is obtained. A segmentation algorithm uses the centerline to propagate a front that collects voxels associated with the vessel. Re-initialization of the algorithm permits control parameter(s) to be adjusted to accommodate local variations at different parts of the vessel. Termination of the front occurs, among other things, upon vessel departure, for example, indicated by a speed of front evolution falling below a predetermined threshold.