Abstract: Maximum and minimum dimensional characteristics of a conduit are determined by imaging a portion of the conduit into which an expandable medical device is to be implanted at appropriate points in the cardiac cycle (or other suitable cycle, such as the respiratory cycle, or at other suitable times). The dimensional characteristics of the conduits within the portion of interest may be evaluated and compared to the maximum and minimum dimensional characteristics of the medical device to be implanted in the conduit to determine whether the medical device is of an appropriate size for properly fitting in the conduit.