Title :
Shape-based tracking of left ventricular wall motion
Author :
McEachen, John C., II ; Duncan, James S.
Author_Institution :
Dept. of Electr. & Comput. Eng., Naval Postgraduate Sch., Monterey, CA, USA
fDate :
6/1/1997 12:00:00 AM
Abstract :
An approach for tracking and quantifying the nonrigid, nonuniform motion of the left ventricular (LV) endocardial wall from two-dimensional (2-D) cardiac image sequences, on a point-by-point basis over the entire cardiac cycle, is presented. Given a set of boundaries, motion computation involves first matching local segments on one contour to segments on the next contour in the sequence using a shape-based strategy. Results from the match process are incorporated with a smoothness term into an optimization functional. The global minimum of this functional is found, resulting in a smooth flow field that is consistent with the match data. The computation is performed for all pairs of frames in the temporal sequence and equally sampled points on one contour are tracked throughout the sequence, resulting in a composite flow field over the entire sequence. Two perspectives on characterizing the optimization functional are presented which result in a tradeoff resolved by the confidence in the initial boundary segmentation. Experimental results for contours derived from diagnostic image sequences of three different imaging modalities are presented. A comparison of trajectory estimates with trajectories of gold-standard markers implanted in the LV wall are presented for validation. The results of this comparison confirm that although cardiac motion is a three-dimensional (3-D) problem, two-dimensional (2-D) analysis provides a rich testing ground for algorithm development.
Keywords :
angiocardiography; biomedical NMR; cardiology; image segmentation; image sequences; medical image processing; smoothing methods; 2-D cardiac image sequences; cardiac motion; composite flow field; contrast X-ray angiogram images; diagnostic image sequences; global minimum; gold-standard markers; imaging modalities; initial boundary segmentation; left ventricular endocardial wall; left ventricular wall motion; local segment matching; magnetic resonance tagging; motion computation; nonrigid nonuniform motion; optimization functional; point-by-point basis; shape-based strategy; shape-based tracking; smooth flow field; smoothness term; temporal sequence; three-dimensional problem; trajectory estimates; Computed tomography; Heart; Image motion analysis; Image segmentation; Image sequences; Magnetic resonance imaging; Optical imaging; Tracking; Two dimensional displays; X-ray imaging; Algorithms; Animals; Dogs; Echocardiography; Heart; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Models, Cardiovascular; Myocardial Contraction; Ventricular Function, Left;
Journal_Title :
Medical Imaging, IEEE Transactions on