Respiratory motion of the heart from free breathing coronary angiograms

Respiratory motion compensation for cardiac imaging requires knowledge of the heart's motion and deformation during breathing. This paper presents a method for measuring the natural tidal respiratory motion of the heart from free breathing coronary angiograms. A three-dimensional (3-D) deformation field describing the cardiac and respiratory motion of the coronary arteries is recovered from a biplane acquisition. A cardiac respiratory parametric model is formulated and used to decompose the deformation field into cardiac and respiratory components. Angiograms from ten patients were analyzed. A 3-D translation motion model was sufficient for describing the motion of the heart in only two patients. For all patients, the heart translated caudally (mean, 4.9 +/- 1.9 mm; range, 2.4 to 8.0 mm) and underwent a cranio-dorsal rotation (mean, 1.5degrees +/- 0.9degrees; range, 0.2degrees to 3.5degrees) during inspiration. In eight patients, the heart also translated anteriorly (mean, 1.3 +/- 1.8 mm; range, -0.4 to 5.1 mm) and rotated in a caudo-dextral direction (mean, 1.2degrees +/- 1.3degrees; range, -1.9degrees to 3.2degrees).