PURPOSE: To measure the effect of cardiac motion on coronary artery stent position during the cardiac cycle as a first step toward exploring the feasibility of stereotactic external beam radiation therapy targeted at restenotic stented coronary arteries. METHODS AND MATERIALS: The three-dimensional (3D) position of eight coronary artery stents in 8 patients immobilized in a stereotactic body frame was studied noninvasively by single-breathhold ECG-gated multislice spiral computed tomography (MSCT) during 10 retrospectively selected phases, equally distributed throughout the R-R interval of consecutive cardiac cycles. The volume encompassing all measured 3D positions of the stent was measured. RESULTS: Stent volumes measured by MSCT closely agreed with measurements by quantitative coronary angiography (r > 0.99). The mean of the maximum 3D stent center of mass displacement between any two phases during the cardiac cycle for all eight coronary arteries was 7.5 mm (range 3.3-20.5 mm) in the lateral direction, 8.6 mm (range 2.7-21.6 mm) in the ventrodorsal direction, and 8.2 mm (range 2.5-19.7 mm) in the craniocaudal direction. As was anticipated, the volume encompassing all measured 3D positions of the stent represented only a fraction of the whole heart volume in all patients, i.e., less than 0.6%. CONCLUSIONS: ECG-gated MSCT allowed the measurement of the volume encompassing multiphase 3D positions of coronary artery stents during the cardiac cycle. This volume, a measure of the cardiac motion effect on coronary artery stent position during the cardiac cycle, represents a moving gross target for stereotactic external beam radiation therapy.

*Myocardial Contraction, *Radiosurgery, *Stents, Aged, Coronary Angiography, Coronary Restenosis/physiopathology/radiography/*surgery, Electrocardiography, Feasibility Studies, Female, Humans, Male, Middle Aged, Physical Phenomena, Physics, Tomography, X-Ray Computed/*methods
dx.doi.org/10.1016/S0360-3016(01)02679-7, hdl.handle.net/1765/4800
International Journal of Radiation: Oncology - Biology - Physics
Erasmus MC: University Medical Center Rotterdam

Leter, E.M, Nowak, P.J.C.M, Nieman, K, Carlier, S.G, Munne, A, Serruys, P.W.J.C, … Levendag, P.C. (2002). Definition of a moving gross target volume for stereotactic radiation therapy of stented coronary arteries. International Journal of Radiation: Oncology - Biology - Physics, 52(2), 560–565. doi:10.1016/S0360-3016(01)02679-7