Axial movement of the intravascular ultrasound probe during the cardiac cycle: Implications for three-dimensional reconstruction and measurements of coronary dimensions

Background Motion of the intravascular ultrasound (IVUS) probe within the c oronary artery from cardiac contraction may result in artifacts during 3-di mensional ultrasound image reconstruction and inaccurate measurements of co ronary compliance. The purpose of this study was to establish whether longi tudinal movement of the IVUS transducer in the coronary artery occurs and t o quantify such motion. Methods In 31 patients we positioned IVUS transducers at 59 coronary branch points: 41 in the left anterior descending coronary artery, 11 in the left circumflex coronary artery, and 7 in the right coronary artery. In each im age sequence the branching vessel oscillated in and out of the imaging plan e during the cardiac cycle, confirming longitudinal transducer movement. Th e extent of movement was estimated by IVUS from the dimension of the branch vessel traversed. In addition, angiographic visualization and measurement of IVUS probe motion was performed at 17 branch points in 12 patients. Results Average longitudinal transducer movement as measured by IVUS was 1. 50 +/- 0.80 mm (n = 46, range 0.5 to 5.5 mm). Because IVUS could not accoun t for probe motion that exceeded the vessel branch diameter, the values obt ained represent minimum movement. Average probe motion as assessed by cinea ngiography in a subset of 12 patients was 2.43 +/- 1.42 mm (range 0.57 to 6 .56 mm). Conclusions This study establishes that longitudinal movement of IVUS trans ducers within coronary vessels occurs during the cardiac cycle. Because doc umented extent of motion may be sufficient to influence analysis, IVUS imag es are best obtained with electrocardiographic gating.