Compensation of in-plane rigid motion for in vivo intracoronary ultrasound image sequence.

Intracoronary ultrasound (ICUS) is an interventional imaging modality that is used to acquire a series of tomographic images from the vascular lumen, for diagnosis and treatment of coronary artery diseases in clinical settings. Motion artifacts caused by cardiac dynamics and the pulsatile blood flow within the vascular lumen, during continuous pullback (non-gated) ICUS image acquisition, hinder visualization of longitudinal cuts, assessment of arterial morphology and hemodynamics, and three-dimensional (3-D) vessel reconstruction. The aim of this study is to develop a method to compensate for in-plane rigid motion in non-gated in vivo ICUS sequences. The signals associated with cardiac motion are first detected from the gray-scale image sequence. They are represented with rigid motion parameters between luminal contours extracted from successive slices. Subsequently, the signals were filtered to separate the dynamic components caused by cardiac motion from those caused by the irregular morphology of the vascular lumen. Dynamic components were then compensated by performing a back transformation of related pixels within the vessel region in each frame. The method is validated by computer-simulation and using real ICUS image data. Possible sources of error are discussed based on the experimental results.