title: Efficient postacquisition synchronization of 4-D nongated cardiac images obtained from optical coherence tomography: application to 4-D reconstruction of the chick embryonic heart.
abstract: Four-dimensional (4-D) imaging of the embryonic heart allows study of cardiac morphology and function in vivo during development. However, 4-D imaging of the embryonic heart using current techniques, including optical coherence tomography (OCT), is limited by the rate of image acquisition. Here, we present a nongated 4-D imaging strategy combined with an efficient postacquisition synchronization procedure that circumvents limitations on acquisition rate. The 4-D imaging strategy acquires a time series of images in B mode at several different locations along the heart, rendering out-of-phase image sequences. Then, our synchronization procedure uses similarity of local structures to find the phase shift between neighboring image sequences, employing M-mode images (extracted from the acquired B-mode images) to achieve computational efficiency. Furthermore, our procedure corrects the phase shifts by considering the phase lags introduced by peristaltic-like contractions of the embryonic heart wall. We applied the 4-D imaging strategy and synchronization procedure to reconstruct the cardiac outflow tract (OFT) of a chick embryo, imaged with OCT at early stages of development (Hamburger-Hamilton stage 18). We showed that the proposed synchronization procedure achieves efficiency without sacrificing accuracy and that the reconstructed 4-D images properly captured the dynamics of the OFT wall motion.
authors.affiliation: Oregon Health & Science University, School of Medicine, Division of Biomedical Engineering, 3303 SW Bond Ave., Mail Code CH13B, Portland, Oregon 97239, USA.
authors.forename: Aiping
authors.initials: A
authors.lastname: Liu
authors.forename: Ruikang
authors.initials: R
authors.lastname: Wang
authors.forename: Kent L
authors.initials: KL
authors.lastname: Thornburg
authors.forename: Sandra
authors.initials: S
authors.lastname: Rugonyi
mesh_terms: D000465:Algorithms; D000818:Animals; D055424:Cardiac-Gated Imaging Techniques; D002642:Chick Embryo / Q000033:anatomy & histology*; D006321:Heart / Q000033:anatomy & histology* / Q000196:embryology*; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D010363:Pattern Recognition, Automated / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D041623:Tomography, Optical Coherence / Q000379:methods*