Echocardiography as an indication of continuous-time cardiac quiescence

• Type of Material: Article
• Authors: CA Wick, Emory University; William F Auffermann, Emory University; Amit J. Shah, Emory University; OT Inan, Georgia Institute of Technology; PT Bhatti, Georgia Institute of Technology; Srini Tridandapani, Emory University
• Language: English
• Date: 2016-07-21
• Publisher: IOP Publishing
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2016 Institute of Physics and Engineering in Medicine.
• Final Published Version (URL): http://dx.doi.org/10.1088/0031-9155/61/14/5297
• Title of Journal or Parent Work: Physics in Medicine and Biology
• ISSN: 0031-9155
• Volume: 61
• Issue: 14
• Start Page: 5297
• End Page: 5310
• Grant/Funding Information: Dr. Tridandapani was supported in part by Award Number K23EB013221 from the National Institute of Biomedical Imaging and Bioengineering.; In addition, Dr. Shah was supported by the National Center for Advancing Translational Sciences of the National Institutes of Health under award numbers UL1TR000454 and KL2TR000455.
• Keywords: Engineering, Biomedical; Technology; WINDOWS; cardiac quiescence; Science & Technology; CT; computed tomography; Engineering; cardiac gating; CORONARY-ARTERY MOTION; angiography; ANGIOGRAPHY; IDENTIFICATION; Life Sciences & Biomedicine; HEART PHASES; echocardiography; RECONSTRUCTION; Radiology, Nuclear Medicine & Medical Imaging; SELECTION; CYCLE
• Research Categories: Health Sciences, Epidemiology; Health Sciences, Public Health; Health Sciences, Radiology

Abstract

Cardiac computed tomography (CT) angiography using prospective gating requires that data be acquired during intervals of minimal cardiac motion to obtain diagnostic images of the coronary vessels free of motion artifacts. This work is intended to assess B-mode echocardiography as a continuous-time indication of these quiescent periods to determine if echocardiography can be used as a cost-efficient, non-ionizing modality to develop new prospective gating techniques for cardiac CT. These new prospective gating approaches will not be based on echocardiography itself but on CT-compatible modalities derived from the mechanics of the heart (e.g. seismocardiography and impedance cardiography), unlike the current standard electrocardiogram. To this end, echocardiography and retrospectively-gated CT data were obtained from ten patients with varied cardiac conditions. CT reconstructions were made throughout the cardiac cycle. Motion of the interventricular septum (IVS) was calculated from both echocardiography and CT reconstructions using correlation-based, deviation techniques. The IVS was chosen because it (1) is visible in echocardiography images, whereas the coronary vessels generally are not, and (2) has been shown to be a suitable indicator of cardiac quiescence. Quiescent phases were calculated as the minima of IVS motion and CT volumes were reconstructed for these phases. The diagnostic quality of the CT reconstructions from phases calculated from echocardiography and CT data was graded on a four-point Likert scale by a board-certified radiologist fellowship-trained in cardiothoracic radiology. Using a Wilcoxon signed-rank test, no significant difference in the diagnostic quality of the coronary vessels was found between CT volumes reconstructed from echocardiography- and CT-selected phases. Additionally, there was a correlation of 0.956 between the echocardiography- and CT-selected phases. This initial work suggests that B-mode echocardiography can be used as a tool to develop CT-compatible gating techniques based on modalities derived from cardiac mechanics rather than relying on the ECG alone.