Wick C A, Auffermann W F, Shah A J, Inan O T, Bhatti P T, Tridandapani S
Department of Radiology and Imaging Sciences, Emory University, Atlanta, GA, USA.
Phys Med Biol. 2016 Jul 21;61(14):5297-310. doi: 10.1088/0031-9155/61/14/5297. Epub 2016 Jun 30.
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.
使用前瞻性门控的心脏计算机断层扫描（CT）血管造影要求在心脏运动最小的间期采集数据，以获取无运动伪影的冠状动脉诊断图像。这项工作旨在评估B型超声心动图作为这些静止期的连续时间指示，以确定超声心动图是否可用作一种经济高效的非电离模态，为心脏CT开发新的前瞻性门控技术。与当前标准的心电图不同，这些新的前瞻性门控方法将不基于超声心动图本身，而是基于源自心脏力学的CT兼容模态（例如心震图和阻抗心动图）。为此，从10名患有不同心脏疾病的患者中获取了超声心动图和回顾性门控CT数据。在整个心动周期中进行CT重建。使用基于相关性的偏差技术，从超声心动图和CT重建中计算室间隔（IVS）的运动。选择IVS是因为它（1）在超声心动图图像中可见，而冠状动脉通常不可见，以及（2）已被证明是心脏静止的合适指标。将静止期计算为IVS运动的最小值，并为这些阶段重建CT容积。由一名经过心胸放射学专科培训的获得委员会认证的放射科医生，根据四点李克特量表对从超声心动图和CT数据计算出的阶段进行的CT重建的诊断质量进行分级。使用Wilcoxon符号秩检验，发现在从超声心动图选择的阶段和CT选择的阶段重建的CT容积之间，冠状动脉的诊断质量没有显著差异。此外，超声心动图选择的阶段和CT选择的阶段之间的相关性为0.956。这项初步工作表明，B型超声心动图可以用作一种工具，来开发基于源自心脏力学的模态而非仅依赖心电图的CT兼容门控技术。
