Deng Zhonghua, Ye Huiling, Zhang Yingjie, Zhang Xiangbin, Xie Li, Gong Pan, Liu Denghong, Wang Xuetao, Gao Xinrui, Leung Vincent Wan Shun, Guo Mengya, Zhong Renming
Radiotherapy Physics & Technology Center, Cancer Center, West China Hospital, Sichuan University, Chengdu, China.
Innovation Institute for Integration of Medicine and Engineering, Med-X Center for Manufacturing, West China Hospital, Sichuan University, Chengdu, China.
Quant Imaging Med Surg. 2025 Jun 6;15(6):5334-5346. doi: 10.21037/qims-24-1579. Epub 2025 May 30.
Theoretically, electrocardiogram-gated computed tomography (ECG-CT) can more precisely characterize the motion of a beating heart. However, cardiac motion involves both pulsatile cardiac activity and respiratory-induced movement. ECG-CT has high temporal resolution and fast scanning speed, requiring image acquisition to be completed within a single cardiac cycle. As a result, it is challenging to assess the full range of respiratory motion. In contrast, respiratory-gated four-dimensional computed tomography (4D CT) enables synchronized integration of both cardiac pulsation and respiratory motion. This study aimed to compare cardiac substructure motion using ECG-CT versus 4D CT, evaluate a gating plan for breast cancer patients, and explore an image registration method in cardiac radiation.
A total of 20 left-sided breast cancer patients underwent both ECG-CT and 4D CT scanning. Parameters such as the absolute motion, volume increment ratios, the Dice similarity coefficient (DSC), and the Hausdorff distance (HD) of cardiac substructures were evaluated. Additionally, unlike ECG-CT, 4D CT offered inherent gating capability. Therefore, three optimal phases from 4D CT were utilized for the gating plan to assess the dose of cardiac substructures.
Except for the left anterior descending (LAD) artery, the motion of other cardiac substructures analyzed by ECG-CT in the superior-inferior (SI) direction was significantly smaller than that assessed by 4D CT. The motion evaluated by ECG-CT for ascending aorta (AAo), left atrium (LA), left ventricle + ventricular wall (LV_S), and superior vena cava (SVC) in right-left (RL) and anterior-posterior (AP) directions and pulmonary artery (PA) in RL direction was significantly larger than that of 4D CT. Based on 4D CT, the gating plan showed significant dose advantages compared to the average intensity projection (AIP) plan (1,685.85±355.99 1,844.05±394.43 cGy, P<0.01).
4D CT is a superior method for evaluating the motion of cardiac substructures compared to ECG-CT in the SI direction. A 4D CT-based gating plan provides a viable alternative to reducing the LAD dose when deep-inspiration breath-hold (DIBH) is unavailable. Furthermore, the heart, descending aorta (DAo), and RA + RV can serve as reference structures for cardiac radiation ablation.
从理论上讲，心电图门控计算机断层扫描（ECG-CT）能够更精确地表征跳动心脏的运动。然而，心脏运动既包括心脏的搏动活动，也包括呼吸引起的运动。ECG-CT具有高时间分辨率和快速扫描速度，要求在单个心动周期内完成图像采集。因此，评估呼吸运动的全范围具有挑战性。相比之下，呼吸门控四维计算机断层扫描（4D CT）能够实现心脏搏动和呼吸运动的同步整合。本研究旨在比较使用ECG-CT与4D CT时心脏亚结构的运动，评估乳腺癌患者的门控方案，并探索心脏放疗中的图像配准方法。
共有20例左侧乳腺癌患者接受了ECG-CT和4D CT扫描。评估了心脏亚结构的绝对运动、体积增加率、骰子相似系数（DSC）和豪斯多夫距离（HD）等参数。此外，与ECG-CT不同，4D CT具有固有的门控能力。因此，利用4D CT的三个最佳相位进行门控方案，以评估心脏亚结构的剂量。
除左前降支（LAD）动脉外，ECG-CT分析的其他心脏亚结构在上下（SI）方向的运动明显小于4D CT评估的运动。ECG-CT评估的升主动脉（AAo）、左心房（LA）、左心室+室壁（LV_S）和上腔静脉（SVC）在左右（RL）和前后（AP）方向以及肺动脉（PA）在RL方向的运动明显大于4D CT评估的运动。基于4D CT，门控方案与平均强度投影（AIP）方案相比显示出显著的剂量优势（1,685.85±355.99对1,844.05±394.43 cGy，P<0.01）。
在SI方向上，与ECG-CT相比，4D CT是评估心脏亚结构运动的更优方法。当无法进行深吸气屏气（DIBH）时，基于4D CT的门控方案为降低LAD剂量提供了可行的替代方案。此外，心脏、降主动脉（DAo）和右心房+右心室可作为心脏放射消融的参考结构。
