Eccles Cynthia L, Tse Regina V, Hawkins Maria A, Lee Mark T, Moseley Douglas J, Dawson Laura A
Radiation Medicine Program, Department of Radiation Oncology, Princess Margaret Cancer Centre, University of Toronto, Toronto, Canada.
C.L.E. and M.A.H. are currently at the CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom.
Adv Radiat Oncol. 2016 Jan 26;1(1):43-50. doi: 10.1016/j.adro.2016.01.001. eCollection 2016 Jan-Mar.
Liver tumors are challenging to visualize on cone beam computed tomography (CBCT) without intravenous (IV) contrast. Image guidance for liver cancer stereotactic body ablative radiation therapy (SABR) could be improved with the direct visualization of hepatic tumors and vasculature. This study investigated the feasibility of the use of IV contrast-enhanced CBCT (IV-CBCT) as a means to improve liver target visualization.
Patients on a liver SABR protocol underwent IV-CBCT before 1 or more treatment fractions in addition to a noncontrast CBCT. Image acquisition was initiated 0 to 30 seconds following injection and acquired over 60 to 120 seconds. "Stop and go" exhale breath-hold CBCT scans were used whenever feasible. Changes in mean CT number in regions of interest within visible vasculature, tumor, and adjacent liver were quantified between CBCT and IV-CBCT.
Twelve pairs of contrast and noncontrast CBCTs were obtained in 7 patients. Intravenous-CBCT improved hepatic tumor visibility in breath-hold scans only for 3 patients (2 metastases, 1 hepatocellular carcinoma). Visible tumors ranged in volume from 124 to 564 mL. Small tumors in free-breathing patients did not show enhancement on IVCBT.
Intravenous-CBCT may enhance the visibility of hepatic vessels and tumor in CBCT scans obtained during breath hold. Optimization of IV contrast timing and reduction of artifacts to improve tumor visualization warrant further investigation.
在没有静脉注射（IV）造影剂的情况下，肝脏肿瘤在锥形束计算机断层扫描（CBCT）上很难显影。肝癌立体定向体部消融放疗（SABR）的图像引导可以通过直接显示肝脏肿瘤和血管来改善。本研究探讨了使用静脉注射造影剂增强CBCT（IV-CBCT）来改善肝脏靶区显影的可行性。
接受肝脏SABR方案治疗的患者，除了进行非增强CBCT扫描外，在1个或更多治疗分次前还接受了IV-CBCT扫描。在注射后0至30秒开始图像采集，并在60至120秒内完成采集。只要可行，就采用“屏气-呼吸”CBCT扫描。对CBCT和IV-CBCT之间可见血管、肿瘤及相邻肝脏区域内感兴趣区的平均CT值变化进行量化。
7例患者共获得12对造影剂增强和非增强CBCT图像。静脉注射造影剂增强CBCT仅在3例患者（2例转移瘤，1例肝细胞癌）的屏气扫描中提高了肝脏肿瘤的可见性。可见肿瘤体积在124至564 mL之间。自由呼吸患者的小肿瘤在IV-CBCT上未显示增强。
静脉注射造影剂增强CBCT可能会提高屏气扫描时CBCT上肝脏血管和肿瘤的可见性。优化静脉注射造影剂的时机和减少伪影以改善肿瘤显影值得进一步研究。
