基于形变配准获得的强化4DCT制定肝癌个体化IGTV可行性研究

目的 研究基于形变配准技术实现的强化4DCT进行HCC个体化IGTV制定的可行性。方法 选择首次放疗的HCC患者 10例,依次完成自由呼吸下4DCT扫描,ABC辅助下平静EI屏气3DCT平扫和动脉期强化扫描,将4DCT依呼吸时相分为10个序列。在各序列CT图像中勾画GTV和肝脏,将4DCT各时相GTV融合为IGTV₁;将强化3DCT的GTV形变配准到4DCT各时相图像上,获得10个GTV_DR,并融合为IGTV_DR。配对t检验比较不同靶区体积差异。结果 4DCT和平扫3DCT在肝癌靶区勾画时较难确定靶区边缘。强化3DCT可清晰显示肿瘤边缘,GTV较4DCT和平扫3DCT平均增加了37.99%(P=0.002)。形变配准后4DCT各时相GTV平均增加了36.34%(P=0.011),与强化3DCT的基本相当(P=0.632)。IGTV_DR较IGTV₁平均增加了19.91%(P=0.017)。结论 形变配准技术结合强化3DCT和4DCT图像实现的强化4DCT图像可显著提高HCC的IGTV勾画精度。

To study the feasibility of defining the internal gross tumor volume for hepatocellular carcinoma applying the enhanced 4DCT images obtained by deformable registration technology

Objective To study the feasibility of defining the internal gross tumor volume (IGTV) of hepatocellular carcinoma applying the enhanced four-dimensional computed tomography (4DCT) images with deformable registration technology. Methods Ten HCC patients who accepted radiation therapy were selected in this study. The 4DCT in free breathing, non-enhanced 3DCT and arterial phase enhanced 3DCT in end inspiration breath holding associated with active breathing coordinator were acquired sequentially. 4DCT were sorted into ten series CT images according to breath phase, and named CT₀₀, CT₁₀…CT₉₀. Gross tumor volume (GTV) were contoured on different CT series and the IGTV₁ was merged by ten phases GTVs of 4DCT. The GTV of enhanced 3DCT was registered to different CT series of 4DCT and the IGTV_DR was obtained by merging the GTVs after deformable registration. The target volumes differences were compared by paired t-test. Results The edge of tumor was difficult to define on 4DCT and non-enhanced 3DCT images. The enhanced 3DCT image showed clearer tumor edge, and the GTV increased by mean 37.99% compared to GTV on 4DCT different series images and non-enhanced 3DCT image (P=0.002). The GTV after deformable registration on 4DCT different phase images increased by mean 36.34%(P=0.011), which were similar to GTV on enhanced 3DCT image (P=0.632). The IGTV_DR increased by 19.91%(P=0.017), compared to IGTV₁. Conclusions The contrast-enhanced 4DCT image which was obtained by combining enhanced 3DCT and 4DCT images with deformable registration technology could raise the position precision of the HCC IGTV effectively.