van Baardwijk Angela, Bosmans Geert, Boersma Liesbeth, Buijsen Jeroen, Wanders Stofferinus, Hochstenbag Monique, van Suylen Robert-Jan, Dekker André, Dehing-Oberije Cary, Houben Ruud, Bentzen Søren M, van Kroonenburgh Marinus, Lambin Philippe, De Ruysscher Dirk
Department of Radiation Oncology (MAASTRO), GROW, University Hospital Maastricht, Maastricht, The Netherlands.
Int J Radiat Oncol Biol Phys. 2007 Jul 1;68(3):771-8. doi: 10.1016/j.ijrobp.2006.12.067. Epub 2007 Mar 29.
To compare source-to-background ratio (SBR)-based PET-CT auto-delineation with pathology in non-small-cell lung cancer (NSCLC) and to investigate whether auto-delineation reduces the interobserver variability compared with manual PET-CT-based gross tumor volume (GTV) delineation.
Source-to-background ratio-based auto-delineation was compared with macroscopic tumor dimensions to assess its validity in 23 tumors. Thereafter, GTVs were delineated manually on 33 PET-CT scans by five observers for the primary tumor (GTV-1) and the involved lymph nodes (GTV-2). The delineation was repeated after 6 months with the auto-contour provided. This contour was edited by the observers. For comparison, the concordance index (CI) was calculated, defined as the ratio of intersection and the union of two volumes (A intersection B)/(A union or logical sum B).
The maximal tumor diameter of the SBR-based auto-contour correlated strongly with the macroscopic diameter of primary tumors (correlation coefficient = 0.90) and was shown to be accurate for involved lymph nodes (sensitivity 67%, specificity 95%). The median auto-contour-based target volumes were smaller than those defined by manual delineation for GTV-1 (31.8 and 34.6 cm(3), respectively; p = 0.001) and GTV-2 (16.3 and 21.8 cm(3), respectively; p = 0.02). The auto-contour-based method showed higher CIs than the manual method for GTV-1 (0.74 and 0.70 cm(3), respectively; p < 0.001) and GTV-2 (0.60 and 0.51 cm(3), respectively; p = 0.11).
Source-to-background ratio-based auto-delineation showed a good correlation with pathology, decreased the delineated volumes of the GTVs, and reduced the interobserver variability. Auto-contouring may further improve the quality of target delineation in NSCLC patients.
比较基于非小细胞肺癌（NSCLC）中源本底比（SBR）的PET-CT自动勾画与病理情况，并研究与基于PET-CT手动勾画大体肿瘤体积（GTV）相比，自动勾画是否能降低观察者间的变异性。
将基于源本底比的自动勾画与宏观肿瘤尺寸进行比较，以评估其在23个肿瘤中的有效性。此后，由五名观察者在33例PET-CT扫描上手动勾画原发性肿瘤（GTV-1）和受累淋巴结（GTV-2）的GTV。6个月后，利用提供的自动轮廓重复勾画。观察者对该轮廓进行编辑。为进行比较，计算一致性指数（CI），定义为两个体积的交集与并集之比（A交集B）/（A并集或逻辑和B）。
基于SBR的自动轮廓的最大肿瘤直径与原发性肿瘤的宏观直径密切相关（相关系数 = 0.90），并且对受累淋巴结显示准确（敏感性67%，特异性95%）。基于自动轮廓的靶体积中位数小于GTV-1手动勾画定义的体积（分别为31.8和34.6 cm³；p = 0.001）以及GTV-2手动勾画定义的体积（分别为16.3和21.8 cm³；p = 0.02）。基于自动轮廓的方法在GTV-1（分别为0.74和0.70 cm³；p < 0.001）和GTV-2（分别为0.60和0.51 cm³；p = 0.11）方面显示出比手动方法更高的CI。
基于源本底比的自动勾画与病理情况具有良好相关性，减小了GTV的勾画体积，并降低了观察者间的变异性。自动轮廓勾画可能进一步提高NSCLC患者靶区勾画的质量。
