Erlich F, Camisão C, Nogueira-Rodrigues A, Altino S, Ferreira C G, Mamede M
Radiation Oncology Service, National Cancer Institute of Brazil, Rio de Janeiro, Brazil.
Rev Esp Med Nucl Imagen Mol. 2013 May-Jun;32(3):162-6. doi: 10.1016/j.remn.2012.06.003. Epub 2012 Jul 24.
To evaluate a semi-automated PET-image tumor segmentation algorithm for gross tumor volume (GTV) delineation in patients with locally advanced cervical cancer.
Thirty-two patients with locally advanced cervical cancer were retrospectively evaluated. Semi-automated PET-image-based GTV delineation was applied using a previous established algorithm (GTV2SD) and 2 fixed threshold-based methods (GTV40% and GTV50%). GTV2SD was determined as the pixel with the mean value plus 2-standard deviation of the liver intensity, and GTV40% and GTV50% with 40% and 50% of the maximum tumor intensity (Tmax), respectively. The derived volumes were then compared with the GTVs generated manually using MR (GTVMR).
The mean value of GTV2SD, GTV40% and GTV50% was 85.3cc, 16.2cc and 24.1cc, respectively. Good agreement was noticed between GTV2SD and GTVMR (ρ=0.88). GTV40% and GTV50% showed weaker correlation with GTVMR (ρ=0.68 and ρ=0.71, respectively).
This study provides preliminary evidence that metabolic tumor volume delineation is feasible using computer-generated measurements in (18)F-FDG PET images. Generation of PET-based tumor volumes is affected by the choice of threshold level used. Metabolic tumor bulk calculated using the pixel with the mean value plus 2-standard deviations of the liver intensity (GTV2SD) correlates better with the MR-derived tumor volumes. The method is a simple and clinically applicable approach to generate PET-derived GTV for radiation therapy planning of cervical cancer.
评估一种半自动PET图像肿瘤分割算法，用于局部晚期宫颈癌患者大体肿瘤体积（GTV）的勾画。
回顾性评估32例局部晚期宫颈癌患者。使用先前建立的算法（GTV2SD）和2种基于固定阈值的方法（GTV40%和GTV50%）进行基于PET图像的半自动GTV勾画。GTV2SD被确定为具有肝脏强度平均值加2个标准差的像素，GTV40%和GTV50%分别为最大肿瘤强度（Tmax）的40%和50%。然后将得出的体积与使用MR手动生成的GTV（GTVMR）进行比较。
GTV2SD、GTV40%和GTV50%的平均值分别为85.3cc、16.2cc和24.1cc。注意到GTV2SD与GTVMR之间具有良好的一致性（ρ=0.88）。GTV40%和GTV5�与GTVMR的相关性较弱（分别为ρ=0.68和ρ=0.71）。
本研究提供了初步证据，表明在（18）F-FDG PET图像中使用计算机生成的测量值进行代谢肿瘤体积勾画是可行的。基于PET的肿瘤体积生成受所用阈值水平选择的影响。使用具有肝脏强度平均值加2个标准差的像素计算的代谢肿瘤体积（GTV2SD）与MR得出的肿瘤体积相关性更好。该方法是一种简单且临床适用的方法，可用于生成用于宫颈癌放射治疗计划的PET衍生GTV。
