GTV spatial conformity between different delineation methods by 18FDG PET/CT and pathology in esophageal cancer

Yu, Wen; Fu, Xiao-Long; Zhang, Ying-Jian; Xiang, Jia-Qing; Shen, Lei; Jiang, Guo-Liang; Chang, Joe Y.

doi:10.1016/j.radonc.2009.07.003

« Previous Next »Radiotherapy & Oncology
Volume 93, Issue 3 , Pages 441-446, December 2009

GTV spatial conformity between different delineation methods by ¹⁸FDG PET/CT and pathology in esophageal cancer

Wen Yu
- Department of Radiation Oncology, Cancer Hospital, Fudan University, Shanghai, China
Xiao-Long Fu
- Department of Radiation Oncology, Cancer Hospital, Fudan University, Shanghai, China
- Corresponding author. Address: Department of Radiation Oncology, Cancer Hospital, Fudan University, 270 Dong An Road, Xu Hui District, Shangahi 200032, China.
Ying-Jian Zhang
- Department of Nuclear Medicine, Cancer Hospital, Fudan University, Shanghai, China
Jia-Qing Xiang
- Department of Thoracic Surgery, Cancer Hospital, Fudan University, Shanghai, China
Lei Shen
- Department of Pathology, Cancer Hospital, Fudan University, Shanghai, China
Guo-Liang Jiang
- Department of Radiation Oncology, Cancer Hospital, Fudan University, Shanghai, China
Joe Y. Chang
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA

Received 1 March 2009; received in revised form 18 May 2009; accepted 6 July 2009. published online 17 August 2009.

Abstract

Purpose

To find optimal threshold of length and GTV delineation for esophageal cancer using ¹⁸FDG PET/CT.

Materials and methods

Sixteen patients with esophageal carcinoma underwent surgery. For each patient, six GTVs were defined. GTV_CT was based on CT data alone. GTV_20%, GTV_40%, GTV_2.5 and GTV_40%M were generated by PET/CT, using SUV_bgd+20%(SUV_max(slice)−SUV_bgd), SUV_bgd+40%(SUV_max(slice)−SUV_bgd), 2.5 and 40%SUV_max(total) as thresholds. GTV_path was derived from pathology. Lengths of GTVs were recorded as L_CT, L_20%, L_40%, L_2.5, L_40%M and L_path, respectively. The former five GTVs/lengths were compared with GTV_path/L_path by means of a conformity index CI/CI′, which is the square of intersection of two GTVs/lengths divided by their product.

Results

Mean L_CT, L_20%, L_40%, L_2.5, L_40%M and L_path were 6.30±2.69, 5.55±2.48, 6.80±2.92, 6.65±2.66, 4.88±1.99 and 5.90±2.38cm. Mean , , , and were 0.68±0.16, 0.84±0.17, 0.76±0.14, 0.78±0.15 and 0.80±0.11. and was significantly superior to (P<0.05). Mean GTV_CT, GTV_20%, GTV_40%, GTV_2.5, GTV_40%M and GTV_path were 29.16±18.56, 18.75±12.37, 12.52±8.08, 22.69±14.84, 9.18±5.96 and 28.16±17.02cm³. Mean CIs increased significantly from CI_40%&path(0.27±0.09) and CI_40%M&path(0.28±0.08)<CI_20%&path(0.52±0.16) and CI_2.5&path(0.52±0.20)<CI_CT&path(0.77±0.17).

Conclusions

The SUV_bgd+20%(SUV_max(slice)−SUV_bgd) method optimally estimated gross tumor length, but only reached an unsatisfactory CI for GTV. Due to possible motion factor enveloped in PET images and lack of histopathologic transverse reference, the information from both PET and CT should be referred to complementarily when delineating GTV.

Keywords: Fluorodeoxyglucose (FDG), Positron emission tomography/computer tomography (PET/CT), Esophageal carcinoma, Optimal threshold, Target volume delineation