Background and purpose: To investigate the differences between endoscopic ultrasonography (EUS)-based longitudinal gross target volumes (GTV) (GTV(EUS)) and computed tomography (CT)-based longitudinal GTV (GTV(CT)) in diagnosing esophageal squamous carcinoma.
Methods: Thirty-six patients underwent EUS to define the superior and inferior extents of the tumor by using hemoclips. CT-planning scan was performed with the patient in the supine position during the treatment. GTV(CT) and GTV(EUS) were contoured respectively. The respective lengths (L(CT) and L(EUS)) and spatial locations of longitudinal GTV(CT) and longitudinal GTV(EUS) were compared.
Results: The mean LCT was 7.8 ± 3.2 cm and the mean L(EUS) was 7.4 ± 2.7 cm. No statistical difference was found between L(CT) and L(EUS) (P > 0.05) with a correlation coefficient of 0.61 (P<0.05). The mean conformal index was 0.79 ± 0.18 with spatial variations found in 71% (24/34) of the patients.
Conclusions: EUS can provide additional information to CT in defining longitudinal GTV in thoracic esophageal squamous cell carcinoma, especially superficial and submucosal carcinomas, which may contribute to the development of better individual treatment regimens.