The Value of Dual-time-point FDG PET-CT on Involved-field Radiotherapy for Non–small-cell Lung Cancer

Abstract

To discuss the value of dual-time-point 18FDG PET-CT imaging on involved-field radiotherapy for hilar and mediastinal metastatic lymph nodes in patients with non–small cell lung cancer(NSCLC). Fifty-four patients with NSCLC were included in this analysis. All were underwent 2 sequential 18FDG/CT scans 3–5 days before surgery, one (standard single-time-point imaging) was the whole body and the other(delayed imaging) was the thorax. The pathologic data was used as golden standard to determine the difference between the standard single-time-point and dual-time-point 18FDG-CT imaging in the definition of gross target volume (GTV) of involved-field radiotherapy for metastatic lymph nodes. For hilar metastatic lymph nodes, the GTV defined by single-time-point imaging were found consistent with pathologic GTV in 21 patients (39%), compared with 31 patients (57%) by dual-time-point imaging, meanwhile the GTV defined by dual-time-point imaging were found inconsistent with pathologic GTV in 23 patients (43%) compared with 33 patients(61%) by single-time-point imaging. Use pathologic data as golden standard, GTV alteration defined by single-time-point imaging had statistical significance compared with that defined by dual-time-point imaging(u=519.0, p = 0.023). For mediastinal metastatic lymph nodes, the GTV defined by single-time-point imaging were found consistent with pathologic GTV in 30 patients (56%), compared with 36 patients (67%) by dual-time-point imaging, meanwhile the GTV defined by dual-time-point imaging were found inconsistent with pathologic GTV in 18 patients (33%) compared with 24 patients (44%) by single-time-point imaging. Use pathologic data as golden standard, GTV alteration defined by single-time-point imaging had no statistical significance compared with that defined by dual-time-point imaging (u = 397.5, p = 0.616). GTV definition for hilar and mediastinal metastatic lymph nodes delineated by dual-time-point imaging is more consistent with that delineated by pathologic data, and dual-time-point imaging has a larger value in terms of involved-field radiotherapy target delineation for hilar and mediastinal metastatic lymph nodes in NSC.