PURPOSE: To investigate the feasibility of integrating multiple imaging modalities for image-
guided radiotherapy in rectal cancer. PATIENTS AND METHODS: Magnetic resonance
imaging (MRI) and fluorodeoxyglucose positron emission tomography/computed
tomography (FDG-PET/CT) were performed before, during, and after preoperative
chemoradiotherapy (CRT) in patients with resectable rectal cancer. The FDG-PET signals
were segmented with an adaptive threshold-based and a gradient-based method. Magnetic …