Imaging Diagnosis of Locally Advanced Rectal Cancer: Tumor Staging before and after Preoperative Chemoradiotherapy

Abstract

Recently, treatment strategy of rectal cancer has changed dramatically. The application of total mesorectal excision (TME) and preoperative chemoradiation therapy (PCRT) has become standard procedure for locoregional and locally advanced rectal cancer, respectively. For the planning of patient-specific therapy, both functional and morphological radiologic evaluation as well as multidisciplinary approach is essential. In other words, the needs for more accurate T- and N-staging and assessment of circumferential resection margin, both before and after PCRT, are increasing rapidly. Although so far there is no consensus on the role of diagnostic imaging (endorectal ultrasound, CT, MRI) in the evaluation of rectal cancer patient, MRI with diffusion-weighted image is emerging as an essential imaging modality, especially in the assessment of tumor response and depiction of complete remission after PCRT. In this review, we intended to demonstrate the present diagnostic role of various imaging modalities in tumor assessment of locally advanced rectal cancer before and after PCRT, with the introduction of new emerging imaging tool.