[The role of cross-sectional imaging in staging of rectal cancer]

Imaging and Diagnosis for Planning the Surgical Procedure

The preoperative imaging diagnosis of rectal cancer lies at the heart of oncological staging and has a crucial influence on patient management and therapy planning. Rectal cancer is common, and accurate preoperative staging of tumors using high-resolution magnetic resonance imaging (MRI) is a crucial part of modern multidisciplinary team management (MDT). Indeed, rectal MRI has the ability to accurately evaluate a number of important findings that maBay impact patient management, including distance of the tumor to the mesorectal fascia, presence of lymph nodes, presence of extramural vascular invasion (EMVI), and involvement of the anterior peritoneal reflection/peritoneum and the sphincter complex. Many of these findings are difficult to assess in non-expert hands. In this chapter, we present currently used staging modalities with focus on MRI, including optimization of imaging techniques, tumor staging, interpretation help as well as essentials for reporting.

[Role of neoadjuvant radiotherapy for rectal cancer : Is MRI-based selection a future model?]

Following the introduction of total mesorectal excision (TME) in the curative treatment of rectal cancer, the role of neoadjuvant therapy has evolved. By improving the surgical technique the local recurrence rate could be reduced by TME surgery alone to below 8 %. Even if local control was further improved by additional preoperative irradiation this did not lead to a general survival benefit. Guidelines advocate that all patients in UICC stage II and III should be pretreated; however, the stage-based indications for neoadjuvant therapy have limitations. This is mainly attributable to the facts that patients with T3 tumors comprise a very heterogeneous prognostic group and preoperative lymph node diagnostics lack accuracy. In contrast, in recent years the circumferential resection margin (CRM) has become an important prognostic parameter. Patients with tumors that are very close to or infiltrate the pelvic fascia (positive CRM) have a higher rate of local recurrence and poorer survival. With high-resolution pelvic magnetic resonance imaging (MRI) examination in patients with rectal cancer, the preoperative CRM can be determined with a high sensitivity and specificity. Improved T staging and better prediction of the resection margins by pelvic MRI potentially facilitate the selection of patients for study-based treatment strategies omitting neoadjuvant radiotherapy.

[Local imaging of rectal cancer--update 2015: MRI as imaging biomarker]

The significance of state of the art magnetic resonance imaging (MRI) for rectal cancer goes far beyond the detection and diagnostics of local dispersion and is increasingly focusing on patient prognosis. The identification of prognostic factors, such as tumor (T) and nodal (N) status, involvement of the circumferential resection margin, presence of extramural vascular invasion, tumor response prediction following neoadjuvant therapy, therapy-related changes in microcirculation, permeability and tissue cellularity and structured reporting are important elements of advanced rectal cancer imaging. In this context, multiparametric MRI is progressively evolving into a powerful imaging biomarker.