Diagnostic Value of Diffusion-weighted Magnetic Resonance in High-risk Colorectal and Appendiceal Neoplasms

Diffusion-weighted magnetic resonance imaging (DWI/MRI) has been described in recent literature as a highly sensitive and specific modality for the detection of peritoneal metastases PM. It has been demonstrated to be superior to CT for patients with known peritoneal disease from colorectal and gynaecological malignancies as a staging tool for cytoreductive surgery. It was also demonstrated to be superior for the detection of PM for gastric cancer patients otherwise considered with a resectable tumor. However, the literature is scarce on the role of DWI/MRI in the detection of peritoneal recurrence for patients with high-risk features, either colorectal cancer (CRC) or appendiceal neoplasms (AN).The aim of this study is to prospectively assess the added value of whole-body DWI/MRI (WB-DWI/MRI) to CT and diagnostic laparoscopy for detection of PM in the follow-up of patients presenting with CRC or AN and high-risk features for peritoneal recurrence and evaluate how it correlates with intraoperative findings.

Inclusion Criteria:Confirmed diagnosis of colorectal cancer or high-risk appendiceal neoplasm (High grade Appendiceal Mucinous Neoplasm (HAMN), goblet-cell carcinoma or adenocarcinoma).No evidence of residual peritoneal disease based on referring surgeon operating report and preoperative imaging.At least one high-risk feature for peritoneal recurrence, including:Synchronous peritoneal metastases resected at index surgery;Synchronous ovarian metastases resected at index surgery;Perforated primary tumor.No evidence of distant metastases.Patient fit for cytoreductive surgery, if required (ECOG 0 or 1).Exclusion Criteria:Unresected synchronous peritoneal metastases at referral.Low grade Appendiceal Mucinous Neoplasm (LAMN).No high-risk feature for peritoneal recurrence.Evidence of distant metastases on preoperative imaging.Patient who is unable to have MRI.Patient unfit for cytoreductive surgery, if required (ECOG 2 or more).