[New preoperative imaging and navigation systems for the treatment of colorectal cancer]

Recently, many new preoperative imaging and navigation systems for the treatment of colorectal cancer have become available based on highly developed imaging hardware, software, and clinical techniques. In this paper, we describe and review the clinical role of these new methods. Computed tomography colonography (3D-CT) is a feasible and accurate method to diagnose the location, degree of invasion, and presence of extracolonic metastases in colorectal cancer. 3D-CT with CT angiography is also helpful to assess the vascular branching anatomy before and during surgery. With the use of polyethylene glycol solution plus contrast medium bowel preparation, 3D-CT shows the total colon without blind spots and good differentiation between polyps and residual fluid because the residual fluid is tagged with contrast medium. Magnetic resonance (MR) colonography and diffusion-weighted MR imaging provide additional preoperative information without radiation exposure. Positron-emission tomography/CT colonography has the potential to become an accepted technique for evaluation of the nonvisualized part of the colon caused by stenosis and it can increase the diagnostic yield of masses and clinically important polyps in this part of the colon. Although further prospective randomized trials are needed, sentinel node mapping and detection of micrometastases may be clinically relevant in colorectal cancer and may improve the selection of patients for chemotherapy.