Computed tomography colonography in 2014: An update on technique and indications

Abstract

Twenty years after its introduction, computed tomographic colonography (CTC) has reached its maturity, and it can reasonably be considered the best radiological diagnostic test for imaging colorectal cancer (CRC) and polyps. This examination technique is less invasive than colonoscopy (CS), easy to perform, and standardized. Reduced bowel preparation and colonic distention using carbon dioxide favor patient compliance. Widespread implementation of a new image reconstruction algorithm has minimized radiation exposure, and the use of dedicated software with enhanced views has enabled easier image interpretation. Integration in the routine workflow of a computer-aided detection algorithm reduces perceptual errors, particularly for small polyps. Consolidated evidence from the literature shows that the diagnostic performances for the detection of CRC and large polyps in symptomatic and asymptomatic individuals are similar to CS and are largely superior to barium enema, the latter of which should be strongly discouraged. Favorable data regarding CTC performance open the possibility for many different indications, some of which are already supported by evidence-based data: incomplete, failed, or unfeasible CS; symptomatic, elderly, and frail patients; and investigation of diverticular disease. Other indications are still being debated and, thus, are recommended only if CS is unfeasible: the use of CTC in CRC screening and in surveillance after surgery for CRC or polypectomy. In order for CTC to be used appropriately, contraindications such as acute abdominal conditions (diverticulitis or the acute phase of inflammatory bowel diseases) and surveillance in patients with a long-standing history of ulcerative colitis or Crohn’s disease and in those with hereditary colonic syndromes should not be overlooked. This will maximize the benefits of the technique and minimize potential sources of frustration or disappointment for both referring clinicians and patients.

Keywords: Computed tomographic colonography; Virtual colonoscopy; Computed tomographic colonography, technique; Computed tomographic colonography, neoplasm; Computed tomographic colonography, polyp; Computed tomographic colonography, indications; Computed tomographic colonography, colorectal cancer screening; Computed tomographic colonography, diverticular disease; Computed tomographic colonography, surveillance

Core tip: Computed tomographic colonography (CTC) is easy to perform, standardized, and patient-friendly. Radiation exposure is minimized and image interpretation is facilitated by the use of a computer-aided detection algorithm. The diagnostic accuracies for colorectal cancer (CRC) and large polyps are similar to that of colonoscopy (CS) and are largely superior to that of barium enema. Incomplete, failed, or unfeasible CS and investigation of symptomatic, elderly, and frail patients and diverticular disease are clear indications. CTC is recommended for CRC screening and in surveillance after surgery or polypectomy if CS is unfeasible. Acute abdominal conditions and surveillance in patients with ulcerative colitis, Crohn’s disease, and hereditary colonic syndromes are known contraindications.