CT colonography: revisited after 30 years

Computed tomography colonography (CTC), also known as virtual colonoscopy, is a well-tolerated, minimally invasive and effective procedure. Used for over two decades and supported by extensive studies and meta-analyses, CTC has demonstrated performance comparable to that of optical colonoscopy (OC). However, CTC remains generally underutilized in many countries, including the United States of America; in contrast, in some countries, such as the United Kingdom, it is widely used. CTC requires bowel preparation with laxative and fecal contrast-agent tagging, followed by colonic distension with low-pressure, automated, CO₂ insufflation. It enables detailed image analysis with postprocessing software and is highly sensitive and specific for detecting cancers and significant benign precursors ≥ 10 mm (adenomatous and sessile-serrated polyps) years before potential malignant transformation. After reviewing the state of the art of CTC acquisition, analysis and reporting, we wrote this article to update the new, potential and emerging CTC indications. CTC is increasingly used after incomplete OC, for undetermined colonic anomalies, in elderly and/or fragile patients or when OC is refused. Recent routine clinical use has broadened CTC's applications, proving its usefulness in local colon-cancer staging, preoperative laparoscopic surgery planning, and selecting patients with severe diverticular disease for elective sigmoidectomy. CRITICAL RELEVANCE STATEMENT: Beyond its excellent performance in detecting advanced adenomas and cancers, CTC provides precise staging of locally advanced tumors, guiding decisions on neoadjuvant therapy, and coupled with contrast-enhanced thoracic-abdominal-pelvic acquisition, enables comprehensive, preoperative evaluation for laparoscopic colectomy. KEY POINTS: CT colonography (CTC) and optical colonoscopy (OC) are similarly able to detect advanced adenomas (≥ 10 mm) and early-stage colorectal cancer. CTC enables a "one-stop shop" examination for laparoscopic surgery planning, with precise localization and detailed vascular mesenteric mapping. With the rise of neoadjuvant treatments for advanced colorectal cancer, CTC may become pivotal in radiological staging.