Optical colonoscopy is considered the gold standard for detecting colorectal cancer, but the procedure is technically difficult and is associated with a significant risk of procedural complications. It also requires sedation and often is painful.As reported in the September issue of Alimentary Pharmacology & Therapeutics, Dr. Owen Epstein of the Royal Free and University College Medical School in London and his colleagues compared minimally invasive 3-D virtual colonoscopy with traditional optical colonoscopy in symptomatic patients to see whether the virtual method could provide screening results that were as accurate.The researchers used a CT scanner from General Electric Medical Systems on 100 patients. The images were processed with Viatronix V3D colon software, which generated realistic color images of the colon in approximately 10 min. A gastrointestinal radiologist recorded the findings and graded them based on previously established methods. The patients then underwent optical colonoscopies. Polyps that were detected from either the virtual or the standard method were removed and sent for histologic evaluation.Optical colonoscopy was completed in 91 patients, and was not completed in eight patients as a result of technical difficulties or pain. Virtual colonoscopy was successful in 99 patients and incomplete in one patient who was unable to retain air during the CT scan. Comparison was possible in 90 patients: The virtual method revealed 11 polyps ≥6 mm in diameter in nine patients, while the optical method revealed 10 polyps ≥6 mm in diameter in nine patients. Both techniques revealed the three cancers that had been histologically confirmed. The researchers believe their results indicate that the minimally invasive virtual colonoscopy technique could be used as the primary screening method for symptomatic patients.