Virtual colonoscopy-comparison with optical colonoscopy for the detection of colonic space- occupying lesions

ABSTRACT

This prospective study was performed on 20 consecutive patients with suspected or known colonic neoplasia to evaluate the sensitivity and accuracy of a new virtual colonoscopy technique for the detection of colorectal lesions in comparison with optical [conventional] colonoscopy as the standard of reference. They were 12 males and 8 females with age ranging between 48-72 years and mean age of 56.3 years. All patients were subjected to a thorough history and clinical examination, routine laboratory tests and abdominal ultrasonography. After standard bowel preparation, all patients underwent a non-contrast helical CT scan of the abdomen and pelvis followed by conventional colonoscopy in the same day. The images of CT colonography were reconstructed into a virtual colonoscopy [VC] presentation and compared with subsequent conventional colonoscopy in a blinded manner. Conventional colonoscopy identified 22 polyps 5 mm or greater in 12 patients, and no polyps were detected in 8 patients. Virtual colonoscopy correctly identified 5 polyps of 9 polyps 5-9 mm in size, and 11 of 13 lesions greater than or equal to 10 mm in diameter. Per-patient findings of VC for lesions 5-9 mm were; sensitivity 55.6%, specificity 81.8%, positive predictive value 71.4%, negative predictive value 69.2%, over all accuracy 70% and for lesions greater than or equal to 10 mm were; sensitivity 91.7%, specificity 87.5%, positive predictive value 91.7%, negative predictive value 87.5%, over all accuracy 90%. It could he concluded that VC is feasible and has excellent sensitivity and specificity for detection of colorectal lesions 10 mm and larger and provide another effective complement for the diagnosis and screening