Virtual colonoscopy: Utility, impact and overview

Abstract

Computed tomography (CT) colonoscopy is a well-established technique for evaluation of colorectal cancer. Significant advances have been made in the technique of CT colonoscopy since its inception. Excellent results can be achieved in detecting both colorectal cancer and significant sized polyps as long as a meticulous technique is adopted while performing CT colonoscopy. Furthermore, it is important to realize that there is a learning curve involved in interpreting these studies and adequate experience is essential to achieve high sensitivity and specificity with this technique. Indications, contraindications, technique and interpretation, including potential pitfalls in CT colonoscopy imaging, are reviewed in this article. Recent advances and the current role of CT colonoscopy in colorectal cancer screening are also discussed.

Diagnostic value of computed tomography colonography (CTC) after incomplete optical colonoscopy

“…However, especially if fecal-fluid tagging techniques are used, the specificity and negative predictive value for small polyps are good [1,64e66]. Although CTC sensitivity is reduced in small sized polyps, the risk of malignancy in a polyp less than 1 cm in diameter is less than 1% [11,66]. According to this, all our 5 patients were recommended for therapeutic colonoscopy which confirmed CTC findings.…”

“…Each scan is acquired in approximately 3e4 s. The total room time is generally less than 15 min, as in our study [4,15,31]. As in our practice, the use of dose modulation devices, adaptive statistical iterative reconstruction and model-based iterative reconstructions, are employed to reduce dose exposure up to 50% [4,6,11]. The data is elaborated with a dedicated software, and 2D images in multiple planes and 3D surface-rendered and endoluminal views are displayed [4,15,31].…”

“…included in our study. It has been reported that diverticulosis is more commonly demonstrated at CTC than colonoscopy [56,57] and it has been suggested that in case of established diverticular disease, CTC can provide a balanced view of the disease by incorporating visual analysis with quantitative analysis by using a CTC-based diverticular disease severity score which appears to correlate with relevant coexisting lesions and can potentially influence therapeutic decision-making [4,11,58]. Although the capability of CT colonography to depict polyps is both operator and technique dependent, this modality has a relatively high specificity [59e63].…”

“…CTC examination process is standardized and consists of four consecutive steps: bowel cleansing, colon distention, CT protocol, and image analysis [2,4,11,43]. In order to obtain a CTC study of good quality it is essential to achieve a clean and well-distended colon.…”

The Additional Diagnostic Value of the Three-dimensional Volume Rendering Imaging in Routine Radiology Practice

“…Both the American College of Radiology and the American Cancer Society have approved CTC for colorectal cancer screening in patients older than 50 years, those with a positive fecal occult blood test, and individuals at moderate risk with a personal history of adenoma or colorectal cancer or with family history of adenoma or cancer in any first-degree relative [19, 20]. CTC with 3DVR enables the acquisition of multiple thin sections, superior multiplanar reconstructions, and a faster imaging time for the detection of colorectal cancer and polyps [21].…”