Fecal tagging is currently used in CT colonography (CTC) to mark and distinguish fecal contents from colonic lesions; the use of tagging material allows not only to reduce cathartic preparation but also to improve and accelerate the CTC datasets reading in 2D. “Electronic cleansing” is a spectrum of algorithms finalized to digital subtraction of the tagging material that represents the prerequisite for evaluation of tagged datasets in 3D. As a first step, we have analyzed the impact of electronic subtraction cleansing in the assessment of...

We retrospectively evaluated 13 patients (polyps enriched), whom underwent CTC and resulted positive for small polyps confirmed by conventional colonoscopy. Each examination had been evaluated with and without electronic cleansing, in a total of 26 datasets, and in supine and prone position, than in a total of 52 observations. Patients underwent a three-day non- cathartic preparation followed by a same day fecal tagging protocol (500ml of water and 50 ml of diatrizoate dimeglumine 3-4 hours before CTC). Images were processed by a novel bowel cleansing...

In 2D analysis image quality of cleansed CTC images did not differ significantly from that of source CTC datasets in the various colonic segments (cecum and ascending colon 4.31±0.48 vs 4.54±0.66; transverse colon 4.38±0.65 vs 4.38±0.51; descending colon 3.92±0.49 vs 3.92±0.64, sigmoid colon 3.38±0.77 vs 3.46±0.66; Wilcoxon signed rank test, p> 0.05) (Fig.1). Electronic cleansing allows a significantly higher diagnostic rate concerning 3D images; in fact, 24 findings were correctly identified (92.3%) with cleansing, than without (7.7%, Fisher’s exact test p<0.001) (Fig. 2). Digital colonic...

In our opinion the better way to assess the reliability of cleansed images was a preliminary analisys on 2D, and the good results obtained have prompted us to apply this algorithm in 3D. We have demonstrated how diagnostic rate of 3D cleansed images can be affected only in the case of not adequate stool labellig rather than the action of cleansing itself. The artifacts inherent in the software although noisy do not impair diagnostic performance both in 2D and 3D.

[1] Tagging-based, electronically cleansed CT colonography: evaluation of patient comfort and image readability. Zalis ME, Perumpillichira JJ, Magee C, Kohlberg G, Hahn PF. Radiology. 2006 Apr;239(1):149-59. Erratum in: Radiology. 2006 Jul;240(1):304. [2] CT colonography: visualization methods, interpretation, and pitfalls. Dachman AH, Lefere P, Gryspeerdt S, Morin M. Radiol Clin North Am. 2007 Mar;45(2):347-59. Review [3] CT colonography: digital subtraction bowel cleansing with mucosal reconstruction initial observations. Zalis ME, Perumpillichira J, Del Frate C, Hahn PF. Radiology. 2003 Mar;226(3):911-7. Epub 2003 Jan 24 [4] Noncathartic CT...