Computed tomographic colonography without cathartic preparation for the detection of colorectal polyps

Department of Radiological Sciences, University of Rome, Rome, Italy.
Gastroenterology (Impact Factor: 16.72). 11/2004; 127(5):1300-11. DOI: 10.1053/j.gastro.2004.08.025
Source: PubMed


We prospectively compared the performance of low-dose multidetector computed tomographic colonography (CTC) without cathartic preparation with that of colonoscopy for the detection of colorectal polyps.
A total of 203 patients underwent low-dose CTC without cathartic preparation followed by colonoscopy. Before CTC, fecal tagging was achieved by adding diatrizoate meglumine and diatrizoate sodium to regular meals. No subtraction of tagged feces was performed. Colonoscopy was performed 3-7 days after CTC. Three readers interpreted the CTC examinations separately and independently using a primary 2-dimensional approach using multiplanar reconstructions and 3-dimensional images for further characterization. Colonoscopy with segmental unblinding was used as reference standard. The sensitivity of CTC was calculated both on a per-polyp and a per-patient basis. For the latter, specificity, positive predictive values, and negative predictive values were also calculated.
CTC had an average sensitivity of 95.5% (95% confidence interval [CI], 92.1%-99%) for the identification of colorectal polyps > or =8 mm. With regard to per-patient analysis, CTC yielded an average sensitivity of 89.9% (95% CI, 86%-93.7%), an average specificity of 92.2% (95% CI, 89.5%-94.9%), an average positive predictive value of 88% (95% CI, 83.3%-91.5%), and an average negative predictive value of 93.5% (95% CI, 90.9%-96%). Interobserver agreement was high on a per-polyp basis (kappa statistic range, .61-.74) and high to excellent on a per-patient basis (kappa statistic range, .79-.91).
Low-dose multidetector CTC without cathartic preparation compares favorably with colonoscopy for the detection of colorectal polyps.

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    • "While most patients prefer CT colonography over conventional colonoscopy [9], the majority of those who have undergone CT colonography state that bowel preparation is the most unpleasant part of the examination. Research is therefore aimed at developing less invasive preparations (so-called " reducedcathartic " ) or even eliminating the need for bowel preparation at all ( " prep-less " approach) [8] [9] [10] [11] [12]. "
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    ABSTRACT: Bowel preparation represents an essential part of CT colonography, as the accuracy of the exam is strongly related to the adequacy of colonic cleansing, and a poor bowel preparation may compromise the diagnostic quality even despite optimization of all other acquisition parameters. Residual stool and fluid in the large bowel may affect the interpretation of the exam and may increase the number of false positives and false negatives. In this regard, the majority of patients having undergone CT colonography state that bowel preparation is the most unpleasant part. Unfortunately, to date no definite consensus has been reached about the ideal bowel preparation technique, and there is great variability in preparation strategies across diagnostic centers. The purpose of this review article is to describe the development and evolution of bowel preparation techniques in order to choose the best approach for optimizing the diagnostic quality of CT colonography in each patient.
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    • "The resulting higher attenuation of fecal and fluid residues simplifies their distinction from colonic abnormality. Whereas some authors prefer tagging with barium only, others have reported good results with iodine or a combination of both to achieve fecal and fluid tagging.[2] [36] [37] [38] "

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    • "This is achieved by labelling it with some type of contrast agent, e.g. barium or meglumine diatrizoate taken orally before the CT (Iannaccone et al., 2004). "

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