European Journal of Radiology 82 (2013) 1137–1143 Contents lists available at SciVerse ScienceDirect European Journal of Radiology jo ur nal ho me page: www.elsevier.com/locate/ejrad Bowel preparation for CT colonography Emanuele Neri a,∗,1 , Philippe Lefere b , Stefaan Gryspeerdt b , Pietro Bemi a , Annalisa Mantarro a , Carlo Bartolozzi a a Diagnostic and Interventional Radiology, University of Pisa, Italy b Department of Radiology, Stedelijk Ziekenhuis, Roeselare, Belgium a r t i c l e i n f o Article history: Received 29 October 2012 Accepted 5 November 2012 Keywords: CT colonography Bowel preparation Colon Iodine Laxatives Barium a b s t r a c t 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 diag- nostic 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. © 2012 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Bowel preparation represents an essential part of CT colonogra- phy, as the accuracy of the exam is strongly related to the adequacy of colonic cleansing, and a poor bowel preparation may compro- mise 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 fact, retained stool can mimic polyps, thus decreasing specificity, whereas retained fluid can obscure them, resulting in lower sensitivity [1]. Moreover the quality of acquisition, and the accuracy of repor- ting, depend on radiologist’s skills, successful bowel preparation relies mainly on patient compliance. To this respect, the majority of patients having undergone CT colonography state that bowel preparation is the most unpleasant part [2]. Unfortunately, to date no agreement has been reached about the ideal bowel preparation technique, and there is great variability in preparation strategies across diagnostic centers [3]. ∗ Corresponding author at: Diagnostic and Interventional Radiology, Department of Traslational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy. E-mail address: emanuele.neri@med.unipi.it (E. Neri). 1 Nuovo Ospedale S. Chiara, UO Radiodiagnostica 1, Via Paradisa 2, 56100 Pisa, Italy. The review article describes the development and evolution of bowel preparation techniques for CT colonography. 2. Bowel preparation Protocols for bowel preparation are extremely variable because, in the early years of CT colonography, different groups of researchers used protocols derived from double-contrast barium enema or conventional colonoscopy, according to local practices. However, all preparation schemes were at that time composed of two basic steps [4]: (1) a low-residue diet; (2) the administration of laxative drugs. 3. Low-residue diet In all bowel preparation schemes, a low-residue diet is recom- mended starting a few days before CT colonography in order to limit the intake of slowly absorbed or non-absorbable food (such as vegetable) that would remain in the large bowel at the time of the exam, thus potentially mimicking or hiding parietal lesions. The low-residue diet lasts for a period from one to five days, with most centers prescribing a diet of 1–3 days. However, evidence exists that low-residue diet could even be avoided, as it does not seem to sig- nificantly affect proper intestinal cleansing [5]. Yet, patients with chronic constipation are suggested to increase their fiber intake in the days before CT colonography so to reduce intestinal transit 0720-048X/$ – see front matter © 2012 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ejrad.2012.11.006