How To Avoid Pitfalls In Imaging: Causes And Solutions To Overcome False-Negatives And False-Positives

A major requisite, prior to the use of computed tomography-colonography (CTC) as a screening tool, has been to achieve an accuracy level comparative to that of conventional colonoscopy. Until now, a wide range of sensitivities has been reported (Fletcher et al. 2005), even for the largest lesions (>9 mm): Johnson et al (2003) reported a major inter-observer variability, with sensitivity ranges of only 32–73%, whereas Pockhardt et al (2003) reported excellent sensitivities of 93.8%. This wide range of reported sensitivities is one of the major reasons for gastrointestinal endoscopists not to advocate the technique as a screening tool yet (Hwang and Wong 2005; Pickhardt 2005). In-depth analysis of the different results has shown numerous possible causes for the reported differences in accuracy, including a learning curve, influencing sensitivity (Spinzi et al. 2001), as well as specificity (Gluecker et al. 2002). This learning curve includes the whole process of CTC: patient preparation, scanning technique (including patient positioning, colon insufflation, and scanning parameters), and image manipulation and interpretation (Taylor et al. 2004).