Extracolonic findings

In the final part of the report the radiologist should communicate clinically relevant extracolonic findings and suggest follow-up examinations, if necessary. Further issues related to extracolonic assessment are reported in the specific section. 

Extracolonic findings represent an important controversy with regard to low dose CTC, especially if the examination is proposed for screening of asymptomatic individuals. Detection of important abdominal and pelvic extracolonic abnormalities may benefit individuals undergoing CTC, but due to the high level of image noise, the definition of such lesions requires additional studies, thus increasing both patient anxiety and cost (Sosna et al. 2005). 

Hara AK, Johnson CD, MacCarty RL et al (2000) Incidental extracolonic findings at CT colonography. Radiology 215 353-357... 

Pickhardt PJ, Taylor AJ (2006) Extracolonic findings identified in asymptomatic adults at screening CT colonography. AJR Am J Roentgenol 186 718-728 Pineau BC, Paskett ED, Chen GJ et al (2003) Virtual colonoscopy using oral contrast compared with colonoscopy for the detection of patients with colorectal polyps. Gastroenterology 125 304-310... 

Sosna J, Krskal JB, Bar-Ziv J et al (2005) Extracolonic findings at CT colonography Abdom Imaging 30 709-713... 

Does Patient Population Affect Extracolonic Findings 132... 

Detection of incidental extracolonic findings has many possible advantages, such as early detection of malignant disease or of an unruptured abdominal aortic aneurysm. Early treatment can improve a patient s prognosis and decrease costs owing to less complicated surgical procedures and shorter hospital stays. 

On the other hand, extracolonic findings leading to further workup may cause unnecessary patient anxiety, entailing higher costs and superfluous exposure to radiation. 

Detection and evaluation of extracolonic findings therefore balances between potential benefits and potential harm. 

This chapter gives a review of the current literature and some reflections upon ethical and medicolegal aspects of detection and evaluation of extracolonic findings. 

Extracolonic findings are categorised by most authors as highly important, moderately important or of low importance. 

The results of the major studies published after 2000, and reporting upon extracolonic findings and their follow-up, are tabulated in Tables 10.1-10.3 and Figs. 10.1 and 10.2. 

The reported percentages of incidental lesions is high, but shows a rather high inter-study variability, with a median of 68.9% of patients with incidental extracolonic findings. 

Table 10.1. Extracolonic findings on CT colonography from primary papers published since 2000 reporting details upon further follow-up. Overall evaluation...

IV contrast Dose Screening or diagostic No. of patients Avg age Extracolonic findings Lesions Lesions/ Patients patient % patients... 

A total of 2566 patients are included in those 7 studies, with 233 patients (9%) having extracolonic findings of high importance, 31 patients having... 

Finally, the different nature of possibly important extracolonic findings necessitates the evaluation of the axial images in different window settings, e.g. abdominal window settings, lung window settings and bone window settings (Fig. 10.3). 

Looking at the age of patients, again, the study of Pickhard et al. (Pickhard et al. 2003), has the youngest patient population, indicating that extracolonic findings increase with age. 

In our institution, we use a low dose technique (140 KV, with 10 mAs for supine, and 30 mAs for prone scanning), without IV contrast. For the evaluation of the colon, 0.6-mm slices are reconstructed at every 0.3 mm for the evaluation of extracolonic findings, 3 mm thick slices are reconstructed at every 1.5 mm. The latter reduces noise, enabling visualisation of solid organ lesions (Fig. 10.4). 

Since the use of IV contrast and normal dose might influence diagnosis of extracolonic findings, an active online physician monitoring could be considered to identify immediately patients who need IV contrast (Kara et al. 2000). 

It is clear that in case of true positive findings, such as the early diagnosis of abdominal aortic aneurysm or renal cell carcinoma, patients will benefit from incidental extracolonic findings. 

However, data for axial images showing extracolonic findings have still been obtained. 

The incidence of extracolonic findings is high, but the majority of patients will have benign disease. 

A minority of patients will undergo medical or surgical treatment for previously undiagnosed extracolonic findings. 

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