Incidental Findings in CT Colonography: Literature Review and Survey of Current Research Practice

Abstract

J ust over ten years ago, the first human trials of virtual colonoscopy, or computed tomography (CT) colonography, were performed. 1 CT colonography (CTC), as it is now called, is a low radiation dose CT examination of the abdomen and pelvis following bowel purgation cleansing and insuflation (inflation) of the colon and rectum. High spatial resolution CT datasets of the abdomen and pelvis are obtained while the patient is lying in the prone and supine positions, with the entire procedure lasting about ten minutes. The resulting images are interactively reviewed on a dedicated computer workstation using 2D multiplanar images and 3D endoluminal displays of the colon. Over the past decade, rapid technological advancements in image acquisition, 3D display techniques, colonic insuflation, and stool tagging (i.e., labeling of stool with ingested radio-opaque contrast) have occurred, which have greatly improved the ability of CT colonography to detect colorectal polyps and cancer.Probably due to physician-researchers conducting early CT colonography research, the importance of incidental findings (IFs) discovered during CT colonography was quickly recognized. Several early studies suggested that the incidence of extracolonic findings that require further medical investigation or medical/ operative treatment was 10-11 percent and surpassed the incidence of large colorectal polyps in asymptomatic research subjects undergoing CT colonography. 2

Management of incidental findings during imaging research in “healthy” volunteers: current UK practice

“…N With regard to disclosure, the commonest approach was to disclose relevant IFs in contrast to Siddiki et al, who found the most frequent strategy was routine disclosure (47% in our study compared with Siddiki et als' 42% for relevant reporting; 26% in our study compared with Siddiki et als' 58% for routine reporting) [9]. 19% of PIs in our study never disclosed IFs, compared with ,11% in a United States study that also incorporated genomic research [15].…”

“…There is limited published data on practice in handling incidental imaging findings in healthy volunteers; all such data are from outside the UK [9,15,16], and the primary aims of those studies differed from our survey. Wider interpretation of previous studies is also limited by low response rate (11%) [16], small sample (12 researchers) [9] or their scope, such as analysis of information from research websites only [15].…”

“…Wider interpretation of previous studies is also limited by low response rate (11%) [16], small sample (12 researchers) [9] or their scope, such as analysis of information from research websites only [15]. Some comparisons can, however, be made with these studies performed outside the UK:…”

“…Their prevalence on brain MRI was 2.7% across 16 studies involving 19 559 participants [7] and may be as high as 12.8% on body MRI [8]. Extracolonic IFs at CT colonography require further investigation, medical or surgical intervention in 5-8% [9]. There are, therefore, important implications for informed consent, clinical review of images and mechanisms for notifying the subject.…”

To tell or not to tell? A systematic review of ethical reflections on incidental findings arising in genetics contexts

“…1 In recent years, much has been published on IFs in general and IFs arising in imaging contexts. 1, [4][5][6] There is yet to be a systematic overview of IFs arising in genetics contexts. This gap in the research is not because IFs do not occur in genetics contexts.…”