CT Colonography with Computer-aided Detection: Recognizing the Causes of False-Positive Reader Results

Abstract

1Computed tomography (CT) colonography is a screening modality used to detect colonic polyps before they progress to colorectal cancer. Computer-aided detection (CAD) is designed to decrease errors of detection by finding and displaying polyp candidates for evaluation by the reader. CT colonography CAD false-positive results are common and have numerous causes. The relative frequency of CAD false-positive results and their effect on reader performance on the basis of a 19-reader, 100-case trial shows that the vast majority of CAD false-positive results were dismissed by readers. Many CAD false-positive results are easily disregarded, including those that result from coarse mucosa, reconstruction, peristalsis, motion, streak artifacts, diverticulum, rectal tubes, and lipomas. CAD false-positive results caused by haustral folds, extracolonic candidates, diminutive lesions (<6 mm), anal papillae, internal hemorrhoids, varices, extrinsic compression, and flexural pseudotumors are almost always recognized and disregarded. The ileocecal valve and tagged stool are common sources of CAD falsepositive results associated with reader false-positive results. Nondismissable CAD soft-tissue polyp candidates larger than 6 mm are another common cause of reader false-positive results that may lead to further evaluation with follow-up CT colonography or optical colonoscopy. Strategies for correctly evaluating CAD polyp candidates are important to avoid pitfalls from common sources of CAD false-positive results.

Artificial Intelligence in the Era of Precision Oncological Imaging

“…Although CAD can improve polyp detection rates, several structures can result in false-positive readings, including haustral folds, coarse mucosa, diverticula, rectal tubes, extracolonic findings, and lipomas. 48 The experience of the reader is thereby essential for the appropriate interpretation and reporting ( Figures 2 and 3 ). Several CAD algorithms improved the detection of prostatic malignancies on MRI, 49 including difficult-to-assess areas such as the central part of the gland or the transition zone.…”

CT colonography: implementation, indications, and technical performance – a follow-up national survey

“…CAD systems are primarily designed for polyp detection, and have been shown to improve detection of polyps, at least for less experienced readers, with a limited decrease in specificity (10,11). With increasing experience in reading CTC, however, CAD has a smaller impact on the final evaluation (10,11). CAD must be seen as a complement to the normal reading and cannot make up for lack of experience or substitute proper training in CTC reading.…”

“…CAD is a software developed to mark suspicious findings and thereby improve the diagnostic performance of the reader. CAD systems are primarily designed for polyp detection, and have been shown to improve detection of polyps, at least for less experienced readers, with a limited decrease in specificity (10,11). With increasing experience in reading CTC, however, CAD has a smaller impact on the final evaluation (10,11).…”

A Multi-User Virtual Reality Application For Visualization And Analysis In Medical Imaging

“…Both the perception of the environment and the user's interaction with it can be modeled based on reality. This virtual environment is already taking place in CT colonography which unlike traditional colonoscopy, which requires a scope to be inserted into the rectum, virtual colonoscopy uses hundreds of CT images to reconstruct and digitally manipulate a detailed view of the inside of the colon [10].…”