The effect of diagnostic confidence on the probability of optical colonoscopic confirmation of potential polyps detected on CT colonography: prospective assessment in 1,339 asymptomatic adults.
OBJECTIVE
We sought to evaluate the effect of interpreter confidence on the likelihood that a lesion detected on CT colonography (CTC) will correspond to a matched polyp seen on optical colonoscopy.


METHODS
Same-day CTC and optical colonoscopy were performed on 1,339 asymptomatic adults. A standard matching algorithm for polyp size and location was used. For each potential polyp detected on CTC, the level of diagnostic confidence was prospectively rated on a 3-point scale (1, least certain; 2, intermediate; and 3, most certain).


RESULTS
For CTC-detected lesions 6 mm or larger, diagnostic confidence levels of 1, 2, and 3 corresponded to matched polyps on optical colonoscopy in 33.3% (45/135), 50.0% (103/206), and 66.8% (157/235) of cases, respectively (p < 0.01). Similar trends were present for categories of lesions that measured 6-7 mm, 8-9 mm, and 10 mm or larger, rising to a match rate of 82.1% (55/67) for lesions 10 mm or larger that were diagnosed with a level-3 confidence rating. The likelihood that a matched polyp was adenomatous increased with greater levels of diagnostic confidence. Of note, level-3 confidence for lesions measuring 8-9 mm on CTC more often yielded a matching neoplasm on optical colonoscopy than level-1 or level-2 confidence for lesions measuring 10 mm or larger (60.3% [35/58] vs 20.8% [10/48]; p < 0.0001).


CONCLUSIONS
Greater diagnostic confidence for an individual lesion detected on CTC correlates with a significantly increased likelihood that a matching polyp will be found on optical colonoscopy and that this matched polyp will be neoplastic. Although polyp size represents the primary criterion for CTC screening algorithms, this data could help guide the decision to opt for noninvasive CTC surveillance versus optical colonoscopy for polypectomy.
Pickhardt
Perry J
PJ
Department of Radiology, University of Wisconsin Medical School, E3/311 Clinical Science Center, 600 Highland Ave., Madison, WI 53792-3252, USA.
Choi
J Richard
JR
Nugent
Pamela A
PA
Schindler
William R
WR
D000368:Aged; D000465:Algorithms; D016009:Chi-Square Distribution; D002983:Clinical Competence; D003111:Colonic Polyps / Q000000981:diagnostic imaging*; D023881:Colonography, Computed Tomographic; D003113:Colonoscopy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011446:Prospective Studies