To the Editor: In their multicenter cross-sectional study of the diagnostic accuracy of computed tomographic (CT) colonography for the detection of advanced neoplasia in individuals at increased risk of colorectal carcinoma, Dr Regge and colleagues1 did not provide the frequency of adenomas that were nonpolypoid flat (ie, with a height of less than half of the lesion diameter) and depressed (ie, with a base that is lower than the normal mucosa) detected at colonoscopy. Such lesions are recognized with increasing frequency by skilled endoscopists in the United States,2,3 may compose up to about 17% of precancerous adenomas,4 and are often missed by CT colonography (with as many as 66% of flat lesions of 5-9 mm and 40% of flat lesions ≥10 mm missed4).
Matuchansky C. Computed Tomographic Colonography for Detecting Advanced Neoplasia. JAMA. 2009;302(14):1527-1529. doi:10.1001/jama.2009.1434