Abstract
Flat lesions have been a source of controversy because of concerns that CT colonography (CTC) is insensitive in detecting these lesions, yet they may harbor a high incidence of advanced neoplasia. The wide variation in the reported incidence of flat lesions may in part be due to the lack of a uniform definition of “flat”, and in fact in many prior reports the inclusion criteria for flat are not even clearly specified. Emphasis on the more recent CTC literature suggests that when limited the target lesion to neoplasia (adenomas or adenocarcinoma), the incidence of flat lesions is low and most can be detected by CTC. Using fecal tagging and careful attention to the proper methods of searching for flat lesions with both 3D and 2D techniques can maximize the detection of flat lesions at CTC. Computer-aided detection may be helpful.





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References
Ross AS, Waxman I (2006) Flat and depressed neoplasms of the colon in Western populations. Am J Gastroenterol 101:172–180
Rembacken BJ, Fujii T, Cairns A, et al. (2000) Flat and depressed colonic neoplasms: a prospective study of 1000 colonoscopies in the UK. Lancet 355(9211):1211–1214
Tsuda S, Veress B, Toth E, et al. (2002) Flat and depressed colorectal tumours in a southern Swedish population: a prospective chromoendoscopic and histopathological study. Gut 51:550–555
Sawada T, Hojo K, Moriya Y (1989) Colonoscopic management of focal and early colorectal carcinoma. Baillieres Clin Gastroenterol 3:627–645
Soetikno R, Friedland S, Kaltenbach T, et al. (2006) Nonpolypoid (flat and depressed) colorectal neoplasms. Gastroenterology 130(2):566–576
Hurlstone DP, Karajeh M, Sanders DS, et al. (2005) Rectal aberrant crypt foci identified using high-magnification-chromoscopic colonoscopy: biomarkers for flat and depressed neoplasia. Am J Gastroenterol 100(6):1283–1289
Kudo S, Kashida H, Nakajima T, et al. (1997) Endoscopic diagnosis and treatment of early colorectal cancer. World J Surg 21:694–701
Kudo S, Kashida H, Tamura T, et al. (2000) Colonoscopic diagnosis and management of nonpolypoid early colorectal cancer. World J Surg 24(9):1081–1090
The Paris endoscopic classification of superficial neoplastic lesions: esophagus, stomach, and colon. Gastrointest Endosc 58(Suppl 6):S3–S43 (2003)
Pickhardt PJ, Nugent PA, Choi JR, et al. (2004) Flat colorectal lesions in asymptomatic adults: implications for screening with CT virtual colonoscopy. AJR 183:1343–1347
Gluecker TM, Fletcher JG, Welch TJ, et al. (2004) Characterization of lesions missed on interpretation of CT colonography using a 2D search method. AJR 182(4):881–889
Zalis ME, Barish MA, Choi JR, et al. (2005) CT colonography reporting and data system: a consensus proposal. Radiology 236:3–9
Robbins J, Pickhardt P, Kim D (2009) Flat (nonpolypoid) lesions at CT colonography: imaging and histologic characteristics using a new morphologic definition [Abstract]. Annual Meeting of the ARRS. Boston, MA
Lostumbo A, Tsai J, Suzuki K, et al. (2009) Comparison of 2D and 3D views for evaluation of flat lesions in CT colonography. Acad Radiol (in press)
Kim DH, Pickhardt PJ, Taylor AJ (2007) Characteristics of advanced adenomas detected at CT colonographic screening: implications for appropriate polyp size thresholds for polypectomy versus surveillance. AJR 188(4):940–944
Anonymous (1983) General rules for the clinical and pathological studies on cancer of the colon, rectum and anus. Part I. Clinical classification. Japanese Research Society for Cancer of the Colon and Rectum. Jpn J Surg 13:557–573
Anonymous (1983) General rules for the clinical and pathological studies on cancer of the colon, rectum and anus. Part II. Histopathological classification. Japanese Research Society for Cancer of the Colon and Rectum. Jpn J Surg 13:574–598
Park SH, Lee SS, Choi EK, et al. (2007) Flat colorectal neoplasms: definition, importance, and visualization on CT colonography. AJR 188:953–959
Fidler J, Johnson C (2009) Flat polyps of the colon: accuracy of detection by CT colonography and histologic significance. Abdom Imaging 34:157–171
Fidler JL, Johnson CD, MacCarty RL, et al. (2002) Detection of flat lesions in the colon with CT colonography. Abdom Imaging 27:292–300
Silva AC, Wellnitz CV, Hara AK (2006) Three-dimensional virtual dissection at CT colonography: unraveling the colon to search for lesions. Radiographics 26(6):1669–1686
Fidler JL, Fletcher JG, Johnson CD, et al. (2004) Understanding interpretive errors in radiologists learning computed tomography colonography. Acad Radiol 11(7):750–756
Mang TG, Schaefer-Prokop C, Maier A, et al. (2005) Detectability of small and flat polyps in MDCT colonography using 2D and 3D imaging tools: results from a phantom study. AJR 185(6):1582–1589
Park SH, Ha HK, Kim MJ, et al. (2005) False-negative results at multi-detector row CT colonography: multivariate analysis of causes for missed lesions. Radiology 235(2):495–502
Johnson DC, Mei-Hsiu C, Toledano AY, et al. (2008) Accuracy of CT colonography for detection of large adenomas and cancers. N Engl J Med 359(12):1207–1217
Young BM, Fletcher JG, Paulsen SR, et al. (2007) Polyp measurement with CT colonography: Multiple-reader, multiple-workstation comparison. AJR 188(1):122–129
Park SH, Ha HK, Kim AY, et al. (2006) Flat polyps of the colon: detection with 16-MDCT colonography—preliminary results. AJR 186:1611–1617
Morimoto T, Iinuma G, Shiraishi J, et al. (2008) Computer-aided detection in computed tomography colonography: current status and problems with detection of early colorectal cancer. Radiat Med 26(5):261–269
Summers RM, Frentz SM, Liu J, et al. (2009) Conspicuity of colorectal polyps at CT colonography: visual assessment, CAD performance, and the important role of polyp height. Acad Radiol 16(1):4–14
Taylor SA, Suzuki N, Beddoe G, et al. (2009) Flat neoplasia of the colon: CT colonography with CAD. Abdom Imaging 34:173–181
Rockey D, Paulson E, Niedzwiecki D, et al. (2005) Analysis of air contrast barium enema, computed tomographic colonography, and colonoscopy: prospective comparison. Lancet 365:305–311
Suzuki K, Sheu I, Rockey CD, et al. (2009) A CAD utilizing 3D massive-training ANNs for detection of flat lesions in CT colonography: preliminary results. Proc SPIE 7260:72601A1–72601A7
Suzuki K, Yoshida H, Nappi J, Armato SG III, Dachman AH (2008) Mixture of expert 3D massive-training ANNs for reduction of multiple types of false positives in CAD for detection of polyps in CT colonography. Med Phys 35:694–703
Park SH, Kim SY, Lee SS (2009) Sensitivity of CT colonography for nonpolypoid colorectal lesions interpreted by human readers and with computer-aided detection. AJR 193:1–9
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Lostumbo, A., Suzuki, K. & Dachman, A.H. Flat lesions in CT colonography. Abdom Imaging 35, 578–583 (2010). https://doi.org/10.1007/s00261-009-9562-3
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DOI: https://doi.org/10.1007/s00261-009-9562-3

