Automated measurement of colorectal polyp height at CT colonography: hyperplastic polyps are flatter than adenomatous polyps.

OBJECTIVE Hyperplastic polyps are more difficult to detect than adenomatous polyps at CT colonography (CTC), and it has been theorized that this difference in detectability is because hyperplastic polyps are flatter. Using automated software that computes polyp height, we determined whether hyperplastic colonic polyps on CTC are indeed flatter than adenomatous polyps of comparable width. MATERIALS AND METHODS At three medical centers, 1,186 patients underwent oral contrast-enhanced CTC and same-day optical colonoscopy (OC) with segment unblinding for colorectal cancer screening. One hundred eighty-five of the patients had at least one hyperplastic or adenomatous polyp 6-10 mm visible at both OC and CTC, where size was determined by a calibrated guidewire at OC. To assess flatness, the heights of the polyps at CTC were measured using a validated automated software program. The heights and height-to-width ratios of the hyperplastic polyps were compared with those of the adenomatous polyps using a Student's t test (two-tailed, unpaired, unequal variance). RESULTS There were 176 adenomatous and 83 hyperplastic polyps visible at segment-unblinded OC. The fraction of these polyps that were measurable at CTC using the automated software was not significantly different for adenomatous versus hyperplastic polyps (158/176 [89.8%] vs 73/87 [83.9%], respectively; p = 0.2). The average height-to-width ratios using automated width measurements were 15% less for hyperplastic polyps: 0.39 +/- 0.20 (n = 158) and 0.33 +/- 0.19 (n = 73) for adenomatous and hyperplastic polyps, respectively (p = 0.03). When polyps of comparable OC size or CTC width were considered, the heights of hyperplastic polyps were up to 27% less than those of adenomatous polyps. CONCLUSION For 6-10 mm polyps of a given size as determined by OC or a given width at CTC, hyperplastic polyps tend to be flatter (i.e., have lower height) compared with adenomatous polyps.

[1]  M. O'brien.  Hyperplastic and serrated polyps of the colorectum. , 2007, Gastroenterology clinics of North America.

[2]  L J van Vliet,et al.  Protrusion method for automated estimation of polyp size on CT colonography. , 2008, AJR. American journal of roentgenology.

[3]  P. Pickhardt,et al.  Computed tomographic virtual colonoscopy to screen for colorectal neoplasia in asymptomatic adults. , 2003, The New England journal of medicine.

[4]  Jianhua Yao,et al.  Conspicuity of colorectal polyps at CT colonography: visual assessment, CAD performance, and the important role of polyp height. , 2009, Academic radiology.

[5]  Y. Nakamura,et al.  Genetic alterations during colorectal-tumor development. , 1988, The New England journal of medicine.

[6]  A. Zauber,et al.  Initial management and follow-up surveillance of patients with colorectal adenomas. , 1997, Gastroenterology clinics of North America.

[7]  Joel G Fletcher,et al.  Automated polyp measurement with CT colonography: preliminary observations in a phantom colon model. , 2007, AJR. American journal of roentgenology.

[8]  G. Stemmermann,et al.  Pathogenesis of hyperplastic polyps of the colon: a hypothesis based on ultrastructure and in vitro cell kinetics. , 1974, Gastroenterology.

[9]  S. Winawer,et al.  Management of colorectal polyps , 1997, CA: a cancer journal for clinicians.

[10]  Jianhua Yao,et al.  Adaptive deformable model for colonic polyp segmentation and measurement on CT colonography. , 2007, Medical physics.

[11]  G. Lehman,et al.  Disappearing rectal polyps. , 1991, Gastrointestinal endoscopy.

[12]  D. Rex,et al.  Colonoscopic miss rates of adenomas determined by back-to-back colonoscopies. , 1997, Gastroenterology.

[13]  Jun Yong Jeong,et al.  Manual and automated polyp measurement comparison of CT colonography with optical colonoscopy. , 2008, Academic radiology.

[14]  Jin Ho Kim,et al.  Flat polyps of the colon: detection with 16-MDCT colonography--preliminary results. , 2006, AJR. American journal of roentgenology.

[15]  Perry J Pickhardt,et al.  Electronic cleansing and stool tagging in CT colonography: advantages and pitfalls with primary three-dimensional evaluation. , 2003, AJR. American journal of roentgenology.

[16]  Perry J Pickhardt,et al.  Nonadenomatous polyps at CT colonography: prevalence, size distribution, and detection rates. , 2004, Radiology.

[17]  Jiang Li,et al.  Polyp height and width measurement using topographic height map , 2008, SPIE Medical Imaging.

[18]  D. Heresbach,et al.  Miss rate for colorectal neoplastic polyps: a prospective multicenter study of back-to-back video colonoscopies , 2008, Endoscopy.

[19]  Ronald M Summers,et al.  Improving the accuracy of CTC interpretation: computer-aided detection. , 2010, Gastrointestinal endoscopy clinics of North America.

[20]  G. Bedogni,et al.  Visual "disappearing phenomenon" can reliably predict the nonadenomatous nature of rectal and rectosigmoid diminutive polyps at endoscopy. , 1994, Gastrointestinal endoscopy.

[21]  Walter Park,et al.  Prevalence of nonpolypoid (flat and depressed) colorectal neoplasms in asymptomatic and symptomatic adults. , 2008, JAMA.

[22]  D. Ransohoff,et al.  Nonpolypoid neoplastic lesions of the colorectal mucosa. , 2008, Gastrointestinal endoscopy.

[23]  Perry J Pickhardt,et al.  Flat colorectal lesions in asymptomatic adults: implications for screening with CT virtual colonoscopy. , 2004, AJR. American journal of roentgenology.

[24]  D. Altman,et al.  STATISTICAL METHODS FOR ASSESSING AGREEMENT BETWEEN TWO METHODS OF CLINICAL MEASUREMENT , 1986, The Lancet.

[25]  Ronald M. Summers,et al.  Employing topographical height map in colonic polyp measurement and false positive reduction , 2009, Pattern Recognit..

[26]  J. Yee,et al.  CT colonography reporting and data system: a consensus proposal. , 2005, Radiology.

[27]  P. Bossuyt,et al.  Polyp Miss Rate Determined by Tandem Colonoscopy: A Systematic Review , 2006, The American Journal of Gastroenterology.

[28]  A. Hara,et al.  Detection of flat lesions in the colon with CT colonography , 2002, Abdominal Imaging.

[29]  Steve Halligan,et al.  CT colonography: automated measurement of colonic polyps compared with manual techniques--human in vitro study. , 2007, Radiology.

[30]  R. Summers.  Polyp size measurement at CT colonography: what do we know and what do we need to know? , 2010, Radiology.

[31]  Jessica B Robbins,et al.  Flat (nonpolypoid) colorectal lesions identified at CT colonography in a U.S. screening population. , 2010, Academic radiology.

[32]  J. Waye,et al.  Rectal hyperplastic polyps: now you see them, now you don't--a differential point. , 1990, The American journal of gastroenterology.

[33]  J. Yee,et al.  Accuracy of ct colonography for detection of large adenomas and cancers , 2009 .