HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Taylor, S. A. Articles by Atkin, W. Search for Related Content PubMed PubMed Citation Articles by Taylor, S. A. Articles by Atkin, W. Related Collections Related Article

Multi–Detector Row CT Colonography: Effect of Collimation, Pitch, and Orientation on Polyp Detection in a Human Colectomy Specimen¹

¹ From the Departments of Intestinal Imaging (S.A.T., S.H., C.I.B., N.F.), Pathology (I.C.T.), Surgery (K.K.), and Endoscopy (B.P.S.) and the Cancer Research UK Colorectal Cancer Unit (S.H., B.P.S., W.A.), St Mark’s Hospital, Northwick Park, Watford Rd, Harrow, Middlesex HA1 3UJ, England; and General Electric Medical Systems, Slough, England (P.R.M.). Received May 10, 2002; revision requested June 14; final revision received February 5, 2003; accepted March 3. Address correspondence to S.H. (e-mail: s.halligan@ic.ac.uk).

PURPOSE: To investigate the effects of orientation, collimation, pitch, and tube current setting on polyp detection at multi–detector row computed tomographic (CT) colonography and to determine the optimal combination of scanning parameters for screening.

MATERIALS AND METHODS: A colectomy specimen containing 117 polyps of different sizes was insufflated and imaged with a multi–detector row CT scanner at various collimation (1.25 and 2.5 mm), pitch (3 and 6), and tube current (50, 100, and 150 mA) settings. Two-dimensional multiplanar reformatted images and three-dimensional endoluminal surface renderings from the 12 resultant data sets were examined by one observer for the presence and conspicuity of polyps. The results were analyzed with Poisson regression and logistic regression to determine the effects of scanning parameters and of specimen orientation on polyp detection.

RESULTS: The percentage of polyps that were detected significantly increased when collimation (P = .008) and table feed (P = .03) were decreased. Increased tube current resulted in improved detection only of polyps with a diameter of less than 5 mm. Polyps of less than 5 mm were optimally depicted with a collimation of 1.25 mm, a pitch of 3, and a tube current setting of 150 mA; polyps with a diameter greater than 5 mm were adequately depicted with 1.25-mm collimation and with either pitch setting and any of the three tube current settings. Small polyps in the transverse segment (positioned at a 90° angle to the z axis of scanning) were significantly less visible than those in parallel or oblique orientations (P < .001). The effective radiation dose, calculated with a Monte Carlo simulation, was 1.4–10.0 mSv.

CONCLUSION: Detection of small polyps (<5 mm) with multi–detector row CT is highly dependent on collimation, pitch, and, to a lesser extent, tube current. Collimation of 1.25 mm, combined with pitch of 6 and tube current of 50 mA, provides for reliable detection of polyps 5 mm or larger while limiting the effective radiation dose. Polyps smaller than 5 mm, however, may be poorly depicted with use of these settings in the transverse colon.

© RSNA, 2003

Index terms: Colon, CT, 75.1211 • Colon neoplasms, 75.311 • Computed tomography (CT), technology

Related Article

What Multi–Detector Row CT Parameters Are Best for Detection of Colon Polyps?

James A. Brink
Radiology 2003 229: 1-2. [Full Text] [PDF]

This article has been cited by other articles:

				A. H. de Vries, H. W. Venema, J. Florie, C. Y. Nio, and J. Stoker Influence of Tagged Fecal Material on Detectability of Colorectal Polyps at CT: Phantom Study Am. J. Roentgenol., October 1, 2008; 191(4): W181 - W189. [Abstract] [Full Text] [PDF]

				S. H. Kim, J. M. Lee, C.-I. Shin, H. C. Kim, J.-G. Lee, J. H. Kim, J. Y. Choi, H. W. Eun, J. K. Han, J. Y. Lee, et al. Effects of Spatial Resolution and Tube Current on Computer-aided Detection of Polyps on CT Colonographic Images: Phantom Study Radiology, August 1, 2008; 248(2): 492 - 503. [Abstract] [Full Text] [PDF]

				S. Jensch, A. H. de Vries, J. Peringa, S. Bipat, E. Dekker, L. C. Baak, J. F. Bartelsman, A. Heutinck, A. D. Montauban van Swijndregt, and J. Stoker CT Colonography with Limited Bowel Preparation: Performance Characteristics in an Increased-Risk Population Radiology, April 1, 2008; 247(1): 122 - 132. [Abstract] [Full Text] [PDF]

				C. D. Johnson, J. G. Fletcher, R. L. MacCarty, J. N. Mandrekar, W. S. Harmsen, P. J. Limburg, and L. A. Wilson Effect of Slice Thickness and Primary 2D Versus 3D Virtual Dissection on Colorectal Lesion Detection at CT Colonography in 452 Asymptomatic Adults Am. J. Roentgenol., September 1, 2007; 189(3): 672 - 680. [Abstract] [Full Text] [PDF]

				T. Mang, A. Maier, C. Plank, C. Mueller-Mang, C. Herold, and W. Schima Pitfalls in Multi-Detector Row CT Colonography: A Systematic Approach RadioGraphics, March 1, 2007; 27(2): 431 - 454. [Abstract] [Full Text] [PDF]

				A SLATER Alteration in bowel habit Imaging, December 1, 2006; 18(4): 208 - 217. [Abstract] [Full Text] [PDF]

				A. Graser, B. J. Wintersperger, C. Suess, M. F. Reiser, and C. R. Becker Dose reduction and image quality in MDCT colonography using tube current modulation. Am. J. Roentgenol., September 1, 2006; 187(3): 695 - 701. [Abstract] [Full Text] [PDF]

				A S Lowe and C L Kay Recent developments in CT: a review of the clinical applications and advantages of multidetector computed tomography Imaging, June 1, 2006; 18(2): 62 - 67. [Abstract] [Full Text] [PDF]

				K. T. Johnson, C. D. Johnson, J. G. Fletcher, R. L. MacCarty, and R. L. Summers CT Colonography Using 360{degrees} Virtual Dissection: A Feasibility Study Am. J. Roentgenol., January 1, 2006; 186(1): 90 - 95. [Abstract] [Full Text] [PDF]

				T. G. Mang, C. Schaefer-Prokop, A. Maier, E. Schober, G. Lechner, and M. Prokop Detectability of Small and Flat Polyps in MDCT Colonography Using 2D and 3D Imaging Tools: Results from a Phantom Study Am. J. Roentgenol., December 1, 2005; 185(6): 1582 - 1589. [Abstract] [Full Text] [PDF]

				M. Macari and E. J. Bini CT Colonography: Where Have We Been and Where Are We Going? Radiology, December 1, 2005; 237(3): 819 - 833. [Abstract] [Full Text] [PDF]

				C. D. Furtado, D. A. Aguirre, C. B. Sirlin, D. Dang, S. K. Stamato, P. Lee, F. Sani, M. A. Brown, D. L. Levin, and G. Casola Whole-Body CT Screening: Spectrum of Findings and Recommendations in 1192 Patients Radiology, November 1, 2005; 237(2): 385 - 394. [Abstract] [Full Text] [PDF]

				M. A. Barish, J. A. Soto, and J. T. Ferrucci Consensus on Current Clinical Practice of Virtual Colonoscopy Am. J. Roentgenol., March 1, 2005; 184(3): 786 - 792. [Abstract] [Full Text] [PDF]

				J. A. Brink What Multi-Detector Row CT Parameters Are Best for Detection of Colon Polyps? Radiology, October 1, 2003; 229(1): 1 - 2. [Full Text] [PDF]