Authors: Ayso H de Vries Shandra Bipat Evelien Dekker Marjolein H Liedenbaum Jasper Florie Paul Fockens Roel van der Kraan Elizabeth M MathusVliegen Johannes B Reitsma Roel Truyen Frans M Vos Aeilko H Zwinderman Jaap Stoker
Publish Date: 2009/12/22
Volume: 20, Issue: 6, Pages: 1404-1413
Abstract
Gastroenterologists measured 51 polyps by visual estimation forceps comparison and linear probe CT colonography observers randomly assessed polyp size twodimensionally abdominal and intermediate window and threedimensionally manually and semiautomatically Linear mixed models were used to assess the variability and systematic differences between CT colonography and optical colonoscopy techniquesThe variability of forceps and linear probe measurements was comparable and both showed less variability than measurement by visual assessment Measurements by linear probe were 07 mm smaller than measurements by visual assessment or by forceps The variability of all CT colonography techniques was lower than for measurements by forceps or visual assessment and sometimes lower only 2D intermediate window and manual 3D compared with measurements by linear probe All CT colonography measurements judged polyps to be larger than optical colonoscopy with differences ranging from 07 to 23 mmA linear probe does not reduce the measurement variability of endoscopists compared with the forceps Measurement differences between observers on CT colonography were usually smaller than at optical colonoscopy Polyps appeared larger when using various CT colonography techniques than when measured during optical colonoscopyCT colonography has been consistently shown to have a high accuracy in the detection of colorectal neoplasia 1 The method is less invasive and less burdensome than optical colonoscopy 2 However assessment of malignancy by obtaining tissue samples for histological analysis is not possible with this technique As a surrogate for histopathology polyp size is used for patient management strategies 3Currently according to the US screening guidelines for CT colonography 4 all patients with a polyp 6 mm or larger should be referred for optical colonoscopy However whether optical colonoscopy is indicated for polyps 6–9 mm is still under debate as the prevalence of advanced features was reported to be low 5 6 Surveillance for growth with CT colonography has been suggested as a safe alternative 7 Small 6 mm polyps may be safely left in situ because of a negligible risk of malignant transformationTwo pivotal invitro studies report an underestimation of polyp size by the endoscopists and an accurate or slight overestimation of CT colonography 8 9 compared with optical colonoscopy measurements However factors that may influence polyp measurement such as difficult viewing angles or bowel motility are not considered in these analyses
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