Optimization of CT Colonography Technique: Prospective Trial in 180 Patients1
Joel G. Fletcher, MD,
C. Daniel Johnson, MD,
Timothy J. Welch, MD,
Robert L. MacCarty, MD,
David A. Ahlquist, MD,
Judd E. Reed, BS,
William S. Harmsen, MS and
Lynn A. Wilson, RN
1 From the Department of Diagnostic Radiology (J.G.F., C.D.J., T.J.W., R.L.M., L.A.W.), the Division of Gastroenterology and Hepatology and Internal Medicine (D.A.A.), the Division of Information Systems Services (J.E.R.), and the Section of Biostatistics (W.S.H.), Mayo Clinic and Mayo Foundation, 200 First Street SW, Rochester, MN 55905. Received June 22, 1999; revision requested July 30; revision received November 16; accepted December 17. Supported by National Institutes of Health grant R01 CA 75333. Address correspondence to J.G.F. (e-mail: fletcher.joel@mayo.edu).
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Figure 1. Bar graph shows the causes of all false-negative studies for polyps 1 cm in diameter or larger.
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Figure 2. Bar graph shows numbers of additional lesions 1 cm or larger per colonic segment that were identified prospectively by using combined prone and supine data sets (ie, polyps that were not seen by the reader of supine images alone) and causes of supine image reader error. Asc = ascending colon, Desc = descending colon, Hep Fl = hepatic flexure, Rec = rectum; Sig = sigmoid colon, Spl Fl = splenic flexure, Trans = transverse colon.
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Figure 3. Bar graph shows numbers of additional polyps 0.5-0.9 cm per colonic segment that were identified prospectively by using the combined prone and supine data set (ie, polyps that were not seen by the reader of supine images alone) and causes of supine image reader error. Asc = ascending colon, Desc = descending colon, Hep Fl = hepatic flexure, Rec = rectum; Sig = sigmoid colon, Spl Fl = splenic flexure, Trans = transverse colon.
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Figure 4. Bar graph shows causes of interpretive error for false-positive studies in patients with polyps 1 cm in size or larger.
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Figure 5. Bar graph shows the effect of oral iodinated contrast medium on the sensitivity of CT colonography. Pts = patients.
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Figure 6. Bar graph shows the effect of increased colonic fluid attenuation on the sensitivity for detection of polyps with the combination of supine and prone CT colonographic images.
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Figure 7a. (a) Transverse CT colonographic image from a supine data set demonstrates luminal collapse (arrowheads) at the splenic flexure in a 68-year-old man. (b) Corresponding transverse CT colonographic image from the prone data set demonstrates a 1.0-cm sessile polyp (arrowheads) dangling dependently from a haustral fold. (c) Endoluminal three-dimensional CT colonographic image from the prone data set demonstrates the same polyp (arrowheads) as in b. A 1.0-cm adenoma was found at colonoscopy.
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Figure 7b. (a) Transverse CT colonographic image from a supine data set demonstrates luminal collapse (arrowheads) at the splenic flexure in a 68-year-old man. (b) Corresponding transverse CT colonographic image from the prone data set demonstrates a 1.0-cm sessile polyp (arrowheads) dangling dependently from a haustral fold. (c) Endoluminal three-dimensional CT colonographic image from the prone data set demonstrates the same polyp (arrowheads) as in b. A 1.0-cm adenoma was found at colonoscopy.
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Figure 7c. (a) Transverse CT colonographic image from a supine data set demonstrates luminal collapse (arrowheads) at the splenic flexure in a 68-year-old man. (b) Corresponding transverse CT colonographic image from the prone data set demonstrates a 1.0-cm sessile polyp (arrowheads) dangling dependently from a haustral fold. (c) Endoluminal three-dimensional CT colonographic image from the prone data set demonstrates the same polyp (arrowheads) as in b. A 1.0-cm adenoma was found at colonoscopy.
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Figure 8a. (a) Transverse CT colonographic image from the supine data set demonstrates a suggestive lobulated mass (arrowheads) with soft-tissue attenuation along the posterior wall of the ascending colon in a 70-year-old woman. It is difficult to discern if the suggestive mass represents stool and fluid or a true lesion. (b) Corresponding transverse CT colonographic image from the prone data set demonstrates a large complex lesion (arrow) suspended from the posterior wall and clearly protruding into the colonic lumen. (c) Same image as in b but displayed with lung window settings (level = -500 HU, width = 2,000 HU) shows that the mass arises from several haustral folds (arrowheads). A large tubulovillous adenoma in the ascending colon was identified at colonoscopy.
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Figure 8b. (a) Transverse CT colonographic image from the supine data set demonstrates a suggestive lobulated mass (arrowheads) with soft-tissue attenuation along the posterior wall of the ascending colon in a 70-year-old woman. It is difficult to discern if the suggestive mass represents stool and fluid or a true lesion. (b) Corresponding transverse CT colonographic image from the prone data set demonstrates a large complex lesion (arrow) suspended from the posterior wall and clearly protruding into the colonic lumen. (c) Same image as in b but displayed with lung window settings (level = -500 HU, width = 2,000 HU) shows that the mass arises from several haustral folds (arrowheads). A large tubulovillous adenoma in the ascending colon was identified at colonoscopy.
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Figure 8c. (a) Transverse CT colonographic image from the supine data set demonstrates a suggestive lobulated mass (arrowheads) with soft-tissue attenuation along the posterior wall of the ascending colon in a 70-year-old woman. It is difficult to discern if the suggestive mass represents stool and fluid or a true lesion. (b) Corresponding transverse CT colonographic image from the prone data set demonstrates a large complex lesion (arrow) suspended from the posterior wall and clearly protruding into the colonic lumen. (c) Same image as in b but displayed with lung window settings (level = -500 HU, width = 2,000 HU) shows that the mass arises from several haustral folds (arrowheads). A large tubulovillous adenoma in the ascending colon was identified at colonoscopy.
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Copyright © 2000 by the Radiological Society of North America.
