101
|
Mori K, Deguchi D, Sugiyama J, Suenaga Y, Toriwaki J, Maurer CR, Takabatake H, Natori H. Tracking of a bronchoscope using epipolar geometry analysis and intensity-based image registration of real and virtual endoscopic images††A preliminary version of this paper was presented at the Medical Image Computing and Computer-Assisted Intervention (MICCAI) Conference, Utrecht, The Netherlands (Mori et al., 2001). Med Image Anal 2002; 6:321-36. [PMID: 12270236 DOI: 10.1016/s1361-8415(02)00089-0] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
This paper describes a method for tracking the camera motion of a flexible endoscope, in particular a bronchoscope, using epipolar geometry analysis and intensity-based image registration. The method proposed here does not use a positional sensor attached to the endoscope. Instead, it tracks camera motion using real endoscopic (RE) video images obtained at the time of the procedure and X-ray CT images acquired before the endoscopic examination. A virtual endoscope system (VES) is used for generating virtual endoscopic (VE) images. The basic idea of this tracking method is to find the viewpoint and view direction of the VES that maximizes a similarity measure between the VE and RE images. To assist the parameter search process, camera motion is also computed directly from epipolar geometry analysis of the RE video images. The complete method consists of two steps: (a) rough estimation using epipolar geometry analysis and (b) precise estimation using intensity-based image registration. In the rough registration process, the method computes camera motion from optical flow patterns between two consecutive RE video image frames using epipolar geometry analysis. In the image registration stage, we search for the VES viewing parameters that generate the VE image that is most similar to the current RE image. The correlation coefficient and the mean square intensity difference are used for measuring image similarity. The result obtained in the rough estimation process is used for restricting the parameter search area. We applied the method to bronchoscopic video image data from three patients who had chest CT images. The method successfully tracked camera motion for about 600 consecutive frames in the best case. Visual inspection suggests that the tracking is sufficiently accurate for clinical use. Tracking results obtained by performing the method without the epipolar geometry analysis step were substantially worse. Although the method required about 20 s to process one frame, the results demonstrate the potential of image-based tracking for use in an endoscope navigation system.
Collapse
Affiliation(s)
- K Mori
- Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
| | | | | | | | | | | | | | | |
Collapse
|
102
|
Abstract
The potential role of virtual colonoscopy is not limited to colorectal cancer screening, although that is its greatest potential. Same-day VC should be offered for patients undergoing an incomplete colonoscopy. Conversely, faster, more accurate interpretation by the radiologist on the same day as a VC should lead to the consideration by the gastroenterologist of same-day colonoscopy for patients with a suspicious, significantly sized polyp.
Collapse
Affiliation(s)
- Abraham H Dachman
- Department of Radiology, MC 2026, University of Chicago, 5841 South Maryland Avenue, Chicago, IL 60637, USA.
| |
Collapse
|
103
|
Kim JK, Ahn JH, Park T, Ahn HJ, Kim CS, Cho KS. Virtual cystoscopy of the contrast material-filled bladder in patients with gross hematuria. AJR Am J Roentgenol 2002; 179:763-8. [PMID: 12185059 DOI: 10.2214/ajr.179.3.1790763] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE The objective of this study was to evaluate the usefulness of virtual cystoscopy of the contrast material-filled bladder in evaluating patients with gross hematuria. SUBJECTS AND METHODS Seventy-three consecutive patients who had gross hematuria and whose upper urinary tracts had a normal appearance on single-detector helical CT scans were prospectively evaluated with virtual cystoscopy. Source CT data for virtual cystoscopy were obtained on a multidetector CT scanner with 1.25-mm slice thickness and transferred to a workstation for interactive navigation using volume rendering. Two radiologists independently interpreted the virtual cystoscopic images, and discrepancies were resolved by consensus. All patients also underwent conventional cystoscopy. We assessed the agreement between the findings on virtual and conventional cystoscopy. Using conventional cystoscopy as the gold standard, we evaluated the usefulness of virtual cystoscopy as an aid in identifying bladder lesions and detecting abnormal bladders. RESULTS Virtual cystoscopy depicted 60 lesions in the bladders of 43 patients. Fifty-six lesions (in 41 bladders) revealed on virtual cystoscopy were true-positive findings. Four lesions in two bladders with abnormal findings were false-positive. On virtual cystoscopy, the radiologists missed three lesions in two abnormal bladders that were identified on conventional cystoscopy. On virtual cystoscopy, 15 (88%) of 17 lesions smaller than 0.5 cm were identified. The agreement between the findings of virtual and conventional cystoscopy was excellent in the reviewers' identification of bladder lesions (kappa = 0.83) and detection of abnormal bladders (kappa = 0.89). The sensitivity and specificity of virtual cystoscopy were 95% and 87% for identifying bladder lesions and 95% and 93% for detecting abnormal bladders. CONCLUSION Virtual cystoscopy of the contrast material-filled bladder is useful for the evaluation of the bladder in patients with gross hematuria.
Collapse
Affiliation(s)
- Jeong Kon Kim
- Department of Radiology, Asan Medical Center, University of Ulsan, 388-1 Poongnap-dong, Songpa-gu, Seoul, 138-736, South Korea
| | | | | | | | | | | |
Collapse
|
104
|
Macari M, Bini EJ, Xue X, Milano A, Katz SS, Resnick D, Chandarana H, Krinsky G, Klingenbeck K, Marshall CH, Megibow AJ. Colorectal neoplasms: prospective comparison of thin-section low-dose multi-detector row CT colonography and conventional colonoscopy for detection. Radiology 2002; 224:383-92. [PMID: 12147833 DOI: 10.1148/radiol.2242011382] [Citation(s) in RCA: 199] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
PURPOSE To prospectively compare thin-section low-dose multi-detector row computed tomographic (CT) colonography with conventional colonoscopy for the detection of colorectal neoplasms. MATERIALS AND METHODS One hundred five patients underwent CT colonography immediately before colonoscopy. Supine and prone CT colonographic acquisitions to image the region during a 30-second breath hold were performed. CT colonographic images were prospectively interpreted for the presence, location, size, and morphologic features of polyps. The time of image interpretation was noted. Sensitivity, specificity, and positive and negative predictive values of CT colonography were calculated, with 95% CIs, by using colonoscopic findings as the reference standard. The weighted CT dose index was calculated on the basis of measurements in a standard body phantom. Effective dose was calculated by using commercially available software. RESULTS Median CT data interpretation time was 12 minutes. One hundred thirty-two polyps in 59 patients were identified at colonoscopy; no polyps were detected in 46 patients. Sensitivities for detection of polyps smaller than 5 mm, 6-9 mm, and larger than 10 mm in diameter were 12% (11 of 91 polyps), 70% (19 of 27 polyps), and 93% (13 of 14 polyps), respectively. Estimated overall specificity was 97.7% (515 of 527 imaging results). The total weighted CT dose index for combined supine and prone CT colonography was 11.4 mGy. The effective doses for combined CT colonography were 5.0 mSv and 7.8 mSv for men and women, respectively. CONCLUSION Low-dose multi-detector row CT colonography has excellent sensitivity and specificity for detection of colorectal neoplasms 10 mm and larger.
Collapse
Affiliation(s)
- Michael Macari
- Department of Radiology, New York University Medical Center, Tisch Hospital, 560 First Ave, Suite HW 207, New York, NY 10016, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
105
|
Lefere PA, Gryspeerdt SS, Dewyspelaere J, Baekelandt M, Van Holsbeeck BG. Dietary fecal tagging as a cleansing method before CT colonography: initial results polyp detection and patient acceptance. Radiology 2002; 224:393-403. [PMID: 12147834 DOI: 10.1148/radiol.2241011222] [Citation(s) in RCA: 250] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
PURPOSE To compare reduced colonic cleansing based on dietary fecal tagging (FT) with standard (non-FT) colonic cleansing with regard to patient acceptance, sensitivity, and specificity. MATERIALS AND METHODS In 50 patients (FT group), FT was performed by means of diet, magnesium citrate, and a barium suspension. In another 50 patients (non-FT group), preparation was based on polyethylene glycol administration. All patients underwent conventional colonoscopy after computed tomographic (CT) colonography. Sensitivity and specificity for polyp detection were calculated by using conventional colonography as the reference standard. At CT colonography, fecal residue was evaluated. Patients were interviewed to determine discomfort, side effects, sleep quality, final opinion on examination comfort, and whether they would be reluctant to undergo the same examination again. RESULTS FT left more fecal residue but improved differentiation from polyps (FT specificity, 88% [30 of 34 patients]; non-FT, 77% [23 of 30 patients]). Sensitivities were comparable: FT, 88% (14 of 16 patients); non-FT, 85% (17 of 20 patients). FT significantly reduced discomfort, side effects, and sleep disturbance, and resulted in an improved final opinion of how comfortable the examination was (P <.05). Although FT improved patient willingness to repeat the examination, this improvement was not statistically significant (P >.05). CONCLUSION FT offers the patient a well-tolerated preparation and improves specificity, with improved differentiation of polyps from residual stool.
Collapse
Affiliation(s)
- Philippe A Lefere
- Department of Radiology, Stedelijk Ziekenhuis, Bruggesteenweg 90, 8800 Roeselare, Belgium.
| | | | | | | | | |
Collapse
|
106
|
van Gelder RE, Venema HW, Serlie IWO, Nio CY, Determann RM, Tipker CA, Vos FM, Glas AS, Bartelsman JFW, Bossuyt PMM, Laméris JS, Stoker J. CT colonography at different radiation dose levels: feasibility of dose reduction. Radiology 2002; 224:25-33. [PMID: 12091658 DOI: 10.1148/radiol.2241011126] [Citation(s) in RCA: 162] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
PURPOSE To investigate the sensitivity and specificity of polyp detection and the image quality of computed tomographic (CT) colonography at different radiation dose levels and to study effective doses reported in literature on CT colonography. MATERIALS AND METHODS CT colonography and colonoscopy were performed with 100 mAs in 50 consecutive patients at high risk for colorectal cancer; 50- and 30-mAs CT colonographic examinations were simulated with controlled addition of noise to raw transmission measurements. One radiologist randomly evaluated all original and simulated images for the presence of polyps and scored image quality. Differences in image quality were assessed with the Wilcoxon rank test. Scan protocols from the literature and recent (unpublished) updates were collected. RESULTS In nine of 10 patients with polyps 5 mm in diameter or larger (sensitivity, 90%) and in seven of 17 patients with polyps smaller than 5 mm, polyps were correctly identified with CT colonography at all dose levels. Specificity for patients without polyps 5 mm or larger was 53%-60% at all dose levels and for patients without any polyps was 26% (at 100 and 50 mAs) and 48% (at 30 mAs). Image quality decreased significantly as the dose level decreased. The median effective doses (supine and prone positions) calculated from protocols reported in the literature and updates were 7.8 and 8.8 mSv, respectively. CONCLUSION Although image quality decreases significantly at 30 mAs (3.6 mSv), polyp detection remains unimpaired. The median dose for CT colonography at institutions that perform CT colonographic research is currently 8.8 mSv.
Collapse
Affiliation(s)
- Rogier E van Gelder
- Department of Radiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
107
|
Yoshida H, Näppi J, MacEneaney P, Rubin DT, Dachman AH. Computer-aided diagnosis scheme for detection of polyps at CT colonography. Radiographics 2002; 22:963-79. [PMID: 12110726 DOI: 10.1148/radiographics.22.4.g02jl16963] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Colon cancer is one of the leading causes of cancer deaths in the United States. However, most colon cancers can be prevented if precursor colonic polyps are detected and removed. An advanced computer-aided diagnosis (CAD) scheme was developed for the automated detection of polyps at computed tomographic (CT) colonography. A region encompassing the colonic wall is extracted from an isotropic volume data set obtained by interpolating CT colonographic scans along the axial direction. Polyp candidates are detected with computation of three-dimensional (3D) geometric features that characterize polyps, followed by extraction of polyps with hysteresis thresholding and fuzzy clustering using these geometric features. The number of false-positive findings is reduced by extracting 3D texture features from polyp candidates and applying quadratic discriminant analysis to the candidates. This CAD scheme was applied in 71 patients who underwent CT colonography, 14 of whom had colonoscopically confirmed polyps (n = 21). At by-patient analysis, sensitivity was 100%, with an average false-positive rate of 2.0 per patient. At by-polyp analysis, the scheme detected 90% of the polyps at the same false-positive rate. This CAD scheme permits accurate detection of suspicious lesions and thus has the potential to reduce radiologists' interpretation time and improve their diagnostic accuracy in the detection of polyps at CT colonography.
Collapse
Affiliation(s)
- Hiroyuki Yoshida
- Department of Radiology, University of Chicago, 5841 S Maryland Ave, MC20206, IL 60637, USA.
| | | | | | | | | |
Collapse
|
108
|
Affiliation(s)
- Douglas K Rex
- Indiana University Medical Center, Indianapolis, Indiana 46202-5121, USA
| |
Collapse
|
109
|
Abstract
Virtual endoscopy is a new-generation technique which combines the features of endoscopic viewing and cross-sectional volumetric imaging. In the evaluation of gastrointestinal cancers, virtual endoscopy has been most commonly used in colorectal carcinomas and to a much lesser extent in gastric carcinomas. In this review, the current status of virtual colonoscopy was reviewed together with a brief discussion of virtual gastroscopy.
Collapse
Affiliation(s)
- Aytekin Oto
- Department of Radiology, Hacettepe University, Kirkpinar Sokak 3-9, Cankaya, Ankara, Turkey.
| |
Collapse
|
110
|
Abstract
Recent years have seen notable advances in imaging technologies. Three-dimensional computer-rendered techniques with rapid image acquisition have led to the development of virtual reality imaging. Virtual reality imaging allows interactive intraluminal navigation through any hollow viscus, simulating conventional endoscopy. This technique of virtual endoscopy has been applied to many organs, including the urinary tract. Virtual reality endoscopy is beginning to challenge the gold standard of conventional endoscopic evaluation. Recent advances in laparoscopic surgery are largely attributable to technological improvements in imaging equipment. Laparoscopic ultrasound has become a common adjunct in laparoscopic surgery. In particular, advances in video cameras and digital imaging technology have decreased the steep learning curve associated with laparoscopic procedures. Telerobotic systems offer several advantages to laparoscopic surgery, such as all six degrees of freedom, dexterity enhancement, tremor filtering, and stereovision. In addition, technological breakthroughs allow many procedures to evolve from open operations involving lengthy hospital stays to imaging-guided minimally invasive procedures performed on an outpatient basis. Finally, Internet-based imaging is changing the way in which urology services are delivered, by allowing rapid communication between remote locations.
Collapse
|
111
|
Ginnerup Pedersen B, Moller Christiansen TE, Viborg Mortensen F, Christensen H, Laurberg S. Bowel cleansing methods prior to CT colonography. A prospective, comparative, randomized blinded study. Acta Radiol 2002. [DOI: 10.1034/j.1600-0455.2002.430312.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
112
|
Ng CS, Doyle TC, Pinto EM, Courtney HM, Miller R, Bull RK, Freeman AH, Dixon AK. Caecal carcinomas in the elderly: useful signs in minimal preparation CT. Clin Radiol 2002; 57:359-64. [PMID: 12014932 DOI: 10.1053/crad.2001.0841] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Frail, elderly and immobile patients frequently have difficulty in tolerating formal colonic investigations. Caecal tumours may account for up to 35% of colonic tumours. Barium enema and colonoscopy have limitations in assessing this region. The aims of this study were to evaluate the accuracy of a minimal preparation CT technique (merely with prolonged oral contrast medium) in identifying caecal carcinomas and to determine helpful radiological signs. MATERIALS AND METHODS The CT technique involved helical acquisition following 2 days of preparation with oral contrast medium. The outcome of 4 years' experience (1995-1998) was reviewed. The gold-standards were pathological and cancer registration records, together with colonoscopy and barium enema where available, with a minimum of 15 months' follow-up. RESULTS CT correctly identified 27 of 30 caecal carcinomas, and missed three, in a total of 1077 CT studies in 1031 patients (median age 80 years). There were also 21 false-positive cases in which CT incorrectly raised the possibility of a caecal tumour. The sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) were 90%, 98%, 99% and 56%, respectively. Serosal margin blurring, tumour length, presence of abnormal peri-colic fat and terminal ileal wall thickening were identified as useful radiological signs. CONCLUSIONS Minimal preparation CT is able to identify caecal carcinomas with fair accuracy. Such evaluation may become important given the increasing population age and evidence of a 'proximal shift' in the site of colonic tumours in the elderly.
Collapse
Affiliation(s)
- C S Ng
- Department of Radiology, Addenbrooke's NHS Trust and the University of Cambridge, Cambridge, UK.
| | | | | | | | | | | | | | | |
Collapse
|
113
|
Power NP, Pryor MD, Martin A, Horrocks J, McLean AM, Reznek RH. Optimization of scanning parameters for CT colonography. Br J Radiol 2002; 75:401-8. [PMID: 12036832 DOI: 10.1259/bjr.75.893.750401] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
To determine the optimal collimation, pitch and reconstruction interval for CT colonography, 10 spherical polyps between 1 mm and 10 mm diameter and made of tissue equivalent material with a CT number of 40 Hounsfield units (HU) were placed in the colon of an anthropomorphic phantom. The phantom was scanned at slice thicknesses of 3 mm, 5 mm and 7 mm and pitches of 1.0, 1.3, 1.5, 1.7 and 2.0 on an IGE Hispeed advantage system. Images were reconstructed for each scanning parameter at the minimum intervals allowed along the z-axis. The optimum scanning protocol was assessed by measuring maximum contrast between the polyp and air, sensitivity for detection of each polyp along the z-axis, and relative radiation dose. In addition, images were reviewed separately by two radiologists who graded polyp conspicuity as: 0, not seen; 1, faintly seen; 2, well seen. It was found that varying the scanning parameters caused a marked alteration in the maximum contrast between each polyp and air. For example, for the 5 mm polyp, the range of contrasts from best to worst case was 910-490 HU. It was noted that with contrasts of less than 500 HU, polyps were only faintly seen. A slice thickness of 3 mm with a pitch of 2 offers optimal polyp conspicuity with a relatively low radiation dose, we conclude that scanning parameters can be optimized for threshold contrast, radiation dose and subjective conspicuity. We propose an optimal parameter of 3 mm slice thickness and pitch 2.
Collapse
Affiliation(s)
- N P Power
- Department of Radiology, St. Bartholomew's Hospital, West Smithfield, London EC1A 7EB, UK
| | | | | | | | | | | |
Collapse
|
114
|
Lauenstein TC, Goehde SC, Ruehm SG, Holtmann G, Debatin JF. MR colonography with barium-based fecal tagging: initial clinical experience. Radiology 2002; 223:248-54. [PMID: 11930074 DOI: 10.1148/radiol.2231010887] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
PURPOSE To assess a strategy for fecal tagging with barium sulfate as an inexpensive tagging agent in conjunction with magnetic resonance (MR) colonography in patients suspected of having colorectal lesions. MATERIALS AND METHODS Twenty-four patients suspected of having colonic lesions because of rectal bleeding, positive fecal occult blood test results, or altered bowel habits underwent MR colonography and subsequent conventional colonoscopy. A 200-mL dose of a barium sulfate-containing contrast agent was ingested with each of four low-fiber meals, beginning 36 hours before the examination. For MR colonography, the colon was filled with tap water. Gadobenate dimeglumine was injected intravenously. Images were acquired 75 seconds after gadobenate dimeglumine administration by using only a T1-weighted three-dimensional gradient-echo sequence. Images were reviewed by two radiologists blinded to conventional colonoscopic data. By using colonoscopy as the reference standard, sensitivity and specificity of MR colonography were determined for detecting colorectal masses. RESULTS On the basis of MR colonography, 15 polyps of 5-20 mm and 10 carcinomas were detected and later confirmed with conventional colonoscopy. Conventional colonoscopy depicted three additional lesions less than 8 mm in diameter. Thus, sensitivity of MR colonography was 89.3% (25 of 28) for lesions and 91.7% (22 of 24) for patients. CONCLUSION Barium-tagged MR colonography obviates bowel cleansing and depicts all lesions exceeding 8 mm in diameter.
Collapse
Affiliation(s)
- Thomas C Lauenstein
- Department of Diagnostic Radiology, University Hospital Essen, Hufelandstrasse 55, D-45122 Essen, Germany
| | | | | | | | | |
Collapse
|
115
|
Abstract
Computerized tomographic colonography (CT colonography) is a new, non-invasive technique that has been developed over the last few years; it looks at the large bowel in detail. In this chapter we look at how the examination is performed and we consider how the images are displayed. We describe the normal features of the colon, as seen using this technique, as well as the features of common pathological conditions. We will discuss screening for colorectal cancer and the performance of CT colonography; we compare the latter with other procedures currently employed in the screening and diagnosis of colorectal pathology. We consider the difficulties in interpreting these CT colonographic images and look at ways to overcome such difficulties. Finally we discuss future developments of this exciting, new technique.
Collapse
Affiliation(s)
- Clare S Smith
- Department of Radiology, Mater Misercordiae Hospital, Eccles Street, Dublin 7, Ireland
| | | |
Collapse
|
116
|
Näppi J, Yoshida H. Automated detection of polyps with CT colonography: evaluation of volumetric features for reduction of false-positive findings. Acad Radiol 2002; 9:386-97. [PMID: 11942653 DOI: 10.1016/s1076-6332(03)80184-8] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
RATIONALE AND OBJECTIVES To achieve high performance in computer-assisted diagnosis (CAD) of polyps with computed tomographic (CT) colonography, the authors (a) developed new gradient concentration and directional gradient concentration (DGC) features for differentiating between the true-positive and false-positive (FP) findings generated by the authors' CAD scheme, and (b) used receiver operating characteristic (ROC) analysis to quantify the differentiation performance of these and other volumetric features. MATERIALS AND METHODS CT colonography was performed in 43 patients prone and supine with a helical CT scanner; there were 12 polyps in 11 patients. The polyp candidates generated by the authors' CAD scheme were characterized by nine statistics of six volumetric features, and the resulting 54 feature statistics were combined by a linear or quadratic discriminant classifier. The discrimination performance was measured with round-robin method by ROC analysis and the FP rate of the CAD scheme. RESULTS The mean value of shape index (SI) yielded the highest individual ROC performance (area under the curve = 0.92). Among combinations, the mean values of SI and DGC and the variance of CT value yielded a high ROC performance (area under the curve = 0.95). With quadratic classifier, the sensitivity and FP rate of the case-based (data set-based) analysis was 100% (95%) with 2.4 FP findings per patient (1.7 FP findings per data set), respectively. CONCLUSION Combination of the mean values of SI and DGC and the variance of CT value reduced the FP rate substantially without sacrificing sensitivity. These three features are potentially useful in improving the performance of the authors' CAD scheme for detecting polyps with CT colonography.
Collapse
Affiliation(s)
- Janne Näppi
- Department of Radiology, University of Chicago, IL 60637, USA
| | | |
Collapse
|
117
|
Mendelson RM, Forbes GM. Computed tomography colonography (virtual colonoscopy): review. AUSTRALASIAN RADIOLOGY 2002; 46:1-12. [PMID: 11966581 DOI: 10.1046/j.1440-1673.2001.00988.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Computed tomography examination of the colon performed after bowel cleansing and distension of the lumen with gas goes by several different names--CT colonography (CTC) and CT colography perhaps being the most common. Strictly, the term 'virtual colonoscopy' (VC), should be reserved for the process of examining 3-D, simulated endoluminal images with a capability to navigate through the bowel using appropriate software. Computed tomography colonography appears to be the name that has gained favour among radiologists, although it is suspected that 'virtual colonoscopy' will persist as a generic term due to its attractive 'high-tech' connotations for non-radiological medical and lay persons. Whatever the name, the technique has been made possible through the advent of fast helical CT scanners which allow acquisition of a volume of data, and of proprietary software which enables multiplanar reformatting and 3-D endoluminal reconstructions. It is evident that if CTC/VC can be shown to be acceptable to patients, safe, affordable and accurate, it has enormous potential as a diagnostic and screening tool for colorectal neoplasia.
Collapse
|
118
|
Laghi A, Iannaccone R, Carbone I, Catalano C, Di Giulio E, Schillaci A, Passariello R. Detection of colorectal lesions with virtual computed tomographic colonography. Am J Surg 2002; 183:124-31. [PMID: 11918874 DOI: 10.1016/s0002-9610(01)00857-1] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND The aim of our study was to compare the performance of virtual computed tomographic colonography with that of conventional colonoscopy in a blinded, prospective study in 165 patients with suspected colorectal lesions. METHODS There were 165 patients, all referred for conventional colonoscopy, who underwent preliminary virtual computed tomographic colonography. Computed tomograhic images of all suspected lesions were analyzed and subsequently compared with conventional colonoscopy findings. RESULTS There were 30 colorectal cancers and 37 polyps identified at conventional colonoscopy. Virtual computed tomographic colonography correctly detected all cancers, as well as 11 of 12 polyps of 10 mm in diameter or larger (sensitivity, 92%); 14 of 17 polyps between 6 and 9 mm (sensitivity, 82%); and 4 of 8 polyps of 5 mm or smaller (sensitivity, 50%). The per-patient sensitivity and specificity were 92% and 97%, respectively. CONCLUSIONS Virtual computed tomographic colonography has a diagnostic sensitivity similar to that of conventional colonoscopy for the detection of colorectal lesions larger than 6 mm in diameter.
Collapse
Affiliation(s)
- Andrea Laghi
- Department of Radiology-II Chair, University of Rome, La Sapienza, Policlinico Umberto I, Rome, Italy.
| | | | | | | | | | | | | |
Collapse
|
119
|
Hung PW, Paik DS, Napel S, Yee J, Jeffrey RB, Steinauer-Gebauer A, Min J, Jathavedam A, Beaulieu CF. Quantification of distention in CT colonography: development and validation of three computer algorithms. Radiology 2002; 222:543-54. [PMID: 11818626 DOI: 10.1148/radiol.2222010600] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Three bowel distention-measuring algorithms for use at computed tomographic (CT) colonography were developed, validated in phantoms, and applied to a human CT colonographic data set. The three algorithms are the cross-sectional area method, the moving spheres method, and the segmental volume method. Each algorithm effectively quantified distention, but accuracy varied between methods. Clinical feasibility was demonstrated. Depending on the desired spatial resolution and accuracy, each algorithm can quantitatively depict colonic diameter in CT colonography.
Collapse
Affiliation(s)
- Peter W Hung
- Department of Radiology, Stanford University Medical Center, MC 5105, 300 Pasteur Dr, Stanford, CA 94305, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
120
|
Vining DJ. Overview of CT, MRI, and Ultrasound in the Imaging and Staging of Colorectal Cancer. COLORECTAL CANCER 2002. [DOI: 10.1007/978-1-59259-160-2_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
121
|
Abstract
In summary, technical advances in the performance of VC are occurring at a very rapid pace. These technical improvements will undoubtedly improve the polyp detection rate and reduce false-positive and false-negative examinations. The concept of VC is clearly attractive and the general public is enamored with everything that has an association with virtual reality. As other articles in this issue have revealed, there are many techniques in development to help stratify patients at risk for colon cancer. As we begin to focus our health care resources on those at highest risk, the less need there is for inexpensive, broadly based screening techniques. Clearly, those patients at high risk for having polyps are better served by colonoscopy because of its therapeutic potential. That being said, in the view of this author, if a virtual preparation can be achieved and the cost of VC can be kept relatively low, then this technique will become part of our mainstream clinical practice. If an immaculate colon preparation must be performed and if the costs reflect standard abdominal and pelvic CT rather than a special reduced cost for VC, then it is doubtful that there will be any significant impact from this technology
Collapse
Affiliation(s)
- Robert H Hawes
- Digestive Disease Center, Division of Gastroenterology and Hepatology, Medical University of South Carolina, Charleston, USA.
| |
Collapse
|
122
|
Virtual Colonoscopy for Colorectal Cancer Screening and Surveillance. COLORECTAL CANCER 2002. [DOI: 10.1007/978-1-59259-160-2_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
123
|
Affiliation(s)
- H M Fenlon
- Department of Radiology, Mater Misericordiae Hospital, Eccles Street, Dublin 7, Ireland.
| |
Collapse
|
124
|
Abstract
Screening for colorectal cancer is commanding increasing attention. Other cancer screening programmes have been a part of public consciousness for some time, but, until recently, colorectal cancer screening has remained in the background. Fuelled by new research, market opportunities and increased recognition of individual risk, screening for colorectal cancer is becoming a recommended procedure, but controversy about how best to implement widespread screening remains.
Collapse
Affiliation(s)
- Robert E Schoen
- Division of Gastroenterology, Pennsylvania University Hospital, Pittsburgh 15213-2582, USA.
| |
Collapse
|
125
|
Diagnosis and Clinical Features of Colorectal Cancer. COLORECTAL CANCER 2002. [DOI: 10.1007/978-3-642-56008-8_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
126
|
Mendelson RM, Forbes GM. Computed tomography colonography. HOSPITAL MEDICINE (LONDON, ENGLAND : 1998) 2001; 62:740-6. [PMID: 11810733 DOI: 10.12968/hosp.2001.62.12.1702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Computed tomography colonography (virtual colonoscopy) is an exciting technique that continues to evolve but promises to be a valuable tool for diagnosis of and screening for colorectal neoplasia.
Collapse
Affiliation(s)
- R M Mendelson
- Department of Radiology, Royal Perth Hospital, Perth, Western Australia 6847
| | | |
Collapse
|
127
|
Göktürk SB, Tomasi C, Acar B, Beaulieu CF, Paik DS, Jeffrey RB, Yee J, Napel S. A statistical 3-D pattern processing method for computer-aided detection of polyps in CT colonography. IEEE TRANSACTIONS ON MEDICAL IMAGING 2001; 20:1251-60. [PMID: 11811825 DOI: 10.1109/42.974920] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Adenomatous polyps in the colon are believed to be the precursor to colorectal carcinoma, the second leading cause of cancer deaths in United States. In this paper, we propose a new method for computer-aided detection of polyps in computed tomography (CT) colonography (virtual colonoscopy), a technique in which polyps are imaged along the wall of the air-inflated, cleansed colon with X-ray CT. Initial work with computer aided detection has shown high sensitivity, but at a cost of too many false positives. We present a statistical approach that uses support vector machines to distinguish the differentiating characteristics of polyps and healthy tissue, and uses this information for the classification of the new cases. One of the main contributions of the paper is the new three-dimensional pattern processing approach, called random orthogonal shape sections method, which combines the information from many random images to generate reliable signatures of shape. The input to the proposed system is a collection of volume data from candidate polyps obtained by a high-sensitivity, low-specificity system that we developed previously. The results of our ten-fold cross-validation experiments show that, on the average, the system increases the specificity from 0.19 (0.35) to 0.69 (0.74) at a sensitivity level of 1.0 (0.95).
Collapse
MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Algorithms
- Colonic Polyps/diagnostic imaging
- Colonography, Computed Tomographic/classification
- Colonography, Computed Tomographic/methods
- Colonography, Computed Tomographic/statistics & numerical data
- Diagnosis, Differential
- Female
- Humans
- Imaging, Three-Dimensional/methods
- Imaging, Three-Dimensional/statistics & numerical data
- Male
- Middle Aged
- Pattern Recognition, Automated
- ROC Curve
- Radiographic Image Interpretation, Computer-Assisted/methods
- Reproducibility of Results
- Sensitivity and Specificity
- Tomography, X-Ray Computed/methods
Collapse
Affiliation(s)
- S B Göktürk
- Department of Electrical Engineering, Stanford University, CA 94305-9010, USA.
| | | | | | | | | | | | | | | |
Collapse
|
128
|
Abstract
Virtual colonoscopy (CT colonography) promises to become a primary method for colorectal cancer screening and return radiologists to a major role in colon cancer prevention. Results from major centers in the United States show accuracy to be comparable to conventional colonoscopy for detection of polyps of significant size--that is, greater than 10 mm--with few false-positives. The advent of virtual colonoscopy has also heightened awareness of the natural history of colonic polyps, particularly in terms of identifying an appropriate target size for detection in colorectal screening programs. Small polyps (<10 mm) are often either hyperplastic on histology or are unlikely to progress to frank cancer in the patient's lifetime and are therefore of little clinical significance for the average adult. Thus, the rationale for detecting and removing each and every colonic polyp regardless of size has come under increasing scrutiny in the context of cost-benefit analysis of various test strategies for colorectal cancer screening. Virtual colonoscopy may allow patients to obtain reliable information about the status of their colonic mucosa noninvasively and thus make a more informed decision as to whether to proceed to conventional colonoscopy for polypectomy.
Collapse
Affiliation(s)
- J T Ferrucci
- Department of Radiology, Boston Medical Center, Boston University School of Medicine, 88 E. Newton St., Boston, MA 02118, USA
| |
Collapse
|
129
|
Abstract
CT colonography is an evolving noninvasive imaging technique that allows detection of colorectal polyps and cancers. When assessing the clinical results of this test, several points need to be emphasized. First, as computed tomography (CT) technology improves, so will clinical results. Therefore, earlier results reporting the accuracy of CT colonography may not be applicable to the current state of the art. Second, as clinical experience has grown, an understanding of the limitations and pitfalls of the technique has increased. A learning curve is involved and, with increased experience, results should improve. This article will focus on the evolving clinical results of CT colonography.
Collapse
Affiliation(s)
- M Macari
- Department of Radiology, Abdominal Imaging, New York University Medical Center, Tisch Hospital, New York 10016, USA.
| |
Collapse
|
130
|
Abstract
Computed tomography (CT) colonography provides both a multiplanar and endoluminal perspective of the air-filled, distended, cleansed colon, offering an alternative to traditional approaches to colorectal cancer screening. However, there are still limitations associated with CT colonography that need to be resolved, including inadequate bowel distention and poorly prepared colons that make it difficult to distinguish between stool and mucosal lesions including submerged polyps as well as flat or sessile polyps which can often be overlooked. In an effort to help distinguish the bowel wall and mural abnormalities from luminal contents, we have found the use of intravenous contrast material significantly improves both bowel wall conspicuity and reader confidence for examining the colon. In addition, we have found that the use of intravenous contrast material improves the diagnostic accuracy for the detection of medium and probably large polyps.
Collapse
Affiliation(s)
- M M Morrin
- Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
| | | |
Collapse
|
131
|
Abstract
The success of a virtual endoscopy is essentially dependent on the image quality of the corresponding 3-dimensional reconstructions. Before loading image data on a post-processing computer, certain prerequisites concerning the source data must be met. To carry out a CT colonography, the source data must be of good quality. High spatial resolution in all geometrical directions, continuous data acquisition without gaps, and artefact-free images are pivotal factors influencing source data. A generally applicable rule is that the size of the smallest detectable polyp is limited by the nominal slice thickness, emphasizing the ultimate importance of the initially chosen primary slice collimation. Furthermore, calculation of an endoluminal view is impossible without sufficient distension of the bowels. Thorough patient preparation that accommodates the technical circumstances for post-processing is also required for attaining a high sensitivity in polyp detection.
Collapse
Affiliation(s)
- P Rogalla
- Department of Radiology, Charité Hospital, Humholdt-Universität zu Berlin, Germany.
| | | |
Collapse
|
132
|
Abstract
CT colonography (virtual colonoscopy) is a safe, noninvasive method of examining the large bowel. Since its first description in 1994, the technique has undergone rapid development, stimulating considerable interest in its potential as both a diagnostic and screening tool. Diagnostic performance statistics have been encouraging, with predictive values rivaling those of barium enema and approaching those of endoscopic colonoscopy. Improvements are underway in methods of bowel preparation, scanning procedure, and image display. Increasing experience with the technique is reflected in better understanding and characterization of both two-dimensional and three-dimensional findings, resulting in improved study performance and interpretation. This review attempts to chart the development of CT colonography, with an emphasis on published results and current research interests. We propose potential directions for future study and means toward effective implementation of CT colonography in clinical practice.
Collapse
Affiliation(s)
- J F Bruzzi
- Department of Radiology, Mater Misericordiae Hospital, Eccles Street, Dublin 7, Ireland.
| | | | | |
Collapse
|
133
|
Lauenstein T, Holtmann G, Schoenfelder D, Bosk S, Ruehm SG, Debatin JF. MR colonography without colonic cleansing: a new strategy to improve patient acceptance. AJR Am J Roentgenol 2001; 177:823-7. [PMID: 11566681 DOI: 10.2214/ajr.177.4.1770823] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE MR colonography permits accurate detection of colonic polyps larger than 8 mm. Patient acceptance remains limited because of the need for bowel cleansing. The aim of this study was to develop and assess a strategy obviating colonic cleansing by performing MR colonography in conjunction with fecal tagging based on the oral administration of barium. SUBJECTS AND METHODS Six healthy volunteers and six patients with suspected colorectal tumors, undergoing conventional colonoscopy within 1 week of MR imaging, were included in this study. For fecal tagging, 200 mL of a barium-containing contrast agent was ingested with each of four principal meals preceding the examination. For MR colonography, the colon was filled with a barium and water mixture while gadobenate dimeglumine (0.2 mmol/kg) was injected IV. RESULTS The combination of fecal tagging and colonic filling with barium resulted in a homogeneously low signal throughout the colonic lumen in all 12 subjects. IV injection of gadolinium caused avid enhancement of the colonic wall. Similarly, lesions arising from the colonic wall enhanced avidly. In the six evaluated patients, MR colonography correctly identified two colonic carcinomas in two patients and one polyp in each of another two patients. CONCLUSION Fecal tagging obviates bowel cleansing and should, therefore, enhance patient acceptance for MR colonoscopy. Barium used as the tagging agent is promising because it is inexpensive, commercially available, and characterized by an excellent safety profile.
Collapse
Affiliation(s)
- T Lauenstein
- Department of Diagnostic Radiology, University Hospital Essen, Hufelandstr. 55, D-45122 Essen, Germany
| | | | | | | | | | | |
Collapse
|
134
|
Summers RM, Hara AK, Luboldt W, Johnson CD. Computed tomographic and magnetic resonance colonography: summary of progress from 1995 to 2000. Curr Probl Diagn Radiol 2001; 30:147-67. [PMID: 11550007 DOI: 10.1067/mdr.2001.115292] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- R M Summers
- Diagnostic Radiology Department, Warren Grant Magnuson Clinical Center, National Institutes of Health, Bethesda, Maryland, USA
| | | | | | | |
Collapse
|
135
|
Abstract
Magnetic resonance (MR) imaging is finding an ever-growing role in the evaluation of a wide range of conditions in the abdomen. No longer confined to problem solving regarding abnormalities in solid organs, such as the liver and kidneys, MR imaging is increasingly being applied to the evaluation of the pancreatic and biliary ductal systems and even the bowel. Recent technical advances in hardware and software have allowed the acquisition of MR images that are largely free of artifact secondary to bowel peristalsis or respiratory motion; images providing excellent anatomic detail can now be obtained routinely. Faster sequences have reduced image acquisition time, thereby improving patient acceptance and allowing more efficient utilization of machine time. New three-dimensional sequences allow rapid image acquisition, reducing section misregistration and motion artifact while improving multiplanar reformations. The potential of MR imaging to provide functional and anatomic information is intriguing, and new techniques, including diffusion and perfusion imaging, are being evaluated. This review considers the advances in imaging hardware and pulse sequence design that underlie the increasing role of MR imaging in evaluation of the abdomen and discusses evolving clinical applications.
Collapse
Affiliation(s)
- M T Keogan
- Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, One Deaconess Rd, Boston, MA 02215, USA.
| | | |
Collapse
|
136
|
Callstrom MR, Johnson CD, Fletcher JG, Reed JE, Ahlquist DA, Harmsen WS, Tait K, Wilson LA, Corcoran KE. CT colonography without cathartic preparation: feasibility study. Radiology 2001; 219:693-8. [PMID: 11376256 DOI: 10.1148/radiology.219.3.r01jn22693] [Citation(s) in RCA: 203] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE To evaluate methods for contrast material labeling of stool in the unprepared colon for computed tomographic (CT) colonography and to determine their sensitivity for polyp detection. MATERIALS AND METHODS Fifty-six patients with suspected or known polyps were assigned to five groups. Two to seven doses of 225 mL of dilute contrast material were orally administered during 24 or 48 hours. Transverse CT images were assessed for effectiveness of stool labeling. Colonoscopy was performed in all patients and was the standard. Two radiologists blinded to prior imaging and colonoscopic results assessed polyp detection. RESULTS For each group, average stool labeling scores and ranges were as follows: 24 hour two dose, 16% and 8%-21%; 24 hour five dose, 53% and 27%-66%; 48 hour four dose, 38% and 22%-48%; 48 hour six dose, 68% and 54%-77%; and 48 hour seven dose, 88% and 75%-98%. Sensitivity for the two radiologists for the identification of patients with polyps 1 cm or larger for each group was as follows: 24 hour two dose, 50% and 67%; 24 hour five dose, 100% and 100%; 48 hour four dose, 58% and 75%; 48 hour six dose, 56% and 67%; and 48 hour seven dose, 100% and 80%. CONCLUSION Ingestion of contrast material adequately labels stool for lesion identification; a 48-hour lead time and multiple doses of contrast material are required. Sensitivity for polyp detection in patients with adequate stool labeling approaches the sensitivity for polyp detection in prepared colons.
Collapse
Affiliation(s)
- M R Callstrom
- Department of Diagnostic Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
137
|
Yee J, Akerkar GA, Hung RK, Steinauer-Gebauer AM, Wall SD, McQuaid KR. Colorectal neoplasia: performance characteristics of CT colonography for detection in 300 patients. Radiology 2001; 219:685-92. [PMID: 11376255 DOI: 10.1148/radiology.219.3.r01jn40685] [Citation(s) in RCA: 307] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
PURPOSE To determine the sensitivity and specificity of computed tomographic (CT) colonography for colorectal polyp and cancer detection by using colonoscopy as the reference standard. MATERIALS AND METHODS Three hundred patients underwent CT colonography followed by standard colonoscopy. Bowel preparation consisted of magnesium citrate and polyethylene glycol. After colonic air insufflation, patients underwent scanning in the supine and prone positions with 3-mm collimation during a single breath hold. The transverse CT images, sagittal and coronal reformations, and three-dimensional endoluminal images were interpreted by two radiologists independently, and then a consensus reading was performed. CT colonographic findings were correlated with standard colonoscopic and histologic findings. RESULTS The overall sensitivity and specificity of CT colonography for polyp detection were 90.1% (164 of 182) and 72.0% (85 of 118), respectively. By using direct polyp matching, the overall sensitivity was 69.7% (365 of 524). The sensitivity was 90% (74 of 82) for the detection of polyps 10 mm or larger, 80.1% (113 of 141) for polyps 5.0-9.9 mm, and 59.1% (178 of 301) for polyps smaller than 5 mm. The sensitivity was 94% (64 of 68) for the detection of adenomas 10 mm or larger, 82% (72 of 88) for adenomas 5.0-9.9 mm, and 66.9% (95 of 142) for adenomas smaller than 5 mm. CT colonography was used to identify all eight carcinomas. CONCLUSION CT colonography has excellent sensitivity for the detection of clinically important colorectal polyps and cancer.
Collapse
Affiliation(s)
- J Yee
- Department of Radiology, Veterans Affairs Medical Center, 4150 Clement St, San Francisco, CA 94121, USA.
| | | | | | | | | | | |
Collapse
|
138
|
Hara AK, Johnson CD, MacCarty RL, Welch TJ, McCollough CH, Harmsen WS. CT colonography: single- versus multi-detector row imaging. Radiology 2001; 219:461-5. [PMID: 11323473 DOI: 10.1148/radiology.219.2.r01ma28461] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
PURPOSE To compare respiratory artifacts, colonic distention, and polyp detection at computed tomographic (CT) colonography by using single- and multi-detector row helical CT systems. MATERIALS AND METHODS A total of 237 consecutive patients received subcutaneously administered glucagon and underwent prone and supine CT colonography with single-detector row CT (n = 77) and multi-detector row CT (n = 160), followed by colonoscopy. Examination results were graded for colonic distention, respiratory artifacts, and polyp depiction by two radiologists working independently. RESULTS Suboptimal colonic distention was significantly more common with single-detector row CT and was present in at least one segment in 52% (40 of 77 patients) of examinations versus only 19% (30 of 160 patients) with multi-detector row CT (P <.001). Mild respiratory artifacts were present in 61% (47 of 77 patients) of single-detector row CT examinations versus only 16% (26 of 160 patients) of multi-detector row CT examinations (P <.001). Depiction of polyps larger than 10 mm was 89% (eight of nine polyps) for single-detector row CT and 80% (eight of 10 polyps) for multi-detector row CT (P >.05). CONCLUSION CT colonography performed with multi-detector row CT significantly improved the demonstration of colonic distention and depicted fewer respiratory artifacts compared with single-detector row CT. No significant differences in the depiction of polyps larger than 10 mm were demonstrated between single- and multi-detector row CT for a small number of polyps. Studies with a larger prevalence of clinically important polyps are needed for further evaluation of differences in polyp detection.
Collapse
Affiliation(s)
- A K Hara
- Department of Diagnostic Radiology, Mallinckrodt Institute of Radiology, 510 S Kingshighway Blvd, St Louis, MO 63110, USA.
| | | | | | | | | | | |
Collapse
|
139
|
Lomas DJ, Sood RR, Graves MJ, Miller R, Hall NR, Dixon AK. Colon carcinoma: MR imaging with CO2 enema--pilot study. Radiology 2001; 219:558-62. [PMID: 11323488 DOI: 10.1148/radiology.219.2.r01ma10558] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Prior to surgery, seven patients with known colonic tumors underwent breath-hold single-shot fast spin-echo magnetic resonance imaging during a CO2 enema. The images were evaluated for depiction of tumor, adjacent structures, and the remaining colon, and findings were compared with findings at surgery. In all seven patients, the tumor was demonstrated, and in four (57%), breach of the muscularis propria was correctly predicted.
Collapse
Affiliation(s)
- D J Lomas
- Department of Radiology, University of Cambridge and Addenbrooke's Hospital, Box 219, Hills Rd, Cambridge, CB2 2QQ, England.
| | | | | | | | | | | |
Collapse
|
140
|
Summers RM, Johnson CD, Pusanik LM, Malley JD, Youssef AM, Reed JE. Automated polyp detection at CT colonography: feasibility assessment in a human population. Radiology 2001; 219:51-9. [PMID: 11274534 DOI: 10.1148/radiology.219.1.r01ap0751] [Citation(s) in RCA: 206] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
PURPOSE To test the feasibility of and improve a computer algorithm to automatically detect colonic polyps in real human computed tomographic (CT) colonographic data sets. MATERIALS AND METHODS Twenty patients with known polyps underwent CT colonography in the supine position. CT colonographic data were processed by using a shape-based algorithm that depicts masses that protrude into the lumen. We studied nine shape criteria and three isosurface threshold settings. Results were compared with those of conventional colonoscopy performed the same day. RESULTS There were 50 polyps (28 were > or =10 mm in size; 12, 5-9 mm; 10, <5 mm). The sensitivity with optimal settings for detecting polyps 10 mm or greater was 64% (18 of 28). Sensitivity improved to 71% (10 of 14) for polyps 10 mm or greater in well-distended colonic segments. Performance decreased for polyps less than 10 mm, poorly distended colonic segments, and other shape algorithms. There was a mean of six false-positive lesion sites per colon. These sites were reduced 39% to 3.5 per colon by sampling CT attenuation at the lesion site and discarding sites having attenuation less than a threshold. CONCLUSION Automated detection of colonic polyps, especially clinically important large polyps, is feasible. Colonic distention is an important determinant of sensitivity. Further increases in sensitivity may be achieved by adding prone CT colonography.
Collapse
Affiliation(s)
- R M Summers
- Diagnostic Radiology Department, Warren Grant Magnuson Clinical Center, National Institutes of Health, Bldg 10, Rm 1C660, 10 Center Dr, MSC 1182, Bethesda, MD 20892-1182, USA
| | | | | | | | | | | |
Collapse
|
141
|
Abstract
Advances in computed tomography (CT) technology and computer capabilities have contributed to the development of a new imaging modality for colorectal lesions called CT colonography or virtual colonoscopy. Virtual colonoscopy is a rapid, minimally invasive scan of the cleansed and distended colon. Early work has demonstrated that this test is safe and well tolerated, and that it may be sensitive and specific enough to identify most significant precancerous or cancerous lesions. A number of technical and practical problems remain before virtual colonoscopy can be applied at a population level.
Collapse
Affiliation(s)
- D T Rubin
- Section of Gastroenterology, Department of Medicine, University of Chicago, 5841 South Maryland Avenue, Chicago, IL 60637-1470, USA.
| | | |
Collapse
|
142
|
Abstract
Colorectal cancer is a leading cause of cancer mortality in the industrialized world. Survival remains poor because most cases are diagnosed at an advanced stage. It is a preventable disease as colorectal cancers usually develop slowly from an identifiable precursor lesion, the adenoma. The existing strategies for colorectal cancer prevention include dietary prevention, chemoprevention and endoscopic intervention. The exact relationship between diet, particularly fibre, and colorectal cancer remains unclear, with the most recent studies suggesting that dietary fibre may not decrease colorectal cancer risk as previously thought. Non-steroidal anti-inflammatory drugs have been shown to have a protective effect against colorectal cancer, but the adverse effect profile of the non COX-2 selective drugs, particularly the risk of gastrointestinal haemorrhage, precludes their widespread use. There is increasing evidence that colorectal cancer incidence and mortality can be decreased from endoscopic polypectomy and early detection of cancer. Faecal occult blood testing in the general population ('average-risk') has been shown in randomized trials to decrease mortality from colorectal cancer by 15--33%. Long-term results of randomized trials of the effectiveness of flexible sigmoidoscopy and colonoscopy screening in the general population are awaited. Targeting high risk individuals may also be an effective and efficient way to decrease the colorectal cancer burden. As many as 15--30% of colorectal cases may be due to hereditary factors. Individuals with one or two direct relatives affected are at moderate risk for colorectal cancer (empirical lifetime mortality from colorectal cancer approximately 10%) and approximately 2--3% of cases arise in individuals harbouring highly penetrant autosomal dominant mutations, which puts them at high-risk for colorectal cancer. Surveillance colonoscopy is offered to individuals at moderate and high risk for colorectal cancer.
Collapse
Affiliation(s)
- I Dove-Edwin
- ICRF Family Cancer Clinic, St Mark's Hospital, Harrow, Middlesex, UK
| | | |
Collapse
|
143
|
Angtuaco TL, Banaad-Omiotek GD, Howden CW. Differing attitudes toward virtual and conventional colonoscopy for colorectal cancer screening: surveys among primary care physicians and potential patients. Am J Gastroenterol 2001; 96:887-93. [PMID: 11280570 DOI: 10.1111/j.1572-0241.2001.03639.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVES To investigate attitudes among primary care physicians and potential patients concerning "virtual" and conventional colonoscopy for colorectal cancer screening. METHODS We sent 1000 questionnaires to primary care physicians by electronic or postal mail and administered 400 to potential patients. Questionnaires contained progressively detailed information about the tests and asked for choices based on information presented. RESULTS One hundred eight-eight primary care physicians and 323 potential patients were included. Results indicated the following: 76.6% of potential patients and 47.3% of physicians initially preferred virtual colonoscopy because of its noninvasive nature; 23.6% of potential patients and 52.9% of physicians valued the ability of conventional colonoscopy to visualize the mucosa directly; and 67.4% of potential patients and 51.6% of physicians preferred virtual colonoscopy because it does not require sedation. Considering all information, most potential patients preferred virtual to conventional colonoscopy (60.2% vs 25.7%), whereas more physicians preferred conventional to virtual colonoscopy (44.9% vs 30.3%). Additionally, 82.3% of potential patients would comply more with recommendations for colorectal cancer screening, and 61.7% of physicians would refer more patients for screening, if virtual colonoscopy was available. CONCLUSIONS Potential patients preferred virtual to conventional colonoscopy, whereas physicians favored conventional colonoscopy. Physicians placed more importance on the ability of conventional colonoscopy to visualize the mucosa directly, the opportunity for therapy, and cost. Potential patients were more encouraged than physicians by the availability of virtual colonoscopy for improving participation in colorectal cancer screening.
Collapse
Affiliation(s)
- T L Angtuaco
- Rush-Presbyterian-St. Luke's Medical Center and Northwestern University Medical School, Chicago, Illinois, USA
| | | | | |
Collapse
|
144
|
McFarland EG, Brink JA, Pilgram TK, Heiken JP, Balfe DM, Hirselj DA, Weinstock L, Littenberg B. Spiral CT colonography: reader agreement and diagnostic performance with two- and three-dimensional image-display techniques. Radiology 2001; 218:375-83. [PMID: 11161149 DOI: 10.1148/radiology.218.2.r01ja47375] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
PURPOSE To assess the diagnostic performance and reader agreement with two-dimensional (2D) and three-dimensional (3D) display techniques for detecting colorectal polyps with spiral computed tomographic (CT) colonography. MATERIALS AND METHODS A test set of 30 colonic segments was developed from spiral CT colonographic studies (12 with polyps and 18 without). The 12 segments with polyps contained 22 lesions (11 polyps <10 mm, 11 polyps or cancers >/=10 mm), with all findings verified with colonoscopy. Three specific 2D and 3D image-display techniques were tested. Three experienced abdominal radiologists independently analyzed each test case and were retested 6 weeks later. RESULTS The results of readings 1 and 2 were similar for all image-display techniques among the readers. Pooled segment results were sensitivity of 89%-92% and specificity of 72%-83%. Pooled polyp size results for sensitivity and positive predictive value were 77%-86% and 74%-86% (all polyps, n = 22), 91%-100% and 85%-100% (polyps or cancers >10 mm, n = 11), and 61%-73% and 61%-80% (polyps 5-9 mm, n = 11), respectively. Overall intraobserver agreement was good for the three display techniques (kappa, 0.60-1.00); however, interobserver agreement for 2D multiplanar reformation was lower (kappa, 0.53-0.80). CONCLUSION Among experienced abdominal radiologists, similar diagnostic performance in polyp detection was found among 2D multiplanar reformation and 3D display techniques, although individual cases showed improved characterization with 3D display techniques. Evaluation of reader agreement demonstrated good intraobserver agreement, with variable interobserver agreement.
Collapse
Affiliation(s)
- E G McFarland
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S Kingshighway Blvd, St Louis, MO 63110, USA.
| | | | | | | | | | | | | | | |
Collapse
|
145
|
Abstract
Virtual endoscopy is a technique in which three-dimensional viewing of hollow structures is conducted through the utilization of high-resolution imaging and unique computer processing methods. The basic components of this technique and its applications for urology and other clinical disciplines are reviewed.
Collapse
Affiliation(s)
- D G Assimos
- Department of Urology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157-1094, USA.
| | | |
Collapse
|
146
|
Spinzi G, Belloni G, Martegani A, Sangiovanni A, Del Favero C, Minoli G. Computed tomographic colonography and conventional colonoscopy for colon diseases: a prospective, blinded study. Am J Gastroenterol 2001; 96:394-400. [PMID: 11232681 DOI: 10.1111/j.1572-0241.2001.03550.x] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVES Computed tomographic (CT) colonography or virtual colonoscopy is a new diagnostic method for the colon and rectum, developed on the basis of spiral computed axial tomography and employing virtual reality technology. The aim of this study was to determine the sensitivity, specificity, and diagnostic accuracy of CT colonography compared with colonoscopy in a prospective, blinded study in one single institution in Italy. METHODS Ninety-nine patients randomly selected among those attending the open-access endoscopy unit for diagnostic colonoscopy underwent colonoscopy and spiral CT. The images obtained were transmitted to generate the virtual colonoscopy pictures. A supervisor compared the results with the findings of conventional colonoscopy. RESULTS CT colonography diagnosed seven of eight tumors, one being missed because the patient had been inadequately prepared. In 28 patients, CT colonography identified 26 polyps of 45 (57.8% sensitivity, 92.6% specificity, 86.7% positive predictive value), regardless of their size. The sensitivity in detecting colonic polyps was 31.8% (7/22) in the first 25 cases and 91.6% (11/12) in the last 20 patients. CT colonography missed one flat adenoma, some angioectasias and colonic lesions because of portal hypertension in one patient, Crohn's disease ulcers in two patients, and ulcerative colitis lesions in three. CONCLUSIONS CT colonography shows poor sensitivity for identifying colonic polyps and does not always detect neoplastic lesions. Flat lesions are impossible to see by this method.
Collapse
Affiliation(s)
- G Spinzi
- Department of Internal Medicine, H. Valduce-Como, Italy
| | | | | | | | | | | |
Collapse
|
147
|
Heiken JP. Colon cancer screening. Cancer Imaging 2001. [PMCID: PMC4448630 DOI: 10.1102/1470-7330.2001.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/06/2022] Open
Affiliation(s)
- Jay P. Heiken
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Missouri USA
| |
Collapse
|
148
|
Macari M, Lavelle M, Pedrosa I, Milano A, Dicker M, Megibow AJ, Xue X. Effect of different bowel preparations on residual fluid at CT colonography. Radiology 2001; 218:274-7. [PMID: 11152814 DOI: 10.1148/radiology.218.1.r01ja31274] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The effect of different bowel preparations on residual fluid during computed tomographic (CT) colonography was evaluated. Forty-two patients received either a polyethylene glycol electrolyte solution preparation or a phospho-soda preparation the day prior to CT colonography. The amount of residual fluid was calculated for each patient. On average, a phospho-soda preparation provided significantly less residual fluid than a polyethylene glycol electrolyte solution preparation.
Collapse
Affiliation(s)
- M Macari
- Department of Radiology, Division of Abdominal Imaging, New York University Medical Center, Tisch Hospital, New York, NY 10016, USA.
| | | | | | | | | | | | | |
Collapse
|
149
|
Song JH, Francis IR, Platt JF, Cohan RH, Mohsin J, Kielb SJ, Korobkin M, Montie JE. Bladder tumor detection at virtual cystoscopy. Radiology 2001; 218:95-100. [PMID: 11152786 DOI: 10.1148/radiology.218.1.r01ja4995] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
PURPOSE To investigate the utility of computed tomographic (CT) virtual cystoscopy in the detection of bladder tumors. MATERIALS AND METHODS Twenty-six patients suspected or known to have bladder neoplasms underwent CT virtual and conventional cystoscopy. The bladder was insufflated with carbon dioxide through a Foley catheter. Helical CT of the bladder was then performed. The data were downloaded to a workstation for interactive intraluminal navigation. Two radiologists blinded to the results of conventional cystoscopy independently reviewed the transverse and virtual images, with consensus readings for cases with discrepant results. RESULTS Thirty-six (90%) of 40 bladder lesions proved at conventional cystoscopy were detected with a combination of transverse and virtual images. Four (10%) of 40 bladder lesions, all smaller than 5 mm, were undetected. Transverse and virtual images were complementary, since six polypoid lesions smaller than 5 mm depicted on the virtual images were not seen on the transverse images. In contrast, areas of wall thickening were more readily appreciated on transverse images. CT with patients in both supine and prone positions was necessary, since seven (19%) and five (14%) of 36 lesions were seen only on supine and prone images, respectively. CONCLUSION CT virtual cystoscopy is a promising technique for use in bladder tumor detection of lesions larger than 5 mm. Optimal evaluation requires adequate bladder distention with the patient in both supine and prone positions and interpretation of both transverse and virtual images.
Collapse
Affiliation(s)
- J H Song
- Dept. of Radiology, University of Michigan Hospital, UH B2B311D/0030, 1500 E Medical Center Dr, Ann Arbor, MI 48109-0030, USA.
| | | | | | | | | | | | | | | |
Collapse
|
150
|
Morrin MM, Hochman MG, Farrell RJ, Marquesuzaa H, Rosenberg S, Edelman RR. MR colonography using colonic distention with air as the contrast material: work in progress. AJR Am J Roentgenol 2001; 176:144-6. [PMID: 11133554 DOI: 10.2214/ajr.176.1.1760144] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- M M Morrin
- Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave., Boston MA 02215, USA
| | | | | | | | | | | |
Collapse
|