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| 2. |
- Asplund, Sara, 1976, et al.
(författare)
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Extended analysis of the effect of learning with feedback on the detectability of pulmonary nodules in chest tomosynthesis
- 2011
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. ; 7966
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In chest tomosynthesis, low-dose projections collected over a limited angular range are used for reconstruction of section images of the chest, resulting in a reduction of disturbing anatomy at a moderate increase in radiation dose compared to chest radiography. In a previous study, we investigated the effects of learning with feedback on the detection of pulmonary nodules in chest tomosynthesis. Six observers with varying degrees of experience of chest tomosynthesis analyzed tomosynthesis cases for presence of pulmonary nodules. The cases were analyzed before and after learning with feedback. Multidetector computed tomography (MDCT) was used as reference. The differences in performance between the two readings were calculated using the jackknife alternative free-response receiver operating characteristics (JAFROC-2) as primary measure of detectability. Significant differences between the readings were found only for observers inexperienced in chest tomosynthesis. The purpose of the present study was to extend the statistical analysis of the results of the previous study, including JAFROC-1 analysis and FROC curves in the analysis. The results are consistent with the results of the previous study and, furthermore, JAFROC-1 gave lower p-values than JAFROC-2 for the observers who improved their performance after learning with feedback. © 2011 SPIE.
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| 4. |
- Asplund, Sara, 1976, et al.
(författare)
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Learning aspects and potential pitfalls regarding detection of pulmonary nodules in chest tomosynthesis and proposed related quality criteria.
- 2011
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Ingår i: Acta radiologica. - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 52:5, s. 503-512
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Tidskriftsartikel (refereegranskat)abstract
- Background In chest tomosynthesis, low-dose projections collected over a limited angular range are used for reconstruction of an arbitrary number of section images of the chest, resulting in a moderately increased radiation dose compared to chest radiography. Purpose To investigate the effects of learning with feedback on the detection of pulmonary nodules for observers with varying experience of chest tomosynthesis, to identify pitfalls regarding detection of pulmonary nodules, and present suggestions for how to avoid them, and to adapt the European quality criteria for chest radiography and computed tomography (CT) to chest tomosynthesis. Material and Methods Six observers analyzed tomosynthesis cases for presence of nodules in a jackknife alternative free-response receiver-operating characteristics (JAFROC) study. CT was used as reference. The same tomosynthesis cases were analyzed before and after learning with feedback, which included a collective learning session. The difference in performance between the two readings was calculated using the JAFROC figure of merit as principal measure of detectability. Results Significant improvement in performance after learning with feedback was found only for observers inexperienced in tomosynthesis. At the collective learning session, localization of pleural and subpleural nodules or structures was identified as the main difficulty in analyzing tomosynthesis images. Conclusion The results indicate that inexperienced observers can reach a high level of performance regarding nodule detection in tomosynthesis after learning with feedback and that the main problem with chest tomosynthesis is related to the limited depth resolution.
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| 6. |
- Fisichella, Valeria A, 1974, et al.
(författare)
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Computer-aided detection (CAD) as a second reader using perspective filet view at CT colonography: effect on performance of inexperienced readers.
- 2009
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Ingår i: Clinical Radiology. - : Elsevier BV. - 1365-229X .- 0009-9260. ; 64:10, s. 972-82
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Tidskriftsartikel (refereegranskat)abstract
- AIM: To evaluate whether computer-aided detection (CAD) as a second reader using perspective filet view [three-dimensional (3D) filet] improves the performance of inexperienced readers at computed tomography colonography (CTC) compared with unassisted 3D filet and unassisted two-dimensional (2D) CTC. MATERIAL AND METHODS: Fifty symptomatic patients underwent CTC and same-day colonoscopy with segmental unblinding. Two inexperienced readers read the CTC studies on 3D filet and 2D several weeks apart. Four months later, readers re-read the cases only evaluating CAD marks using 3D filet. Suspicious CAD marks not previously described on 3D filet were recorded. Jackknife free-response receiver operating characteristic (JAFROC-1) analysis was used to compare the observers' performances in detecting lesions with 3D filet, 2D and 3D filet with CAD. RESULTS: One hundred and three lesions > or =3mm were detected at colonoscopy with segmental unblinding. CAD alone had a sensitivity of 73% (75/103) at a mean false-positive rate per patient of 12.8 in supine and 11.4 in prone. For inexperienced readers sensitivities with 3D filet with CAD were 58% (60/103) and 48% (50/103) with an improvement of 14-16 percentage points (p<0.05) compared with 2D and of 10-11 percentage points (p<0.05) compared with 3D filet. For inexperienced readers, the false-positive rate was 25-41% and 71-200% higher with 3D filet with CAD compared with 3D filet and 2D, respectively. JAFROC-1 analysis showed no significant differences in per-lesion overall performance among reading modes (p=0.8). CONCLUSION: CAD applied as a second reader using 3D filet increased both sensitivity and the number of false positives by inexperienced readers compared with 3D filet and 2D, thus not improving overall performance, i.e., the ability to distinguish between lesions and non-lesions.
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| 7. |
- Fisichella, Valeria A, 1974, et al.
(författare)
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Evaluation of image quality and lesion perception by human readers on 3D CT colonography: comparison of standard and low radiation dose
- 2010
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Ingår i: European Radiology. - 1432-1084. ; 20:3, s. 630-9
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: We compared the prevalence of noise-related artefacts and lesion perception on three-dimensional (3D) CT colonography (CTC) at standard and low radiation doses. METHODS: Forty-eight patients underwent CTC (64 x 0.625 mm collimation; tube rotation time 0.5 s; automatic tube current modulation: standard dose 40-160 mA, low dose 10-50 mA). Low- and standard-dose acquisitions were performed in the supine position, one after the other. The presence of artefacts (cobblestone and snow artefacts, irregularly delineated folds) and the presence of polyps were evaluated by five radiologists on 3D images at standard dose, the original low dose and a modified low dose, i.e. after manipulation of opacity on 3D. RESULTS: The mean effective dose was 3.9 +/- 1.3 mSv at standard dose and 1.03 +/- 0.4 mSv at low dose. The number of images showing cobblestone artefacts and irregularly delineated folds at original and modified low doses was significantly higher than at standard dose (P < 0.0001). Most of the artefacts on modified low-dose images were mild. No significant difference in sensitivity between the dose levels was found for polyps >/=6 mm. CONCLUSIONS: Reduction of the effective dose to 1 mSv significantly affects image quality on 3D CTC, but the perception of >/=6 mm lesions is not significantly impaired.
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| 8. |
- Johnsson, Åse (Allansdotter), 1966, et al.
(författare)
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Nodule detection by chest tomosynthesis
- 2009
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Ingår i: 2nd World Congress of Thoracic Imaging and Diagnosis in Chest Disease, 30 May-2 June 2009, Valencia, Spain.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 9. |
- Johnsson, Åse (Allansdotter), 1966, et al.
(författare)
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Pulmonary nodule size evaluation with chest tomosynthesis.
- 2012
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Ingår i: Radiology. - : Radiological Society of North America (RSNA). - 1527-1315 .- 0033-8419. ; 265:1, s. 273-82
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To evaluate intra- and interobserver variability, as well as agreement for nodule size measurements on chest tomosynthesis and computed tomographic (CT) images. Materials and Methods: The Regional Ethical Review Board approved this study, and all participants gave written informed consent. Thirty-six segmented nodules in 20 patients were included in the study. Eight observers measured the left-to-right, inferior-to-superior, and longest nodule diameters on chest tomosynthesis and CT images. Intra- and interobserver repeatability, as well as agreement between measurements on chest tomosynthesis and CT images, were assessed as recommended by Bland and Altman. Results: The difference between the mean manual and the segmented diameter was -2.2 and -2.3 mm for left-to-right and -2.6 and -2.2 mm for the inferior-to-superior diameter for measurements on chest tomosynthesis and CT images, respectively. Intraobserver 95% limits of agreement (LOA) for the longest diameter ranged from a lower limit of -1.1 mm and an upper limit of 1.0 mm to -1.8 and 1.8 mm for chest tomosynthesis and from -0.6 and 0.9 mm to -3.1 and 2.2 mm for axial CT. Interobserver 95% LOA ranged from -1.3 and 1.5 mm to -2.0 and 2.1 mm for chest tomosynthesis and from -1.8 and 1.1 mm to -2.2 and 3.1 mm for axial CT. The 95% LOA concerning the mean of the observers' measurements of the longest diameter at chest tomosynthesis and axial CT were ±2.1 mm (mean measurement error, 0 mm). For the different observers, the 95% LOA between the modalities ranged from -2.2 and 1.6 mm to -3.2 and 2.8 mm. Conclusion: Measurements on chest tomosynthesis and CT images are comparable, because there is no evident bias between the modalities and the repeatability is similar. The LOA between measurements for the two modalities raise concern if measurements from chest tomosynthesis and CT were to be used interchangeably. © RSNA, 2012 Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12111459/-/DC1.
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| 10. |
- Svalkvist, Angelica, et al.
(författare)
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Evaluation of an improved method of simulating lung nodules in chest tomosynthesis
- 2012
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 53:8, s. 874-884
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Tidskriftsartikel (refereegranskat)abstract
- Background: Simulated pathology is a valuable complement to clinical images in studies aiming at evaluating an imaging technique. In order for a study using simulated pathology to be valid, it is important that the simulated pathology in a realistic way reflect the characteristics of real pathology. Purpose: To perform a thorough evaluation of a nodule simulation method for chest tomosynthesis, comparing the detection rate and appearance of the artificial nodules with those of real nodules in an observer performance experiment. Material and Methods: A cohort consisting of 64 patients, 38 patients with a total of 129 identified pulmonary nodules and 26 patients without identified pulmonary nodules, was used in the study. Simulated nodules, matching the real clinically found pulmonary nodules by size, attenuation, and location, were created and randomly inserted into the tomosynthesis section images of the patients. Three thoracic radiologists and one radiology resident reviewed the images in an observer performance study divided into two parts. The first part included nodule detection and the second part included rating of the visual appearance of the nodules. The results were evaluated using a modified receiver-operating characteristic (ROC) analysis. Results: The sensitivities for real and simulated nodules were comparable, as the area under the modified ROC curve (AUC) was close to 0.5 for all observers (range, 0.43-0.55). Even though the ratings of visual appearance for real and simulated nodules overlapped considerably, the statistical analysis revealed that the observers to were able to separate simulated nodules from real nodules (AUC values range 0.70-0.74). Conclusion: The simulation method can be used to create artificial lung nodules that have similar detectability as real nodules in chest tomosynthesis, although experienced thoracic radiologists may be able to distinguish them from real nodules.
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| 11. |
- Fisichella, Valeria A, 1974, et al.
(författare)
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Availability, indications, and technical performance of computed tomographic colonography: a national survey
- 2006
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Ingår i: Acta Radiol. - : SAGE Publications. - 0284-1851. ; 47:3, s. 231-7
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To determine the availability, indications, and technique of computed tomographic colonography (CTC) in Sweden and to investigate opinions on its future role in colon imaging. MATERIAL AND METHODS: In May 2004, a questionnaire on CTC was mailed to all Departments of Radiology in Sweden, and one year later a telephone interview was conducted with the departments that intended to start a CTC service. RESULTS: Ninety-nine departments (83%) answered the questionnaire, indicating that 23/ 99 (23.2%) offered a CTC service. Reasons for non-implementation of CTC were lack of CTC training in 34/73 (46.6%) and non-availability of multi-detector row CT scanners in 33/73 (45.2%), while 26% were awaiting further scientific documentation on CTC. Incomplete colonoscopy was the main indication for CTC in 21/23 (91.3%) departments performing CTC. Dual positioning, room air insufflation, and thin-slice collimation were used in all the responding departments. The number of CTC studies performed varied from 1-5 (26.1%) to more than 200 (17.4%). Intravenous contrast material was routinely administered by 9/23 (39.1%) departments. Out of 30 (39.5%) departments that in 2004 intended to start CTC, 9 (30%) had done so by June 2005. A total of 32/99 (32.3%) departments had therefore started CTC by June 2005. Half of the departments that replied believed that CTC would absolutely or probably replace barium enema in the future. CONCLUSION: The survey shows relatively limited diffusion of CTC practice in Sweden, with approximately one-third of radiology departments offering a CTC service, mostly on a small scale. A wider dissemination of CTC requires further scientific documentation of its capability, intensified educational efforts, and additional funding.
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| 12. |
- Fisichella, Valeria A, 1974
(författare)
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CT Colonography: implementation and technical developments
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Computed tomographic colonography (CTC) is a minimally invasive imaging method for the detection of colorectal neoplasms. Uncertainty about its diagnostic performance, optimal visualization method, long learning curve and radiation exposure are among problems with CTC, affecting its implementation in routine health care. Potential means of improvements include novel three-dimensional (3D) CTC displays, such as “Perspective-filet view” (3D Filet), and computer-aided detection (CAD). Increasing awareness of radiation doses in CT promotes low-dose techniques, the effects of which on the prevalence of noise-related artefacts and lesion perception on 3D images are unknown. Aims: I. To determine the availability and technical performance of CTC in Sweden. II. To compare lesion detection by inexperienced CTC readers using primary 3D Filet analysis versus primary 2D analysis and to evaluate the effect of combined 3D Filet+2D analysis. III. To investigate whether CAD applied to 3D Filet improves the inexperienced reader´s performance compared to CAD-unassisted 3D Filet and 2D. IV.To compare the prevalence of noise-related artefacts and lesion perception on 3D Filet at standard and low radiation doses. Methods: I. Questionnaires on CTC implementation and technical performance were sent to all radiology departments in Sweden in 2005 and in 2009. II. Fifty symptomatic patients were prospectively enrolled and examined with CTC followed by same-day colonoscopy with segmental unblinding. An experienced reader prospectively performed 3D Filet analysis, followed by complete 2D analysis (3D Filet+2D). Two inexperienced readers, blinded to CTC and colonoscopy findings, performed 3D Filet analysis and, after 5 weeks, 2D analysis. True positives ≥6 mm detected by the inexperienced readers with 3D Filet and/or 2D were combined to obtain 3D Filet+2D. III. Four months later, the inexperienced readers re-read the cases only evaluating CAD marks on 3D Filet. IV. Forty-eight patients underwent CTC at standard and at low radiation dose. Noise-related artefacts and perception of polyps on 3D Filet images were evaluated at standard dose, original low dose and modified low dose, i.e. after manipulation of opacity on 3D images. Results: I. In 2009, CTC is performed in 42% of the radiology departments, i.e. 18 additional departments compared to 2005. Attitudes of radiologists are increasingly in favour of CTC. II. For the inexperienced readers, there was no significant difference between 3D Filet and 2D analysis regarding sensitivity and reading time. III. CAD applied as second reader on 3D Filet increased the sensitivity by inexperienced readers, but also the number of false positives, compared to CAD-unassisted 3D Filet and 2D, thus not improving overall performance, i.e. the ability to distinguish between lesions and non-lesions. IV. The mean effective dose was 3.9±1.3 mSv at standard dose and 1.03±0.4 mSv at low dose. Image quality was significantly affected on 3D Filet at low dose compared with standard dose. Reduction of the effective radiation dose to 1 mSv did not significantly impair the perception of lesions ≥6 mm. Conclusions: CTC is increasingly available in Sweden as an alternative to barium enema and complement to colonoscopy. Lesion detection by inexperienced readers does not seem to be influenced by the choice of the display method. It can be improved by the use of CAD. At low-dose CTC corresponding to 1 mSv effective dose, image quality is worsened, but detection of clinically important lesions is not significantly affected.
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| 13. |
- Fisichella, Valeria A, 1974, et al.
(författare)
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Primary three-dimensional analysis with perspective-filet view versus primary two-dimensional analysis: evaluation of lesion detection by inexperienced readers at computed tomographic colonography in symptomatic patients
- 2009
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 50:3, s. 244-55
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Tidskriftsartikel (refereegranskat)abstract
- Background: “Perspective-filet view” is a novel three-dimensional (3D) viewing technique for computed tomography colonography (CTC). Studies with experienced readers have shown a sensitivity for perspective-filet view similar to that of 2D or 3D endoluminal fly-through in detection of colorectal lesions. It is not known whether perspective-filet view, compared to axial images, improves lesion detection by inexperienced readers. Purpose: To compare primary 3D analysis using perspective-filet view (3D Filet) with primary 2D analysis, as used by inexperienced CTC readers. Secondary aims were to compare lesion detection by 3D Filet when used by experienced and inexperienced readers, and to evaluate the effect of combined 3D Filet + 2D analysis. Material and Methods: Fifty symptomatic patients were prospectively enrolled. An experienced reader performed 3D Filet analysis followed by complete 2D analysis (3D Filet + 2D), before colonoscopy with segmental unblinding. Two inexperienced readers (readers 2 and 3), blinded to CTC and colonoscopy findings, retrospectively performed 3D Filet analysis and, after 5 weeks, 2D analysis. True positives ≥6 mm detected by the inexperienced readers with 3D Filet and/or 2D were combined to obtain 3D Filet + 2D. Results: Colonoscopy revealed 116 lesions: 16 lesions ≥10 mm, 19 lesions 6–9 mm, and 81 lesions ≤5 mm. For the experienced reader, sensitivities for lesions ≥6 mm with 3D Filet and 3D Filet + 2D were 77% and 83%, respectively. For the inexperienced readers, sensitivities for lesions ≥6 mm with 3D Filet and 2D were 51% and 57% (reader 2) and 40% and 43% (reader 3), respectively. There was no significant difference between 3D Filet and 2D regarding sensitivity and reading time. For lesions ≥6 mm, 3D Filet + 2D improved the sensitivity of reader 2 to 63% and of reader 3 to 51%. Conclusion: Lesion detection by inexperienced readers using perspective-filet view is comparable to that obtained by 2D. Lesion detection improves by combining 3D Filet + 2D, but not to the level of an experienced reader.
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| 14. |
- Fisichella, Valeria A, 1974, et al.
(författare)
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Survey update on implementation, indications, and technical performance of computed tomography colonography in Sweden
- 2010
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Ingår i: Acta Radiologica. - 0284-1851. ; 51:1, s. 4-8
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Computed tomographic colonography (CTC) has gained increased acceptance in the last few years as a valid substitute for double-contrast barium enema (DCBE). However, implementation of new technologies is complex, since several factors may influence the process. PURPOSE: To evaluate the current situation in Sweden concerning implementation of CTC, as compared to a previous national survey in 2005. MATERIAL AND METHODS: In December 2008, a structured, self-assessed questionnaire regarding implementation and technical performance of CTC was mailed to all radiology departments in Sweden. In March 2009, departments who had not replied were contacted by e-mail or by telephone. All (100%, 119/119) departments answered the questionnaire. RESULTS: CTC is currently performed in 50/119 (42%) departments, i.e., 18 additional departments compared to 2005. Twenty-three out of 60 (38%) responding departments stated that they intend to start to perform CTC in the near future. DCBE is currently performed in 77/119 (65%) departments, 12 departments less compared to 2005. The most common reasons for non-implementation of CTC are non-availability of spiral CT scanner (41%, 26/64) and/or multidetector-row CT scanner (39%, 25/64), and lack of doctors' time (34%, 22/64). Only 3% (2/64) of departments are "awaiting further scientific documentation" on CTC, a significant reduction compared to 2005 (P=0.002). Until 2009, 59% (29/49) of CTC centers had performed more than 200 CTCs compared to 13% (4/32) of CTC centers in 2005. Intravenous contrast material is routinely administered in 86% (42/49), and carbon dioxide is used to distend the colon in 90% (44/49). Almost all radiology departments (93%, 93/100) currently believe that CTC will "absolutely" or "probably" replace barium enema in the future, while in 2005 only 56% (55/99) gave similar answers. CONCLUSION: The survey reflects a further transition process from DCBE to CTC, with attitudes of radiologists increasingly in favor of CTC, although DCBE is still performed by the majority of radiology departments. DCBE should be replaced by colonoscopy and CTC, but the transition requires both human and economic resources.
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