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Chang KJ, Caovan DB, Grand DJ, Huda W, Mayo-Smith WW. Reducing radiation dose at CT colonography: decreasing tube voltage to 100 kVp. Radiology 2012; 266:791-800. [PMID: 23264348 DOI: 10.1148/radiol.12120134] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To assess the effect of a decrease in tube voltage from 120 kVp to 100 kVp on dose, contrast-to-noise ratio (CNR), and three-dimensional (3D) image quality in patients undergoing computed tomographic (CT) colonography as well as to determine how these changes are affected by patient size. MATERIALS AND METHODS This HIPAA-compliant and institutional review board-approved retrospective study included 63 consecutive patients who underwent CT colonography and who waived informed consent. Scanning was performed with patients in the supine (120 kVp) and prone (100 kVp) positions, with other parameters unchanged. Volume CT dose index (CTDI(vol)), dose-length product (DLP), image noise, attenuation of selected materials, and CNR were compared with the Wilcoxon matched-pairs signed rank test. Two readers blinded to tube voltage independently assessed 3D endoluminal image quality. The k coefficients were calculated for interobserver agreement. Average image quality ratings were compared with the Wilcoxon signed rank test. All recorded data were stratified by patient anteroposterior diameter to determine effects of patient size. RESULTS Decreasing tube voltage from 120 to 100 kVp resulted in a 20% decrease in CTDI(vol) (P < .001) and a 16% decrease in DLP (P < .001). Image noise increased by 32% (P < .001). Mean attenuation of tagged fluid increased from 395 to 487 HU (P < .001). There was no change in mean CNR of tagged fluid (17.1 at 120 kVp, 16.8 at 100 kVp; P = .37), regardless of patient size. The 3D image quality decreased slightly from a median score of 5 out of 5 to 4 out of 5 (P < .001). There was substantial interobserver agreement. CONCLUSION A decrease in tube voltage from 120 to 100 kVp results in a significant decrease in radiation dose but only a minimal decrease in 3D image quality at all patient sizes. © RSNA, 2012.
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Affiliation(s)
- Kevin J Chang
- Department of Diagnostic Imaging, Warren Alpert Medical School of Brown University, Rhode Island Hospital, 593 Eddy St, Providence, RI 02903, USA.
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Pickhardt PJ, Lubner MG, Kim DH, Tang J, Ruma JA, del Rio AM, Chen GH. Abdominal CT with model-based iterative reconstruction (MBIR): initial results of a prospective trial comparing ultralow-dose with standard-dose imaging. AJR Am J Roentgenol 2012; 199:1266-74. [PMID: 23169718 PMCID: PMC3689212 DOI: 10.2214/ajr.12.9382] [Citation(s) in RCA: 242] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVE The purpose of this study was to report preliminary results of an ongoing prospective trial of ultralow-dose abdominal MDCT. SUBJECTS AND METHODS Imaging with standard-dose contrast-enhanced (n = 21) and unenhanced (n = 24) clinical abdominal MDCT protocols was immediately followed by ultralow-dose imaging of a matched series of 45 consecutively registered adults (mean age, 57.9 years; mean body mass index, 28.5). The ultralow-dose images were reconstructed with filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and model-based iterative reconstruction (MBIR). Standard-dose series were reconstructed with FBP (reference standard). Image noise was measured at multiple predefined sites. Two blinded abdominal radiologists interpreted randomly presented ultralow-dose images for multilevel subjective image quality (5-point scale) and depiction of organ-based focal lesions. RESULTS Mean dose reduction relative to the standard series was 74% (median, 78%; range, 57-88%; mean effective dose, 1.90 mSv). Mean multiorgan image noise for low-dose MBIR was 14.7 ± 2.6 HU, significantly lower than standard-dose FBP (28.9 ± 9.9 HU), low-dose FBP (59.2 ± 23.3 HU), and ASIR (45.6 ± 14.1 HU) (p < 0.001). The mean subjective image quality score for low-dose MBIR (3.0 ± 0.5) was significantly higher than for low-dose FBP (1.6 ± 0.7) and ASIR (1.8 ± 0.7) (p < 0.001). Readers identified 213 focal noncalcific lesions with standard-dose FBP. Pooled lesion detection was higher for low-dose MBIR (79.3% [169/213]) compared with low-dose FBP (66.2% [141/213]) and ASIR (62.0% [132/213]) (p < 0.05). CONCLUSION MBIR shows great potential for substantially reducing radiation doses at routine abdominal CT. Both FBP and ASIR are limited in this regard owing to reduced image quality and diagnostic capability. Further investigation is needed to determine the optimal dose level for MBIR that maintains adequate diagnostic performance. In general, objective and subjective image quality measurements do not necessarily correlate with diagnostic performance at ultralow-dose CT.
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Affiliation(s)
- Perry J Pickhardt
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, E3/311 Clinical Science Center, 600 Highland Ave, Madison, WI 53792-3252, USA.
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Cost-effectiveness of computed tomography colonography in colorectal cancer screening: a systematic review. Int J Technol Assess Health Care 2012; 28:415-23. [PMID: 23006522 DOI: 10.1017/s0266462312000542] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVES The European Code Against Cancer recommends individuals aged ≥ 50 should participate in colorectal cancer screening. CT-colonography (CTC) is one of several screening tests available. We systematically reviewed evidence on, and identified key factors influencing, cost-effectiveness of CTC screening. METHODS PubMed, Medline, and the Cochrane library were searched for cost-effectiveness or cost-utility analyses of CTC-based screening, published in English, January 1999 to July 2010. Data was abstracted on setting, model type and horizon, screening scenario(s), comparator(s), participants, uptake, CTC performance and cost, effectiveness, ICERs, and whether extra-colonic findings and medical complications were considered. RESULTS Sixteen studies were identified from the United States (n = 11), Canada (n = 2), and France, Italy, and the United Kingdom (1 each). Markov state-transition (n = 14) or microsimulation (n = 2) models were used. Eleven considered direct medical costs only; five included indirect costs. Fourteen compared CTC with no screening; fourteen compared CTC with colonoscopy-based screening; fewer compared CTC with sigmoidoscopy (8) or fecal tests (4). Outcomes assessed were life-years gained/saved (13), QALYs (2), or both (1). Three considered extra-colonic findings; seven considered complications. CTC appeared cost-effective versus no screening and, in general, flexible sigmoidoscopy and fecal occult blood testing. Results were mixed comparing CTC to colonoscopy. Parameters most influencing cost-effectiveness included: CTC costs, screening uptake, threshold for polyp referral, and extra-colonic findings. CONCLUSION Evidence on cost-effectiveness of CTC screening is heterogeneous, due largely to between-study differences in comparators and parameter values. Future studies should: compare CTC with currently favored tests, especially fecal immunochemical tests; consider extra-colonic findings; and conduct comprehensive sensitivity analyses.
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Patel SS, Floyd A, Doorly MG, Ortega AE, Ault GT, Kaiser AM, Senagore AJ. Current controversies in the management of colon cancer. Curr Probl Surg 2012; 49:398-460. [PMID: 22682507 DOI: 10.1067/j.cpsurg.2012.03.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Lee BI, Hong SP, Kim SE, Kim SH, Kim HS, Hong SN, Yang DH, Shin SJ, Lee SH, Kim YH, Park DI, Kim HJ, Yang SK, Kim HJ, Jeon HJ. [Korean guidelines for colorectal cancer screening and polyp detection]. THE KOREAN JOURNAL OF GASTROENTEROLOGY 2012; 59:65-84. [PMID: 22387833 DOI: 10.4166/kjg.2012.59.2.65] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Colorectal cancer is the second most common cancer in males and the fourth most common in females in Korea. Since the most of colorectal cancer occur through the prolonged transformation of adenomas into carcinomas, early detection and removal of colorectal adenomas are one of the most effective methods to prevent colorectal cancer. Considering the increasing incidence of colorectal cancer and polyps in Korea, it is very important to establish Korean guideline for colorectal cancer screening and polyp detection. Korean Multi-Society Take Force developed the guidelines with evidence-based methods. Parts of the statements drawn by systematic reviews and meta-analyses. Herein we discussed the epidemiology of colorectal cancers and adenomas in Korea, optimal screening methods for colorectal cancer, and detection for adenomas including fecal occult blood tests, radiologic tests, and endoscopic examinations.
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Affiliation(s)
- Bo In Lee
- Department of Internal Medicine, The Catholic University of Korea College of Medicine, Seoul, Korea
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Cipriano LE, Levesque BG, Zaric GS, Loftus EV, Sandborn WJ. Cost-effectiveness of imaging strategies to reduce radiation-induced cancer risk in Crohn's disease. Inflamm Bowel Dis 2012; 18:1240-8. [PMID: 21928375 DOI: 10.1002/ibd.21862] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Accepted: 07/20/2011] [Indexed: 01/14/2023]
Abstract
BACKGROUND The aim was to examine the cost-effectiveness of magnetic resonance enterography (MRE) compared with computed tomography enterography (CTE) for routine imaging of small bowel Crohn's disease (CD) patients to reduce patients' life-time radiation-induced cancer risk. METHODS We developed a Markov model to compare the lifetime costs, benefits (measured in quality-adjusted life-years [QALYs] of survival and cancers averted) and cost-effectiveness of using MRE rather than CTE for routine disease monitoring in hypothetical cohorts of 100,000 20-year-old patients with CD. We assumed each CT radiation exposure conferred an incremental annual risk of developing cancer using the linear, no-threshold model. RESULTS In the base case of 16 mSv per CTE, we estimated that radiation from CTE resulted in 1,206 to 20,146 additional cancers depending on the frequency of patient monitoring. Compared to using CTE only, using MRE until age 30 and CTE thereafter resulted in incremental cost-effectiveness ratios (ICERs) between $37,538 and $41,031 per life-year (LY) gained and between $52,969 and $57,772 per quality-adjusted life-year (QALY) gained. Using MRE until age 50 resulted in ICERs between $58,022 and $62,648 per LY gained and between $84,250 and $90,982 per QALY gained. In a threshold analysis, any use of MRE had an ICER of greater than $100,000 per QALY gained when CT radiation doses are less than 6.0 mSv per CTE exam. CONCLUSIONS MRE is likely cost-effective compared to CTE in patients younger than age 50. Low-dose CTE may be an alternative cost-effective choice in the future.
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Affiliation(s)
- Lauren E Cipriano
- Department of Management Science and Engineering, Stanford University, Stanford, California, USA
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Pendsé DA, Taylor SA. Complications of CT colonography: a review. Eur J Radiol 2012; 82:1159-65. [PMID: 22595505 DOI: 10.1016/j.ejrad.2012.04.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 04/04/2012] [Indexed: 12/23/2022]
Abstract
Since its inception, one of the main advantages of computed tomography colonography (CTC) over colonoscopy has been its assumed superior safety profile. However CTC is not without complication and adverse events are well described. Although the risks of insufflation, bowel preparation, contrast media and radiation dose are very small, they are not insignificant. This review discusses the potential hazards and complications associated with the technique, and discuss precautions, which may lessen the risk of occurrence.
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Affiliation(s)
- D A Pendsé
- Department of Imaging, University College London Hospitals NHS Foundation Trust, London, UK.
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Lee BI, Hong SP, Kim SE, Kim SH, Kim HS, Hong SN, Yang DH, Shin SJ, Lee SH, Park DI, Kim YH, Kim HJ, Yang SK, Kim HJ, Jeon HJ. Korean guidelines for colorectal cancer screening and polyp detection. Clin Endosc 2012; 45:25-43. [PMID: 22741131 PMCID: PMC3363119 DOI: 10.5946/ce.2012.45.1.25] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2011] [Revised: 01/17/2012] [Accepted: 01/17/2012] [Indexed: 12/15/2022] Open
Abstract
Now colorectal cancer is the second most common cancer in males and the fourth most common cancer in females in Korea. Since most of colorectal cancers occur after the prolonged transformation of adenomas into carcinomas, early detection and removal of colorectal adenomas are one of the most effective methods to prevent colorectal cancer. Considering the increasing incidence of colorectal cancer and polyps in Korea, it is very important to establish Korean guideline for colorectal cancer screening and polyp detection. The guideline was developed by the Korean Multi-Society Take Force and we tried to establish the guideline by evidence-based methods. Parts of the statements were draw by systematic reviews and meta-analyses. Herein we discussed epidemiology of colorectal cancers and adenomas in Korea and optimal methods for screening of colorectal cancer and detection of adenomas including fecal occult blood tests, radiologic tests, and endoscopic examinations.
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Affiliation(s)
- Bo-In Lee
- Department of Internal Medicine, The Catholic University of Korea College of Medicine, Seoul, Korea
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Bruining DH, Siddiki HA, Fletcher JG, Sandborn WJ, Fidler JL, Huprich JE, Mandrekar JN, Harmsen WS, Evans PE, Faubion WA, Hanson KA, Ingle SB, Pardi DS, Schroeder KW, Tremaine WJ, Loftus EV. Benefit of computed tomography enterography in Crohn's disease: effects on patient management and physician level of confidence. Inflamm Bowel Dis 2012; 18:219-25. [PMID: 21337477 DOI: 10.1002/ibd.21683] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Accepted: 01/18/2011] [Indexed: 12/09/2022]
Abstract
BACKGROUND Computed tomographic enterography (CTE) has been shown to have a high sensitivity and specificity for active small bowel inflammation. There are only sparse data on the effect of CTE results on Crohn's disease (CD) patient care. METHODS We prospectively assessed 273 patients with established or suspected CD undergoing a clinically indicated CTE. Providers were asked to complete pre- and postimaging questionnaires regarding proposed clinical management plans and physician level of confidence (LOC) for the presence or absence of active small bowel disease, fistula(s), abscess(es), or stricturing disease. Correlative clinical, serologic, and histologic data were recorded. Following revelation of CTE results, providers were questioned if CTE altered their management plans, and whether LOC changes were due to CTE findings (on a 5-point scale). RESULTS CTE altered management plans in 139 cases (51%). CTE changed management in 70 (48%) of those with established disease, prompting medication changes in 35 (24%). Management changes were made post-CTE in 69 (54%) of those with suspected CD, predominantly due to excluding CD (36%). CTE-perceived changes in management were independent of clinical, serologic, and histologic findings (P < 0.0001). Clinically meaningful LOC changes (2 or more points) were observed in 212 (78%). CONCLUSIONS CTE is a clinically useful examination, altering management plans in nearly half of patients with CD, while increasing physician LOC for the detection of small bowel inflammation and penetrating disease. These findings further support the use of CTE in CD management algorithms.
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Affiliation(s)
- David H Bruining
- Division of Gastroenterology & Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
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Lee BI, Hong SP, Kim SE, Kim SH, Kim HS, Hong SN, Yang DH, Shin SJ, Lee SH, Kim YH, Park DI, Kim HJ, Yang SK, Kim HJ, Jeon HJ. Korean Guidelines for Colorectal Cancer Screening and Polyp Detection. Intest Res 2012. [DOI: 10.5217/ir.2012.10.1.67] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/30/2023] Open
Affiliation(s)
- Bo In Lee
- Department of Internal Medicine, The Catholic University of Korea College of Medicine, Seoul, Korea
| | - Sung Pil Hong
- Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
| | - Seong-Eun Kim
- Department of Internal Medicine, Ewha Womans University School of Medicine, Seoul, Korea
| | - Se Hyung Kim
- Department of Radiology, Seoul National University College of Medicine, Seoul, Korea
| | - Hyun-Soo Kim
- Department of Internal Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - Sung Noh Hong
- Department of Internal Medicine, Konkuk University School of Medicine, Seoul, Korea
| | - Dong-Hoon Yang
- Department of Internal Medicine, University of Ulsan College of Medicine, Seoul, Korea
| | - Sung Jae Shin
- Department of Internal Medicine, Ajou University School of Medicine, Suwon, Korea
| | - Suck-Ho Lee
- Department of Internal Medicine, Soonchunhyang University College of Medicine, Cheonan, Korea
| | - Young-Ho Kim
- Department of Internal Medicine, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Dong Il Park
- Department of Internal Medicine, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Hyun Jung Kim
- Department of Preventive Medicine, Korea University College of Medicine, Seoul, Korea
| | - Suk-Kyun Yang
- Department of Internal Medicine, University of Ulsan College of Medicine, Seoul, Korea
| | - Hyo Jong Kim
- Department of Internal Medicine, Kyunghee University College of Medicine, Seoul, Korea
| | - Hae Jeong Jeon
- Department of Radiology, Konkuk University School of Medicine, Seoul, Korea
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Boellaard TN, de Haan MC, Venema HW, Stoker J. Colon distension and scan protocol for CT-colonography: an overview. Eur J Radiol 2011; 82:1144-58. [PMID: 22154604 DOI: 10.1016/j.ejrad.2011.10.030] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Accepted: 10/31/2011] [Indexed: 12/18/2022]
Abstract
This article reviews two important aspects of CT-colonography, namely colonic distension and scan parameters. Adequate distension should be obtained to visualize the complete colonic lumen and optimal scan parameters should be used to prevent unnecessary radiation burden. For optimal distension, automatic carbon dioxide insufflation should be performed, preferably via a thin, flexible catheter. Hyoscine butylbromide is - when available - the preferred spasmolytic agent because of the positive effect on insufflation and pain/burden and its low costs. Scans in two positions are required for adequate distension and high polyp sensitivity and decubitus position may be used as an alternative for patients unable to lie in prone position. The great intrinsic contrast between air or tagging and polyps allows the use of low radiation dose. Low-dose protocol without intravenous contrast should be used when extracolonic findings are deemed unimportant. In patients suspected for colorectal cancer, normal abdominal CT scan protocols and intravenous contrast should be used in supine position for the evaluation of extracolonic findings. Dose reduction can be obtained by lowering the tube current and/or voltage. Tube current modulation reduces the radiation dose (except in obese patients), and should be used when available. Iterative reconstructions is a promising dose reducing tool and dual-energy CT is currently evaluated for its applications in CT-colonography. This review also provides our institution's insufflation procedure and scan parameters.
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Affiliation(s)
- Thierry N Boellaard
- Department of Radiology, Academic Medical Center, University of Amsterdam, PB 22660, 1100 DD Amsterdam, The Netherlands.
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Cash BD, Rockey DC, Brill JV. AGA standards for gastroenterologists for performing and interpreting diagnostic computed tomography colonography: 2011 update. Gastroenterology 2011; 141:2240-66. [PMID: 22098711 DOI: 10.1053/j.gastro.2011.09.043] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Brooks D Cash
- Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
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Phan N, De Lisio M, Parise G, Boreham DR. Biological effects and adaptive response from single and repeated computed tomography scans in reticulocytes and bone marrow of C57BL/6 mice. Radiat Res 2011; 177:164-75. [PMID: 22059980 DOI: 10.1667/rr2532.1] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
This study investigated the biological effects and adaptive responses induced by single and repeated in vivo computed tomography (CT) scans. We postulated that, through the induction of low-level oxidative stress, repeated low-dose CT scans (20 mGy, 2 days/week, 10 weeks) could protect mice (C57BL/6) from acute effects of high-dose radiation (1 Gy, 2 Gy). The micronucleated reticulocyte (MN-RET) count increased linearly after exposure to single CT scans of doses ranging from 20 to 80 mGy (P = 0.033). Ten weeks of repeated CT scans (total dose 400 mGy) produced a slight reduction in spontaneous MN-RET levels relative to levels in sham CT-scanned mice (P = 0.04). Decreases of nearly 10% in γ-H2AX fluorescence levels were observed in the repeated CT-scanned mice after an in vitro challenge dose of 1 Gy (P = 0.017) and 2 Gy (P = 0.026). Spontaneous apoptosis levels (caspase 3 and 7 activation) were also significantly lower in the repeated CT-scanned mice than the sham CT-scanned mice (P < 0.01). In contrast, mice receiving only a single CT scan showed a 19% elevation in apoptosis (P < 0.02) and a 10% increase in γ-H2AX fluorescence levels after a 2-Gy challenge (P < 0.05) relative to sham CT controls. Overall, repeated CT scans seemed to confer resistance to larger doses in mice, whereas mice exposed to single CT scans exhibited transient genotoxicity, enhanced apoptosis, and characteristics of radiation sensitization.
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Affiliation(s)
- Nghi Phan
- Department of Medical Physics and Applied Radiation Sciences, Nuclear Research Building Room 227, 1280 Main St. West, McMaster University, Hamilton, Ontario, Canada, L8S 4K1.
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Buchach CM, Kim DH, Pickhardt PJ. Performing an additional decubitus series at CT colonography. ABDOMINAL IMAGING 2011; 36:538-44. [PMID: 21184064 PMCID: PMC5514551 DOI: 10.1007/s00261-010-9666-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
PURPOSE To determine the rate and associated factors for acquiring a decubitus series at CT colonography (CTC), in addition to the standard supine and prone series. MATERIALS AND METHODS CTC examinations read centrally at one institution but performed at three different centers in 6,380 adults were reviewed to determine the frequency of an additional decubitus series. Results were analyzed according to study indication (primary screening vs. diagnostic for incomplete colonoscopy), practice site (academic vs. community), patient age, gender, body mass index (BMI), and temporal variation. At all sites, the CT technologist determined the need for an additional decubitus series, with infrequent radiologist input in select cases. RESULTS The frequency for the CT technologist to obtain a decubitus series at screening was 9.7% (578/5,952), compared with 22.9% (98/428) following failed colonoscopy (P < 0.001). The decubitus rate for screening at the academic center (9.4%, 550/5,871) was significantly lower than the community hospitals (34.6% combined, 28/81) (P < 0.001). The rate progressively increased with age, from 5.0% under age 50 to 28.0% over age 80. No significant difference was seen between men and women (10.3 vs. 9.2%), but a strong correlation existed with increased BMI, rising to >25% for BMI over 40. Marked temporal variation existed at the academic center, with quarterly rates ranging from 0 to 17%. CONCLUSIONS The frequency for performing a third series at CTC varies considerably according to indication, practice site, patient age, BMI, and time. These results have important implications for clinical practice, including the need for improved training and feedback for CT technologists.
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Affiliation(s)
- Christopher M Buchach
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Clinical Science Center, Madison, 53792-3252, USA
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Chang ML, Hou JK. Cancer risk related to gastrointestinal diagnostic radiation exposure. Curr Gastroenterol Rep 2011; 13:449-457. [PMID: 21833692 DOI: 10.1007/s11894-011-0214-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Exposure to ionizing radiation is associated with an increased risk of cancer. With the growing use of diagnostic imaging studies, there is concern for increasing the risk of radiation associated malignancy of the gastrointestinal tract. The purpose of this review is to summarize the existing literature for risk of gastrointestinal malignancy after ionizing radiation exposure from diagnostic imaging studies. Estimates of organ specific effective doses of radiation vary widely based on the method of measurement and patient factors. Most of the current data are based on calculations of organ effective doses from anthropomorphic phantoms and estimated cancer risk based on radiation exposure from environmental sources. Radiation associated cancer risk is dependent on both the cumulative radiation dose and the radiosensitivity of the particular organ. The majority of radiation exposure and risk associated with gastrointestinal malignancy comes from CT scans, especially of the abdomen/pelvis. Of the abdominal organs, the colon carries the highest lifetime attributable risk of radiation associated malignancy. The attributable risk of malignancy for an individual diagnostic imaging study is low, but measurable, and therefore imaging studies without radiation such as MRI and ultrasound should be considered, especially in patients who require repeated imaging studies. There is a shortage of epidemiological data and an absence of prospective data with adequate follow-up to describe accurate risk estimates of gastrointestinal cancers after diagnostic imaging. More studies are needed to better determine the risks of malignancy from diagnostic imaging.
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Affiliation(s)
- Mimi L Chang
- Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, 1709 Dryden Road, Suite 8.40, MS: BCM 620, Houston, TX 77030, USA
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Ghosh D, Yu H, Tan XF, Lim TK, Zubaidah RM, Tan HT, Chung MCM, Lin Q. Identification of key players for colorectal cancer metastasis by iTRAQ quantitative proteomics profiling of isogenic SW480 and SW620 cell lines. J Proteome Res 2011; 10:4373-87. [PMID: 21854069 DOI: 10.1021/pr2005617] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
This study compared the whole cell proteome profiles of two isogenic colorectal cancer (CRC) cell lines (primary SW480 cell line and its lymph node metastatic variant SW620), as an in vitro metastatic model, to gain an insight into the molecular events of CRC metastasis. Using iTRAQ (isobaric tags for relative and absolute quantitation) based shotgun proteomics approach, we identified 1140 unique proteins, out of which 147 were found to be significantly altered in the metastatic cell. Ingenuity pathway analysis with those significantly altered proteins, revealed cellular organization and assembly as the top-ranked altered biological function. Differential expression pattern of 6 candidate proteins were validated by Western blot. Among these, the low expression level of β-catenin combined with the up-regulation of CacyBP (Calcyclin binding Protein), a β-catenin degrading protein, in the metastatic cell provided a rational guide for the downstream functional assays. The relative expression pattern of these two proteins was further validated in three other CRC cells by Western blot and quantitative immunofluorescence studies. Overexpression of CacyBP in three different primary CRC cell lines showed significant reduction in adhesion characteristics as well as cellular β-catenin level as confirmed by our experiments, indicating the possible involvement of CacyBP in CRC metastasis. In short, this study demonstrates successful application of a quantitative proteomics approach to identify novel key players for CRC metastasis, which may serve as biomarkers and/or drug targets to improve CRC therapy.
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Affiliation(s)
- Dipanjana Ghosh
- Department of Biological Sciences, National University of Singapore , 14 Science Drive 4, Singapore 117543
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Brenner DJ, Shuryak I, Einstein AJ. Impact of reduced patient life expectancy on potential cancer risks from radiologic imaging. Radiology 2011; 261:193-8. [PMID: 21771956 DOI: 10.1148/radiol.11102452] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
PURPOSE To quantify the effect of reduced life expectancy on cancer risk by comparing estimated lifetime risks of lung cancer attributable to radiation from commonly used computed tomographic (CT) examinations in patients with and those without cancer or cardiac disease. MATERIALS AND METHODS With the use of clinically determined life tables, reductions in radiation-attributable lung cancer risks were estimated for coronary CT angiographic examinations in patients with multivessel coronary artery disease who underwent coronary artery bypass graft (CABG) surgery and for surveillance CT examinations in patients treated for colon cancer. Statistical uncertainties were estimated for the risk ratios in patients who underwent CABG surgery and patients with colon cancer versus the general population. RESULTS Patients with decreased life expectancy had decreased radiation-associated cancer risks. For example, for a 70-year-old patient with colon cancer, the estimated reduction in lifetime radiation-associated lung cancer risk was approximately 92% for stage IV disease, versus 8% for stage 0 or I disease. For a patient who had been treated with CABG surgery, the estimated reduction in lifetime radiation-associated lung cancer risk was approximately 57% for a 55-year-old patient, versus 12% for a 75-year-old patient. CONCLUSION The importance of radiation exposure in determining optimal imaging usage is much reduced for patients with markedly reduced life expectancies: Imaging justification and optimization criteria for patients with substantially reduced life expectancies should not necessarily be the same as for those with normal life expectancies.
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Affiliation(s)
- David J Brenner
- Center for Radiological Research and Department of Medicine and Radiology, College of Physicians and Surgeons, Columbia University Medical Center, New York, NY 10032, USA.
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Macari M, Nevsky G, Bonavita J, Kim DC, Megibow AJ, Babb JS. CT Colonography in Senior versus Nonsenior Patients: Extracolonic Findings, Recommendations for Additional Imaging, and Polyp Prevalence. Radiology 2011; 259:767-74. [DOI: 10.1148/radiol.11102144] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Abstract
OBJECTIVES Isolated abdominal pain is seen as a poor indication for colonic investigations. The yield of serious pathology detected by optical colonoscopy (OC) has differed greatly in published series. This study aims to establish the yield of colonic investigations for isolated abdominal pain. METHODS A retrospective analysis of the endoscopy database was undertaken on all OCs performed from 2000 to 2008. The yield of OCs for detection of pathology (polyps, cancers, and inflammatory bowel disease) was compared for the symptoms of abdominal pain, chronic diarrhea, or anemia. Data on computed tomographic colonographies (CTC), performed for isolated abdominal pain in 2008, were used to compare the yield of CTCs and OCs. RESULTS Of the 8564 OCs and 525 CTCs performed, 5.4% and 8.2% were undertaken for isolated abdominal pain, respectively. The yield of OCs for overall pathology detection was not significantly different for abdominal pain (23.87%), compared to other indications (20.34-24.85%). The yield of pathology detection was not significantly different for CTC (20.93%) and OC. Colonic polyps were the most common pathology (OC 16.05%, CTC 18.6%). CONCLUSION Colonic investigations undertaken for isolated abdominal pain had a high yield of incidental colonic pathology. The detection of polyps could be beneficial, but it does not explain the symptoms. CTC offers a less invasive way of detecting colonic pathology in such patients, while maintaining the same yield. If CTC is used as a first line of investigation, it could spare 75% of patients the colonoscopy procedure.
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Wylie PN, Burling D. CT colonography: what the gastroenterologist needs to know. Frontline Gastroenterol 2011; 2:96-104. [PMID: 28839590 PMCID: PMC5517201 DOI: 10.1136/fg.2009.000380] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/09/2010] [Indexed: 02/04/2023] Open
Affiliation(s)
- Peter N Wylie
- Radiology Department, Royal Free Hospital, London, UK
| | - David Burling
- Intestinal Imaging Centre, St Mark's Hospital, Harrow, UK
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Berrington de González A, Kim KP, Knudsen AB, Lansdorp-Vogelaar I, Rutter CM, Smith-Bindman R, Yee J, Kuntz KM, van Ballegooijen M, Zauber AG, Berg CD. Radiation-related cancer risks from CT colonography screening: a risk-benefit analysis. AJR Am J Roentgenol 2011; 196:816-23. [PMID: 21427330 PMCID: PMC3470483 DOI: 10.2214/ajr.10.4907] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE The purpose of this study was to estimate the ratio of cancers prevented to induced (benefit-risk ratio) for CT colonography (CTC) screening every 5 years from the age of 50 to 80 years. MATERIALS AND METHODS Radiation-related cancer risk was estimated using risk projection models based on the National Research Council's Biological Effects of Ionizing Radiation (BEIR) VII Committee's report and screening protocols from the American College of Radiology Imaging Network's National CT Colonography Trial. Uncertainty intervals were estimated using Monte Carlo simulation methods. Comparative modeling with three colorectal cancer microsimulation models was used to estimate the potential reduction in colorectal cancer cases and deaths. RESULTS The estimated mean effective dose per CTC screening study was 8 mSv for women and 7 mSv for men. The estimated number of radiation-related cancers resulting from CTC screening every 5 years from the age of 50 to 80 years was 150 cases/100,000 individuals screened (95% uncertainty interval, 80-280) for men and women. The estimated number of colorectal cancers prevented by CTC every 5 years from age 50 to 80 ranged across the three microsimulation models from 3580 to 5190 cases/100,000 individuals screened, yielding a benefit-risk ratio that varied from 24:1 (95% uncertainty interval, 13:1-45:1) to 35:1 (19:1-65:1). The benefit-risk ratio for cancer deaths was even higher than the ratio for cancer cases. Inclusion of radiation-related cancer risks from CT examinations performed to follow up extracolonic findings did not materially alter the results. CONCLUSION Concerns have been raised about recommending CTC as a routine screening tool because of potential harms including the radiation risks. Based on these models, the benefits from CTC screening every 5 years from the age of 50 to 80 years clearly outweigh the radiation risks.
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Affiliation(s)
- Amy Berrington de González
- Division of Cancer Epidemiology & Genetics, National Cancer Institute, 6120 Executive Blvd, Bethesda, MD 20892, USA.
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Canadian Association of Gastroenterology position statement on screening individuals at average risk for developing colorectal cancer: 2010. CANADIAN JOURNAL OF GASTROENTEROLOGY = JOURNAL CANADIEN DE GASTROENTEROLOGIE 2011; 24:705-14. [PMID: 21165377 DOI: 10.1155/2010/683171] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The Canadian Association of Gastroenterology and the Canadian Digestive Health Foundation published guidelines on colon cancer screening in 2004. Subsequent to the publication of these guidelines, many advances have occurred, thereby necessitating a review of the existing guidelines in the context of new technologies and clinical knowledge. The assembled guideline panel recognized three recent American sets of guidelines and identified seven issues that required comment from a Canadian perspective. These issues included, among others, the role of program-based screening, flexible sigmoidoscopy, computed tomography colonography, barium enema and quality improvement. The panel also provided context for the selection of the fecal immunochemical test as the fecal occult blood test of choice, and the relative role of colonoscopy as a primary screening tool. Recommendations were also provided for an upper age limit for colon cancer screening, whether upper endoscopy should be performed following a negative colonoscopy for a positive fecal occult blood test and when colon cancer screening should resume following negative colonoscopy.
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Abstract
OBJECTIVE Colorectal cancer (CRC) represents the third most common cancer diagnosed and a major cause of cancer-related deaths in women. Despite strong evidence that early screening decreases colorectal cancer incidence and mortality rates, colorectal cancer screening rates in women still lag significantly behind screening rates for breast and cervical cancers. Additionally, women have been found to be less likely than men to undergo CRC screening. This is despite the fact that the overall lifetime risk for the development of colorectal carcinoma is similar in both sexes. Barriers to screening have been found to be different for women compared with men. Screening adherence in women also appears to be associated with various social and demographic factors. CONCLUSION CT colonography (CTC) is an accurate, minimally invasive, and well-tolerated examination that is newly endorsed by the American Cancer Society, U.S. Multisociety Task Force, and the American College of Radiology. Improved screening compliance may occur in women with further dissemination of CTC.
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Informed consent for computed tomography. Am J Emerg Med 2011; 29:230-2. [DOI: 10.1016/j.ajem.2010.09.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2010] [Revised: 09/02/2010] [Accepted: 09/05/2010] [Indexed: 11/19/2022] Open
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Abstract
This article provides basic information about computed tomographic colonography (CTC) and reviews the preparation, methods, and tools required for the procedure. The clinical uses for CTC (screening/diagnosis of colon cancer and colonic obstruction) are outlined, and its accuracy and validity are compared with other diagnostic methods. A summary of the benefits and risks of the test are presented and the current practicalities for implementation are addressed.
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Affiliation(s)
- Ancil K Philip
- Department of General Surgery, University of Wisconsin-Madison, 600 Highland Avenue, Madison, WI 53792-7375, USA
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Sweet A, Lee D, Gairy K, Phiri D, Reason T, Lock K. The impact of CT colonography for colorectal cancer screening on the UK NHS: costs, healthcare resources and health outcomes. APPLIED HEALTH ECONOMICS AND HEALTH POLICY 2011; 9:51-64. [PMID: 21174482 DOI: 10.2165/11588110-000000000-00000] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
BACKGROUND Biennial faecal occult blood testing (FOBT) for individuals aged 60-69 years is the primary screening tool for colorectal cancer (CRC) in the UK NHS, despite a large number of patients undergoing an unnecessary optical colonoscopy (OC) and evidence from modelling studies to suggest that more cost-effective technologies exist. CT colonography (CTC) is an emerging CRC screening technology with the potential to prevent CRC by detecting pre-cancerous polyps and to detect cancer at an earlier stage. OBJECTIVE to assess the impact of introducing CTC into the UK NHS screening programme for CRC on key health outcomes as well as the NHS budget and healthcare resource capacity. METHODS a discrete Markov model was used to reflect the natural history of CRC and the impact of three screening scenarios (biennial FOBT with and without CTC triage of patients referred to OC, and CTC every 5 years) on a range of health outcomes, including the incidence and prevalence of CRC, in a hypothetical cohort of individuals. The yearly costs, health outcomes and healthcare resource capacity requirements were estimated over a 10-year period (2009-18). RESULTS using CTC to follow up FOBT-positive patients (scenario 2) was less costly than directing all FOBT-positive patients to OC (scenario 1); saving £776 283 over 10 years for 100 000 individuals invited for screening (year 2007 values), primarily by avoiding approximately 1700 OCs, but was estimated to require 2200 additional CT scans. Implementing a programme of 5-yearly CTC as a primary screen is expected to be more expensive than FOBT screening over the short term (driven by high screening and diagnosis costs), despite substantial savings in treatment costs for CRC over the 10-year time horizon of the model and improved health outcomes. CONCLUSIONS adding CTC into the existing NHS Bowel Cancer Screening Programme as part of a preventive screening strategy could be less costly to the NHS over the longer term when used to triage FOBT-positive patients to appropriate follow-up. Increased demand for radiology services may be compensated for by reduced demand in endoscopy units.
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Abstract
OBJECTIVE While colonoscopy is currently the preferred test for colorectal cancer (CRC) screening, the invasive and time-consuming characteristics of the test are often cited as reasons for noncompliance with screening. CT colonography (CTC) is a less invasive screening method that is comparable to colonoscopy for the detection of advanced neoplasia. The aim of this project was to assess patient preferences between colonoscopy and CTC in an open access system. MATERIALS AND METHODS Two hundred fifty consecutive average-risk patients undergoing CRC screening completed a survey that assessed reasons for choosing CTC in lieu of colonoscopy, compliance with CRC screening if CTC was not offered, and which of the two tests they preferred. RESULTS The most common reasons for undergoing CTC included convenience (33.6%), recommendation by referring provider (13.2%), and perceived safety (10.8%). Had CTC not been an available option, 91 of the 250 patients (36%) would have foregone CRC screening. Among the 57 patients who had experienced both procedures, 95% (n = 54) preferred CTC. CONCLUSION These findings show the importance of providing CTC as an alternative screening option for CRC at our institution, which may increase CRC adherence screening rates.
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Abstract
Computed tomographic (CT) colonography is a noninvasive method to evaluate the colon and has received considerable attention in the last decade as a colon-imaging tool. The technique has also been proposed as a potential primary colon cancer-screening method in the United States. The accuracy of the technique for the detection of large lesions seems to be high, perhaps in the range of colonoscopy. Overall, the field is rapidly evolving. Available data suggest that CT colonography, although a viable colon cancer screening modality in the United States, is not ready for widespread implementation, largely because of the lack of standards for training and reading and the limited number of skilled readers.
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Affiliation(s)
- Don C Rockey
- Division of Digestive and Liver Diseases, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-8887, USA.
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Shuryak I, Sachs RK, Brenner DJ. Cancer risks after radiation exposure in middle age. J Natl Cancer Inst 2010; 102:1628-36. [PMID: 20975037 PMCID: PMC2970575 DOI: 10.1093/jnci/djq346] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Revised: 07/26/2010] [Accepted: 08/06/2010] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Epidemiological data show that radiation exposure during childhood is associated with larger cancer risks compared with exposure at older ages. For exposures in adulthood, however, the relative risks of radiation-induced cancer in Japanese atomic bomb survivors generally do not decrease monotonically with increasing age of adult exposure. These observations are inconsistent with most standard models of radiation-induced cancer, which predict that relative risks decrease monotonically with increasing age at exposure, at all ages. METHODS We analyzed observed cancer risk patterns as a function of age at exposure in Japanese atomic bomb survivors by using a biologically based quantitative model of radiation carcinogenesis that incorporates both radiation induction of premalignant cells (initiation) and radiation-induced promotion of premalignant damage. This approach emphasizes the kinetics of radiation-induced initiation and promotion, and tracks the yields of premalignant cells before, during, shortly after, and long after radiation exposure. RESULTS Radiation risks after exposure in younger individuals are dominated by initiation processes, whereas radiation risks after exposure at later ages are more influenced by promotion of preexisting premalignant cells. Thus, the cancer site-dependent balance between initiation and promotion determines the dependence of cancer risk on age at radiation exposure. For example, in terms of radiation induction of premalignant cells, a quantitative measure of the relative contribution of initiation vs promotion is 10-fold larger for breast cancer than for lung cancer. Reflecting this difference, radiation-induced breast cancer risks decrease with age at exposure at all ages, whereas radiation-induced lung cancer risks do not. CONCLUSION For radiation exposure in middle age, most radiation-induced cancer risks do not, as often assumed, decrease with increasing age at exposure. This observation suggests that promotional processes in radiation carcinogenesis become increasingly important as the age at exposure increases. Radiation-induced cancer risks after exposure in middle age may be up to twice as high as previously estimated, which could have implications for occupational exposure and radiological imaging.
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Affiliation(s)
- Igor Shuryak
- Center for Radiological Research, Department of Radiation Oncology, Columbia University Medical Center, New York, NY, USA
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Ball CG, Correa-Gallego C, Howard TJ, Zyromski NJ, House MG, Pitt HA, Nakeeb A, Schmidt CM, Akisik F, Lillemoe KD. Radiation dose from computed tomography in patients with necrotizing pancreatitis: how much is too much? J Gastrointest Surg 2010; 14:1529-35. [PMID: 20824381 DOI: 10.1007/s11605-010-1314-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Accepted: 08/09/2010] [Indexed: 01/31/2023]
Abstract
OBJECTIVES Low-dose ionizing radiation from medical imaging has been indirectly linked with subsequent cancer. Computed tomography (CT) is the gold standard for defining pancreatic necrosis. The primary goal was to identify the frequency and effective radiation dose of CT imaging for patients with necrotizing pancreatitis. METHODS All patients with necrotizing pancreatitis (2003-2007) were retrospectively analyzed for CT-related radiation exposure. RESULTS Necrosis was identified in 18% (238/1290) of patients with acute pancreatitis (mean age = 53 years; hospital/ICU length of stay = 23/7 days; mortality = 9%). A median of five CTs/patient [interquartile range (IQR) = 4] were performed during a median 2.6-month interval. The average effective dose was 40 mSv per patient (equivalent to 2,000 chest X-rays; 13.2 years of background radiation; one out of 250 increased risk of fatal cancer). The actual effective dose was 63 mSv considering various scanner technologies. CTs were infrequently (20%) followed by direct intervention (199 interventional radiology, 118 operative, 12 endoscopic) (median = 1; IQR = 2). Magnetic resonance imaging did not have a CT-sparing effect. Mean direct hospital costs increased linearly with CT number (R = 0.7). CONCLUSIONS The effective radiation dose received by patients with necrotizing pancreatitis is significant. Management changes infrequently follow CT imaging. The ubiquitous use of CT in necrotizing pancreatitis raises substantial public health concerns and mandates a careful reassessment of its utility.
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Affiliation(s)
- Chad G Ball
- Department of Surgery, Indiana University, 545 Barnhill Drive, Emerson Hall 203, Indianapolis, IN 46202, USA.
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Abstract
Computed tomography colonography (CTC) in colorectal cancer (CRC) screening has two roles: one present and the other potential. The present role is, without any further discussion, the integration into established screening programs as a replacement for barium enema in the case of incomplete colonoscopy. The potential role is the use of CTC as a first-line screening method together with Fecal Occult Blood Test, sigmoidoscopy and colonoscopy. However, despite the fact that CTC has been officially endorsed for CRC screening of average-risk individuals by different scientific societies including the American Cancer Society, the American College of Radiology, and the US Multisociety Task Force on Colorectal Cancer, other entities, such as the US Preventive Services Task Force, have considered the evidence insufficient to justify its use as a mass screening method. Medicare has also recently denied reimbursement for CTC as a screening test. Nevertheless, multiple advantages exist for using CTC as a CRC screening test: high accuracy, full evaluation of the colon in virtually all patients, non-invasiveness, safety, patient comfort, detection of extracolonic findings and cost-effectiveness. The main potential drawback of a CTC screening is the exposure to ionizing radiation. However, this is not a major issue, since low-dose protocols are now routinely implemented, delivering a dose comparable or slightly superior to the annual radiation exposure of any individual. Indirect evidence exists that such a radiation exposure does not induce additional cancers.
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Does the amount of tagged stool and fluid significantly affect the radiation exposure in low-dose CT colonography performed with an automatic exposure control? Eur Radiol 2010; 21:345-52. [PMID: 20700594 DOI: 10.1007/s00330-010-1922-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Revised: 06/29/2010] [Accepted: 07/02/2010] [Indexed: 10/19/2022]
Abstract
OBJECTIVE To determine whether the amount of tagged stool and fluid significantly affects the radiation exposure in low-dose screening CT colonography performed with an automatic tube-current modulation technique. METHODS The study included 311 patients. The tagging agent was barium (n = 271) or iodine (n = 40). Correlation was measured between mean volume CT dose index (CTDI (vol)) and the estimated x-ray attenuation of the tagged stool and fluid (ATT). Multiple linear regression analyses were performed to determine the effect of ATT on CTDI (vol ) and the effect of ATT on image noise while adjusting for other variables including abdominal circumference. RESULTS CTDI (vol) varied from 0.88 to 2.54 mGy. There was no significant correlation between CTDI (vol) and ATT (p = 0.61). ATT did not significantly affect CTDI (vol) (p = 0.93), while abdominal circumference was the only factor significantly affecting CTDI (vol) (p < 0.001). Image noise ranged from 59.5 to 64.1 HU. The p value for the regression model explaining the noise was 0.38. CONCLUSION The amount of stool and fluid tagging does not significantly affect radiation exposure.
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Performance improvements of imaging-based screening tests. Best Pract Res Clin Gastroenterol 2010; 24:493-507. [PMID: 20833352 DOI: 10.1016/j.bpg.2010.04.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Revised: 03/19/2010] [Accepted: 04/03/2010] [Indexed: 01/31/2023]
Abstract
Endoscopic and radiologic tests appear to be more accurate than stool-tests in detecting advanced neoplasia because of direct visualisation of colorectal mucosa. Further technological advances are expected to improve the performance and acceptability of these tests. Several attempts at increasing the adenoma detection rate of colonoscopy have been tested, and in vivo histologic differentiation between neoplastic and hyperplastic polyps may lead to substantial saving in economic and medical resources. Low-volume and non-cathartic bowel preparations may improve CT colonography acceptability, whilst computer-aided detection and low-dose protocols may result in a higher accuracy and safety of this procedure. Despite the lack of ionising radiation, significant drawbacks will likely to limit the role of MR colonography in screening programs. Colon capsule endoscopy appears to be a safe and technically feasible procedure. The suboptimal accuracy of the first generation seems to be substantially improved by the second generation of this device.
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Reducing the radiation dose for CT colonography using adaptive statistical iterative reconstruction: A pilot study. AJR Am J Roentgenol 2010; 195:126-31. [PMID: 20566805 DOI: 10.2214/ajr.09.3855] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVE The purpose of our study was to evaluate the feasibility of preserving image quality during CT colonography (CTC) using a reduced radiation dose with adaptive statistical iterative reconstruction (ASIR). MATERIALS AND METHODS A proven colon phantom was imaged at standard dose settings (50 mAs) and at reduced doses (10-40 mAs) using six different ASIR levels (0-100%). We assessed 2D and 3D image quality and noise to determine the optimal dose and ASIR setting. Eighteen patients were then scanned with a standard CTC dose (50 mAs) in the supine position and at a reduced dose of 25 mAs with 40% ASIR in the prone position. Three radiologists blinded to the scanning techniques assessed 2D and 3D image quality and noise at three different colon locations. A score difference of > or = 1 was considered clinically important. Actual noise measures were compared between the standard-dose and low-dose acquisitions. RESULTS The phantom study showed image noise reduction that correlated with a higher percentage of ASIR. In patients, no significant image quality differences were identified between standard- and low-dose images using 40% ASIR. Overall image quality was reduced for both image sets as body mass index increased. Measured image noise was less with the low-dose technique using ASIR. CONCLUSION The results of this pilot study show that the radiation dose during CTC can be reduced 50% below currently accepted low-dose techniques without significantly affecting image quality when ASIR is used. Further evaluation in a larger patient group is warranted.
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Spada C, Hassan C, Marmo R, Petruzziello L, Riccioni ME, Zullo A, Cesaro P, Pilz J, Costamagna G. Meta-analysis shows colon capsule endoscopy is effective in detecting colorectal polyps. Clin Gastroenterol Hepatol 2010; 8:516-22. [PMID: 20215066 DOI: 10.1016/j.cgh.2010.02.018] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2009] [Revised: 02/15/2010] [Accepted: 02/23/2010] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS Colon capsule endoscopy (CCE) is a noninvasive and painless technique used to explore the colon without sedation or air insufflation. We performed a systematic review and meta-analysis to assess the accuracy of CCE in detecting colorectal polyps. METHODS The MEDLINE, EMBASE, and SCOPUS databases were searched, from 2006 to 2009, for the terms "colon capsule" and "Pillcam colon"; searches included abstracts. Studies were included that focused on detecting colorectal polyps with CCE and that were verified using within-subject reference colonoscopy. The risk of bias within each study was ascertained according to Quality Assessment of Diagnostic Accuracy in Systematic Reviews recommendations. The per-patient sensitivity and specificity were calculated for polyps of any size and for significant findings (polyps, > or =6 mm in size or >3 in number). Forest plots were produced based on random-effect models. The risk of bias across studies was assessed using the interstudy heterogeneity statistic, meta-regression, and the Egger test. RESULTS Eight studies provided data on 837 patients; the prevalences of polyps and significant findings were 57% and 27.4%, respectively. CCE sensitivity for polyps of any size and significant findings were 71% and 68%, respectively. CCE specificity for polyps of any size and significant findings were 75% and 82%, respectively. High levels of heterogeneity (interstudy heterogeneity, >75%) were not detected. Moderate heterogeneity partially was explained by the different design of individual studies. CCE identified 16 of the 21 cancerous lesions detected by colonoscopy (pooled sensitivity, 76%). CONCLUSIONS CCE sensitivity for polyps and significant findings compares favorably with other noninvasive colorectal cancer screening strategies. CCE specificity is likely to be underestimated because reference colonoscopy examination results are blinded.
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Cody DD, Kim HJ, Cagnon CH, Larke FJ, McNitt-Gray MM, Kruger RL, Flynn MJ, Seibert JA, Judy PF, Wu X. Normalized CT dose index of the CT scanners used in the National Lung Screening Trial. AJR Am J Roentgenol 2010; 194:1539-46. [PMID: 20489094 PMCID: PMC3015146 DOI: 10.2214/ajr.09.3268] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE The National Lung Screening Trial includes 33 participating institutions that performed 75,133 lung cancer screening CT examinations for 26,724 subjects during 2002-2007. For trial quality assurance reasons, CT radiation dose measurement data were collected from all MDCT scanners used in the trial. MATERIALS AND METHODS A total of 247 measurements on 96 MDCT scanners were collected using a standard CT dose index (CTDI) measurement protocol. The scan parameters used in the measurements (tube voltage, milliampere-seconds [mAs], and detector-channel configuration) were set according to trial protocol for average size subjects. The normalized weighted CT dose index (CTDI(w)) (computed as CTDI(w)/mAs) obtained from each trial-participating scanner was tabulated. RESULTS We found a statistically significant difference in normalized CT dose index among CT scanner manufacturers, likely as a result of design differences, such as filtration, bow-tie design, and geometry. Our findings also indicated a statistically significant difference in normalized CT dose index among CT scanner models from the same manufacturer (e.g., GE Healthcare, Siemens Healthcare, and Philips Healthcare). We also found a statistically significant difference in normalized CT dose index among all models and all manufacturers; furthermore, we found a statistically significant difference in normalized CT dose index among CT scanners from all manufacturers when we compared scanners with four or eight data channels to those with 16, 32, or 64 channels, suggesting that more complex scanners have improved dose efficiency. CONCLUSION Average normalized CT dose index values varied by a factor of almost two for all scanners from all manufacturers. This study was focused on machine-specific normalized CT dose index; patient dose and image quality were not addressed.
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Affiliation(s)
- Dianna D Cody
- Department of Imaging Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.
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Tan CH, Iyer R. Use of computed tomography in the management of colorectal cancer. World J Radiol 2010; 2:151-8. [PMID: 21161029 PMCID: PMC2999018 DOI: 10.4329/wjr.v2.i5.151] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Revised: 04/21/2010] [Accepted: 04/28/2010] [Indexed: 02/06/2023] Open
Abstract
Computed tomography (CT) plays an important role in the management of colorectal cancer (CRC). The use of CT (colonography) as a screening tool for CRC has been validated and is expected to rise over time. The results of prior studies suggest that CT is suboptimal for assessment of local T stage and moderate for N stage disease. Recent advances in CT technology are expected to lead to some improvement in staging accuracy. At present, the main role of CT in pre-treatment imaging assessment lies in its use for the detection of distant metastases, especially in the liver. In a select group of patients, routine post-treatment surveillance with CT confers survival benefits. The role of CT for post-treatment assessment has been radically altered and improved with the advent of fusion positron emission tomography/CT. Perfusion CT shows promise as another functional imaging modality but further experience with this technique is necessary before it can be applied to routine clinical practice.
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Abstract
Computed tomography colonography (CTC) has the potential to become a major component of colorectal cancer (CRC) screening programs and to have a significant effect on CRC prevention. This article describes the potential role of CTC within the framework of colorectal cancer screening. Current screening recommendations and traditional screening tests are reviewed, followed by a summary of recent study results on the use of CTC as a screening tool. Several factors that are affecting the acceptance and adoption of CTC are outlined. Although CTC is valuable and holds considerable promise as a way to increase the use of CRC screening, these issues need to be addressed before CTC becomes more widely disseminated as a screening modality.
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de Gonzalez AB, Kim KP, Yee J. CT colonography: perforation rates and potential radiation risks. Gastrointest Endosc Clin N Am 2010; 20:279-91. [PMID: 20451817 PMCID: PMC2956272 DOI: 10.1016/j.giec.2010.02.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Computed tomographic colonography (CTC) has emerged as an alternative screening tool for colorectal cancer due to the potential to provide good efficacy combined with greater acceptability than optical colonoscopy or fecal occult blood testing. However, some organizations have raised concerns about the potential harms, including perforation rates and radiation-related cancer risks, and have not recommended that it currently be used as a screening tool in the general population in the US. In this article the authors review the current evidence for these potential harms from CTC and compare them to the potential harms from the alternatives including colonoscopy and double-contrast barium enema.
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Affiliation(s)
| | - Kwang Pyo Kim
- Department of Nuclear Engineering, Kyung Hee University, 1 Seocheondong, Giheung-gu, Yongin-si, Gyeonggi-do, Republic of Korea
| | - Judy Yee
- University of California, San Francisco, VA Medical Center, 4150 Clement Street, San Francisco, CA 94121, USA.
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91
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Current techniques in the performance, interpretation, and reporting of CT colonography. Gastrointest Endosc Clin N Am 2010; 20:169-92. [PMID: 20451809 DOI: 10.1016/j.giec.2010.02.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The technical objective of computed tomographic colonography (CTC) is to acquire high-quality computed tomography images of the cleansed, well-distended colon for polyp detection. In this article the authors provide an overview of the technical components of CTC, from preparation of the patient to acquisition of the imaging data and basic methods of interpretation. In each section, the best evidence for current practices and recommendations is reviewed. Each of the technical components must be optimized to achieve high sensitivity in polyp detection.
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92
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Akhtar R, Lee M, Itzkowitz SH. Colonoscopy Versus Computed Tomography Colonography for Colorectal Cancer Screening. ACTA ACUST UNITED AC 2010; 77:214-24. [DOI: 10.1002/msj.20175] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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93
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Liang Z, Richards R. Virtual colonoscopy vs optical colonoscopy. EXPERT OPINION ON MEDICAL DIAGNOSTICS 2010; 4:159-169. [PMID: 20473367 PMCID: PMC2869208 DOI: 10.1517/17530051003658736] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
IMPORTANCE OF THE FIELD: The high prevalence of colon carcinoma combined with the low compliance of currently recommended screening guidelines explains the continued high mortality rate of colon cancer. Utilizing a strategy of virtual colonoscopy (VC) in asymptomatic patients over 50, with optical colonoscopy (OC) follow-up for removal of detected adenomatous polyps may result in lowering the colon cancer death rate. However, the screening potential of VC has not yet been widely recognized. Debates and doubts of its potential benefits have been frequently seen in the literature since VC was first reported in 1994. AREAS COVERED IN THIS REVIEW: This article reviews the currently available screening options and discuss their advantages and drawbacks. TAKE HOME MESSAGE: VC has many advantages over the existing screening options and its several drawbacks can be mitigated so that it would become a valuable screening modality. A strategy that utilizes VC for population-based screening over the age of 50 and OC for screening high-risk individuals and those with positive VC findings would result in a significantly reduced rate of colon cancer deaths.
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Affiliation(s)
- Zhengrong Liang
- IEEE Fellow, Professor of Radiology, Computer Science and Biomedical Engineering, School of Medicine, L4-120, Health Sciences Center, Stony Brook University, Stony Brook, NY 11794-8460, USA, (Tel): +1 631-444-7837, (Fax): +1 631-444-6450
| | - Robert Richards
- Associate Professor, Program Director - GI Fellowship, Department of Medicine/Gastroenterology, Health Science Center, Level 17, Room 060, Stony Brook University, Stony Brook, NY 11794-8173, USA, (Tel): +1 631-444-7623
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94
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CT colonography standards. Clin Radiol 2010; 65:474-80. [PMID: 20451015 DOI: 10.1016/j.crad.2009.12.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 11/30/2009] [Accepted: 12/06/2009] [Indexed: 12/17/2022]
Abstract
Computed tomography (CT) colonography is the established successor to the barium enema for the detection of colonic neoplasia due to superior performance and patient experience. Consequently, CT colonography is widely disseminated across Western populations and increasingly provided by both subspecialist and general radiologists alike. As a result, CT colonography is now part of the core training curriculum for radiology in the UK. However, study data shows wide performance gaps between centres and between individuals of differing experience, which is perhaps unsurprising given the complexity of the CT colonography technique and interpretation. This article summarizes the background, evolution and recommendations of the CT colonography standards document (Appendix) developed by the International CT Colonography Standards Collaboration, which included highly experienced radiologists, radiographers, gastroenterologists, and screening experts. These standards are intended to guide and support radiology teams across the world by promoting methods for improving the quality of CT colonography technique and the patient experience.
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95
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McFarland EG, Fletcher JG, Pickhardt P, Dachman A, Yee J, McCollough CH, Macari M, Knechtges P, Zalis M, Barish M, Kim DH, Keysor KJ, Johnson CD. ACR Colon Cancer Committee white paper: status of CT colonography 2009. J Am Coll Radiol 2010; 6:756-772.e4. [PMID: 19878883 DOI: 10.1016/j.jacr.2009.09.007] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Accepted: 09/02/2009] [Indexed: 12/21/2022]
Abstract
PURPOSE To review the current status and rationale of the updated ACR practice guidelines for CT colonography (CTC). METHODS Clinical validation trials in both the United States and Europe are reviewed. Key technical aspects of the CTC examination are emphasized, including low-dose protocols, proper insufflation, and bowel preparation. Important issues of implementation are discussed, including training and certification, definition of the target lesion, reporting of colonic and extracolonic findings, quality metrics, reimbursement, and cost-effectiveness. RESULTS Successful validation trials in screening cohorts both in the United States with ACRIN and in Germany demonstrated sensitivity > or = 90% for patients with polyps >10 mm. Proper technique is critical, including low-dose techniques in screening cohorts, with an upper limit of the CT dose index by volume of 12.5 mGy per examination. Training new readers includes the requirement of interactive workstation training with 2-D and 3-D image display techniques. The target lesion is defined as a polyp > or = 6 mm, consistent with the American Cancer Society joint guidelines. Five quality metrics have been defined for CTC, with pilot data entered. Although the CMS national noncoverage decision in May 2009 was a disappointment, multiple third-party payers are reimbursing for screening CTC. Cost-effective modeling has shown CTC to be a dominant strategy, including in a Medicare cohort. CONCLUSION Supported by third-party payer reimbursement for screening, CTC will continue to further transition into community practice and can provide an important adjunctive examination for colorectal screening.
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Lee D, Muston D, Sweet A, Cunningham C, Slater A, Lock K. Cost effectiveness of CT colonography for UK NHS colorectal cancer screening of asymptomatic adults aged 60-69 years. APPLIED HEALTH ECONOMICS AND HEALTH POLICY 2010; 8:141-154. [PMID: 20369905 DOI: 10.2165/11535650-000000000-00000] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
BACKGROUND Screening of populations at risk for colorectal cancer (CRC) allows the detection and successful treatment of tumours and their precursor polyps. The current UK CRC screening programme is faecal occult blood testing (FOBT), despite evidence from modelling studies to suggest that more cost-effective technologies exist. OBJECTIVE To assess the cost effectiveness of CT colonography (CTC) for colorectal cancer screening from the perspective of the UK NHS. METHODS A state-transition Markov model was constructed to estimate lifetime costs and health outcomes of a cohort of individuals screened at age 60-69 years using four different CRC screening technologies: FOBT, flexible sigmoidoscopy, optical colonoscopy and CTC. RESULTS CTC screening offered every 10 years was cost saving compared with the current UK programme of biennial FOBT screening. This strategy also yielded greater health benefits (QALYs and life-years) than biennial FOBT screening. The model fit observed CRC epidemiology data well and was robust to changes in underlying parameter values. CTC remained cost effective under a range of assumptions in the univariate sensitivity analysis. However, in the probabilistic sensitivity analysis, CTC dominated FOBT in only 5.9% of simulations and was cost effective at a threshold of pound30,000 per QALY gained in 48% of simulations. CONCLUSIONS CTC has the potential to provide a cost-effective option for CRC screening in the UK NHS and may be cost saving compared with the current programme of biennial FOBT. Further analysis is required to assess the impact of introducing CTC to the UK CRC screening programme on the NHS budget and capacity.
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Affiliation(s)
- David Lee
- Health Economics - Americas, GE Healthcare, Waukesha, Wisconsin 53188-1615, USA
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Abstract
The use of CT in the US has been increasing exponentially over the past decade. The greatest increases in CT use have been in pediatric diagnosis and adult screening. Unfortunately, there is little cognizance among health-care providers (or their patients) about the relative latent cancer risks associated with repetitive exposure to ionizing radiation. Given the exposure of a relatively high proportion of the population to these tests, it is incumbent on health-care providers to have an improved understanding of these risks and discuss them accordingly with their patients. The risks and benefits of these tests should be carefully analyzed and radiation exposure risk assessment should be conducted as part of the selection of diagnostic and screening tests. Appropriate discussion between physicians and patients of the risks associated with radiographic studies is warranted to inform patients of the longitudinal risks of subsequent testing.
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Zijta FM, Bipat S, Stoker J. Magnetic resonance (MR) colonography in the detection of colorectal lesions: a systematic review of prospective studies. Eur Radiol 2009; 20:1031-46. [PMID: 19936754 PMCID: PMC2850516 DOI: 10.1007/s00330-009-1663-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2009] [Revised: 08/26/2009] [Accepted: 09/17/2009] [Indexed: 12/16/2022]
Abstract
Objective To determine the diagnostic accuracy of MR-colonography for the detection of colorectal lesions. Methods A comprehensive literature search was performed for comparative MR-colonography studies, published between May 1997 and February 2009, using the MEDLINE, EMBASE and Cochrane databases. We included studies if MR-colonography findings were prospectively compared with conventional colonoscopy in (a)symptomatic patients. Two reviewers independently extracted study design characteristics and data for summarising sensitivity and specificity. Heterogeneity in findings between studies was tested using I2 test statistics. Sensitivity and specificity estimates with 95% confidence intervals (CI) were calculated on per patient basis and summary sensitivity on per polyp basis, using bivariate and univariate statistical models. Results Thirty-seven studies were found to be potentially relevant and 13 fulfilled the inclusion criteria. The study population comprised 1,285 patients with a mean disease prevalence of 44% (range 22–63%). Sensitivity for the detection of CRC was 100%. Significant heterogeneity was found for overall per patient sensitivity and specificity. For polyps with a size of 10 mm or larger, per patient sensitivity and specificity estimates were 88% (95% CI 63–97%; I2 = 37%) and 99% (95% CI 95–100%; I2 = 60%). On a per polyp basis, polyps of 10 mm or larger were detected with a sensitivity of 84% (95% CI 66–94%; I2 = 51%). The data were too heterogeneous for polyps smaller than 6 mm and 6–9 mm. Conclusion MR-colonography can accurately detect colorectal polyps more than 10 mm in size
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Affiliation(s)
- Frank M Zijta
- Department of Radiology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
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Giraud P, Henni M, Cosset JM. Risques de l’irradiation en hépato-gastro-entérologie. Presse Med 2009; 38:1680-9. [DOI: 10.1016/j.lpm.2008.09.027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2008] [Accepted: 09/03/2008] [Indexed: 11/16/2022] Open
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