In vivo reduction of radiation exposure with a single-source coronary CT angiography: effects of optimal parameters settings in real life conditions

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1 In vivo reduction of radiation exposure with a single-source coronary CT angiography: effects of optimal parameters settings in real life conditions Poster No.: C-1111 Congress: ECR 2011 Type: Authors: Keywords: DOI: Scientific Paper A. Tavildari, L. Maillard, F. Vochelet; Aix en Provence/FR Cardiac, Radioprotection, CT, CT-Angiography, Technical aspects, Dosimetry /ecr2011/C-1111 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 12

2 Purpose To assess the feasibility of in vivo radiation reduction only by modifying acquisition parameters in real life conditions with a single source 64-slice CT Comparison of radiation exposure between two acquisition modes and with conventional angiography Methods and Materials Patients : Over 18 YO Co-morbidities including diabetes mellitus and overweight were not excluded Coronary calcifications were not excluded All patients recieved sublingual nitrate Target heart rate was under 65 bpm at acquisition time Atenolol intraveinously was given if needed Informed consent was obtained for all patients Acquisition parameters : General Electric VCT XTe Prospective acquisition if heart rate (HR) under 65 bpm 80 kv or 100 kv 120 ma to 400 ma Acquisition at 75% of R-R intervall No padding Retrospective acquisition if HR between 65 and 75 bpm 80 kv or 100 kv Modulation limited to 400 ma (maximum around phase 75%) Reconstruction every 10% from phase 0% to phase 90% Image quality : Evaluatued on a per-segment basis using the American Heart Association coronary model Two independant observers gradded image quality on a 4 point scale 1 : excellent : vessel fully evaluable, no artifact 2 : good : vessel fully evaluable, slight artifacts 3 : fair : evaluable concerning the presence of stenosis, blurred vessel margins 4 : unevaluable Page 2 of 12

3 Average quotation was taken into account if in case of difference between the 2 observers Radiation dose Based on the dose-lenght product (DLP, mgy.cm), and effective dose (ED, msv) ED derived from DLP using a conversion factor of for male and for female Conventional angiography Performed for patients with coronary stenosis on CT GE Innova all-digital X-Ray system No ventriculography Radiation dose expressed with Dose Surface Product Conversion factor for ED = 0.2 Images for this section: Fig. 1: Image quality = 1 Page 3 of 12

4 Fig. 2: Image quality = 2 Page 4 of 12

5 Fig. 3: Image quality = 3 Page 5 of 12

6 Fig. 4: Image quality = 4 Page 6 of 12

7 Results Patients characteristics (n=137): Characteristics Values Age (yr) 62 +/ Sex ratio (%male) 84 % Body mass index (kg/m2) 27 +/- 4.1 Heart rate (bpm) 62+/- 6.7 Use of atenolol 52 % Image quality Over 2055 segments : 97.7 % were evaluable (quality score 1,2 or3) 86 % were good or excellent (quality score 1 or 2) Prospective acquisition has been performed for 85.4 % of patients (n=117) Conventional angiography done for 20 patients to confirm coronary stenosis seen on CT Radiation exposure : Mean DLP of 56+/ mgy.cm (0.7+/-0.3 msv) was obtained with prospective acquisition Mean DLP of 575+/ mgy.cm (7.4+/-1.8 msv) was obtained with prospective acquisition Mean effective dose of 8.39 msv+/-2.16 msv was obtained with conventional angiography Images for this section: Page 7 of 12

8 Fig. 1: Comparison of effective doses between conventional angiography, retrospective acquisition and prospective acquisition : for the whole population, radiation exposure is lower with CCTA, and prospective mode is more than ten times less radiating than conventional coronary angiography. Page 8 of 12

9 Conclusion Our study was able to demonstrate that very low dose coronary CT is feasible with a standard 64 slice CT Radiation dose was dramatically reduced in all acquisition modes compared to historical data and to conventional angiography Prefered mode is prospective These data may reconsider the decisional algorithm for coronary artery stenosis detection Radiation dose for the whole studied population is nearly as low as a mammogram CCTA could be proposed, with the parameter settings used in this study, for screening asymptomatic patients with high cardio-vascular risk factors References 1. Stein PD, Yaekoub AY, Matta F, Sostman HD. 64-slice CT for diagnosis of coronary artery disease: a systematic review. Am J Med. 2008;121(8): Bluemke DA, Achenbach S, Budoff M, Gerber TC, Gersh B, Hillis LD, Hundley WG, Manning WJ, Printz BF, Stuber M, Woodard PK. Noninvasive coronary artery imaging: magnetic resonance angiography and multidetector computed tomography angiography: a scientific statement from the american heart association committee on cardiovascular imaging and intervention of the council on cardiovascular radiology and intervention, and the councils on clinical cardiology and cardiovascular disease in the young. Circulation. 2008;118(5): Miller JM, Rochitte CE, Dewey M, Arbab-Zadeh A, Niinuma H, Gottlieb I, Paul N, Clouse ME, Shapiro EP, Hoe J, Lardo AC, Bush DE, de Roos A, Cox C, Brinker J, Lima JA. Diagnostic performance of coronary angiography by 64-row CT. N Engl J Med. 2008;359(22): Budoff MJ, Dowe D, Jollis JG, Gitter M, Sutherland J, Halamert E, Scherer M, Bellinger R, Martin A, Benton R, Delago A, Min JK. Diagnostic performance of 64-multidetector row coronary computed tomographic angiography for evaluation of coronary artery stenosis in individuals without known coronary artery disease: results from the prospective multicenter ACCURACY (Assessment by Coronary Computed Tomographic Angiography of Individuals Undergoing Invasive Coronary Angiography) trial. J Am Coll Cardiol. 2008;52(21): Page 9 of 12

10 5. Einstein AJ, Henzlova MJ, Rajagopalan S. Estimating risk of cancer associated with radiation exposure from 64-slice computed tomography coronary angiography. JAMA. 2007;298(3): Hirai N, Horiguchi J, Fujioka C, Kiguchi M, et al. Prospective versus retrospective ECGgated 64-detector coronary CT angiography: assessment of image quality, stenosis, and radiation dose. Radiology. 2008;248(2): Shuman WP, Branch KR, May JM, et al. Prospective versus retrospective ECG gating for 64-detector CT of the coronary arteries: comparison of image quality and patient radiation dose. Radiology. 2008;248(2): Austen WG, Edwards JE, Frye RL, et al. A reporting system on patients evaluated for coronary artery disease. Report of the Ad Hoc Committee for Grading of Coronary Artery Disease, Council on Cardiovascular Surgery, American Heart Association. Circulation. 1975;51(4 Suppl): Einstein AJ, Moser KW, Thompson RC, Cerqueira MD, Henzlova MJ. Radiation dose to patients from cardiac diagnostic imaging. Circulation. 2007;116(11): Hausleiter J, Meyer T, Hermann F, et al.estimated radiation dose associated with cardiac CT angiography. JAMA. 2009;301(5): Gaspar T, Halon DA, Lewis BS, et al.diagnosis of coronary in-stent restenosis with multidetector row spiral computed tomography. J Am Coll Cardiol. 2005;46(8): Morin RL, Gerber TC, McCollough CH. Radiation dose in computed tomography of the heart. Circulation. 2003;107(6): Gerber TC, Stratmann BP, Kuzo RS, Kantor B, Morin RL. Effect of acquisition technique on radiation dose and image quality in multidetector row computed tomography coronary angiography with submillimeter collimation. Invest Radiol. 2005;40(8): Coles DR, Smail MA, Negus IS, et al.comparison of radiation doses from multislice computed tomography coronary angiography and conventional diagnostic angiography. J Am Coll Cardiol. 2006;47(9): Trabold T, Buchgeister M, Kuttner A, et al.estimation of radiation exposure in 16- detector row computed tomography of the heart with retrospective ECG-gating. Rofo. 2003;175(8): Kalender WA, Wolf H, Suess C, Gies M, Greess H, Bautz WA. Dose reduction in CT by on-line tube current control: principles and validation on phantoms and cadavers. Eur Radiol. 1999;9(2): Page 10 of 12

11 17. Weustink AC, Mollet NR, Pugliese F, et al. Optimal electrocardiographic pulsing windows and heart rate: effect on image quality and radiation exposure at dual-source coronary CT angiography. Radiology. 2008;248(3): Steigner ML, Otero HJ, Cai T, et al. Narrowing the phase window width in prospectively ECG-gated single heart beat 320-detector row coronary CT angiography. Int J Cardiovasc Imaging. 2009;25(1): Ketelsen D, Luetkhoff MH, Thomas C, et al. Estimation of the radiation exposure of a chest pain protocol with ECG-gating in dual-source computed tomography. Eur Radiol. 2009;19(1): Horiguchi J, Kiguchi M, Fujioka C, et al. Variability of repeated coronary artery calcium scoring and radiation Dose on 64- and 16-slice computed tomography by prospective electrocardiographically-triggered axial and retrospective electrocardiographically-gated spiral computed tomography: a phantom study. Acad Radiol. 2008;15(8): Scheffel H, Alkadhi H, Leschka S, et al. Low-dose CT coronary angiography in the step-and-shoot mode: diagnostic performance. Heart. 2008;94(9): Leschka S, Stolzmann P, Schmid FT, et al. Low kilovoltage cardiac dual-source CT: attenuation, noise, and radiation dose. Eur Radiol. 2008;18(9): Rybicki FJ, Otero HJ, Steigner ML, et al. Initial evaluation of coronary images from 320-detector row computed tomography. Int J Cardiovasc Imaging. 2008;24(5): Agatston AS, Janowitz WR, Hildner FJ, Zusmer NR, Viamonte M, Jr., Detrano R. Quantification of coronary artery calcium using ultrafast computed tomography. J Am Coll Cardiol. 1990;15(4): Hendee WR, Edwards FM. ALARA and an integrated approach to radiation protection. Semin Nucl Med. 1986;16(2): Personal Information Alain TAVILDARI MD, François VOCHELET MD, Luc MAILLARD MDPhD Service de Cardiologie Clinique AXIUM 21 avenue Alfred CAPUS AIX EN PROVENCE Contact : atavildari@aol.fr Page 11 of 12

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