Bestimmung des koronaren Kalzium-Scores mittels 64-Zeilen-CT - Variabilität der Scores und Einfluss des Rekonstruktionszeitpunktes

Zusammenfassung

Ziel: Evaluation der Variabilität des koronaren Kalzium-Scores in Abhängigkeit des Rekonstruktionszeitpunktes mittels 64-Zeilen-CT. Material und Methoden: Bei 30 Patienten (18 männlich, 12 weiblich, mittleres Alter 57 ± 9 Jahre) mit einer mittleren Herzrate von 66 ± 10 Schlägen/Minute wurde der koronare Kalzium-Score mittels 64-Zeilen-CT (Somatom Sensation 64, Siemens Medical Solutions, Erlangen) und eines standardisierten Untersuchungsprotokolls bestimmt. Orale β-Blocker wurden bei 12 Patienten mit einer Herzfrequenz > 70 Schlägen/Minute appliziert. Die Bildrekonstruktion erfolgte in 10 %-Schritten von 10 - 100 % des RR-Intervalls im EKG. Für jede dieser Bildrekonstruktionen berechneten zwei erfahrene, geblindete Untersucher den Agatston-Score (AS), den Kalzium-Massen-Score (MS) und den Kalzium-Volumen-Score (VS). Die Ergebnisse wurden mit entsprechenden Studien aus der 16-Zeilen-CT verglichen. Ergebnisse: Die Mittelwerte und mittleren Variationskoeffizienten für alle Patienten waren wie folgt: AS, 397 ± 829, 109 % MS, 88 ± 225, 154 % VS, 335 ± 669, 100 %. Bezüglich des Rekonstruktionsintervalls waren die mittleren Variationskoeffizienten wie folgt: 107 % (AS), 97 % (VS), 116 % (MS). Für keinen Score konnte ein spezifisches Rekonstruktionsintervall identifiziert werden, welches eine statistisch signifikant geringere Variabilität aufwies. Die Interobserver-Übereinstimmung war hoch (K = 0,98). 10/30 Patienten (pts) konnten mit statistischer Signifikanz (p < 0,05) mehr als einer Risikogruppe (RG) zugeordnet werden: 6 pts = 2 RG; 3 pts = 3 RG; 1 pts = 4 RG. Bei 5/30 Patienten wurde ein Score von null in zumindest einem Rekonstruktionsintervall gefunden, jedoch konnte mittels weiterer Bildrekonstruktionen Kalzium nachgewiesen werden. Die Anzahl von Patienten, die mehreren Risikogruppen zugeordnet werden konnten, war signifikant geringer im Vergleich zu publizierten Daten für die 16-Zeilen-CT (p < 0,05). Schlussfolgerung: Die Bestimmung der koronaren Kalzium-Scores mittels 64-Zeilen-CT weist, wie bereits für die 16-Zeilen-CT beschrieben, eine hohe Variabilität in Abhängigkeit des Rekonstruktionszeitpunktes auf. Unsere Ergebnisse zeigen im Vergleich zu früheren Studien, dass mit CT-Geräten dieser Herstellergeneration der Einfluss der Score-Schwankungen auf die Risikostratifizierung reduziert werden kann.

Abstract

Purpose: To evaluate the variability of coronary calcium scores depending on the image reconstruction interval using a 64-slice CT scanner. Materials and Methods: 30 patients (18 male, 12 female; mean age 57 ± 9 yrs; mean heart rate 66 ± 10 bpm) underwent coronary calcium scoring using a 64-slice CT scanner (Somatom Sensation 64, Siemens Medical Solutions, Erlangen) and a standardized scanning protocol. Oral β-blockers were administered to 12 patients with a baseline heart rate > 70 bpm. Images were reconstructed in 10 % increments from 10 - 100 % of the RR interval. Two blinded experienced observers independently calculated Agatston (AS), calcium mass (MS) and volume scores (VS) for every reconstructed image series. The results were compared to similar studies for 16-slice CT scanners. Results: The mean values and mean coefficients of variation among all patients were as follows: AS, 397 ± 829, 109 % MS, 88 ± 225, 154 % VS, 335 ± 669, 100 %. Regarding the reconstruction intervals, the mean coefficients of variation were as follows: 107 % (AS), 97 % (VS), 116 % (MS). No specific image reconstruction interval with statistically significant lower variability for each score could be identified. High inter-observer agreement was achieved (K = 0.98). With statistical significance (p < 0.05) 10/30 patients (pts) were able to be allocated to more than one risk group (RG): 6 pts = 2 RG; 3 pts = 3 RG; 1 pts = 4 RG. The scores for 5/30 patients were zero for at least one reconstruction interval, but further reconstructions revealed calcifications. The number of patients assignable to different risk groups was significantly lower compared to published data using a 16-slice scanner (p < 0.05). Conclusion: Coronary calcium scores determined using a 64-slice scanner display a wide range of variability depending on the image reconstruction interval as already described for 16-slice CT scanners. However, compared to previous studies, our data indicate that this vendor’s generation of scanners reduces the influence of score variations on the risk stratification.

cardiac imaging - computed tomography - coronary calcium - calcium scoring

Literatur

• 1 WHO Statistical Information System .Mortality. WHO 2006 www.who.int/whosis
• 2 Agatston A S, Janowitz W R, Hildner F J. et al . Quantification of coronary artery calcium using ultrafast computed tomography.  J Am Coll Cardiol. 1990;  15 827-832
• 3 Rumberger J A, Simons D B, Fitzpatrick L A. et al . Coronary artery calcium area by electron-beam computed tomography and coronary atherosclerotic plaque area: a histopathologic correlation study.  Circulation. 1995;  92 2157-2162
• 4 Detrano R C, Wong N D, Doherty T M. et al . Coronary calcium does not accurately predict near-term future coronary events in high-risk adults.  Circulation. 1999;  99 2633-2638
• 5 Raggi P, Callister T Q, Cooil B. et al . Identification of patients at increased risk of first unheralded acute myocardial infarction by electron-beam computed tomography.  Circulation. 2000;  101 850-855
• 6 Arad Y, Spadaro L A, Goodman K. et al . Prediction of coronary events with electron beam computed tomography.  J Am Coll Cardiol. 2000;  36 1253-1260
• 7 Wong N D, Hsu J C, Detrano R C. et al . Coronary artery calcium evaluation by electron beam computed tomography and its relation to new cardiovascular events.  Am J Cardiol. 2000;  86 495-498
• 8 Park R, Detrano R, Xiang M. et al . Combined use of computed tomography coronary calcium scores and C-reactive protein levels in predicting cardiovascular events in nondiabetic individuals.  Circulation. 2002;  106 2073-2077
• 9 Kondos G T, Hoff J A, Sevrukov A. et al . Electron-beam tomography coronary artery calcium and cardiac events. A 37-month follow-up of 5,635 initially asymptomatic low- to intermediate-risk adults.  Circulation. 2003;  107 2571-2576
• 10 Breen J F, Sheedy II P F, Schwartz R S. et al . Coronary artery calcification detected with ultrafast CT as an indication of coronary artery disease.  Radiology. 1992;  185 435-439
• 11 Laudon D A, Vukov L F, Breen J F. et al . Use of electron-beam computed tomography in the evaluation of chest pain patients in the emergency department.  Ann Emerg Med. 1999;  33 15-21
• 12 Mautner G C, Mautner S L, Froehlich J. et al . Coronary artery calcification: assessment with electron beam CT and histomorphometric correlation.  Radiology. 1994;  192 619-623
• 13 Sangiorgi G, Rumberger J A, Severson A. et al . Arterial calcification and not lumen stenosis is highly correlated with atherosclerotic plaque burden in humans: a histologic study of 723 coronary artery segments using nondecalcifying methodology.  J Am Coll Cardiol. 1998;  31 126-133
• 14 Rumberger J A, Sheedy P F, Breen J F. et al . Electron beam computed tomographic coronary calcium score cutpoints and severity of associated angiographic lumen stenosis.  J Am Coll Cardiol. 1997;  29 1542-1548
• 15 Greenland P, LaBree L, Azen S P. et al . Coronary artery calcium score combined with Framingham score for risk prediction in asymptomatic individuals.  J Am Med Assoc. 2004;  291 210-215
• 16 Callister T Q, Raggi P, Cooil B. et al . Effect of HMG-CoA reductase inhibitors on coronary artery disease as assessed by electron-beam computed tomography.  N Engl J Med. 1998;  339 1972-1978
• 17 Maher J E, Bielak L F, Raz J A. et al . Progression of coronary artery calcification: a pilot study.  Mayo Clin Proc. 1999;  74 347-355
• 18 Horiguchi J, Yamamoto H, Akiyama Y. et al . Variability of repeated coronary artery calcium measurements by 16-MDCT with retrospective reconstruction.  AJR Am J Roentgenol. 2005;  184 1917-1923
• 19 Ooijen P M van, Vliegenthart R, Witteman J C. et al . Influence of scoring parameter settings on Agatston and volume scores for coronary calcification.  Eur Radiol. 2005;  15 102-110
• 20 Rumberger J A, Brundage B H, Radar D J. Electron beam computed tomographic coronary calcium scanning: a review and guidelines for use in asymptomatic persons.  Mayo Clin Proc. 1999;  74 243-252
• 21 Devries S, Wolfkiel C, Shah V. et al . Reproducibility of the measurement of coronary calcium with ultrafast computed tomography.  Am J Cardiol. 1995;  75 973-975
• 22 Wang S, Detrano R C, Secci A. et al . Detection of coronary calcification with electron-beam CT-beam computed tomography: evaluation of interexamination reproducibility and comparison of three image-acquisition protocols.  Am Heart J. 1996;  132 550-558
• 23 Ulzheimer S, Kalender W A. Assessment of calcium scoring performance in cardiac computed tomography.  Eur Radiol. 2003;  13 484-497
• 24 Hong C, Becker C R, Schoepf U J. et al . Coronary artery calcium: absolute quantification in nonenhanced and contrast-enhanced multi-detector row CT studies.  Radiology. 2002;  223 474-480
• 25 Shemesh J, Tenenbaum A, Kopecky K K. et al . Coronary calcium measurements by double helical computed tomography. Using the average instead of peak density algorithm improves reproducibility.  Invest Radiol. 1997;  32 503-506
• 26 Becker C R, Knez A, Ohnesorge B. et al . Visualization and quantification of coronary calcifications with electron beam and spiral computed tomography.  Eur Radiol. 2000;  10 629-635
• 27 Budoff M J, Mao S, Zalace C P. et al . Comparison of spiral and electron beam tomography in the evaluation of coronary calcification in asymptomatic persons.  Int J Cardiol. 2001;  77 181-188
• 28 Hong C, Bae K T, Pilgram T K. Coronary artery calcium: accuracy and reproducibility of measurements with multi-detector row CT-assessment of effects of different thresholds and quantification methods.  Radiology. 2003;  227 795-801
• 29 Ohnesorge B, Flohr T, Fischbach R. et al . Reproducibility of coronary calcium quantification in repeat examinations with retrospectively ECG-gated multisection spiral CT.  Eur Radiol. 2002;  12 1532-1540
• 30 Mahnken A H, Wildberger J E, Sinha A M. et al . Variation of the coronary calcium score depending on image reconstruction interval and scoring algorithm.  Invest Radiol. 2002;  37 496-502
• 31 Schlosser T, Hunold P, Schmermund A. et al . Coronary artery calcium score: influence of reconstruction interval at 16-detector row CT with retrospective electrocardiographic gating.  Radiology. 2004;  233 586-589
• 32 Sandstede J J, Stoffels J, Wendel F. et al . Different reconstruction intervals for exclusion of coronary artery calcifications by retrospectively gated MDCT.  AJR Am J Roentgenol. 2006;  186 193-197
• 33 Hoff J A, Chomka E V, Krainik A J. et al . Age and gender distributions of coronary artery calcium detected by electron beam tomography in 35,246 adults.  Am J Cardiol. 2001;  87 1335-1339
• 34 Cohen J. A coefficient of agreement for nominal scales.  Educational and Psychological Measurement. 1960;  20 37-46
• 35 Flohr T, Stierstorfer K, Raupach R. et al . Performance Evaluation of a 64-Slice CT System with z-Flying Focal Spot.  Fortschr Röntgenstr. 2004;  176 1803-1810
• 36 Flohr T, Bruder H, Stierstorfer K. et al . New Technical Developments in Multislice CT, Part 2: Sub-Millimeter 16-Slice Scanning and Increased Gantry Rotation Speed for Cardiac Imaging.  Fortschr Röntgenstr. 2002;  174 1022-1027
• 37 Yamamura J, Stevendaal U van, Köster R. et al . Experimental 16-Row CT Evaluation of In-Stent Restenosis using New Stationary and Moving Cardiac Stent Phantoms: Experimental Examination.  Fortschr Röntgenstr. 2006;  178 1079-1085
• 38 Kovacs A, Probst C, Sommer T. et al . CT-Koronarangiographie bei Patienten mit Vorhofflimmern.  Fortschr Röntgenstr. 2005;  177 1655-1662
• 39 Dewey M, Hoffmann H, Hamm B. Multislice CT Coronary Angiography: Effect of Sublingual Nitroglycerine on the Diameter of Coronary Arteries.  Fortschr Röntgenstr. 2006;  178 600-604
• 40 Husmann L, Leschka S. et al . Einfluss des Bodymass-Index auf den Kontrast in den Koronararterien mit der 64-Schicht-CT.  Fortschr Röntgenstr. 2006;  178 1007-1013
• 41 Schlosser T, Hunold P, Voigtlander T. et al . Coronary artery calcium scoring: influence of reconstruction interval and reconstruction increment using 64-MDCT.  AJR Am J Roentgenol. 2007;  188 1063-1068
• 42 Muhlenbruch G, Klotz E, Wildberger J E. et al . The accuracy of 1- and 3-mm slices in coronary calcium scoring using multi-slice CT in vitro and in vivo.  Eur Radiol. 2007;  17 321-329
• 43 Muhlenbruch G, Thomas C, Wildberger J E. et al . Effect of varying slice thickness on coronary calcium scoring with multislice computed tomography in vitro and in vivo.  Invest Radiol. 2005;  40 695-699
• 44 Horiguchi J, Yamamoto H, Hirai N. et al . Variability of repeated coronary artery calcium measurements on low-dose ECG-gated 16-MDCT.  AJR Am J Roentgenol. 2006;  187 W1-6
• 45 Lawler L P, Horton K M, Scatarige J C. et al . Coronary artery calcification scoring by prospectively triggered multidetector-row computed tomography: is it reproducible?.  J Comput Assist Tomogr. 2004;  28 40-45
• 46 Thomas C K, Muhlenbruch G, Wildberger J E. et al . Coronary artery calcium scoring with multislice computed tomography: in vitro assessment of a low tube voltage protocol.  Invest Radiol. 2006;  41 668-673
• 47 Muhlenbruch G, Hohl C, Das M. et al . Evaluation of automated attenuation-based tube current adaptation for coronary calcium scoring in MDCT in a cohort of 262 patients.  Eur Radiol. DOI: 10.1007/s00330 -006-0543-4
• 48 Jakobs T F, Wintersperger B J, Herzog P. et al . Ultra-low-dose coronary artery calcium screening using multislice CT with retrospective ECG gating.  Eur Radiol. 2003;  13 1923-1930