Coronary Artery Calcium Score: Influence of the Reconstruction Interval on Cardiac Risk Stratification in Asymptomatic Patients using Dual-Source Computed Tomography

Zusammenfassung

Ziel: Ziel dieser Studie war es, den Einfluss unterschiedlicher Rekonstruktionszeitpunkte auf den koronaren Kalkscore bei der Dual-Source-Computertomografie (DSCT) und den Einfluss auf die individuelle kardiovaskuläre Risikoabschätzung zu untersuchen. Material und Methoden: Bei 61 konsekutiven Patienten wurde die Bestimmung des Agatston-Scores mittels DSCT durchgeführt. Für jeden Patienten erfolgte die Berechnung von fünf diastolischen Datensätzen (50 %, 55 %, 60 %, 65 % und 70 % des R–R-Intervalls). Für alle Rekonstruktionsintervalle wurden der mittlere Agatston-Score, der Volumenscore sowie die jeweilige relative Variabilität bestimmt. Auf Basis eines alters- und geschlechtbasierten Normalkollektives erfolgte die Einschätzung des individuellen kardiovaskulären Risikos. Ergebnisse: Der mittlere Agatston-Score lag bei 184,8 ± 377,9 (relative Variabilität 47 ± 52 %). Der mittlere Volumenscore lag bei 164,4 ± 310,1 (relative Variabilität 49 ± 58 %). Es zeigte sich eine negative Korrelation zwischen dem Agatston-Score und der relativen Variabilität (r = –0,37; p < 0,01). Abhängig vom Rekonstruktionsintervall wurden 18 vornehmlich jüngere Patienten zu mehr als einer Risikogruppe zugeordnet. Schlussfolgerung: Trotz erhöhter zeitlicher Auflösung der DSCT-Untersuchungen hängen Agatston- und Volumenscores von dem jeweiligen Rekonstruktionsintervall während des Herzzyklus ab. Die Tatsache, dass die höchste relative Variabilität der Agatston- und Volumenscores sich bei jungen Patienten mit geringen koronaren Kalkwerten finden, kann unterschiedliche Behandlungsstrategien zur Folge haben. Die Auswertung mehrerer Rekonstruktionsintervalle könnte gegebenenfalls zu einer genaueren Analyse des koronaren Kalkscores und somit zu einer besseren Risikostratifizierung führen.

Abstract

Purpose: To evaluate the impact of the reconstruction interval on coronary calcium score and cardiac risk stratification using dual-source computed tomography (DSCT). Materials and Methods: DSCT coronary calcium scoring was performed in 61 consecutive patients, and five data sets per patient were reconstructed within diastole (50 – 70 % of the R–R interval). The Agatston score, volumetric score and the relative variability were assessed for all reconstructions. To assess the individual cardiovascular risk, patients were assigned to risk groups based on age and gender-matched percentile ranks. Results: The mean Agatston score was 184.8 ± 377.9 (relative variability 47 % ± 52 %). The mean volumetric score was 164.4 ± 310.1 (relative variability 49 % ± 58 %). There was a negative correlation between the total Agatston score and the relative variability (r = –0.37; p < 0.01). Depending on the reconstruction interval used, 18 predominantly young patients were assigned to more than one risk group. Conclusion: Despite the increased temporal resolution of DSCT examinations, the Agatston and volumetric scores depend on the reconstruction time within the cardiac cycle. The fact that the greatest relative variability for both the Agatston score and the volumetric score was found in young patients with small amounts of coronary calcium may result in different treatment strategies for young patients depending on the reconstruction used. Therefore, more accurate risk stratification may require the analysis of multiple reconstruction intervals.

Key words

cardiac - CT - calcium scoring - Agatston score - cardiac risk stratification

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