RESUMEN
BACKGROUND: Cardiac computed tomography angiography (cardiac CTA) is an increasingly used versatile imaging method to evaluate coronary and cardiac morphology. Owing to improvements in technology, image quality has continuously improved over the last 10-20 years. At the same time, numerous non-randomized and randomized studies have been performed to reduce the associated radiation exposure. Currently, it is unclear if the advances in technology and knowledge about radiation reduction translated into reduced levels of cardiac CTA radiation dose in daily clinical practice as well as a wide utilization of dose-saving strategies. METHODS: The PROTECTION VI study is a multicenter, prospective, worldwide registry designed to evaluate radiation dose exposure, utilization of dose-saving strategies and diagnostic image quality during cardiac CTA in current daily practice. Assessment of image quality will be addressed by the evaluation of diagnostic image quality at the local study site and the calculation of quantitative image quality parameters in an imaging core laboratory. Above 4000 patients will be enrolled from approximately 70 sites in Europe, North America, South America, Asia and Australia. The study will analyze median radiation dose levels, image quality, frequency of use and efficacy of algorithms for dose reduction, and patient and study-related predictors associated with radiation dose. CONCLUSIONS: The PROTECTION VI study is designed to provide a reliable estimate of current radiation dose for cardiac CTA and to assess the potential for additional dose reductions.
Asunto(s)
Angiografía por Tomografía Computarizada , Angiografía Coronaria/métodos , Vasos Coronarios/diagnóstico por imagen , Dosis de Radiación , Exposición a la Radiación , Sistema de Registros , Asia , Australia , Angiografía por Tomografía Computarizada/efectos adversos , Angiografía Coronaria/efectos adversos , Europa (Continente) , Humanos , América del Norte , Valor Predictivo de las Pruebas , Estudios Prospectivos , Exposición a la Radiación/efectos adversos , Exposición a la Radiación/prevención & control , Proyectos de Investigación , Medición de Riesgo , América del SurRESUMEN
OBJECTIVES: The purpose of this study was to evaluate image quality and radiation dose using a prospectively electrocardiogram (ECG)-triggered axial scan protocol compared with standard retrospective ECG-gated helical scanning for coronary computed tomography angiography. BACKGROUND: Concerns have been raised regarding radiation exposure during coronary computed tomography angiography. Although the use of prospectively ECG-triggered axial scan protocols may effectively lower radiation dose compared with helical scanning, it is unknown whether image quality is maintained in a clinical setting. METHODS: In a prospective, multicenter, multivendor trial, 400 patients with low and stable heart rates were randomized to either an axial or a helical coronary computed tomography angiography scan protocol. The primary endpoint was to demonstrate noninferiority in image quality with the axial scan protocol, which was assessed on a 4-point scale (1 = nondiagnostic, 4 = excellent image quality). Secondary endpoints included radiation dose and the rate of downstream testing during 30-day follow-up. RESULTS: Image quality in patients scanned with the axial scan protocol (score 3.36 ± 0.59) was not inferior compared with helical scan protocols (3.37 ± 0.59) (p for noninferiority <0.004). Axial scanning was associated with a 69% reduction in radiation exposure (dose-length product [estimated effective dose] 252 ± 147 mGy · cm [3.5 ± 2.1 mSv] vs. 802 ± 419 mGy · cm [11.2 ± 5.9 mSv] for axial vs. helical scan protocols, p < 0.001). The rate of downstream testing did not differ (13.8% vs. 15.9% for axial vs. helical scan protocols, p = 0.555). CONCLUSIONS: In patients with stable and low heart rates, the prospectively ECG-triggered axial scan protocol maintained image quality but reduced radiation exposure by 69% compared with helical scanning. Axial computed tomography data acquisition should be strongly recommended in suitable patients to avoid unnecessarily high radiation exposure.