European Journal of Radiology 81 (2012) e94–e100 Contents lists available at ScienceDirect European Journal of Radiology journal homepage: www.elsevier.com/locate/ejrad Review Prospective versus retrospective ECG-gated multislice CT coronary angiography: A systematic review of radiation dose and diagnostic accuracy Zhonghua Sun a,∗ , Kwan-Hoong Ng b a Discipline of Medical Imaging, Department of Imaging and Applied Physics, Curtin University of Technology, GPO Box U1987 Perth, Western Australia 6845, Australia b Department of Biomedical Imaging, University of Malaya, Kuala Lumpur 50603, Malaysia article info Article history: Received 28 September 2010 Received in revised form 11 January 2011 Accepted 17 January 2011 Keywords: Coronary artery disease Prospective ECG-gating Radiation dose Image quality CT angiography abstract Purpose: To perform a systematic review of the radiation dose and diagnostic accuracy of prospective versus retrospective ECG-gated multislice CT coronary angiography. Materials and methods: A search of Pubmed/Medline and Sciencedirect databases for English literature was performed to identify studies comparing prospective and retrospective ECG-gated multislice CT angiography in the diagnosis of coronary artery disease. Effective dose, dose length product, image quality and diagnostic value were compared between two groups of studies. Results: 22 studies were included for analysis. The mean effective dose of prospective ECG-gated scans was 4.5 mSv (95% CI: 3.6, 5.3 mSv), which is significantly lower than that of retrospective scans, which is 13.8 mSv (95% CI: 11.5, 16.0 mSv) (p < 0.001). The mean dose length product was 225 mGy cm (95% CI: 188, 262 mGy cm) and 822 mGy cm (95% CI: 630, 1013 mGy cm) for the prospective and retrospective ECG-gated scans, respectively, indicating a statistically significant difference between these two protocols (p < 0.0001). The mean sensitivity and specificity of multislice CT angiography in the diagnosis of coronary artery disease was 97.7% (95% CI: 93.7%, 100%) and 92.1% (95% CI: 87.2%, 97%) for prospective ECG- gated scans; 95.2% (95% CI: 91%, 99.5%) and 94.4% (95% CI: 88.5%, 100%) for retrospective ECG-gated scans, respectively, with no significant difference for sensitivity but significant difference for specificity (p = 0.047). Conclusion: Multislice CT coronary angiography with prospective ECG-gating leads to a significant reduc- tion of radiation dose when compared to that of retrospective ECG-gating, while offering comparable image quality and diagnostic value. © 2011 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Since the introduction of 64- or more-slice CT technology, mul- tislice CT (MSCT) angiography has been increasingly used in the diagnosis of coronary artery disease (CAD) due to its improved spa- tial and temporal resolution [1–4]. Studies have shown that MSCT angiography is a highly accurate method compared to invasive coronary angiography as it provides high sensitivity and speci- ficity [1–6]. In particular, MSCT angiography has been reported to demonstrate a very high negative predictive value (more than 95%), indicating that it can be used as a reliable screening technique for patients suspected of CAD, thereby reducing the need for invasive coronary angiography [5]. The non-invasive nature of MSCT angiog- raphy and increased availability of MSCT scanners have led to rapidly increasing numbers of CT examinations performed world- wide. However, high radiation dose of MSCT angiography and its ∗ Corresponding author. Tel.: +61 8 9266 7509; fax: +61 8 9266 2377. E-mail address: z.sun@curtin.edu.au (Z. Sun). associated risk of radiation-induced malignancy have raised serious concerns in the medical field [7–10]. In response to these concerns, tremendous progress has been made to lower radiation dose for cardiac MSCT angiography, and various strategies have been proposed to address this issue. These include automatic tube current modulation, reduced X-ray tube voltage and tube current, scan range, and prospective ECG- gating [11]. Of these dose-saving strategies, prospective ECG-gated scanning represents the most recently developed approach with significant reduction of radiation dose when compared to conven- tional retrospective ECG-gating [12]. Radiation exposure with prospective ECG-gating has been increasingly studied and evaluated with retrospective-gating in the literature [11–14]. Despite promising results having been achieved in dose reduction, there are concerns about the image quality and diagnostic value of prospective ECG-gating, since only a portion of data is acquired when compared to the volumetric data that is available with retrospective-gating protocol. Thus, the purpose of this study was to perform a systematic review of radiation dose and diagnostic accuracy of prospective versus retrospective ECG-gated 0720-048X/$ – see front matter © 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrad.2011.01.070