Meta-analysis: Diagnostic Performance of Low-Radiation-Dose Coronary Computed Tomography Angiography

Background: A new radiation dose-saving technique for noninvasive coronary artery imaging with computed tomography (CT) is available. Purpose: To summarize current evidence about the ability of low-dose coronary CT angiography to rule out coronary artery disease (CAD) in symptomatic adults. Data Sources: Online databases, including MEDLINE, EMBASE, and the Cochrane Library, from inception through 31 October 2010; abstract databases; gray literature; reference lists of identified articles; and experts. No language restrictions were applied. Study Selection: All investigators screened and selected studies that compared prospective electrocardiography-gated coronary CT angiography with catheter coronary angiography (the reference standard) in symptomatic patients with suspected CAD. Data Extraction: Two investigators independently extracted patient and study protocol characteristics and rated methodological quality; differences were resolved by consensus or by a third reader. Multivariate random-effects models were used to obtain pooled estimates. Data Synthesis: 16 studies, comprising 960 patients, were found (7 studies of single-source, 64-slice CT; 4 of dual-source, 64-slice CT; 2 of single-source, 320-slice CT; 1 dual-source, 128-slice CT; 1 of single-source, 128-slice CT; and 1 of single-source, 256-slice CT). On average, 2.4% of the coronary arterial segments were of non-diagnostic image quality, and 1 or more segments were nondiagnostic in 9.5% of the patients. The patient-level sensitivity and specificity of CT angiography were 1.00 (95% Cl, 0.98 to 1.00) and 0.89 (Cl, 0.85 to 0.92), respectively. The pooled vessel-and segment-level estimates showed lower sensitivity and higher specificity than the patient-level estimates. Statistically significant heterogeneity was found between studies for vessel-and segment-level estimates, which seemed to be associated with body mass index and prevalence of CAD but not with CT scanner characteristics. Limitations: The small number of studies, half of which were from a single tertiary center, limits generalizability. The potential harms of the imaging tests were not well-evaluated. Conclusion: Early evidence suggests that low-dose coronary CT angiography matches the sensitivity of catheter-based angiography, has low radiation exposure, and is a potentially valid alternative to catheter angiography for triaging symptomatic patients with a clinical suspicion of CAD.