Predicting success of prospective and retrospective gating with dual-source coronary computed tomography angiography: Development of selection criteria and initial experience

BackgroundProspectively gated coronary computed tomographic angiography (CCTA) with dual-source CT allows substantial reduction of radiation exposure but requires prospective single-phase selection and assessment of likelihood of adequate image quality.ObjectiveWe developed and tested the model for predicting success of prospectively gated CCTA.MethodsRetrospectively gated CCTA was acquired with dual-source CT in 162 patients. Two cardiologists assessed by consensus whether diagnostic quality images could have been obtained in a single predefined phase, 70% of R-R interval (70P), thereby identifying patients in whom a prospectively gated scan at 70P would have been successful. Logistic regression models were built with and without a coronary calcium scan. The obtained criteria were applied on 42 additional patients.ResultsBy logistic regression, heart rate before CCTA of ≥70 beats/min, maximal heart rate variation before CCTA of ≥10 beats/min, coronary calcium score ≥ 400 U, and body mass index (in kg/m2) ≥ 30 were independent predictors of unsuccessful prospectively gated CCTA using 70P. Excluding coronary calcium score from the model, these same variables in addition to age > 65 years were found to be predictors of unsuccessful prospectively gated CCTA. Applying this model to 42 additional patients, using prospective gating, only 5 segments in 4 patients were nondiagnostic. Mean radiation dose for prospectively gated CCTA was 2.2 ± 0.8 mSv.ConclusionProspectively gated CCTA with dual-source CT can be successfully implemented with consideration of prescan heart rate, heart rate variability, body mass index, and coronary calcium score.