Reconstructions with identical filling (RIF) of the heart: a physiological approach to image reconstruction in coronary CT angiography.

OBJECTIVES: To compare image quality in coronary artery computed tomography angiography (cCTA) using reconstructions with automated phase detection and Reconstructions computed with Identical Filling of the heart (RIF).
METHODS: Seventy-four patients underwent ECG-gated dual source CT (DSCT) between November 2009 and July 2010 for suspected coronary heart disease (n = 35), planning of transcatheter aortic valve replacement (n = 34) or evaluation of ventricular function (n = 5). Image data sets by the RIF formula and automated phase detection were computed and evaluated with the AHA 15-segment model and a 5-grade Likert scale (1: poor, 5: excellent quality). Subgroups regarding rhythm (sinus rhythm = SR; arrhythmia = ARR) and potential premedication were evaluated by a per-segment, per-vessel and per-patient analysis.
RESULTS: RIF significantly improved image quality in 10 of 15 coronary segments (P < 0.05). More diagnostic segments were provided by RIF regarding the entire cohort (n = 693 vs. 590, P < 0.001) and all of the subgroups (e.g. ARR: n = 143 vs. 72, P < 0.001). In arrhythmic patients (n = 19), more diagnostic vessels (e.g. LAD: n = 10 vs. 3; P < 0.014) and complete data sets (n = 7 vs. 1; P < 0.001) were produced.
CONCLUSIONS: RIF reconstruction is superior to automatic diastolic non-edited reconstructions, especially in arrhythmic patients. RIF theory provides a physiological approach for determining the optimal image reconstruction point in ECG-gated CT angiography. KEY POINTS: Conventional CT coronary angiography suffers from numerous artefacts in patients with irregular rhythms. Coronary computed tomography angiograms (cCTA) were reconstructed with identical cardiac filling (RIF). RIF reconstructions provide improved image quality compared to non-edited standard reconstructions. RIF theory links physiology with cardiac CT.