In vitro measurement of CT density and estimation of stenosis related to coronary soft plaque at 100 kV and 120 kV on ECG-triggered scan

PurposeThe purpose of the study was to compare 100 kV and 120 kV prospective electrocardiograph (ECG)-triggered axial coronary 64-detector CT angiography (64-MDCTA) in soft plaque diagnosis.Materials and methodsCoronary artery models (n = 5) with artificial soft plaques (−32 HU to 53 HU at 120 kV) with three stenosis levels (25%, 50% and 75%) on a cardiac phantom (mimicking slim patient's environment) were scanned in heart rates of 55, 60 and 65 beats per minute (bpm). Four kinds of intracoronary enhancement (205 HU, 241 HU, 280 HU and 314 HU) were simulated. The soft plaque density and the measurement error of stenosis (in percentage), evaluated by two independent observers, were compared between 100 kV and 120 kV. The radiation dose was estimated.ResultsInterobserver correlation of the measurement was excellent (density; r = 0.95 and stenosis measure; r = 0.97). Neither the density of soft plaque nor the measurement error of stenosis was different between 100 kV and 120 kV (p = 0.22 and 0.08). The estimated radiation doses were 2.0 mSv and 3.3 mSv (in 14 cm coverage) on 100 kV and 120 kV prospective ECG-triggered axial scans, respectively.ConclusionThe 100 kV prospective ECG-triggered coronary MDCTA has comparable performance to 120 kV coronary CTA in terms of soft plaque densitometry and measurement of stenosis, with a reduced effective dose of 2 mSv.