Prospective Evaluation of the Influence of Iterative Reconstruction on the Reproducibility of Coronary Calcium Quantification in Reduced Radiation Dose 320 Detector Row CT.

BACKGROUND: Coronary artery calcium (CAC) predicts coronary heart disease events and is important for individualized cardiac risk assessment. This report assesses the interscan variability of CT for coronary calcium quantification using image acquisition with standard and reduced radiation dose protocols and whether the use of reduced radiation dose acquisition with iterative reconstruction (IR; reduced-dose/IR ) allows for similar image quality and reproducibility when compared to standard radiation dose acquisition with filtered back projection (FBP; standard-dose/FBP ) on 320-detector row computed tomography (320-CT). METHODS: 200 consecutive patients (60 ± 9 years, 59% male) prospectively underwent two standard- and two reduced-dose acquisitions (800 total scans, 1600 reconstructions) using 320 slice CT and 120 kV tube voltage. Automated tube current modulation was used and for reduced-dose scans, prescribed tube current was lowered by 70%. Image noise and Agatston scores were determined and compared. RESULTS: Regarding stratification by Agatston score categories (0, 1-10, 11-100, 101-400, \u3e400), reduced-dose/IR versus standard-dose/FBP had excellent agreement at 89% (95% CI: 86-92%) with kappa 0.86 (95% CI: 0.81-0.90). Standard-dose/FBP rescan agreement was 93% (95% CI: 89-96%) with kappa = 0.91 (95% CI: 0.86-0.95) while reduced-dose/IR rescan agreement was similar at 91% (95% CI: 87-94%) with kappa 0.88 (95% CI: 0.83-0.93). Image noise was significantly higher but clinically acceptable for reduced-dose/IR (18 Hounsfield Unit [HU] mean) compared to standard-dose/FBP (16 HU; p \u3c 0.0001). Median radiation exposure was 74% lower for reduced- (0.37 mSv) versus standard-dose (1.4 mSv) acquisitions. CONCLUSION: Rescan agreement was excellent for reduced-dose image acquisition with iterative reconstruction and standard-dose acquisition with filtered back projection for the quantification of coronary calcium by CT. These methods make it possible to reduce radiation exposure by 74%. CLINICAL TRIAL REGISTRATION: URL: https://clinicaltrials.gov/ct2/show/NCT01621594. UNIQUE IDENTIFIER: NCT01621594

Feasibility of Low Radiation Dose Retrospectively-Gated Cardiac CT for Functional Analysis in Adult Congenital Heart Disease.

AbstractBackgroundThe use of cardiac computed tomography (CT) in the evaluation of adult congenital heart disease patients is limited due to concerns of high radiation doses. The purpose of this study was to prospectively assess whether low radiation dose cardiac CT is feasible to evaluate ventricular systolic function in adults with congenital heart disease.MethodsThe study group included 30 consecutive patients with significant congenital heart disease who underwent a total of 35 ECG-gated cardiac CT scans utilizing a 320-detector row CT scanner. Each study included a non-contrast scan and subsequent contrast-enhanced retrospectively-gated acquisition. Effective radiation dose was estimated by multiplying the dose length product by a k-factor of 0.014mSv/mGycm.ResultsThe mean age of the patients was 34.4±8.9years, 60% were men, and mean body mass index was 24.2±4.3kg/m2. A majority of patients (n=28, 93.3%) had contraindications to cardiac MRI. A tube potential of 80kV was used in 27 (77.1%) of the contrast-enhanced scans. The mean signal-to-noise and contrast-to-noise ratios were 11.5±3.9 and 10.3±3.7, respectively. The median radiation dose for non-contrast and contrast-enhanced images were 0.1mSv (0.07–0.2mSv) and 0.94mSv (0.5–2.1mSv), respectively. All 35 CT scans were successfully analyzed for ventricular systolic function.ConclusionsA low radiation contrast-enhanced, retrospectively-gated cardiac CT with a median radiation dose of less than 1mSv was successful in evaluating ventricular systolic function in 30 consecutive adult congenital heart disease patients who underwent a total of 35 scans

Feasibility of low radiation dose retrospectively-gated cardiac CT for functional analysis in adult congenital heart disease

AbstractBackgroundThe use of cardiac computed tomography (CT) in the evaluation of adult congenital heart disease patients is limited due to concerns of high radiation doses. The purpose of this study was to prospectively assess whether low radiation dose cardiac CT is feasible to evaluate ventricular systolic function in adults with congenital heart disease.MethodsThe study group included 30 consecutive patients with significant congenital heart disease who underwent a total of 35 ECG-gated cardiac CT scans utilizing a 320-detector row CT scanner. Each study included a non-contrast scan and subsequent contrast-enhanced retrospectively-gated acquisition. Effective radiation dose was estimated by multiplying the dose length product by a k-factor of 0.014mSv/mGycm.ResultsThe mean age of the patients was 34.4±8.9years, 60% were men, and mean body mass index was 24.2±4.3kg/m2. A majority of patients (n=28, 93.3%) had contraindications to cardiac MRI. A tube potential of 80kV was used in 27 (77.1%) of the contrast-enhanced scans. The mean signal-to-noise and contrast-to-noise ratios were 11.5±3.9 and 10.3±3.7, respectively. The median radiation dose for non-contrast and contrast-enhanced images were 0.1mSv (0.07–0.2mSv) and 0.94mSv (0.5–2.1mSv), respectively. All 35 CT scans were successfully analyzed for ventricular systolic function.ConclusionsA low radiation contrast-enhanced, retrospectively-gated cardiac CT with a median radiation dose of less than 1mSv was successful in evaluating ventricular systolic function in 30 consecutive adult congenital heart disease patients who underwent a total of 35 scans