| Objective:(a) To compare image quality between sinogram affirmed iterativereconstruction (SAFIRE) and filtered back projection (FBP) algorithms in adaptivesequence scan of coronary CT angiography (CTA).(b) To assess the image quality andradiation dose of adaptive sequence scan of CCTA using reduced tube voltage andSAFIRE, in comparison with CT using routine tube voltage and FBP reconstruction.Methods:50patients who had suspected coronary artery disease underwent coronaryCTA using reduced tube voltage and SAFIRE according to body mass index (BMI):(a)80kV for BMI <25kg/m2(group A),(b)100kV for BMI≥25kg/m2(group C). Forcomparison, the two sex-age-and BMI-matched groups using routine tube voltage andFBP reconstruction were selected:(a)100kV for BMI <25kg/m2(group B),(b)120kV for BMI≥25kg/m2(group D). Coronary CTA using prospective ECG-triggeringadaptive sequence scan mode was performed on a2nd generation dual source CTsystem. Acquisition parameters were as follows:2×64×0.6mm detector collimation,280ms gantry rotation time, and320mAs per rotation tube current time product.Parameters for image reconstruction include a slice thickness of0.75mm, increment of0.75mm, and a medium soft convolution kernel (I26f for SAFIRE and B26f for FBP).Contrast medium enhancement was achieved by injecting60-80ml of iodinated contrastmaterial and injected at5.5-6ml/s through an18-G intravenous antecubital catheter byusing a dual-syringe injector. The image noise, signal-to-noise ratio (SNR) andcontrast-to-noise ratio (CNR) were compared respectively between SAFIRE and FBP ineach group. The image noise, SNR, CNR, image quality and radiation dose werecompared respectively in each matched groups (A and B; C and D).Results:In the each group, there was no significant difference in CT attenuation of ascending aorta between two reconstruction algorithms (P>0.05). The image noise wassignificantly lower with SAFIRE than with FBP (P <0.001), and the SNR and CNRwere significantly higher with SAFIRE than with FBP (P <0.001). In patients with aBMI <25kg/m2, the CT attenuation of ascending aorta was significantly higher withSAFIRE and reduced tube voltage (group A) than with FBP and routine tube voltage(group B)(452.1±69.1vs.366.8±56.4HU, P <0.001). The image noise wassignificantly higher in group A than in group B (25.8±5.5vs.21.8±3.8HU, P <0.05).No significant differences in SNR (17.2±4.0vs.15.9±2.9, P>0.05) and CNR (11.7±4.1vs.10.3±3.6, P>0.05) were seen between two groups. There were no significantdifferences in image quality scores between two groups (1.31±0.64vs.1.29±0.62, P>0.05). The effective radiation dose of group A was54.5%lower than that of group B(2.0±0.3vs.4.4±0.8mSv, P <0.001). In patients with a BMI≥25kg/m2, the CTattenuation of ascending aorta was significantly higher with SAFIRE and reduced tubevoltage (group C) than with FBP and routine tube voltage (group D)(336.1±44.3vs.283.7±35.1HU, P <0.001). The image noise was similar between two groups (18.3±3.0vs.18.5±3.5HU, P>0.05). The SNR and CNR were significantly higher in groupC than in group D (18.1±5.2vs.14.4±3.2,11.0±3.9vs.8.2±2.5, P <0.05). Therewere no significant differences in image quality scores between two groups (1.28±0.60vs.1.29±0.61, P>0.05). The effective radiation dose of group C was45.9%lowerthan that of group D (4.0±0.6vs.7.4±1.0mSv, P <0.001).Conclusion:(a) Compared with FBP reconstruction, SAFIRE can reduce image noise and improveimage quality on adaptive sequence scan of coronary CTA using reduced tube voltageor routine tube voltage.(b) Adaptive sequence scan of coronary CTA using reducedtube voltage and SAFIRE can provide equivalent coronary quality, compared with CTusing routine tube voltage and FBP reconstruction, that decreased approximately50%of the radiation dose. |
PDF Full Text Request