[en] Objective: To assess the effect of snapshot freeze (SSF) motion correction algorithm on the image quality of coronary CT angiography (CCTA). Methods: Thirty-one consecutive patients underwent coronary CTA without heart rate control. All of the CCTA images were reconstructed by the means of both standard (STD) and SSF motion correction. Image quality and interpretability of STD and SSF reconstructions were compared. CCTA images were interpreted with Likert 4-points score system by two experienced radiologists. The image qualities were assessed on per-artery and per-segment level, and interpretability was performed on per-segment, per-artery, and per-patient levels. Comparisons of variables were performed with paired Wilcoxon rank sum test and paired Chi-square test. Results: SSF reconstructions showed higher interpretability than STD reconstructions on per-patient [100.0% (31/31) vs 64.5% (20/31), χ"2=9.09, P=0.002] and per-artery [100.0% (124/124) vs 83.9% (104/124), χ"2=18.05, P=0.001] and per-segment level [99.0% (413/417) vs 89.2% (372/417), χ"2=35.56, P=0.001]. Image qualities were higher with the use of SSF than STD reconstructions on LAD [3.3 ± 0.7 vs 2.9 ± 1.0, Z=2.70, P=0.007], LCX [3.1 ±0.8 vs 2.5 ± 1.1, Z=3.23, P=0.001] and RCA [3.3 ±0.6 vs 2.1 ± 0.9, Z=4.60, P=0.001], but they were similar on LM [3.9 ± 0.4 vs 3.7 ± 0.6, Z=1.89, P=0.059]. Image quality was higher with the use of SSF versus STD reconstructions on per-segment [3.5 ± 0.7 vs 3.0 ± 1.0, Z=10.31, P=0.001] level. Conclusions: The use of SSF motion correction algorithm improves image quality and interpretability of coronary CTA without heart rate control. (authors)

[en] Objective: To evaluate effects on image quality and effective radiation with the dose reduction protocol adapted by body mass index (BMI) in coronary artery CT angiography with discovery 750 HD. Methods: Two hundred and seven patients suspected with coronary artery disease (CAD) were enrolled in Group A who were underwent CT angiography with routine radiation, and another 242 patients were enrolled in Group B who received a new scanning protocol with tube voltage and tube current modulation depending on the BMI. The scores of image quality, signal noise ratio(SNR), CT dose index (CTDI_vol), and effective dose (E) were compared and the correlation between the scanning parameters and E was analyzed. Results: The mean radiation dose in Group B(1.2, ranging from 0.8 to 2.5 mSv) was significantly lower than that in Group A(1.9, ranging from 1.5 to 2.3 mSv; Z = -6.24, P < 0.05). The multivariate regression analysis revealed that the first factor affecting effective radiation dose ranked as scanning mode, tube voltage, tube current, and scan length, respectively. The image quality between two groups was not significantly different. The SNR in Group B was greater than that in Group A (Z = -2.22, P < 0.05). Conclusions: Dose reduction protocol in coronary artery CT angiography with discovery 750 HD would help to reduce the radiation dose effectively without sacrificing image quality. (authors)

[en] Objective: To investigate the image quality and radiation dose of the wider detector array CT scanner with low dose scanning mode in young children with congenital heart disease. Methods: Totally 100 consecutive pediatric patients younger than 3 years with congenital heart disease were enrolled. They were divided into two groups. The low dose group with fifty patients underwent axial CT scanning with ECG gating, and the control group with fifty patients were scanned with volume helical shuttle (VHS) technique. CT number and noise of two groups images at the level of ascending aorta, main pulmonary artery, left ventricle, descending aorta and adjacent muscle were measured, and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. The double blind method was used to evaluate subjective image quality of the level of intra-cardiac, extra-cardiac and coronary artery. Effective dose was also calculated for both groups. Results: No significant difference was found in the CT number, image noise, SNR, and CNR between the two groups in the same anatomic regions (P > 0.05). No significant difference was found in subjective image quality between the two groups for the intra-cardiac and extra-cardiac structure (P > 0.05). The subjective image quality of coronary artery was significant higher in low dose group than the control group (4.10 ± 0.90 vs. 2.88 ± 0.82, Z = -5.818, P < 0.05). Effective dose was (0.57 ± 0.30) mSv in group A and (2.39 ± 1.15) mSv in group B with dose savings of 76% (t = -11.642, P < 0.05). Conclusions: The wider detector array CT scanner with low dose scanning mode can improve image quality with lower radiation dose. (authors)