[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 assess the clinical value of volume helical shuttle (VHS) of high definition CT (HDCT) in the diagnosis of congenital heart disease (CHD). Methods: Forty-three patients suffering from CHD were examined with VHS of HDCT and echocardiography (ECHO). Twenty-four patients (21 children, 3 adults) received surgery. Based on surgical data,the diagnostic accuracy of CHD by VHS of HDCT was compared with that by ECHO with respect to the intra-cardiac lesion, extra-cardiac lesion and hemodynamics. The visibility of the origin and proximal course of coronary arteries was also evaluated on VHS. CT effective doses were calculated,using mSv =DLP × K. Results: Thirty-six intra-cardiac deformities were found by operation, and the diagnostic accuracy of both VSH and ECHO were 100.0% (36/36). VHS successfully detected 42 of 44 (95.4%) cardiac-vascular connection and large vascular deformities, whereas ECHO only detected 26 (59.1% ). The right-to-left shunt and left-to-right shunt of septal defects revealed by VHS were 5 and 6 patients respectively, which all coincided with the results of ECHO.Fourteen bi-directional shunt of septal defects were detected by ECHO, and 13 of them were diagnosed as right-to-left shunt by HDCT except an illegibility in 1 patient. The origin and proximal course of coronary arteries were all visible on VHS. Effective dose for children was (3.38 ± 1.86) mSv, and for adults was (10.27 ± 2.59) mSv. Conclusions: VHS of HDCT scan is advantageous in the diagnosis of CHD. It can depict the intra- and extra- cardiac structures as well as coronary arteries and provide hemodynamic information. (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 evaluate the appearance of CT in patients with severe acute respiratory syndrome (SARS) in the recovery phase, and to study the correlation of CT findings with pulmonary function. Methods: From June to August in 2003, 100 patient with confirmed SARS accepted examination in our hospital. Among them, 91 patients (39 men, 52 women, mean age 36.4 years, age range 19-66 years) received CT examination and pulmonary function test on the same day. The interval between SARS onset and the examination ranged from 52 to 125 days (mean 87.4 days). CT appearances of pulmonary parenchymal abnormalities including distribution and extent of involvement were quantitatively analyzed, and four levels on CT scan including the aortic arch, the tracheal carina, the pulmonary venous confluence, and the dome of right diaphragm were selected to score the lesions. The correlation of CT scores with the results of pulmonary function tests was studied. Results: Of the 91 cases, 47 patients had normal CT appearance in the recovery phase, whereas the other 44 patients still had parenchymal abnormalities, including residual ground-glass opacification and reticular shadow. CT visual score had correlation with DLco% (r=-0.618, P<0.001 vs r=-0.498, P<0.001). Conclusion: CT scans show that half of SARS patients has recuperated their health in three months after the initial hospital admission. CT visual score can quantitatively evaluate the abnormal appearance of lungs, and it also indicates the pulmonary function