Résumé
Background: prospectively electrocardiography [ECG]-triggered high-pitch spiral coronary computed tomography angiography [CCTA] is a unique scan mode for dual -source CT [DSCT]. Our reports aim to compare image quality and radiation dose of CCTA using high-pitch spiral or sequential acquisition mode in patients with low and stable heart rates
Materials and Methods: patients with low and stable heart rates [HR] [HR >/= 70 beats per minute [bpm]; heart rate variability [HRV] < 10 bpm] were randomly assigned to high-pitch spiral mode [group A; n = 80] or sequential acquisition mode [group B; n = 80]. Image quality scores, image noise, effective radiation dose and influencing factors on image quality were assessed
Results: mean image quality scores were 1.51 +/- 0.32 and 1.70 +/- 0.38 for groups A and B [P < 0.05], respectively. Image noises of the two groups were 19.05 +/- 4.70 Hu and 27.21 +/- 8.88 Hu [P < 0.05]. Contrast media cost in-group A was lower than group B [P < 0.05]. No statistical difference was found in the rate of diagnostic patients between the two groups [P = 0.416]. The estimated radiation dose of group A was 26.0% reduced compared with group B [0.74 +/- 0.34 mSv vs. 1.00 +/- 0.48 mSv, P < 0.05]
Conclusion: in patients with regular and low heart rates, the prospectively high-pitch spiral acquisition mode can reduce radiation dose and contrast media cost while maintaining image quality compared with the prospectively sequential mode
Résumé
NF-Y transcription factor binds to CCAAT boxes on promoters of cell cycle regulatory genes such as cdc2, cyclin B, cdc25C, and cyclin A. We previously reported that the DNA binding activity of NF-Y is regulated by p53-p21-cdk2 pathway. CBF/HSP70 was originally identified as a transcription factor binding to the CCAAT box on the hsp70 promoter and mediates transcription repression of hsp70 pro- moter by p53. Recently it was demonstrated that CBF/HSP70 interacts and cooperates with NF-Y. In this study, we found that p53 represses the transcription of CBF/HSP70. Since transactivation ability of NF-Y is regulated in a cell cycle-dependent manner, we examined the transcription of CBF/HSP70 during the cell cycle. After synchronization of a human bladder carcinoma cell lacking functional p53 at early S phase, we infect the cells with adenovirus encoding p53. Cells infected with control virus progressed to S and G2 after release from the arrest. In contrast, cells expressing p53 enter S and G2 phases, but arrest at G2/M. The expression of CBF/HSP70 was induced at S/G2 phase in cells infected with a control virus, but kept to be repressed in cells expressing p53. Thus, these results suggest that p53 suppresses the expression of cell cycle regulatory genes though inhibiting both CCAAT binding factors, CBF/HSP70 and NF-Y.