ABSTRACT
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
ABSTRACT
The environmental and ecological issues in the flow-reduced river reach are very serious and are receiving increasingly attention. In this study, we investigate the temporal and spatial changes in Delta 13C and Delta 15N of Periphyton and isotopic relationship between Periphyton and the endangered fish [Ayu, Plecoglossus altivelis] in a flow-reduced river reach in Japan. Much of the spatial and temporal variation in Delta 13C of endangered fish was explained by variation in Periphyton, indicating a strong link between primary production and higher order consumers. The Periphyton Delta 13C was correlated with current velocity while it was not correlated with the Periphyton biomass [Chl. a]. Spatially, the relatively high Delta 13C and Delta 15N of Periphyton in the lower sites of the flow-reduced river reach might be due to high level of anthropogenically derived N and C introduced from the surrounding agricultural activities and human settings. The trophic position of the endangered fish in was estimated to be 1.5-2.2[1.8 +/- 0.3], which agrees with the previous stomach content analysis suggesting that the ayu mainly feed on Periphyton