| Objective:To study the image quality of64slice helical CT low-dose coronary artery calcium score, analysis the influence factors of image quality.Methods:166patients with confirmed or suspected coronary heart disease (CHD) were prospectively and continuously collected, all of them were examined by calcium score scan and the calcium score were calculated. All the patient are divided into2groups using random number table method:83with conventional dose (100mAs) and the other83with low dose (50mAs). Record CTDIvol for every scan, measure and calculate CT value, CT value standard deviation and the signal-to-noise ratio of ROI (set at the center of the ascending aorta in which slice the left coronary artery bifurcate from),make statistical analysis of the data; Two radiologists calculate the calcium score number evaluate the image quality. Make linear related hypothesis test between age, gender, height, weight, BMI and image noise and of the two groups of data, Draw Excel scatter-plot draw and get linear regression equation if there are linear correlation between variables.Results:The differences of subjective image quality score between low dose group and conventional dose group calcification were no statistically significant. Compared with conventional dose radiation doses (1.49±0.06mSv), effective dose of low-dose scan (0.83±0.06)mSv decreased about0.66mSv (P<0.05); The difference of data noise(t=8.83, P<0.05) and signal-to-noise ratio (t=7.61, P<0.05) between two groups were statistically significant; There was linear correlation between BMI and image noise in both groups of data; gender, height, weight of low dose group has no linear correlation with the image quality.Conclusion:BMI and image noise had linear correlation (r=0.7413); low-dose coronary artery calcium score with Multiple-slice helical CT can meet the needs of the calculation and can be regularly used for patients (BMI<42kg/m2) without decreasing the image quality. |
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