ObjectiveTo evaluate the value of 70 kV and sonogram-affirmed iterative reconstruction technique in CT examination for children with congenital heart disease. MethodsThirty children with congenital heart disease who underwent CT scan between January and September 2014 were included in this study. According to the different tube voltage, they were randomly divided into group A (80 kV) and group B (70 kV), with fifteen in each. All the children were scanned on a dual-source-CT (Siemens Definition Flash). Group A used filtered back projection reconstruction. Group B used sonogram-affirmed iterative reconstruction. We measured and calculated the pulmonary artery signal-to-noise ratio at the level of main pulmonary artery window, the signal-to-noise ratio of the ascending aorta, noise ratio contrast between the pulmonary artery and erector spinae and between the ascending aorta and erector spinae. The image quality for congenital heart disease was assessed by two senior radiologists. The measurement of radiation dose included effective dose (ED), volume CT dose index (CTDIvol) and dose length product (DLP). ResultsThere were no significant differences between group A and B in terms of pulmonary artery signal-to-noise ratio (14.54±3.77, 11.23±2.52), the signal-to-noise ratio of the ascending aorta (14.76±3.41, 12.31±3.47), the noise ratio contrast between pulmonary artery and erector spinae (12.04±3.96, 9.18±3.76) and between the ascending aorta and erector spinae (12.47±4.59, 9.77±4.41) (P > 0.05). There was significant difference between group A and group B in CTDIvol[(0.53±0.09), (0.38±0.03) mGy], DLP[(12.93±1.79), (6.67±0.72) mGy·cm], and ED[(0.34±0.05), (0.17±0.02) mSv] (P < 0.05). ConclusionThe application of 70 kV and sonogram-affirmed iterative reconstruction technique in CT examination for children with congenital heart disease can significantly reduce the radiation dose without any influence on image quality.
ObjectiveTo discuss the application value of the two kinds of three dimensional reformatting techniques of spiral CT: volume rendering (VR) and maximum intensity projection (MIP) in the evaluation of children's skeletal abnormality. MethodsEighteen children with skeletal abnormality in our hospital treated between March and June 2014 were recruited in this study, diagnosed by CT transversal images and images of multiplanar reformatting (MPR). VR and MIP were made with the raw data. All three dimensional images were independently evaluated by two doctors of the Radiology Department (a score of 1-4). Images with a score of 4 were excellent. Wilcoxon signed ranks test was done for all scores and Kappa values were calculated. ResultsImages score of VR was 3.28±0.96 and of MIP was 2.89±0.90, without statistically significant difference (Z=-1.732, P=0.125). Kappa value of VR was 0.730 and of MIP was 0.593, with good and moderate consistency. ConclusionWith the special superiority of displaying spatial configuration, VR and MIP can be used to help two dimensional CT images to evaluate children's skeletal abnormality more comprehensively.
ObjectiveTo discuss the value of dual-source CT Flash scanning in reducing the dose of radiation in 3D cardiac imaging. MethodWe collected 60 patients from March to August 2014 who should undergo cardiac 3D CT scanning before radiofrequency ablation. They were randomly divided into group A and B with 30 in each. Patients in group A underwent flash technology scanning, while those in group B accepted conventional retrospective electrocardiography-gated scanning. CARE Dose techniques were used to collect data. Scanning parameters were the same for both groups:collimation was 128×0.6 mm, reconstruction thickness was 0.75 mm, reconstruction interval was 0.7 mm, and field of view was 180-200 mm. After image acquisition, we measured the CT values and noise of left atrium and various branches of the pulmonary veins (upper left, lower left, upper right, and lower right). Statistical software was used for the two groups of images to analyze the carrier noise ratio (CNR), signal noise ratio (SNR), blinded scores, computed tomography dose index (CTDIvol), and dose-length product (DLP) of the left atrium and pulmonary vein. ResultsCNR and SNR of the left atrium and various pulmonary veins between the two groups had no significant differences (P>0.05) . Blinded scores between the two groups were not significantly different (P>0.05) . CTDIvol in group A and group B was respectively (2.92±0.38) and (20.15±12.09) mGy, with a significant difference (t=?7.803, P<0.001) . DLP of group A was (59.30±6.67) mGy·cm, significantly lower than that in group B [(334.43±216.71) mGy·cm] (t=?6.591, P<0.001) . Flash-efficient radiation dose was (0.83±0.94) mSv in group A, far below that in group B [(4.53±3.03) msv], and the difference was statistically significant (t=?6.684, P<0.001) . ConclusionsDual-source CT Flash technology applied in 3D cardiac scanning can reduce radiation dose as well as meet the needs of image diagnosis.