OBJECTIVE: To evaluate the effect of low-dose aspirin on the deposition of platelet at the anastomotic site and the function of coagulation system in order to provide experimental data for clinical use. METHODS: (1) Twenty-eight SD rats were divided into experimental group (n = 21) and control group (n = 7), aspirin were administered through a catheter placed in the femoral vein in dose of 4 mg/kg in the experimental group and the same dose of normal saline in the control group. The experimental group was subdivided into 3 groups, with 7 rats in each group, according to survival time of 24, 48 and 72 hours after dose. Samples of 4 ml blood were taken by heart puncture from each rat to investigate the maximal platelet aggregation rate(MAR), prothrombin time(PT) and kaolin partial thromboplastin time(KPTT). (2) Sixteen New Zealand White rabbits were divided into experimental and control group, 8 rabbits in each group. Drugs were given in the same way. Forty-eight hours later, the bilateral femoral arteries of each rabbit were exposed and arteries between inguinal ligament and the origin of the superficial epigastric arteries were transected and end-to-end anastomosis was completed with interrupted suturing technique. Fifteen and 120 minutes after the recovery of blood flow, the left and the right vessels containing anastomotic sites were harvested respectively and treated with 125I-labeled anti-GP IIb/III a antibody (SZ-21) using radioimmunobinding method. The radioactivities of the anastomosed vessels were measured. RESULTS: The KPTT in the experimental group was longer than that of the control group at 24- and 48-hour group, the mean percentages of increase were 42.56% and 35.33% respectively, and there were very significant differences between the experimental and control group in 24-hour group (P lt; 0.001). The PT value in experimental group was longer than that of the control group, but there was no significant difference (P gt; 0.05), and the maximal aggregation rate of platelet in the experimental group was significantly lower than that of the control group after 72 hours (P lt; 0.001). The radioactivity of the anastomosed arteries in the experimental group were significantly higher than that of the control group (P lt; 0.001) at 15 minutes after the recovery of blood flow, the mean percentage of increase was 110%. CONCLUSION: Low-dose aspirin can significantly affect the function of the intrinsic coagulation system, prevent the aggregation of platelets, but no effect on the function of the extrinsic coagulation system. On the other hand, it can also increase the deposition of platelet on the anastomotic sites after end-to-end anastomosis, especially in the early stage when it is intravenously injected, but it is b enough to cause thrombosis at the anastomotic sites. The effects of low dose aspirin on the coagulation system are inconsistent with its local effects on anastomotic sites.
Objective To discuss the application of dual-source computed tomography （CT） low dose technology in the upper abdomen enhanced inspection. Methods Six hundred consecutive patients from July 2011 to February 2012 in this hospital were orderly divided into ordinal tube current （210 mAs） group and low dose tube current group （200 mAs，190 mAs，180 mAs，170 mAs，and 165 mAs）. The standard deviation （SD） of subcutaneous fat，signal to noise ratio （SNR） of liver and pancreas， contrast to noise ratio （CNR） of liver-erector spinae and pancreas-erector spinae，score of subjective diagnosis and the indexes of radiation dose，including CT dose index （CTDI），dose length product （DLP），effective dose （ED） were measured，calculated，and assessed respectively on CT images of arterial phase and portal phase from each group. Results The SD of subcutaneous fat， SNRs of liver and pancreas，score of subjective diagnosis，and the CTDI，DLP，ED of CT images in arterial phase and portal phase were significantly different from each other （P＜0.05），while CNRs of liver-erector spinae and pancreas-erector spinae were not statistically significant （P＞0.05）. The SNR，radiation dose，and score of subjective diagnosis of the 165 mAs tube current group were the lowest among all the groups，but the images of the 165 mAs tube current group could not fulfill the need of diagnosis. Conclusions It is really feasible that the method of decreasing tube current gradually in the upper abdomen enhanced CT inspection could ensure that the radiologists could adapt the low dose image bit by bit，and this methods could be popularized to all kinds of CT facilities we own currently. The images with 170 mAs as tube current in the upper abdomen enhanced inspection of dual-source CT could fulfill the need of diagnosis，and the radiation dose of patients is apparently lower than that the conventional scan．
ObjectivesTo investigate the influence of scanning parameters (tube voltages and tube currents) on image quality and corresponding radiation doses with simulated lung nodules in chest CT.MethodsThe anthropomorphic chest phantoms with 12 simulated, randomly placed nodules of different diameters and densities in the chest were scanned by different scanning parameters. The detection rate, degree of nodular deformation, image quality (with both subjective and objective evaluation) and the corresponding radiation doses were recorded and evaluated, and the correlation between nodule detection rate, degree of nodular deformation, radiation dose and image quality using different scanning parameters was analyzed.ResultsThe image quality improved with the increase of tube voltage and tube current (P<0.05). When the tube current was constant, the CT values of the vertebral decreased gradually with the increase of tube voltages (P<0.05); however, significant difference was not detected in CT values of the lung field (P>0.05). When the tube current was 100 mAs, the lung nodules with CT values of +100 HU and −630 HU showed statistical difference when using different tube voltage (P<0.05); but there was no significant difference in nodules of −800 HU (P=0.57). When tube voltage was 100 kV and 120 kV each, it was possible to detect all lung nodules with a detection rate of 100%. The detection rate was 33% and 66% in 3 mm diameter when the tube current was 80 kV/15 mA and 80 kV/20 mA, respectively. The nodules deformation in nodules with a CT value of −630 HU and diameter less than 5 mm was the most prominent (P<0.05). After analyzing the relationship between image quality and radiation doses using different tube voltages, we established a system of correlation equations: 80 kV: Y=2.625X+0.038; 100 kV: Y=14.66X+0.158; 120 kV: Y=18.59X+0.093.ConclusionsThe image quality improves with the increase of tube current and tube voltage, as well as the corresponding radiation doses. By reducing the tube voltage and increasing the tube current appropriately, the radiation doses can be reduced. Follow-up CT examination of pulmonary ground glass nodules should apply the same tube voltage imaging parameters, so as to effectively reduce the measurement error of nodule density and evaluate the change of nodules more accurately.