Low-dose aspirin(LDA) is clinically used for the prevention of cardiovascular and cerebrovascular events with the advent of an aging society.On the other hand,a very low dose of aspirin(10 mg daily) decreases the gast...Low-dose aspirin(LDA) is clinically used for the prevention of cardiovascular and cerebrovascular events with the advent of an aging society.On the other hand,a very low dose of aspirin(10 mg daily) decreases the gastric mucosal prostaglandin levels and causes significant gastric mucosal damage.The incidence of LDAinduced gastrointestinal mucosal injury and bleeding has increased.It has been noticed that the incidence of LDA-induced gastrointestinal hemorrhage has increased more than that of non-aspirin non-steroidal anti-inflammatory drug(NSAID)-induced lesions.The pathogenesis related to inhibition of cyclooxygenase(COX)-1 includes reduced mucosal flow,reduced mucus and bicarbonate secretion,and impaired platelet aggregation.The pathogenesis related to inhibition of COX-2 involves reduced angiogenesis and increased leukocyte adherence.The pathogenic mechanisms related to direct epithelial damage are acid back diffusion and impaired platelet aggregation.The factors associated with an increased risk of upper gastrointestinal(GI) complications in subjects taking LDA are aspirin dose,history of ulcer or upper GI bleeding,age > 70 years,concomitant use of non-aspirin NSAIDs including COX-2-selective NSAIDs,and Helicobacter pylori(H.pylori) infection.Moreover,no significant differences have been found between ulcer and non-ulcer groups in the frequency and severity of symptoms such as nausea,acid regurgitation,heartburn,and bloating.It has been shown that the ratios of ulcers located in the body,fundus and cardia are significantly higher in bleeding patients than the ratio of gastroduodenal ulcers in patients taking LDA.Proton pump inhibitors reduce the risk of developing gastric and duodenal ulcers.In contrast to NSAIDinduced gastrointestinal ulcers,a well-tolerated histamine H2-receptor antagonist is reportedly effective in prevention of LDA-induced gastrointestinal ulcers.The eradication of H.pylori is equivalent to treatment with omeprazole in preventing recurrent bleeding.Continuous aspirin therapy for patients 展开更多
目的探讨256层螺旋CT应用低管电流联合迭代重建技术在腹部低剂量增强扫描的可行性。方法对160例拟行腹部CT扫描患者随机分成8组(A^H组),每组20例。A组采用120 k V、250 m As条件进行腹部常规剂量扫描,图像应用滤波反投影重建。B^H组采...目的探讨256层螺旋CT应用低管电流联合迭代重建技术在腹部低剂量增强扫描的可行性。方法对160例拟行腹部CT扫描患者随机分成8组(A^H组),每组20例。A组采用120 k V、250 m As条件进行腹部常规剂量扫描,图像应用滤波反投影重建。B^H组采用固定管电压120 k V,管电流于250~70 m As之间每次间隔30m As减低扫描条件行上腹部低剂量扫描,图像采用迭代重建。采用方差分析比较各组图像噪声、对比噪声比、CT剂量指数、CT剂量长度乘积及有效辐射剂量的差异。并对各组图像分别进行质量评分,确定等同于A组图像质量并满足临床诊断要求最低剂量组。图像噪声与体重指数、腹围相关性采用Pearson相关分析。结果采用迭代算法重建图像的低剂量B^H组主动脉、肝脏、脾脏、胰腺噪声为10.7~23.0 HU,B^F组均较常规剂量组A组图像噪声[(13.8~16.8)HU]低,而G、H组图像噪声均明显高于A组。B^E组图像平均噪声与A组比较,差异无统计学意义(P>0.05),F^H组图像噪声与A组比较,差异有统计学意义(P<0.05)。低剂量组对比噪声比为3.1~14.7,B^E组对比噪声比均高于A组(3.4~7.6),但差异无统计学意义(P>0.05)。F^H组对比噪声比出现不同程度下降,部分低剂量组对比噪声比已低于常规剂量A组。低剂量组B^E组图像质量评分均≥3分,并与常规剂量组A组比较差异无统计学意义。F^H组主观图像质量随管电流减低而明显降低,与常规剂量组A组比较差异有统计学意义(P<0.05)。B^H组辐射剂量差异有统计学意义(P<0.01),A组与B组比较,辐射剂量无统计学意义(P>0.05)。E组为图像质量等同于常规剂量扫描最适低剂量组,辐射剂量降低约35%。图像噪声与体重指数低度相关(r^2=0.316),与腹围高度相关(r^2=0.817)结论迭代重建可以显著降低图像噪声、辐射剂量,提高图像质量,辐射剂量降低35%仍可得到与常规剂量滤波反投影重建相当的图像质量。展开更多
文摘Low-dose aspirin(LDA) is clinically used for the prevention of cardiovascular and cerebrovascular events with the advent of an aging society.On the other hand,a very low dose of aspirin(10 mg daily) decreases the gastric mucosal prostaglandin levels and causes significant gastric mucosal damage.The incidence of LDAinduced gastrointestinal mucosal injury and bleeding has increased.It has been noticed that the incidence of LDA-induced gastrointestinal hemorrhage has increased more than that of non-aspirin non-steroidal anti-inflammatory drug(NSAID)-induced lesions.The pathogenesis related to inhibition of cyclooxygenase(COX)-1 includes reduced mucosal flow,reduced mucus and bicarbonate secretion,and impaired platelet aggregation.The pathogenesis related to inhibition of COX-2 involves reduced angiogenesis and increased leukocyte adherence.The pathogenic mechanisms related to direct epithelial damage are acid back diffusion and impaired platelet aggregation.The factors associated with an increased risk of upper gastrointestinal(GI) complications in subjects taking LDA are aspirin dose,history of ulcer or upper GI bleeding,age > 70 years,concomitant use of non-aspirin NSAIDs including COX-2-selective NSAIDs,and Helicobacter pylori(H.pylori) infection.Moreover,no significant differences have been found between ulcer and non-ulcer groups in the frequency and severity of symptoms such as nausea,acid regurgitation,heartburn,and bloating.It has been shown that the ratios of ulcers located in the body,fundus and cardia are significantly higher in bleeding patients than the ratio of gastroduodenal ulcers in patients taking LDA.Proton pump inhibitors reduce the risk of developing gastric and duodenal ulcers.In contrast to NSAIDinduced gastrointestinal ulcers,a well-tolerated histamine H2-receptor antagonist is reportedly effective in prevention of LDA-induced gastrointestinal ulcers.The eradication of H.pylori is equivalent to treatment with omeprazole in preventing recurrent bleeding.Continuous aspirin therapy for patients
文摘目的探讨256层螺旋CT应用低管电流联合迭代重建技术在腹部低剂量增强扫描的可行性。方法对160例拟行腹部CT扫描患者随机分成8组(A^H组),每组20例。A组采用120 k V、250 m As条件进行腹部常规剂量扫描,图像应用滤波反投影重建。B^H组采用固定管电压120 k V,管电流于250~70 m As之间每次间隔30m As减低扫描条件行上腹部低剂量扫描,图像采用迭代重建。采用方差分析比较各组图像噪声、对比噪声比、CT剂量指数、CT剂量长度乘积及有效辐射剂量的差异。并对各组图像分别进行质量评分,确定等同于A组图像质量并满足临床诊断要求最低剂量组。图像噪声与体重指数、腹围相关性采用Pearson相关分析。结果采用迭代算法重建图像的低剂量B^H组主动脉、肝脏、脾脏、胰腺噪声为10.7~23.0 HU,B^F组均较常规剂量组A组图像噪声[(13.8~16.8)HU]低,而G、H组图像噪声均明显高于A组。B^E组图像平均噪声与A组比较,差异无统计学意义(P>0.05),F^H组图像噪声与A组比较,差异有统计学意义(P<0.05)。低剂量组对比噪声比为3.1~14.7,B^E组对比噪声比均高于A组(3.4~7.6),但差异无统计学意义(P>0.05)。F^H组对比噪声比出现不同程度下降,部分低剂量组对比噪声比已低于常规剂量A组。低剂量组B^E组图像质量评分均≥3分,并与常规剂量组A组比较差异无统计学意义。F^H组主观图像质量随管电流减低而明显降低,与常规剂量组A组比较差异有统计学意义(P<0.05)。B^H组辐射剂量差异有统计学意义(P<0.01),A组与B组比较,辐射剂量无统计学意义(P>0.05)。E组为图像质量等同于常规剂量扫描最适低剂量组,辐射剂量降低约35%。图像噪声与体重指数低度相关(r^2=0.316),与腹围高度相关(r^2=0.817)结论迭代重建可以显著降低图像噪声、辐射剂量,提高图像质量,辐射剂量降低35%仍可得到与常规剂量滤波反投影重建相当的图像质量。
