目的比较两种注射速度(1、1.5 m L/s)钆塞酸二钠(Gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid,Gd-EOB-DTPA)增强磁共振(magnetic resonance,MR)肝脏动态增强动脉期图像质量的优劣性。方法回顾性评估本院2012年12月至2...目的比较两种注射速度(1、1.5 m L/s)钆塞酸二钠(Gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid,Gd-EOB-DTPA)增强磁共振(magnetic resonance,MR)肝脏动态增强动脉期图像质量的优劣性。方法回顾性评估本院2012年12月至2013年9月接受Gd-EOB-DTPA肝脏MR动态增强检查的患者106例,包括注射速度为1 m L/s患者52例,1.5 m L/s患者54例,对动脉期增强图像进行评估。由2名副高以上诊断医师定量评估所有患者肝脏动脉期腹主动脉、肝总动脉、肝脏实质的信噪比(signal noise ratio,SNR)和强化率(contrast-enhancement ratio,CER)的差异性,定性评估腹主动脉、肝总动脉、肝脏实质、门静脉和图像伪影5个项目得分和总分的差异性。结果 Gd-EOB-DTPA注射速度为1 m L/s组和1.5 m L/s组各部分SNR和CER差异无统计学意义(P>0.05),1 m L/s组腹主动脉、肝总动脉强化评分和总分均高于1.5 m L/s组(P<0.05)。结论 Gd-EOB-DTPA注射速度为1 m L/s的肝脏动脉期图像质量优于注射速度为1.5 m L/s的肝脏动脉期图像质量。展开更多
Variational methods have become an important kind of methods in signal and image restoration—a typical inverse problem. One important minimization model consists of the squared ?_2 data fidelity(corresponding to Gaus...Variational methods have become an important kind of methods in signal and image restoration—a typical inverse problem. One important minimization model consists of the squared ?_2 data fidelity(corresponding to Gaussian noise) and a regularization term constructed by a potential function composed of first order difference operators. It is well known that total variation(TV) regularization, although achieved great successes,suffers from a contrast reduction effect. Using a typical signal, we show that, actually all convex regularizers and most nonconvex regularizers have this effect. With this motivation, we present a general truncated regularization framework. The potential function is a truncation of existing nonsmooth potential functions and thus flat on(τ, +∞) for some positive τ. Some analysis in 1 D theoretically demonstrate the good contrast-preserving ability of the framework. We also give optimization algorithms with convergence verification in 2 D, where global minimizers of each subproblem(either convex or nonconvex) are calculated. Experiments numerically show the advantages of the framework.展开更多
文摘目的比较两种注射速度(1、1.5 m L/s)钆塞酸二钠(Gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid,Gd-EOB-DTPA)增强磁共振(magnetic resonance,MR)肝脏动态增强动脉期图像质量的优劣性。方法回顾性评估本院2012年12月至2013年9月接受Gd-EOB-DTPA肝脏MR动态增强检查的患者106例,包括注射速度为1 m L/s患者52例,1.5 m L/s患者54例,对动脉期增强图像进行评估。由2名副高以上诊断医师定量评估所有患者肝脏动脉期腹主动脉、肝总动脉、肝脏实质的信噪比(signal noise ratio,SNR)和强化率(contrast-enhancement ratio,CER)的差异性,定性评估腹主动脉、肝总动脉、肝脏实质、门静脉和图像伪影5个项目得分和总分的差异性。结果 Gd-EOB-DTPA注射速度为1 m L/s组和1.5 m L/s组各部分SNR和CER差异无统计学意义(P>0.05),1 m L/s组腹主动脉、肝总动脉强化评分和总分均高于1.5 m L/s组(P<0.05)。结论 Gd-EOB-DTPA注射速度为1 m L/s的肝脏动脉期图像质量优于注射速度为1.5 m L/s的肝脏动脉期图像质量。
基金supported by National Natural Science Foundation of China (Grant Nos. 11301289 and 11531013)
文摘Variational methods have become an important kind of methods in signal and image restoration—a typical inverse problem. One important minimization model consists of the squared ?_2 data fidelity(corresponding to Gaussian noise) and a regularization term constructed by a potential function composed of first order difference operators. It is well known that total variation(TV) regularization, although achieved great successes,suffers from a contrast reduction effect. Using a typical signal, we show that, actually all convex regularizers and most nonconvex regularizers have this effect. With this motivation, we present a general truncated regularization framework. The potential function is a truncation of existing nonsmooth potential functions and thus flat on(τ, +∞) for some positive τ. Some analysis in 1 D theoretically demonstrate the good contrast-preserving ability of the framework. We also give optimization algorithms with convergence verification in 2 D, where global minimizers of each subproblem(either convex or nonconvex) are calculated. Experiments numerically show the advantages of the framework.
