BACKGROUND Contrast-induced nephropathy(CIN)is a reversible form of acute kidney injury that occurs within 48-72 h of exposure to intravascular contrast material.CIN is the third leading cause of hospital-acquired acu...BACKGROUND Contrast-induced nephropathy(CIN)is a reversible form of acute kidney injury that occurs within 48-72 h of exposure to intravascular contrast material.CIN is the third leading cause of hospital-acquired acute kidney injury and accounts for 12%of such cases.Risk factors for CIN development can be divided into patientand procedure-related.The former includes pre-existing chronic renal insufficiency and diabetes mellitus.The latter includes high contrast volume and repeated exposure over 72 h.The incidence of CIN is relatively low(up to 5%)in patients with intact renal function.However,in patients with known chronic renal insufficiency,the incidence can reach up to 27%.AIM To examine the association between renal enhancement pattern on non-contrast enhanced computed tomographic(CT)images obtained immediately following hepatic artery embolization with development of CIN.METHODS Retrospective review of all patients who underwent hepatic artery embolization between 01/2010 and 01/2011(n=162)was performed.Patients without intraprocedural CT imaging(n=51),combined embolization/ablation(n=6)and those with chronic kidney disease(n=21)were excluded.The study group comprised of 84 patients with 106 procedures.CIN was defined as 25%increase above baseline serum creatinine or absolute increase≥0.5 mg/dL within 72 h post-embolization.Post-embolization CT was reviewed for renal enhancement patterns and presence of renal artery calcifications.The association between noncontrast CT findings and CIN development was examined by Fisher’s Exact Test.RESULTS CIN occurred in 11/106(10.3%)procedures(Group A,n=10).The renal enhancement pattern in patients who did not experience CIN(Group B,n=74 with 95/106 procedures)was late excretory in 93/95(98%)and early excretory(EE)in 2/95(2%).However,in Group A,there was a significantly higher rate of EE pattern(6/11,55%)compared to late excretory pattern(5/11)(P<0.001).A significantly higher percentage of patients that developed CIN had renal artery calcifications(6/11 vs 20/95,55%vs 21%,P=0.02).CONCLUSION A hyperdense renal parenchyma relative to surrounding skeletal muscle(EE pattern)and presence of renal artery calcifications on immediate post-HAE noncontrast CT images in patients with low risk for CIN are independently associated with CIN development.展开更多
Purpose: To evaluate respiratory-triggered three-dimensional (3D) true steady-state free-precession (SSFP) projection magnetic resonance angiographic sequences with time-spatial labeling inversion pulse (Time-SLIP) fo...Purpose: To evaluate respiratory-triggered three-dimensional (3D) true steady-state free-precession (SSFP) projection magnetic resonance angiographic sequences with time-spatial labeling inversion pulse (Time-SLIP) for visualizing the hepatic arteries and to optimize the image acquisition protocol. Materials and Methods: A 1.5-T clinical magnetic resonance imager was used to perform abdominal magnetic resonance angiography (MRA) in 25 consecutive patients before transcatheter arterial chemoembolization or surgery. We compared two selective space-labeling inversion pulse (tag pulse) patterns (Patterns I and II, oblique and parallel tag pulses, respectively). Two experienced radiologists evaluated the number of hepatic arterial branches visible on the acquired MRA images, and the results were referenced with those on images from intra-arterial digital subtraction angiography. Results: Images were acquired from all patients. The two radiologists clearly visualized branches of the left and right hepatic arteries. More peripheral hepatic arterial branches were identified in MRA images captured by using tag pulse Pattern I than in those acquired by using Pattern II (P P > 0.05). Conclusion: Non-contrast-enhanced Time-SLIP hepatic MRA with true SSFP allowed selective visualization of peripheral hepatic vessels.展开更多
高分一号(GF-1)卫星自发射以来,凭借其幅宽大、综合覆盖能力强以及重访周期短等优势,已成为国土资源调查、农业林业遥感监测、国家重大工程建设等领域使用的重要数据源之一。以中巴经济走廊为研究区域,选取GF-1多光谱宽幅覆盖(wide fiel...高分一号(GF-1)卫星自发射以来,凭借其幅宽大、综合覆盖能力强以及重访周期短等优势,已成为国土资源调查、农业林业遥感监测、国家重大工程建设等领域使用的重要数据源之一。以中巴经济走廊为研究区域,选取GF-1多光谱宽幅覆盖(wide field of view,WFV)数据进行对比试验,重点分析了影响遥感影像应用的2个关键因素:如何提高遥感影像的几何定位精度和影像真彩色合成方式。研究结果表明,基于有理函数模型(rational polynomial coefficients,RPC)的区域网平差技术和RGB-NIR色彩合成模型对影像快速定位和提升视觉效果分别有良好的表现。成果正射影像X和Y方向均方根误差分别为0.79和0.83个像素;成果影像的信息熵、平均梯度、均值和标准差等数值均有不同程度的提高,不仅确保了影像色彩真实自然,而且兼顾了信息细节,影像图面效果得到较好优化。该方法有助于进一步提升GF-1 WFV数据在实际生产中的业务化应用。展开更多
Preoperative assessment of the liver volume and function of the remnant liver is a mandatory prerequisite before performing major hepatectomy. The aim of this work is to develop and test a software application for eva...Preoperative assessment of the liver volume and function of the remnant liver is a mandatory prerequisite before performing major hepatectomy. The aim of this work is to develop and test a software application for evaluation of the residual function of the liver prior to the intervention of the surgeons. For this purpose, a complete software platform consisting of three basic modules: liver volume segmentation, visualization, and virtual cutting, was developed and tested. Liver volume segmentation is based on a patient examination with non-contrast abdominal Computed Tomography (CT). The basis of the segmentation is a multiple seeded region growing algorithm adapted for use with CT images without contrast-enhancement. Virtual tumor resection is performed interactively by outlining the liver region on the CT images. The software application then processes the results to produce a three-dimensional (3D) image of the “resected” region. Finally, 3D rendering module provides possibility for easy and fast interpretation of the segmentation results. The visual outputs are accompanied with quantitative measures that further provide estimation of the residual liver function and based on them the surgeons could make a better decision. The developed system was tested and verified with twenty abdominal CT patient sets consisting of different numbers of tomographic images. Volumes, obtained by manual tracing of two surgeon experts, showed a mean relative difference of 4.5%. The application was used in a study that demonstrates the need and the added value of such a tool in practice and in education.展开更多
文摘BACKGROUND Contrast-induced nephropathy(CIN)is a reversible form of acute kidney injury that occurs within 48-72 h of exposure to intravascular contrast material.CIN is the third leading cause of hospital-acquired acute kidney injury and accounts for 12%of such cases.Risk factors for CIN development can be divided into patientand procedure-related.The former includes pre-existing chronic renal insufficiency and diabetes mellitus.The latter includes high contrast volume and repeated exposure over 72 h.The incidence of CIN is relatively low(up to 5%)in patients with intact renal function.However,in patients with known chronic renal insufficiency,the incidence can reach up to 27%.AIM To examine the association between renal enhancement pattern on non-contrast enhanced computed tomographic(CT)images obtained immediately following hepatic artery embolization with development of CIN.METHODS Retrospective review of all patients who underwent hepatic artery embolization between 01/2010 and 01/2011(n=162)was performed.Patients without intraprocedural CT imaging(n=51),combined embolization/ablation(n=6)and those with chronic kidney disease(n=21)were excluded.The study group comprised of 84 patients with 106 procedures.CIN was defined as 25%increase above baseline serum creatinine or absolute increase≥0.5 mg/dL within 72 h post-embolization.Post-embolization CT was reviewed for renal enhancement patterns and presence of renal artery calcifications.The association between noncontrast CT findings and CIN development was examined by Fisher’s Exact Test.RESULTS CIN occurred in 11/106(10.3%)procedures(Group A,n=10).The renal enhancement pattern in patients who did not experience CIN(Group B,n=74 with 95/106 procedures)was late excretory in 93/95(98%)and early excretory(EE)in 2/95(2%).However,in Group A,there was a significantly higher rate of EE pattern(6/11,55%)compared to late excretory pattern(5/11)(P<0.001).A significantly higher percentage of patients that developed CIN had renal artery calcifications(6/11 vs 20/95,55%vs 21%,P=0.02).CONCLUSION A hyperdense renal parenchyma relative to surrounding skeletal muscle(EE pattern)and presence of renal artery calcifications on immediate post-HAE noncontrast CT images in patients with low risk for CIN are independently associated with CIN development.
文摘Purpose: To evaluate respiratory-triggered three-dimensional (3D) true steady-state free-precession (SSFP) projection magnetic resonance angiographic sequences with time-spatial labeling inversion pulse (Time-SLIP) for visualizing the hepatic arteries and to optimize the image acquisition protocol. Materials and Methods: A 1.5-T clinical magnetic resonance imager was used to perform abdominal magnetic resonance angiography (MRA) in 25 consecutive patients before transcatheter arterial chemoembolization or surgery. We compared two selective space-labeling inversion pulse (tag pulse) patterns (Patterns I and II, oblique and parallel tag pulses, respectively). Two experienced radiologists evaluated the number of hepatic arterial branches visible on the acquired MRA images, and the results were referenced with those on images from intra-arterial digital subtraction angiography. Results: Images were acquired from all patients. The two radiologists clearly visualized branches of the left and right hepatic arteries. More peripheral hepatic arterial branches were identified in MRA images captured by using tag pulse Pattern I than in those acquired by using Pattern II (P P > 0.05). Conclusion: Non-contrast-enhanced Time-SLIP hepatic MRA with true SSFP allowed selective visualization of peripheral hepatic vessels.
文摘高分一号(GF-1)卫星自发射以来,凭借其幅宽大、综合覆盖能力强以及重访周期短等优势,已成为国土资源调查、农业林业遥感监测、国家重大工程建设等领域使用的重要数据源之一。以中巴经济走廊为研究区域,选取GF-1多光谱宽幅覆盖(wide field of view,WFV)数据进行对比试验,重点分析了影响遥感影像应用的2个关键因素:如何提高遥感影像的几何定位精度和影像真彩色合成方式。研究结果表明,基于有理函数模型(rational polynomial coefficients,RPC)的区域网平差技术和RGB-NIR色彩合成模型对影像快速定位和提升视觉效果分别有良好的表现。成果正射影像X和Y方向均方根误差分别为0.79和0.83个像素;成果影像的信息熵、平均梯度、均值和标准差等数值均有不同程度的提高,不仅确保了影像色彩真实自然,而且兼顾了信息细节,影像图面效果得到较好优化。该方法有助于进一步提升GF-1 WFV数据在实际生产中的业务化应用。
文摘Preoperative assessment of the liver volume and function of the remnant liver is a mandatory prerequisite before performing major hepatectomy. The aim of this work is to develop and test a software application for evaluation of the residual function of the liver prior to the intervention of the surgeons. For this purpose, a complete software platform consisting of three basic modules: liver volume segmentation, visualization, and virtual cutting, was developed and tested. Liver volume segmentation is based on a patient examination with non-contrast abdominal Computed Tomography (CT). The basis of the segmentation is a multiple seeded region growing algorithm adapted for use with CT images without contrast-enhancement. Virtual tumor resection is performed interactively by outlining the liver region on the CT images. The software application then processes the results to produce a three-dimensional (3D) image of the “resected” region. Finally, 3D rendering module provides possibility for easy and fast interpretation of the segmentation results. The visual outputs are accompanied with quantitative measures that further provide estimation of the residual liver function and based on them the surgeons could make a better decision. The developed system was tested and verified with twenty abdominal CT patient sets consisting of different numbers of tomographic images. Volumes, obtained by manual tracing of two surgeon experts, showed a mean relative difference of 4.5%. The application was used in a study that demonstrates the need and the added value of such a tool in practice and in education.
