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基于概率路线图法的窄道采样与轨迹优化 被引量:6
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作者 徐大也 胡立坤 +1 位作者 王小勇 刘恒佳 《国外电子测量技术》 北大核心 2023年第2期1-8,共8页
提出一种结合莱维飞行和概率路线图法(Lévy-probabilistic roadmap,LPRM)的路径规划算法。将莱维飞行方法应用于窄道采样,障碍物中的随机点通过莱维飞行走至自由空间,并延长碰撞测试来确保采样点位于窄道内,提升狭窄区域的采样质... 提出一种结合莱维飞行和概率路线图法(Lévy-probabilistic roadmap,LPRM)的路径规划算法。将莱维飞行方法应用于窄道采样,障碍物中的随机点通过莱维飞行走至自由空间,并延长碰撞测试来确保采样点位于窄道内,提升狭窄区域的采样质量与效率;为避免大量无效点的生成,在采样前先对地图进行预处理,膨胀障碍并对其进行边界提取,根据边界信息计算狭窄区域采样点数量,保证了全图采样的合理分布;进一步考虑移动机器人的实际工作情况,采用分段贝塞尔曲线对路径轨迹进行优化使其符合运动学约束,提高移动机器人的机动性。仿真实验在不同环境地图下对比了LPRM、传统概率路线图(PRM)和桥测试3种算法,结果表明LPRM算法相较两者在单一窄道环境下规划效率分别提升35.1%和32.2%,在复杂环境下其规划效率分别提升32.9%和15.5%,且提前400和100个采样点达到收敛,规划效率和成功率显著提高,总体耗时更短、路径更优,能减少移动机器人本身的能耗,提高整体工作效率。 展开更多
关键词 路径规划 轨迹优化 窄道采样 概率路线图法 莱维飞行
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窄道宽软盘磁头的研制 被引量:1
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作者 卢萍 冯向军 +1 位作者 库少平 张江陵 《华中理工大学学报》 CSCD 北大核心 1996年第7期74-76,共3页
应用磁记录理论设计了一种新型窄道宽软盘磁头,利用自制和国产加工设备,辅以进口检测设备对该磁头进行了试制,着重分析了研磨工艺品质问题以及玻璃烧结过程中裂纹的产生和预防,并通过联机测试验证设计及工艺的正确性.
关键词 软盘磁头 窄道 研磨 玻璃烧结
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基于叠加法的窄道宽磁头磁场 被引量:1
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作者 卢萍 张江陵 《电子学报》 EI CAS CSCD 北大核心 1997年第5期116-118,共3页
本文采用叠加法近似地模拟窄道磁头,从而得到出窄道宽磁头三维磁场的解析表达式,并进行了计算精度分析,结果表明,在y≥g/2处,叠加法最大误差不超过8%,且随着道宽的增大而减小。
关键词 窄道 叠加法 前隙磁场 磁盘存贮器
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窄道宽磁头边缘磁场读写性能分析
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作者 卢萍 张江陵 《华中理工大学学报》 CSCD 北大核心 1998年第5期69-71,共3页
对窄道宽磁头边缘磁场进行了深入分析,导出了该磁场的三维解析表达式.结果显示,该表达式具有较高精确度,能够揭示窄道宽磁头最优化设计中几何参数的选择规律.在此基础上,讨论了边沿磁场对写入道宽以及读出性能的影响.
关键词 高密度 窄道宽磁头 边缘磁场 读写性能
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窄道宽磁头三维磁头场的计算与分析
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作者 卢萍 《信息记录材料》 1995年第3期26-30,共5页
本文推导了准无限道宽磁头及零道宽磁头的磁头场函数,采用叠加法近似地模拟窄道宽磁头,从而得出窄道宽磁头的三维磁头场,在y≥g/2处,叠加法最大误差不超过8%。
关键词 窄道宽磁头 磁头场 计算与分析 叠加法 磁道宽度 磁头宽度 道密度 水平磁场 坐标系统 磁势
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光辅助磁记录的窄道记录与读出特性
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作者 王步云 《光盘技术》 2003年第1期33-37,共5页
采用TbFeCo垂直磁化膜,对激光辅助(Laser-assisted)磁记录方式的大优点——窄道记录特性进行了研究。评价了基于蓝色LD(Laset Diode:激光二极管)的辅助光束(Assisting beam)直径微小化的效果。根据热模拟和静磁特性说明了消除串扰的特... 采用TbFeCo垂直磁化膜,对激光辅助(Laser-assisted)磁记录方式的大优点——窄道记录特性进行了研究。评价了基于蓝色LD(Laset Diode:激光二极管)的辅助光束(Assisting beam)直径微小化的效果。根据热模拟和静磁特性说明了消除串扰的特性。对照无(消除)串扰特性和NFM观察图像,从宏观上对模拟记录位形状进行了定性解释。指出了作为决定光辅助磁记录的记录/读出性能的首要因素——辅助区温度分布的重要性。研究结果表明,通过介质特性和辅助激光功率的控制,有可能实现相当于光辅助光束直径(Ф0.55μm)1/2以下的窄道距(100ktpi)记录。 展开更多
关键词 光辅助 垂直磁记录 串扰消除 蓝色LD GMR 窄道记录 读出特性
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台励福窄道式电动堆高机
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《叉车技术》 2003年第2期10-10,共1页
关键词 电动堆高机 窄道 贷柜式油压缸 设计
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高铁CA砂浆窄道线上运输设备的研究
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作者 原文利 徐毅 张声军 《建筑机械化》 2013年第5期62-63,共2页
针对特殊路段下高速铁路CA砂浆线上运输的需求,基于现有CA砂浆施工经验,设计研发了CA砂浆线上运输设备,对我国高铁建设具有重要的应用价值。
关键词 高速铁路 CA砂浆 窄道 线上运输 设备
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砂岩型铀矿勘查中航放、航磁信息开发研究 被引量:8
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作者 常树帅 《铀矿地质》 CAS CSCD 2006年第5期300-304,310,共6页
本文以伊犁盆地南缘5个砂岩型铀矿床为研究对象,通过对已知铀矿床航放、航磁特征的研究,强调航放下测铀宽道Udw、上测铀窄道Uu、上测铀宽道Uuw和下测铀窄道Ud 4种参数异常是砂岩型铀矿的直接指示标志;对航放信息相关性分析进行了探讨,... 本文以伊犁盆地南缘5个砂岩型铀矿床为研究对象,通过对已知铀矿床航放、航磁特征的研究,强调航放下测铀宽道Udw、上测铀窄道Uu、上测铀宽道Uuw和下测铀窄道Ud 4种参数异常是砂岩型铀矿的直接指示标志;对航放信息相关性分析进行了探讨,认为航放相关性分析不适合层间氧化带砂岩型铀矿的预测,相关性分析圈定的Th、K元素负相关区带为古河道砂岩型铀矿床产出的有利部位;对弱磁异常进行了研究提取,首次提出用弱磁分布范围来圈定盖层氧化区(带)的观点;建立航放、航磁计算机预测模型,对整个盆地进行了砂岩型铀矿成矿预测,圈定远景区14片,便于进一步开展地面物探工作,继续扩大伊犁盆地的找矿成果。认为航放、航磁在可地浸砂岩型铀矿勘查中仍能发挥重要作用。 展开更多
关键词 下测铀宽道Udw 上测铀窄道Uu 上测铀宽道Uuw 下测铀窄道Ud 相关性分析 弱磁 计算机预测模型
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改进的RRT-Connect双足机器人路径规划算法 被引量:14
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作者 莫栋成 刘国栋 《计算机应用》 CSCD 北大核心 2013年第8期2289-2292,共4页
针对当组态空间内存在大量的窄道时,快速搜索随机树算法(RRT)难以取得连通路径的问题,提出了一种改进的RRT-Connect算法。该算法利用改进的桥梁检测算法来识别和采样窄道,使得路径规划在窄道内能轻易取得连通性;同时将RRT-Connect算法... 针对当组态空间内存在大量的窄道时,快速搜索随机树算法(RRT)难以取得连通路径的问题,提出了一种改进的RRT-Connect算法。该算法利用改进的桥梁检测算法来识别和采样窄道,使得路径规划在窄道内能轻易取得连通性;同时将RRT-Connect算法与任意时间算法相结合,显著地减少了RRT-Connect算法的移动代价。每个算法分别运行100次,与RRT-Connect算法相比,改进后的算法成功次数由34提高到93,规划时间由9.3 s减少到4.2 s。双足机器人的仿真实验结果表明,该算法能在窄道内取得优化路径,同时可以有效地提高路径规划的效率。 展开更多
关键词 快速搜索随机树 桥梁检测 任意时间算法 路径规划 窄道 双足机器人
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广东大型百货商场的经营创新及启示 被引量:2
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作者 王爱林 《江苏商论》 北大核心 2007年第1期20-21,共2页
广东大型百货近几年来发展势头良好,重视经营创新,从促销、人性化服务及突出特色等入手,进行经营模式创新,利用信息化手段由被动变为主动营销,提升了竞争力。广东大型百货经历了前些年亏损、倒闭的艰难困境之后,不断开拓创新,强化特色,... 广东大型百货近几年来发展势头良好,重视经营创新,从促销、人性化服务及突出特色等入手,进行经营模式创新,利用信息化手段由被动变为主动营销,提升了竞争力。广东大型百货经历了前些年亏损、倒闭的艰难困境之后,不断开拓创新,强化特色,已走出低谷,出现了良好的发展态势。 展开更多
关键词 广东大型百货商场 经营创新 窄道营销渠道 启示
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一种仿竹结构异形薄壁管设计及TIG增材成形
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作者 陈涵 周琦 《热加工工艺》 北大核心 2019年第13期152-155,共4页
通过对竹结构显微结构力学性能分析,设计出仿竹结构横向抗压薄壁管结构;并在保持力学性能的前提下进行该结构管简化设计。根据设计要求,在将起弧收弧缺陷控制到最小的基础之上进行焊接路径规划;通过TIG焊接窄道工艺试验,得出该竹结构管... 通过对竹结构显微结构力学性能分析,设计出仿竹结构横向抗压薄壁管结构;并在保持力学性能的前提下进行该结构管简化设计。根据设计要求,在将起弧收弧缺陷控制到最小的基础之上进行焊接路径规划;通过TIG焊接窄道工艺试验,得出该竹结构管薄壁所需的焊接工艺参数。最终通过TIG机器人电弧增材制造获得仿竹结构异型薄壁管。 展开更多
关键词 仿竹结构 路径规划 窄道工艺 增材制造
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台湾最便宜的书店
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《出版参考》 1999年第14期11-11,共1页
台北水准书局,可称是全台湾最便宜的书店。在新兴的连锁书店主导市场,传统书店逐渐式微下,这家书店竟然反其势扩大营业,一度引起书业界的轰动。走进刚搬迁新址的水准书店,迎面一叠叠过期杂志及新到图书把门口挤成一条窄道。
关键词 传统书店 台湾 连锁书店 扩大营业 主导市场 发行商 图书 窄道 书业 交朋友
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安全行车十慢
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作者 刘开顺 《农业开发与装备》 2000年第5期21-21,共1页
情况不明慢,视线不清慢,转弯地段慢,通过便桥慢,进城过街慢,遇有牲畜慢,狭窄道路慢,山坡险路慢,
关键词 安全行车 地段 窄道 车库 刘开
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千里之行,不可直以绳
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《华夏文化》 1994年第2期13-13,共1页
千里之行,不可直以绳《管子·宙合》云:"千里之路,不可扶以绳;万家之都,不可平以准",讲出了事物的道理。千里之路,不可能都是直路;大都市的房屋,不可能一样高低。事物具有多样性。人在路上行走,遇到险道、狭道、弯道,... 千里之行,不可直以绳《管子·宙合》云:"千里之路,不可扶以绳;万家之都,不可平以准",讲出了事物的道理。千里之路,不可能都是直路;大都市的房屋,不可能一样高低。事物具有多样性。人在路上行走,遇到险道、狭道、弯道,这是必然的。不要怕,应鼓足勇气.走过窄... 展开更多
关键词 千里之行 鼓足勇气 意志薄弱 直道 弯道 狭道 窄道 房屋
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Usefulness of biodegradable stents constructed of poly-l-lactic acid monofilaments in patients with benign esophageal stenosis 被引量:30
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作者 Yasuharu Saito Toyohiko Tanaka +6 位作者 Akira Andoh Hideki Minematsu Kazunori Hata Tomoyuki Tsujikawa Norihisa Nitta Kiyoshi Murata Yoshihide Fujiyama 《World Journal of Gastroenterology》 SCIE CAS CSCD 2007年第29期3977-3980,共4页
AIM: To report 13 patients with benign esophagea stenosis treated with the biodegradable stent. METHODS: We developed a Ultraflex-type stent by knitting poly-/-lactic acid rnonofilaments. RESULTS: Two cases were es... AIM: To report 13 patients with benign esophagea stenosis treated with the biodegradable stent. METHODS: We developed a Ultraflex-type stent by knitting poly-/-lactic acid rnonofilaments. RESULTS: Two cases were esophageal stenosis caused by drinking of caustic liquid, 4 cases were due to surgical resection of esophageal cancers, and 7 cases were patients with esophageal cancer who received the preventive placement of biodegradable stents for postendoscopic mucosal dissection (ESD) stenosis. The preventive placement was performed within 2 to 3 d after ESD. In 10 of the 13 cases, spontaneous migration of the stents occurred between 10 to 21 d after placement. In these cases, the migrated stents were excreted with the feces, and no obstructive complications were experienced. In 3 cases, the stents remained at the proper location on d 21 after placement. No symptoms of re-stenosis were observed within the follow-up period of 7 mo to 2 years. Further treatment with balloon dilatation or replacement of the biodegradable stent was not required. CONCLUSION: Biodegradable stents were useful for the treatment of benign esophageal stenosis, particularly for the prevention of post-ESD stenosis. 展开更多
关键词 STENTS Esophageal cancer Endoscopic submucosal dissection
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Comparative study of rendezvous techniques in post-liver transplant biliary stricture 被引量:3
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作者 Jae Hyuck Chang In Seok Lee +6 位作者 Ho Jong Chun Jong Young Choi Seung Kyoo Yoon Dong Goo Kim Young Kyoung You Myung-Gyu Choi Sok Won Han 《World Journal of Gastroenterology》 SCIE CAS CSCD 2012年第41期5957-5964,共8页
AIM: To investigate the usefulness of a new rendezvous technique for placing stents using the Kumpe (KMP) catheter in angulated or twisted biliary strictures. METHODS: The rendezvous technique was performed in pat... AIM: To investigate the usefulness of a new rendezvous technique for placing stents using the Kumpe (KMP) catheter in angulated or twisted biliary strictures. METHODS: The rendezvous technique was performed in patients with a biliary stricture after living donor liver transplantation (LDLT) who required the exchange of percutaneous transhepatic biliary drainage catheters for inside stents. The rendezvous technique was performed using a guidewire in 19 patients (guidewire group) and using a KMP catheter in another 19 (KMP catheter group). We compared the two groups retrospectively. RESULTS: The baseline characteristics did not differ between the groups. The success rate for placing insidestents was 100% in both groups. A KMP catheter was easier to manipulate than a guidewire. The mean pro- cedure time in the KMP catheter group (1012 s, range: 301-2006 s) was shorter than that in the guidewire group (2037 s, range: 251-6758 s, P = 0.022). The cu- mulative probabilities corresponding to the procedure time of the two groups were significantly different (P = 0.008). The factors related to procedure time were the rendezvous technique method, the number of inside stents, the operator, and balloon dilation of the stric- ture (P 〈 0.05). In a multivariate analysis, the rendez- vous technique method was the only significant factor related to procedure time (P = 0.010). The procedural complications observed included one case of mild acute pancreatitis and one case of acute cholangitis in the guidewire group, and two cases of mild acute pancre- atitis in the KMP catheter group. CONCLUSION: The rendezvous technique involving use of the KIVlp catheter was a fast and safe method for placing inside stents in patients with LDLT biliary stric- ture that represents a viable alternative to the guide- wire rendezvous technique, 展开更多
关键词 RENDEZVOUS Biliary stricture Liver trans-plantation Endoscopic retrograde cholangiography Percutaneous transhepatic biliary drainage
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Current endoscopic approach to indeterminate biliary strictures 被引量:3
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作者 David W Victor Stuart Sherman +1 位作者 Tarkan Karakan Mouen A Khashab 《World Journal of Gastroenterology》 SCIE CAS CSCD 2012年第43期6197-6205,共9页
Biliary strictures are considered indeterminate when basic work-up, including transabdominal imaging and endoscopic retrograde cholangiopancreatography with routine cytologic brushing, are non-diagnostic. Indeterminat... Biliary strictures are considered indeterminate when basic work-up, including transabdominal imaging and endoscopic retrograde cholangiopancreatography with routine cytologic brushing, are non-diagnostic. Indeterminate biliary strictures can easily be mischaracterized which may dramatically affect patient's outcome. Early and accurate diagnosis of malignancy impacts not only a patient's candidacy for surgery, but also potential timely targeted chemotherapies. A significant portion of patients with indeterminate biliary strictures have benign disease and accurate diagnosis is, thus, paramount to avoid unnecessary surgery. Current sampling strategies have suboptimal accuracy for the diagnosis of malignancy. Emerging data on other diagnostic modalities, such as ancillary cytology techniques, single operator cholangioscopy, and endoscopic ultrasonography-guided fine needle aspiration, revealed promising results with much improved sensitivity. 展开更多
关键词 Indeterminate stricture Bile duct Single operator cholangioscope CHOLANGIOSCOPY Endoscopic ultrasound Endoscopic retrograde cholangiopancrea-tography Bile duct stricture Indeterminate biliary stricture Confocal microscopy Transpapillary biopsy CHOLANGIOCARCINOMA Primary sclerosing cholangitis Spyglass
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Can patients determine the level of their dysphagia? 被引量:1
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作者 Hafiz Hamad Ashraf Joanne Palmer +4 位作者 Harry Richard Dalton Carolyn Waters Thomas Luff Madeline Strugnell Iain Alexander Murray 《World Journal of Gastroenterology》 SCIE CAS 2017年第6期1038-1043,共6页
To determine if patients can localise dysphagia level determined endoscopically or radiologically and association of gender, age, level and pathology.METHODSRetrospective review of consecutive patients presenting to d... To determine if patients can localise dysphagia level determined endoscopically or radiologically and association of gender, age, level and pathology.METHODSRetrospective review of consecutive patients presenting to dysphagia hotline between March 2004 and March 2015 was carried out. Demographics, clinical history and investigation findings were recorded including patient perception of obstruction level (pharyngeal, mid sternal or low sternal) was documented and the actual level of obstruction found on endoscopic or radiological examination (if any) was noted. All patients with evidence of obstruction including oesophageal carcinoma, peptic stricture, Schatzki ring, oesophageal pouch and cricopharyngeal hypertrophy were included in the study who had given a perceived level of dysphagia. The upper GI endoscopy reports (barium study where upper GI endoscopy was not performed) were reviewed to confirm the distance of obstructing lesion from central incisors. A previously described anatomical classification of oesophagus was used to define the level of obstruction to be upper, middle or lower oesophagus and this was compared with patient perceived level.RESULTSThree thousand six hundred and sixty-eight patients were included, 42.0% of who were female, mean age 70.7 ± 12.8 years old. Of those with obstructing lesions, 726 gave a perceived level of dysphagia: 37.2% had oesophageal cancer, 36.0% peptic stricture, 13.1% pharyngeal pouches, 10.3% Schatzki rings and 3.3% achalasia. Twenty-seven point five percent of patients reported pharyngeal level (upper) dysphagia, 36.9% mid sternal dysphagia and 25.9% lower sternal dysphagia (9.5% reported multiple levels). The level of obstructing lesion seen on diagnostic testing was upper (17.2%), mid (19.4%) or lower (62.9%) or combined (0.3%). When patients localised their level of dysphagia to a single level, the kappa statistic was 0.245 (P < 0.001), indicating fair agreement. 48% of patients reporting a single level of dysphagia were accurate in localising the obstructing pathology. With respect to pathology, patients with pharyngeal pouches were most accurate localising their level of dysphagia (P < 0.001). With respect to level of dysphagia, those with pharyngeal level lesions were best able to identify the level of dysphagia accurately (P < 0.001). No association (P > 0.05) was found between gender, patient age or clinical symptoms with their ability to detect the level of dysphagia.CONCLUSIONPatient perceived level of dysphagia is unreliable in determining actual level of obstructing pathology and should not be used to tailor investigations. 展开更多
关键词 Deglutition disorders Oesophageal stenosis Oesophageal neoplasm GASTROSCOPY FLUOROSCOPY Patient perception Pharyngeal pouch
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Hepatobiliary scintigraphy for detecting biliary strictures after living donor liver transplantation 被引量:6
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作者 Yu Jin Kim Kyu Taek Lee +4 位作者 Young Cheol Jo Kwang Hyuck Lee Jong Kyun Lee Jae-Won Joh Choon Hyuck David Kwon 《World Journal of Gastroenterology》 SCIE CAS CSCD 2011年第21期2626-2631,共6页
AIM:To investigate the diagnostic accuracy of hepatobiliary scintigraphy(HBS) in detecting biliary strictures in living donor liver transplantation(LDLT) patients.METHODS:We retrospectively reviewed 104 adult LDLT rec... AIM:To investigate the diagnostic accuracy of hepatobiliary scintigraphy(HBS) in detecting biliary strictures in living donor liver transplantation(LDLT) patients.METHODS:We retrospectively reviewed 104 adult LDLT recipients of the right hepatic lobe with duct-toduct anastomosis,who underwent HBS and cholangiography.The HBS results were categorized as normal,parenchymal dysfunction,biliary obstruction,or bile leakage without re-interpretation.The presence of biliary strictures was determined by percutaneous cholangiography or endoscopic retrograde cholangiopancreatography(ERCP).RESULTS:In 89 patients with biliary strictures,HBS showed biliary obstruction in 50 and no obstruction in 39,for a sensitivity of 56.2%.Of 15 patients with no biliary strictures,HBS showed no obstruction in 11,for a specificity of 73.3%.The positive predictive value(PPV) was 92.6%(50/54) and the negative predictive value(NPV) was 22%(11/50).We also analyzed the diagnostic accuracy of the change in bile duct size.The sensitivity,NPV,specificity,and PPV were 65.2%,27.9%,80% and 95%,respectively.CONCLUSION:The absence of biliary obstruction on HBS is not reliable.Thus,when post-LDLT biliary strictures are suspected,early ERCP may be considered. 展开更多
关键词 Living donor liver transplantation Tc99m mebrofenin Radionucleotide imaging Hepatobiliary scintigraphy Biliary stricture
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