Vessel enhancement filtering in three-dimensional MR angiograms using long-range signal correlation

Small vessels in three-dimensional MR angiograms have low visibility in maximum-intensity projection images because of their low contrast. In a previous study, we had two nonlinear filters that appeared to give significant improvement in small vessel detail. In this paper, we report on a generalization of this filter that allows a more general modeling of the vessels and a more complete suppression of background. One implementation of the general filter gave a vessel mean contrast-to-noise ratio that is 2.52 and 3.51 times higher than the vessel mean contrast-to-noise ratio obtained using our previously reported maximum-minimum (max-min) filter and cross- section filter, respectively.     

In vivo comparison of two through-plane MR velocity mapping methods: Fast fourier encoding and phase mapping

Magnetic resonance imaging maps of velocity were acquired with a 1.5-T system in 10 subjects in a plane perpendicular to the main pulmonary artery. Velocity images were successively acquired with a method developed from Fourier-encoding velocity imaging (FEVI) principles with eight gradient steps and one excitation, and with two-point phase-subtraction mapping. Reconstruction in FEVI was implemented by zero-filling interpolation around the eight gradient steps and then around the four central steps. The methods were compared by using estimates of noise in velocity measurements based on the difference between the experimental map and a smooth fitted map. For the same acquisition time, FEVI with four encoding steps was more precise in velocity measurements than phase mapping. Precision was further increased by the use of eight encoding steps, but acquisition time was doubled.     

腹部CTA检查的质量保证

目的:探讨螺旋CT血管造影(Spiral CT angiography,SCTA)技术,以期提高SCTA造影的质量。材料与方法:采用Somatom Plus 4螺旋CT扫描系统对10例病人行腹部SCTA检查。扫描技术和造影剂参数按病变范围和性质而定,三维重建采用最大强度投影法(MIP)或表面阴影显示法(SSD)或弯曲平面重建法(CPR)。结果:SCTA检查技术能可靠地显示血管形态和病变,评价腹部肿瘤与邻近血管关系。结论:SCTA是无创伤性的血管成像术,在很大范围可替代创伤性的血管造影。     

Multiresolution,model-based segmentation of MR angiograms

During the last decade, the quality of MR angiograms has risen substantially and their clinical utility has been demonstrated progressively. This acceptance has created a need for tools with which to summarize and display the information available. We have used a model-based segmentation technique to extract vascular morphology and local flow parameters from phase contrast MR angiograms. A multiresolution data structure is used as the basis of recursive decision-making to identify regions of blood flow. The resulting data representation allows more efficient data handling in subsequent processing and visualization and is directly applicable to the creation of a connected graph model of vascular regions. We describe this flow feature extraction algorithm and demonstrate the utility of the results.     

Quantitative relationship between pupillary reflex feature and its diopter in retinoscopy

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计算机自动定量诊断脑萎缩的初步研究

目的研究正常人群脑容积随年龄及性别的变化规律,提出计算机定量诊断脑萎缩的客观标准。方法利用最新提出的脑容积计算机自动定量算法,测量了脑萎缩组487例(男,310例,女,177例)和正常组1901例(男,993例,女,908例)的颅腔容积、脑容积和脑实质分数(BPF),并通过多项式曲线拟合技术,研究正常人BPF随年龄变化的函数关系。结果正常组颅腔容积为(1271322±128699)mm3,脑容积为(1211725±122077)mm3,BPF为(95.3471±2.3453)%;脑萎缩组颅腔容积为(1276900±125180)mm3,脑容积为(1203400±117760)mm3,BPF为(91.8115±2.3035)%。两组之间的颅腔容积和脑容积差异无统计学意义(P>0.05),而BPF差异具有统计学意义(P<0.001);BPF定量与年龄之间的二次多项式函数关系P(x)=-0.0008x2+0.0193x+96.9999能够较为准确表达正常人BPF随年龄变化的函数关系,其95%可信区间下限为y=-0.0008x2+0.0184x+95.1090。结论BPF与年龄之间函数关系的95%可信区间下限,可作为计算机自动定量诊断脑萎缩的客观标准。     

计算机辅助带锁髓内钉固定胫骨骨折全程规划手术系统的实验研究

目的评价计算机辅助带锁髓内钉固定胫骨骨折全程手术规划系统的有效性及临床可行性。方法在分析系统结构和操作流程的基础上,利用塑料胫骨模型(9根)和尸体胫骨(12具下肢肢体)进行基于C型臂透视图像的术中骨折肢体图像拼接、骨折闭合复位及髓内钉置入仿真测量实验；利用胫骨模型及尸体胫骨进行图像拼接精度分析,以验证图像拼接与规划模块的正确性。利用尸体胫骨进行计算机辅助骨折闭合复位试验,分析骨折复位机构模块的操作可行性。结果图像拼接模块只需术中采集7～10张有效的C型臂图像即可拼接出下肢长骨的全景图像,为采集图像所需的术中透视时间为(19．75±0．61)s；计算机进行X线透视图像采集和拼接总时间为(4．17±0．86)min；塑料模型拼接精度达(1．26±0．76)mm。结论该系统实现了基于C型臂拼接图像的计算机辅助胫骨骨折髓内钉内固定全程手术规划,术中可完成骨折复位图像分析、手术规划、虚拟仿真,髓内钉型号选择以及骨折复位等关键操作,为计算机辅助骨科手术系统治疗长骨骨折搭建了精确、安全、稳定的软硬件技术平台。     

下肢静脉病变顺、逆行造影的诊断价值

目的:探讨下肢静脉病变顺、逆行造影X线表现与病理改变的关系。方法:回顾性分析86例(119侧)下肢静脉病变顺、逆行造影X线表现。结果:顺行造影显示原发性下肢深静脉瓣膜关闭不全84侧,交通静脉瓣膜关闭不全14侧,单纯性瓣膜关闭不全11侧,静脉瘤或弥漫性血管湖6侧,先天性下肢静脉发育异常4侧。逆行造影显示0级13侧,Ⅰ级58侧,Ⅱ级21侧,Ⅲ级19侧,Ⅳ级8侧。结论:下肢静脉病变顺、逆行同时造影能更好地显示下肢浅、深静脉瓣膜功能,为临床诊断或治疗提供非常有价值的依据。     

主动脉夹层血肿36例的诊治分析

目的　探讨主动脉夹层血肿的临床特点及诊治方法。方法　回顾性分析 3 6例主动脉夹层血肿的临床资料 ,分析其临床特点、误诊情况、影像学诊断及内科治疗。结果　 86.1%的病例有高血压史和现症高血压 ,其中合并冠心病 7例、糖尿病 4例、高脂血症 17例 ;88.9的病例有胸、腰背或腹痛并呈游走性 ;经治疗病情缓解出院 2 8例 ,占 77.8% ;死亡 8例 ,病死率为 2 2 .2 %。结论　结合临床表现和影像学检查 ,发现内膜撕裂口、钙化的内膜内移或真假腔 ,是确诊主动脉夹层血肿的关键     

SPECT/CT同机图像融合诊断股骨头缺血性坏死

目的 评价SPECT/CT同机图像融合技术诊断股骨头缺血性坏死的临床应用价值.方法 53例临床可疑股骨头缺血性坏死患者行全身骨显像及骨盆局部SPECT/CT断层显像并对SPECT和CT同机图像进行重建与融合.结果 ①融合图像诊断阳性率高于断层图像及平面图像,差异具有显著性;②融合图像对早期病变诊断阳性率高于断层显像及平面显像,差异具有显著性.结论 SPECT/CT同机图像融合技术对于股骨头缺血性坏死的早期诊断、鉴别诊断及疾病分期均有一定的临床价值.