Motion artifact reduction with three-point ghost phase cancellation.

A novel method for "ghost" artifact suppression is introduced. It suppresses ghosts induced by motion in any direction, as well as other types of quasi-periodic signal modulation. Because it requires neither special hardware nor intensive data processing, it can be easily implemented on conventional magnetic resonance (MR) imagers. The method is based on the concept of decomposition of a ghosted complex image into a ghost mask and ideal image. A set of deliberately designed acquisitions are used to generate a set of ghosted complex images in which the ghost components are related in a simple manner. With use of equations describing image decomposition and ghost correlation, the ideal image can be calculated pixel by pixel. The ideal image obtained (representing the time-averaged spin-density distribution) is shown to be a truer representation of physical reality than the ghost-free image obtained with ordered phase encoding. In this technique, both interview and intraview effects are taken into account. The technique is also useful in simultaneously suppressing ghosts from multifrequency signal modulations such as respiratory and cardiac motions. The method was successfully tested with three time-interleaved, phase-encoding-order-shifted acquisitions. Experimental results have shown that it is a simple but effective technique.     

电位滴定法的计算原理及Excel软件应用

阐述了电位滴定法的计算原理以及Excel软件在电位滴定数据处理中的应用。     

Comparison of Radiographic and pQCT Analyses of Healing Rat Tibial Fractures

Fracture healing and callus formation have traditionally been evaluated by using X-ray radiography. Here we compared X-ray radiography and peripheral quantitative computed tomography (pQCT) in evaluating the healing callus of standardized tibial fractures in 141 female rats after a 4- or 8-week follow-up. The results were compared with the tensile (4-week) and compressive (8-week) failure load of the callus. The projectional size of callus, as defined from lateral ex vivo radiographs, correlated significantly with the pQCT-defined cross-sectional area (CSA) of mid-callus. This relationship was dependent on the pQCT attenuation threshold, being higher for the CSA of compact bone (r = 0.85, P < 0.0001) than for the total bone CSA (r = 0.68, P < 0.0001). Radiographically defined callus projectional area also correlated strongly with bone mineral content (BMC) (r = 0.84–0.86, P < 0.0001). The mean optical density of the callus analyzed from the radiographs had only a weak correlation with the pQCT-defined bone mineral density (BMD) of callus. A weak negative relationship was found between CSA and BMD. The optical density analyzed from lateral radiographs did not correlate with the tensile or compressive failure load of callus. Callus size, BMC, and BMD were associated with the compressive failure load, whereas both radiographs and pQCT were poor in explaining the failure load in tension. Received: 28 June 1999 / Accepted: 28 October 1999     

放射治疗计算机信息管理系统的开发与应用

目的　开发放射治疗信息管理系统计算机软件。方法　采用局域网、客户机 服务器模式 ,以SQL SERVERA为数据库服务器 ,使用VisualFoxpro 5 .0为编程语言进行开发。结果　该系统包括放射治疗计划系统和放射治疗科数据管理系统。结论　该系统运行稳定 ,数据安全可靠 ,操作简单 ,易于临床推广使用。     

基于小波变换极大模的多模医学图像融合

多模态医学图像融合由于其对医学临床诊断的意义已引起广泛的关注,基于图像边缘特性的融合方法逐渐成为研究的重点。本文提出了一种基于离散二进小波变换的多尺度边缘检测和图像融合的方法,实现了特征级图像融合。不同于以往的从极大模值点直接重建图像,本文的算法利用极大模值点建立有效的融合规则,然后从融合的小波系数重构信号。融合图像的交互信息和峰值信噪比等检测指标表明此方法优于传统融合算法。     

RELATIONSHIP OF THE EXPRESSION OF MDR1 GENE PRODUCT IN HEPATO CELLULAR CARCINOMA TO INVASION AND METASTASIS

ＩＮＴＲＯＤＵＣＴＩＯＮＰｇｌｙｃｏｐｒｏｔｅｉｎ（Ｐｇｐ），ｔｈｅｐｒｏｄｕｃｔｏｆｔｈｅｍｕｌｔｉｄｒｕｇｒｅｓｉｓｔａｎｃｅ（ＭＤＲ１）ｇｅｎｅ，ｉｓａ１７０Ｋｄａｍｅｍｂｒａｎｅｐｒｏｔｅｉｎｒｅｓｐｏｎｓｉｂｌｅｆｏｒｐｕｍｐｉｎｇ...     

Maruyama软件术前预测胃癌淋巴结转移的前瞻性研究

[目的]研究应用Maruyama软件术前预测胃癌淋巴结转移范围的可靠性和可行性.[方法]选择2002年1月～2004年6月问施行根治术的胃癌病人166例进行前瞻性研究.将患者性别、年龄、Borrmann分型、组织学类型、浸润深度、肿瘤部位及大小等预后因素输入计算机,应用Maruyama软件对淋巴结转移范围进行分析,并与术后病理诊断结果比较.[结果]Maruyama软件对各站淋巴结转移的术前预测准确率分别为N1:82.2%,N2:89.0%,N3:95.8%.[结论]Maruyama软件术前预测胃癌淋巴结转移率准确率较高,如能进一步提高术前对浸润深度的判断,将有望增加该软件的临床使用价值.     

Virtual computed tomography colonoscopy: artifacts, image quality and radiation dose load in a cadaver study

The purpose of our study was to evaluate the interdependency of spatial resolution, image reconstruction artifacts, and radiation doses in virtual CT colonoscopy by comparing various CT scanning protocols. A pig's colon with several artificial polypoid lesions was imaged after air insufflation with helical CT scanning using 1-, 3-, and 5-mm collimation, and pitch values varying from 1.0 to 3.0. Virtual endoscopic images and “fly through” sequences were calculated on a Sun Sparc 20 workstation (Navigator Software, GE Medical Systems, Milwaukee, Wis.). Several reconstruction artifacts as well as overall image quality were evaluated by three independent reviewers. In addition, radiation doses for the different CT protocols were measured as multiple-scan average dose using a 10-cm ion chamber and a standard Plexiglass body phantom. Generally, image quality and reconstruction artifacts were less affected by pitch values than by beam collimation. Thus, narrow beam collimation at higher pitch values (e. g. 3 mm/2.0) seems to be a reasonable compromise between quality of virtual endoscopic images and radiation dose load. Received: 4 February 1999; Revised: 16 June 1999; Accepted: 17 June 1999     

High-resolution magnetic resonance and volume rendering of the labyrinth

Our aim was to verify the feasibility of volume rendering (VR) of high-resolution magnetic resonance (HR-MR) data sets of the labyrinth. We retrospectively reviewed the HR-MR data sets of 16 consecutive patients with no MR evidence of labyrinthine pathology. High-resolution MR data sets were obtained by means of a 3D T2-weighted FSE sequence with the use of a 3-in. circular surface coil for signal reception, and processed with a high-end workstation. Two reviewers performed separately VR of the labyrinth by selecting the signal intensity interval for attribution of opacity and transparency. Concerning the time taken for definition of the volume of interest, the two observers needed, respectively, 28.9 and 33.1 min (SD ± 8.7–9.5 min), whereas the time taken for VR was respectively, 26 and 33.2 min (SD ± 8.8–8.9 min). Concerning the selection of the signal intensity interval, the two observers had, respectively, 86.4 and 88.7 mean lower threshold (SD ± 34.5–33.5), 488.9 and 495.4 mean upper threshold (SD ± 56.3–53.8). In our experience, we have found VR of HR-MR to offer a reliable and reproducible technique for producing 3D representations of the labyrinth. The VR algorithms use all data within the imaging volume and optimize the dynamic range ascribed to the object being visualized. Received: 9 October 1998; Revised: 14 January 1999; Accepted: 30 June 1999     

螺旋CT三维重建及切割软件在诊断颌面部骨折中的应用

目的探讨螺旋CT三维重建及切割软件在诊断颌面部骨折中的应用价值。方法29例颌面部骨折病例,先经螺旋CT扫描,后在工作站上进行三维重建和切割,显示骨折,分析总结二、三维及切割软件在显示骨折方面的效果。结果三维影像在显示浅部颌面部骨折位置,范围,骨碎片移位方面优于二维影像,但在显示深部结构方面不及二维影像;结合使用切割软件可扩大三维重建的应用范围,可同样清楚显示深部的三维结构。结论三维影像可清楚显示颌面部的空间解剖关系,切割软件能扩大三维软件的应用范围,可显示清楚深部结构的三维关系,有重要的临床应用价值。