Volume 23, Issue 5

Two-dimensional (2-D)/three-dimensional (3-D) registration techniques using single-plane fluoroscopy are highly important for analyzing 3-D kinematics in applications such as total knee arthroplasty (TKA) implants. The accuracy of single-plane fluoroscopy-based techniques in the determination of translation perpendicular to the image plane (depth position), however, is relatively poor because a change in the depth position causes only small changes in the 2-D silhouette. Accuracies achieved in depth position using conventional 2-D/3-D registration techniques are insufficient for clinical applications. Therefore, we propose a technique for improving the accuracy of depth position determination in order to develop a system for analyzing knee kinematics over the full six degrees of freedom (6 DOF) using single-plane fluoroscopy. In preliminary experiments, the behaviors of errors for each free variable were quantified as evaluation curves by examining changes in cost function with variations in the free variable. The evaluation curve for depth position was more jagged, and the curve peak less pointy, compared to the evaluation curves of the other five variables, and the curve was found to behave differently. Depth position is therefore optimized independently of the other variables, using an approximate evaluation curve of depth position prepared after initial registration. Accuracy of the proposed technique was evaluated by computer simulation and in vitro tests, with validation of absolute position and orientation performed for each knee component. In computer simulation tests, root-mean-square error (RMSE) in depth position was improved from 2.6 mm (conventional) to 0.9 mm (proposed), whereas for in vitro tests, RMSE improved from 3.2 mm to 1.4 mm. Accuracy of the estimation of the remaining two translational and three rotational variables was found to be almost the same as that obtained by conventional techniques. Results of in vivo tests are also described in which the possibility of full 6 DOF kinematic analysis of TKA implants is shown.

基于单平面荧光透视的二维/三维配准技术对于分析全膝关节置换假体等应用中的三维运动学至关重要。然而，由于深度位置的变化仅引起二维轮廓的微小变化，单平面荧光透视技术确定垂直于图像平面的平移（深度位置）的精度相对较差。传统的二维/三维配准技术所达到的深度位置精度不足以满足临床应用。因此，我们提出了一种提高深度位置确定精度的技术，以开发一种使用单平面荧光透视分析膝关节全六个自由度的运动学系统。在初步实验中，通过检查代价函数随自由变量的变化，将每个自由变量的误差行为量化为评估曲线。与其他五个变量的评估曲线相比，深度位置的评估曲线更呈锯齿状，曲线峰值更不尖锐，并且发现曲线行为不同。因此，在初始配准后，使用准备的深度位置近似评估曲线，将深度位置与其他变量独立优化。通过计算机模拟和体外测试评估了所提出技术的准确性，并对每个膝关节组件进行了绝对位置和方向的验证。在计算机模拟测试中，深度位置的均方根误差从2.6毫米（传统）提高到0.9毫米（所提出），而在体外测试中，均方根误差从3.2毫米提高到1.4毫米。其余两个平移和三个旋转变量的估计精度与传统技术几乎相同。还描述了体内测试的结果，显示了全膝关节置换假体进行全六自由度运动学分析的可能性。

Most image-guided surgery (IGS) systems track the positions of surgical instruments in the physical space occupied by the patient. This task is commonly performed using an optical tracking system that determines the positions of fiducial markers such as infrared-emitting diodes or retroreflective spheres that are attached to the instrument. Instrument tracking error is an important component of th...

大多数图像引导手术系统追踪患者所在物理空间中的手术器械位置。此任务通常使用光学追踪系统完成，该系统通过确定附着在器械上的基准标记（如红外发光二极管或反光球）的位置来工作。器械追踪误差是整体...

In this paper, a fully automatic method for luminal contour segmentation in intracoronary ultrasound imaging is introduced. Its principle is based on a contour with a priori properties that evolves according to the statistics of the ultrasound texture brightness, which is generally Rayleigh distributed. The main interest of the technique is its fully automatic character. This is insured by an init...

本文介绍了一种用于冠状动脉内超声成像中管腔轮廓全自动分割的方法。其原理基于具有先验属性的轮廓，该轮廓根据超声纹理亮度的统计特性演化，通常服从瑞利分布。该技术的主要优势在于其全自动特性，这是通过一种初始...

Monte Carlo (MC) methods can accurately simulate scatter in X-ray imaging. However, when low noise scatter projections have to be simulated these MC simulations tend to be very time consuming. Rapid computation of scatter estimates is essential for several applications. The aim of the work presented in this paper is to speed up the estimation of noise-free scatter projections while maintaining the...

蒙特卡洛（MC）方法能够准确模拟X射线成像中的散射。然而，当需要模拟低噪声散射投影时，这些MC模拟往往非常耗时。快速计算散射估计对于多种应用至关重要。本文旨在加速无噪声散射投影的估计，同时保持...

Bone scintigraphy is an effective method to diagnose bone diseases such as bone tumors. In the scintigraphic images, bone abnormalities are widely scattered on the whole body. Conventionally, radiologists visually check the whole-body images and find the distributed abnormalities based on their expertise. This manual process is time-consuming and it is not unusual to miss some abnormalities. In th...

骨显像是诊断骨肿瘤等骨疾病的有效方法。在显像图像中，骨骼异常广泛分布于全身。传统上，放射科医生根据专业知识目视检查全身图像并发现分布异常的病灶。这一手动过程耗时且容易遗漏一些异常。在...

Mechanical factors such as deformation and strain are thought to play important roles in the maintenance, repair, and degeneration of soft tissues. Determination of soft tissue static deformation has traditionally only been possible at a tissue's surface, utilizing external markers or instrumentation. Texture correlation is a displacement field measurement technique which relies on unique image pa...

机械因素如变形和应变被认为在软组织的维持、修复和退化中起重要作用。传统上，仅能通过使用外部标记或仪器在组织表面测定软组织的静态变形。纹理相关是一种位移场测量技术，依赖于独特的图像模式...

Three-dimensional (3-D) ultrasound is a relatively new technique, which is well suited to imaging superficial blood vessels, and potentially provides a useful, noninvasive method for generating anatomically realistic 3-D models of the peripheral vasculature. Such models are essential for accurate simulation of blood flow using computational fluid dynamics (CFD), but may also be used to quantify at...

三维超声波是一种相对较新的技术，非常适合对浅表血管进行成像，并且可能提供一种有用的、无创的方法来生成外周血管解剖学上真实的三维模型。这种模型对于使用计算流体动力学（CFD）准确模拟血流至关重要，但也可能用于量化在...

In this paper we analyze a result previously published about a comparison between two statistical tests used for evaluation of boundary detection algorithms on medical images. We conclude that the statement made by Chalana and Kim (1997) about the performance of the percentage test has a weak theoretical foundation, and according to our results, is not correct. In addition, we propose a one-sided ...

本文分析了一个先前发表的结果，该结果比较了两种用于评估医学图像边界检测算法的统计检验。我们得出结论，Chalana和Kim（1997）关于百分比检验性能的论述理论基础薄弱，并且根据我们的结果，该论述是不正确的。此外，我们提出了一种单侧...

Previous studies have evaluated the effect of the new still image compression standard JPEG 2000 using nontask based image quality metrics, i.e., peak-signal-to-noise-ratio (PSNR) for nonmedical images. In this paper, the effect of JPEG 2000 encoder options was investigated using the performance of human and model observers (nonprewhitening matched filter with an eye filter, square-window Hotellin...

先前的研究使用非任务型图像质量指标（即峰值信噪比）评估了新的静态图像压缩标准JPEG 2000对非医学图像的影响。本文通过人类和模型观察者（带眼滤波器的非预白化匹配滤波器，方窗霍特林...）的性能，研究了JPEG 2000编码器选项的影响。

Most positron emission tomography (PET) emission scans are corrected for accidental coincidence (AC) events by real-time subtraction of delayed-window coincidences, leaving only the randoms-precorrected data available for image reconstruction. The real-time randoms precorrection compensates in mean for AC events but destroys the Poisson statistics. The exact log-likelihood for randoms-precorrected...

大多数正电子发射断层扫描（PET）发射扫描通过实时减去延迟窗符合事件来校正偶然符合（AC）事件，仅留下随机预校正数据用于图像重建。实时随机预校正补偿了AC事件的均值但破坏了泊松统计。对于随机预校正的精确对数似然...

Face and dentition were measured using a high-resolution three-dimensional laser scanner to circumvent problems of radiation exposure and metal-streak artifacts associated with X-ray computed tomography. The resulting range data were integrated in order to visualize the dentition relative to the face. The acquisition interval for dentition by laser scanner was 0.18 mm, and complicated morphologies...

使用高分辨率三维激光扫描仪测量面部和牙列，以避免X射线计算机断层扫描相关的辐射暴露和金属条纹伪影问题。将所得范围数据进行整合，以可视化相对于面部的牙列。激光扫描仪获取牙列的间隔为0.18毫米，能够捕捉复杂的形态。

The spherical homeomorphism conjecture, proposed by Shattuck and Leahy in 2001, serves as the backbone of their algorithm to correct the topology of magnetic resonance images of the human cerebral cortex. Using a canonical image-thickening technique and the authors' previously proven "spherical homeomorphism theorem for surfaces," we formulate and prove a spherical homeomorphism theorem which is v...

Shattuck和Leahy在2001年提出的球同胚猜想，是他们用于纠正人脑皮层磁共振图像拓扑结构的算法的核心。利用规范的图像加厚技术以及作者先前证明的“曲面球同胚定理”，我们提出并证明了一个球同胚定理，该定理...

Provides a listing of current committee members and society officers.

提供当前委员会成员和学会官员的列表。

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本页或数页特意留白。

Presents the table of contents for this issue of the periodical.

介绍本期期刊的目录。

Provides instructions and guidelines to prospective authors who wish to submit manuscripts.

为有意投稿的作者提供说明和指南。