Volume 18, Issue 8

In this paper the authors present a new approach for the nonrigid registration of contrast-enhanced breast MRI. A hierarchical transformation model of the motion of the breast has been developed. The global motion of the breast is modeled by an affine transformation while the local breast motion is described by a free-form deformation (FFD) based on B-splines. Normalized mutual information is used as a voxel-based similarity measure which is insensitive to intensity changes as a result of the contrast enhancement. Registration is achieved by minimizing a cost function, which represents a combination of the cost associated with the smoothness of the transformation and the cost associated with the image similarity. The algorithm has been applied to the fully automated registration of three-dimensional (3-D) breast MRI in volunteers and patients. In particular, the authors have compared the results of the proposed nonrigid registration algorithm to those obtained using rigid and affine registration techniques. The results clearly indicate that the nonrigid registration algorithm is much better able to recover the motion and deformation of the breast than rigid or affine registration algorithms.

本文提出了一种新的方法，用于对比增强乳腺MRI的非刚性配准。作者开发了一种层次化的乳腺运动变换模型。乳腺的整体运动通过仿射变换建模，而局部运动则通过基于B样条的自由形变（FFD）来描述。使用了归一化互信息...

In this paper, using certain conformal mappings from uniformization theory, the authors give an explicit method for flattening the brain surface in a way which preserves angles. From a triangulated surface representation of the cortex, the authors indicate how the procedure may be implemented using finite elements. Further, they show how the geometry of the brain surface may be studied using this ...

本文利用统一化理论中的某些共形映射，给出了一种保持角度的展平大脑表面的显式方法。作者从皮层三角化表面表示出发，说明了如何使用有限元实现该过程。此外，他们还展示了如何利用这种方法研究大脑表面的几何形状...

In the rapidly evolving field of intravascular ultrasound (IVUS), the assessment of vessel morphology still lacks a geometrically correct three-dimensional (3-D) reconstruction. The IVUS frames are usually stacked up to form a straight vessel, neglecting curvature and the axial twisting of the catheter during the pullback. The authors' method combines the information about vessel cross sections ob...

在快速发展的血管内超声（IVUS）领域，血管形态评估仍缺乏几何正确的三维（3-D）重建。IVUS图像帧通常被堆叠成一条笔直的血管，忽略了导管回撤过程中的弯曲和轴向扭转。作者的方法结合了关于血管横截面的信息，...

It is well understood that binary classifiers have two implicit objective functions (sensitivity and specificity) describing their performance. Traditional methods of classifier training attempt to combine these two objective functions (or two analogous class performance measures) into one so that conventional scalar optimization techniques can be utilized. This involves incorporating a priori inf...

众所周知，二元分类器有两个隐含的目标函数（灵敏度和特异度）来描述其性能。传统的分类器训练方法试图将这两个目标函数（或两个类似的类别性能度量）合并为一个，以便使用传统的标量优化技术。这涉及引入先验信息...

The high computational cost of data processing in volume PET imaging is still hindering the routine application of this successful technique, especially in the case of dynamic studies. This paper describes two new algorithms based on an exact rebinning equation, which can be applied to accelerate the processing of three-dimensional (3-D) PET data. The first algorithm, FOREPROJ, is a fast-forward p...

体积PET成像中数据处理的高计算成本仍然阻碍着这一成功技术的常规应用，尤其是在动态研究中。本文描述了两种基于精确重排方程的新算法，可用于加速三维PET数据的处理。第一种算法FOREPROJ是一种快速前向投影...

This paper analyzes and compares image reconstruction methods based on practical approximations to the exact log likelihood of randoms precorrected positron emission tomography (PET) measurements. The methods apply to both emission and transmission tomography, however, in this paper the authors focus on transmission tomography. The results of experimental PET transmission scans and variance approx...

本文分析和比较了基于随机预校正正电子发射断层扫描(PET)测量精确对数似然的实际近似图像重建方法。该方法适用于发射和透射断层扫描，然而，本文作者重点研究透射断层扫描。实验PET透射扫描和方差近似的结果...

Scatter correction is an important factor in single photon emission computed tomography (SPECT). Many scatter correction techniques, such as multiple-window subtraction and intrinsic modeling with iterative algorithms, have been under study for many years. Previously, the authors developed an efficient slice-to-slice blurring technique to model attenuation and system geometric response in a projec...

散射校正是单光子发射计算机断层扫描（SPECT）中的一个重要因素。许多散射校正技术，如多窗减法和基于迭代算法的内在建模，已研究多年。此前，作者开发了一种高效的切片间模糊技术，用于在投影中建模衰减和系统几何响应...

The purpose of this study was to evaluate acoustic noise in echo planar imaging (EPI) at various magnetic resonance imaging (MRI) centers and to compare EPI acoustic noise with that in other fast pulse sequences. The authors measured A-weighted root-mean-square sound pressure levels and peak impulse sound pressure levels for EPI, under the same conditions, in eleven clinical super-conducting MRI s...

本研究的目的是评估不同磁共振成像中心的回波平面成像（EPI）中的声学噪声，并将EPI声学噪声与其他快速脉冲序列进行比较。作者在相同的条件下，在十一个临床超导MRI系统中测量了EPI的A加权均方根声压级和峰值脉冲声压级。