Volume 16, Issue 1

Radial basis functions are presented as a practical solution to the problem of interpolating incomplete surfaces derived from three-dimensional (3-D) medical graphics. The specific application considered is the design of cranial implants for the repair of defects, usually holes, in the skull. Radial basis functions impose few restrictions on the geometry of the interpolation centers and are suited to problems where the Interpolation centers do not form a regular grid. However, their high computational requirements have previously limited their use to problems where the number of interpolation centers is small (<300). Recently developed fast evaluation techniques have overcome these limitations and made radial basis interpolation a practical approach for larger data sets. In this paper radial basis functions are fitted to depth-maps of the skull's surface, obtained from X-ray computed tomography (CT) data using ray-tracing techniques. They are used to smoothly interpolate the surface of the skull across defect regions. The resulting mathematical description of the skull's surface can be evaluated at any desired resolution to be rendered on a graphics workstation or to generate instructions for operating a computer numerically controlled (CNC) mill.

径向基函数被提出作为解决三维医学图形中不完整表面插值问题的实用方法。具体应用考虑的是设计颅骨植入物以修复颅骨中的缺损（通常是孔洞）。径向基函数对插值中心的几何形状限制很少，适用于插值中心不形成规则网格的问题。然而，它们的高计算要求此前限制了其应用，仅能处理插值中心数量较少（<300）的问题。最近开发的快速评估技术克服了这些限制，使径向基插值成为处理更大数据集的实用方法。本文中，径向基函数被拟合到通过射线追踪技术从X射线计算机断层扫描（CT）数据获得的颅骨表面深度图上，用于平滑插值缺损区域的颅骨表面。由此得到的颅骨表面数学描述可以在任何所需分辨率下进行评估，以便在图形工作站上渲染，或生成用于操作计算机数控铣床的指令。

The authors describe a computerized method to automatically find and label the cortical surface in three-dimensional (3-D) magnetic resonance (MR) brain images. The approach the authors take is to model a prelabeled brain atlas as a physical object and give it elastic properties, allowing it to warp itself onto regions in a preprocessed image. Preprocessing consists of boundary-finding and a morph...

作者描述了一种计算机化方法，用于自动在三维（3D）磁共振（MR）脑图像中找到并标记皮层表面。作者采用的方法是将预标记的脑图谱建模为物理对象并赋予其弹性特性，使其能够变形到预处理图像中的区域上。预处理包括边界检测和形态...

The authors present a new approach for detection of brain tumor boundaries in medical images using a Hopfield neural network. The boundary detection problem is formulated as an optimization process that seeks the boundary points to minimize an energy functional based on an active contour model. A modified Hopfield network is constructed to solve the optimization problem. Taking advantage of the co...

作者提出了一种使用Hopfield神经网络在医学图像中检测脑肿瘤边界的新方法。边界检测问题被表述为一个优化过程，该过程基于活动轮廓模型寻找边界点以最小化能量泛函。构建了一个改进的Hopfield网络来解决优化问题。利用共...

An accurate diagnosis of burns and pressure ulcers in the early stages can be made by computerized image processing. This study describes a critical assessment of potential methodologies for noninvasive wound evaluation using a color imaging system. The authors also developed a method for quantifying histological readings and applied these techniques to a porcine animal model of wound formation. D...

通过计算机图像处理可以早期准确诊断烧伤和压疮。本研究描述了使用彩色成像系统进行无创伤口评估的潜在方法的关键评估。作者还开发了一种量化组织学读数的方法，并将这些技术应用于伤口形成的猪动物模型。D...

Subject motion during brain imaging studies can adversely affect the images through loss of resolution and other artifacts related to movement. The authors have developed and tested a device to measure head motion externally in real-time during emission computed tomographic (ECT) brain imaging studies, to be used eventually to correct ECT data for that motion. The system is based on optical triang...

在脑成像研究中，受试者的运动会由于分辨率损失和其他与运动相关的伪影而对图像产生不利影响。作者开发并测试了一种设备，可以在发射计算机断层扫描（ECT）脑成像研究中实时外部测量头部运动，最终用于校正ECT数据中的运动。该系统基于光学三角测量...

For implementations of iterative reconstruction algorithms that rotate the image matrix, the characteristics of the rotator may affect the reconstruction quality. Desirable qualities for the rotator include: (1) preservation of global and local image counts; (2) accurate count positioning; (3) a uniform and predictable amount of blurring due to the rotation. A new rotation method for iterative rec...

对于旋转图像矩阵的迭代重建算法的实现，旋转器的特性可能会影响重建质量。旋转器所需的特性包括：(1) 保持全局和局部图像计数；(2) 准确的计数定位；(3) 由于旋转而产生的均匀且可预测的模糊量。一种用于迭代重...

A new formulation of the two-dimensional (2-D) deformable template matching problem is proposed. It uses a lower-dimensional search space than conventional methods by precomputing extensions of the deformable template along orthogonal curves. The reduction in search space allows the use of dynamic programming to obtain globally optimal solutions and reduces the sensitivity of the algorithm to init...

提出了一种新的二维可变形模板匹配问题的公式。它通过预计算沿正交曲线的可变形模板扩展，使用比传统方法更低维的搜索空间。搜索空间的减少允许使用动态规划来获得全局最优解，并降低了算法对初始化的敏感性...

In coronary vessels smaller than 1 mm in diameter, it is difficult to accurately identify lumen borders using existing border detection techniques. Computer-detected diameters of small coronary vessels are often severely overestimated due to the influence of the imaging system point spread function and the use of an edge operator designed for a broad range of diameter vessel sizes. Computer-detect...

在直径小于1毫米的冠状动脉血管中，使用现有的边界检测技术难以准确识别管腔边界。由于成像系统点扩散函数的影响以及使用为宽范围血管直径设计的边缘算子，计算机检测的小冠状动脉血管直径往往被严重高估。计算机检测...

A major drawback of statistical iterative image reconstruction for emission computed tomography is its high computational cost. The ill-posed nature of tomography leads to slow convergence for standard gradient-based iterative approaches such as the steepest descent or the conjugate gradient algorithm. Here, new theory and methods for a class of preconditioners are developed for accelerating the c...

统计迭代图像重建用于发射计算机断层扫描的主要缺点是计算成本高。断层扫描的病态性质导致标准梯度迭代方法（如最速下降法或共轭梯度算法）收敛缓慢。本文开发了一类预条件子的新理论和方法，用于加速重建过程。

Presents a model suitable for computing images of absorption cross sections of thick tissue structures illuminated at near infrared (NIR) wavelengths from tomographic projection data. Image reconstruction is accomplished by solving a system of linear equations derived from transport theory. Reconstruction results using different algebraic solvers are shown for anatomical maps of the breast, derive...

提出了一种适用于计算在近红外波长照明的厚组织结构吸收截面图像的模型，该图像来自断层投影数据。图像重建通过求解由输运理论导出的线性方程组完成。使用不同代数求解器的重建结果显示了乳腺解剖图，推导……

A new method of model registration is proposed using graphical templates. A decomposable graph of landmarks is chosen in the template image. All possible candidates for these landmarks are found in the data image using robust relational local operators. A dynamic programming algorithm on the template graph finds the optimal match to a subset of the candidate points in polynomial time. This combina...

提出了一种使用图形模板的模型配准新方法。在模板图像中选择一个可分解的地标图。使用鲁棒的局部关系算子，在数据图像中找到所有这些地标的候选点。模板图上的动态规划算法在多项式时间内找到与候选点子集的最优匹配。这种组合...

A simplified approach involving linear-regression straight-line parameter fitting of dynamic scan data is developed for both specific and nonspecific models. Where compartmental-model topologies apply, the measured activity may be expressed in terms of: its integrals, plasma activity and plasma integrals-all in a linear expression with macroparameters as coefficients. Multiple linear regression, a...

针对特定和非特定模型，开发了一种简化方法，涉及动态扫描数据的线性回归直线参数拟合。在房室模型拓扑适用的情况下，测量到的活性可以用其积分、血浆活性和血浆积分来表示——所有这些都包含在一个以宏观参数为系数的线性表达式中。多元线性回归...