Volume 17, Issue 3

After conception and implementation of any new medical image processing algorithm, validation is an important step to ensure that the procedure fulfils all requirements set forth at the initial design stage. Although the algorithm must be evaluated on real data, a comprehensive validation requires the additional use of simulated data since it is impossible to establish ground truth with in vivo data. Experiments with simulated data permit controlled evaluation over a wide range of conditions (e.g., different levels of noise, contrast, intensity artefacts, or geometric distortion). Such considerations have become increasingly important with the rapid growth of neuroimaging, i.e., computational analysis of brain structure and function using brain scanning methods such as positron emission tomography and magnetic resonance imaging. Since simple objects such as ellipsoids or parallelepipedes do not reflect the complexity of natural brain anatomy, the authors present the design and creation of a realistic, high-resolution, digital, volumetric phantom of the human brain. This three-dimensional digital brain phantom is made up of ten volumetric data sets that define the spatial distribution for different tissues (e.g., grey matter, white matter, muscle, skin, etc.), where voxel intensity is proportional to the fraction of tissue within the voxel. The digital brain phantom can be used to simulate tomographic images of the head. Since the contribution of each tissue type to each voxel in the brain phantom is known, it can be used as the gold standard to test analysis algorithms such as classification procedures which seek to identify the tissue "type" of each image voxel. Furthermore, since the same anatomical phantom may be used to drive simulators for different modalities, it is the ideal tool to test intermodality registration algorithms. The brain phantom and simulated MR images have been made publicly available on the Internet (http://www.bic.mni.mcgill.ca/brainweb).

在构思和实现任何新的医学图像处理算法之后，验证是一个重要步骤，以确保该过程满足初始设计阶段提出的所有要求。虽然算法必须在真实数据上进行评估，但全面的验证还需要额外使用模拟数据，因为无法从体内数据建立金标准...

The problem of parameter estimation from Rician distributed data (e.g., magnitude magnetic resonance images) is addressed. The properties of conventional estimation methods are discussed and compared to maximum-likelihood (ML) estimation which is known to yield optimal results asymptotically. In contrast to previously proposed methods, ML estimation is demonstrated to be unbiased for high signal-t...

本文讨论了从莱斯分布数据（例如，磁共振图像的幅度）进行参数估计的问题。讨论了传统估计方法的性质，并与已知渐近最优的最大似然（ML）估计进行了比较。与先前提出的方法相反，ML估计被证明在高信噪比条件下是无偏的...

Breast cancer continues to be a significant public health problem in the United States. Approximately, 182,000 new cases of breast cancer are diagnosed and 46,000 women die of breast cancer each year. Even more disturbing is the fact that one out of eight women in the United States will develop breast cancer at some point during her lifetime. Since the cause of breast cancer remains unknown, prima...

乳腺癌在美国仍然是一个重大的公共卫生问题。每年约有182,000例新发乳腺癌病例被诊断，46,000名女性死于乳腺癌。更令人不安的是，美国每八名女性中就有一人在其一生中的某个阶段会患上乳腺癌。由于乳腺癌的病因尚不明确，因此...

The authors assess the value of magnetic resonance (MR) image texture in Alzheimer's disease (AD) both as a diagnostic marker and as a measure of progression. T/sub 1/-weighted MR scans were acquired from 40 normal controls and 24 AD patients. These were split into a training set (20 controls, 40 AD) and a test set (20 controls, 14 AD). In addition, five control subjects and five AD patients were ...

作者评估了磁共振（MR）图像纹理在阿尔茨海默病（AD）中作为诊断标志物和进展衡量指标的价值。从40名正常对照和24名AD患者中获取了T1加权MR扫描。这些数据被分为训练集（20名对照，40名AD）和测试集（20名对照，14名AD）。此外，还有5名对照和5名AD患者...

Magnetic resonance imaging (MRI) is unique in its ability to noninvasively and selectively alter tissue magnetization and create tagged patterns within a deforming body such as the heart muscle. The resulting patterns define a time-varying curvilinear coordinate system on the tissue, which the authors track with coupled B-snake grids. B-spline bases provide local control of shape, compact representation, and parametric continuity. Efficient spline warps are proposed which warp an area in the plane such that two embedded snake grids obtained from two tagged frames are brought into registration, interpolating a dense displacement vector field. The reconstructed vector field adheres to the known displacement information at the intersections, forces corresponding snakes to be warped into one another, and for all other points in the plane, where no information is available, a C/sup 1/ continuous vector field is interpolated. The implementation proposed in this paper improves on the authors' previous variational-based implementation and generalizes warp methods to include biologically relevant contiguous open curves, in addition to standard landmark points. The methods are validated with a cardiac motion simulator, in addition to in-vivo tagging data sets.

磁共振成像（MRI）具有独特的能力，能够非侵入性地、选择性地改变组织磁化，并在变形体（如心肌）内部创建标记模式。由此产生的模式定义了组织上随时间变化的曲线坐标系，作者使用耦合的B样条网格对其进行跟踪。B样条基提供了形状的局部控制、紧凑的表征...

An algorithm is developed that detects well-localized, unfragmented, thin edges in medical images based on optimization of edge configurations using a genetic algorithm (GA). Several enhancements were added to improve the performance of the algorithm over a traditional GA. The edge map is split into connected subregions to reduce the solution space and simplify the problem. The edge-map is then op...

一种算法被开发出来，基于遗传算法（GA）优化边缘配置，用于检测医学图像中定位良好、无碎片、细小的边缘。添加了几项增强功能以提高算法相对于传统GA的性能。边缘图被分割成连通的子区域以减少解空间并简化问题。然后对边缘图进行...

Karyotyping involves the visualization and classification of chromosomes into standard classes. In "normal" human metaphase spreads, chromosomes occur in homologous pairs for the autosomal classes 1-22, and X chromosome for females. Many existing approaches for performing automated human chromosome image analysis presuppose cell normalcy, containing 46 chromosomes within a metaphase spread with tw...

核型分析涉及将染色体可视化和分类为标准类别。在“正常”人类中期分裂相中，常染色体类别1-22和女性X染色体以同源对形式出现。许多现有的自动化人类染色体图像分析方法预设细胞正常，包含46条染色体在一个中期分裂相中，且...

To noninvasively quantify tissue elasticity for differentiating malignancy of soft tissue, the authors previously proposed a two-dimensional (2-D) mechanical inverse problem in which simultaneous partial differential equations (PDE's) represented the target distribution globally of relative shear moduli with respect to reference shear moduli such that the relative values could be determined from s...

为了无创量化组织弹性以区分软组织恶性，作者先前提出了一个二维（2-D）力学逆问题，其中联立偏微分方程（PDE）全局地表示了相对于参考剪切模量的相对剪切模量目标分布，从而可以从应变测量确定相对值...

In magnetic resonance imaging, spatial localization is usually achieved using Fourier encoding which is realized by applying a magnetic field gradient along the dimension of interest to create a linear correspondence between the resonance frequency and spatial location following the Larmor equation. In the presence of B/sub 0/ inhomogeneities along this dimension, the linear mapping does not hold ...

在磁共振成像中，空间定位通常通过傅里叶编码实现，这是通过沿感兴趣维度施加磁场梯度来创建共振频率与空间位置之间的线性对应关系，遵循拉莫尔方程。当沿该维度存在B0场不均匀性时，线性映射不再成立……

Computational methods can be used to provide an initial screening or a second opinion in medical settings and may improve the sensitivity and specificity of diagnoses. In the current study, linear discriminant models and artificial neural networks are trained to detect breast cancer in suspicious masses using radiographic features and patient age. Results on 139 suspicious breast masses (79 malign...

计算方法可用于在医疗环境中提供初步筛查或第二意见，并可能提高诊断的敏感性和特异性。在本研究中，使用放射学特征和患者年龄训练线性判别模型和人工神经网络，以检测可疑肿块中的乳腺癌。对139个可疑乳腺肿块（79个恶性...）的结果...

Scatter compensation in Tl-201 single photon emission computed tomography (SPECT) presents an interesting challenge because of the multiple emission energies and relatively large proportion of scattered photons. In this paper, the authors present a simulation study investigating reconstructed image noise levels arising from various implementations of iterative reconstruction-based scatter compensa...

铊-201单光子发射计算机断层扫描（SPECT）中的散射补偿是一个有趣的挑战，因为存在多种发射能量和相对较大比例的散射光子。本文中，作者提出了一项模拟研究，调查了基于迭代重建的散射补偿的各种实现方式所产生的重建图像噪声水平...

Assigning anatomic labels to coronary arteries in X-ray angiograms is an important task in medical imaging, motivated by the desire to standardize the assessment of coronary artery disease and to facilitate the three-dimensional (3-D) reconstruction and visualization of the coronary vasculature. However, automatic labeling poses a number of significant challenges, including the presence of noise, ...

在X射线血管造影中为冠状动脉分配解剖标签是一项重要的医学成像任务，旨在标准化冠状动脉疾病的评估，并促进冠状动脉血管系统的三维重建和可视化。然而，自动标注面临诸多挑战，包括噪声的存在等。

With the recent development in scatter and attenuation correction algorithms, dynamic single photon emission computerized tomography (SPECT) can potentially yield physiological parameters, with tracers exhibiting suitable kinetics such as thallium-201 (Tl-201). A systematic way is proposed to investigate the minimum data acquisition times and sampling requirements for estimating physiological para...

随着散射和衰减校正算法的最新发展，动态单光子发射计算机断层扫描（SPECT）有可能利用具有适当动力学的示踪剂（如铊-201 (Tl-201)）获得生理参数。提出了一种系统的方法来研究估计生理参数所需的最小数据采集时间和采样要求...

The extremum stack, as proposed by Koenderink (1984), is a multiresolution image description and segmentation scheme which examines intensity extrema (minima and maxima) as they move and merge through a series of progressively isotropically diffused images known as scale space. Such a data-driven approach is attractive because it is claimed to he a generally applicable and natural method of image ...

极值栈，由Koenderink（1984）提出，是一种多分辨率图像描述和分割方案，它检查强度极值（最小值和最大值）在一系列逐渐各向同性扩散的图像（称为尺度空间）中移动和合并的过程。这种数据驱动方法很有吸引力，因为它据称是一种通用且自然的图像……

In this paper, the authors present a new reversible decorrelation method of three-dimensional (3-D) medical images for progressive transmission. Progressive transmission of an image permits gradual improvement of image quality while being displayed. When the amount of image data is very large, as a 3-D medical image, the progressive transmission plays an important role in viewing or browsing the i...

本文提出了一种新的用于渐进传输的三维医学图像可逆去相关方法。渐进传输允许在显示过程中逐步提高图像质量。当图像数据量非常大时，如三维医学图像，渐进传输在查看或浏览图像中起着重要作用。

In magnetocardiographic (MCG) localization of arrhythmia substrates, a model of the thorax volume conductor is a crucial component of the calculations. In this study, the authors investigated different models of the thorax, to determine the most suitable to use in the computations. Their methods and results are as follows. They studied 11 patients with overt Wolff-Parkinson-White syndrome, schedul...

在磁心图（MCG）定位心律失常基质时，胸腔容积导体模型是计算的关键组成部分。本研究探讨了不同的胸部模型，以确定最适合用于计算的模型。他们的方法和结果如下：他们研究了11名显性沃尔夫-帕金森-怀特综合征患者，安排...

The n-dimensional (n-D) radon transform, which forms the mathematical basis for a broad variety of tomographic imaging applications, can be viewed as an n-D function in n-D sinogram space. Accurate reconstruction of continuous or discrete tomographic images requires full knowledge of the Radon transform in the corresponding n-D sinogram space. In practice, however, one can have only a finite set o...

n维拉东变换是多种层析成像应用的数学基础，可以看作n维正弦图空间中的n维函数。连续或离散断层图像的精确重建需要完全了解相应n维正弦图空间中的拉东变换。然而，在实践中，我们只能获得有限数量的...

The purpose of this paper is to investigate the effectiveness of the authors' novel dynamic range compression (DRC) for chest radiographs. The purpose of DRC is to compress the gray scale range of the image when using narrow dynamic range viewing systems such as monitors. First, an automated segmentation method was used to detect the lung region. The combined region of mediastinum, heart, and subd...

本文旨在研究作者提出的新型动态范围压缩技术在胸部X线图像中的有效性。动态范围压缩的目的是在使用窄动态范围显示系统（如显示器）时压缩图像的灰度范围。首先，采用自动分割方法检测肺部区域。结合纵隔、心脏和亚...