Volume 29, Issue 11

Optic disc (OD) detection is an important step in developing systems for automated diagnosis of various serious ophthalmic pathologies. This paper presents a new template-based methodology for segmenting the OD from digital retinal images. This methodology uses morphological and edge detection techniques followed by the Circular Hough Transform to obtain a circular OD boundary approximation. It requires a pixel located within the OD as initial information. For this purpose, a location methodology based on a voting-type algorithm is also proposed. The algorithms were evaluated on the 1200 images of the publicly available MESSIDOR database. The location procedure succeeded in 99% of cases, taking an average computational time of 1.67 s. with a standard deviation of 0.14 s. On the other hand, the segmentation algorithm rendered an average common area overlapping between automated segmentations and true OD regions of 86%. The average computational time was 5.69 s with a standard deviation of 0.54 s. Moreover, a discussion on advantages and disadvantages of the models more generally used for OD segmentation is also presented in this paper.

视盘检测是开发各种严重眼科病理自动诊断系统的重要步骤。本文提出了一种新的基于模板的方法，用于从数字视网膜图像中分割视盘。该方法使用形态学和边缘检测技术，然后进行圆形霍夫变换以获得近似的圆形视盘边界。它需要视盘内的一个像素作为初始信息。为此，还提出了一种基于投票类型算法的定位方法。在公开的MESSIDOR数据库的1200张图像上评估了这些算法。定位程序在99%的情况下成功，平均计算时间为1.67秒，标准差为0.14秒。另一方面，分割算法在自动分割与真实视盘区域之间的平均共同区域重叠率为86%。平均计算时间为5.69秒，标准差为0.54秒。此外，本文还讨论了更常用于视盘分割的模型的优缺点。

The magnetic particle imaging (MPI) imaging process is a new method of medical imaging with great promise. In this paper we derive the 1-D MPI signal, resolution, bandwidth requirements, signal-to-noise ratio (SNR), specific absorption rate, and slew rate limitations. We conclude with experimental data measuring the point spread function for commercially available SPIO nanoparticles and a demonstr...

磁粒子成像（MPI）成像过程是一种前景广阔的新型医学成像方法。本文推导了一维MPI信号、分辨率、带宽要求、信噪比（SNR）、比吸收率和压摆率限制。最后，我们通过实验数据测量了市售SPIO纳米颗粒的点扩散函数，并展示了一个演示。

Accurate definition of the similarity measure is a key component in image registration. Most commonly used intensity-based similarity measures rely on the assumptions of independence and stationarity of the intensities from pixel to pixel. Such measures cannot capture the complex interactions among the pixel intensities, and often result in less satisfactory registration performances, especially i...

相似性度量的精确定义是图像配准中的关键组成部分。最常用的基于强度的相似性度量依赖于像素间强度的独立性和平稳性假设。这些度量无法捕捉像素强度之间的复杂相互作用，常常导致配准性能不理想，尤其是...

Iterative methods for 3D image reconstruction have the potential to improve image quality over conventional filtered back projection (FBP) in X-ray computed tomography (CT). However, the computation burden of 3D cone-beam forward and back-projectors is one of the greatest challenges facing practical adoption of iterative methods for X-ray CT. Moreover, projector accuracy is also important for iter...

三维图像重建的迭代方法有潜力在X射线计算机断层扫描（CT）中比传统的滤波反投影（FBP）提高图像质量。然而，三维锥束前向和反向投影器的计算负担是X射线CT迭代方法实际应用面临的最大挑战之一。此外，投影器精度对于迭代方法也很重要……

We present a novel intrinsic method for joint reconstruction of both image and motion in positron emission tomography (PET). Intrinsic motion compensation methods exclusively work on the measured data, without any external motion measurements. Most of these methods separate image from motion estimation: They use deformable image registration/optical flow techniques in order to estimate the motion ...

我们提出了一种新的内在方法，用于在正电子发射断层扫描（PET）中联合重建图像和运动。内在运动补偿方法仅基于测量数据工作，无需任何外部运动测量。这类方法大多将图像与运动估计分开：它们使用可变形图像配准/光流技术来估计运动...

Trabecular bone (TB) is a complex quasi-random network of interconnected plates and rods. TB constantly remodels to adapt to the stresses to which it is subjected (Wolff's Law). In osteoporosis, this dynamic equilibrium between bone formation and resorption is perturbed, leading to bone loss and structural deterioration. Both bone loss and structural deterioration increase fracture risk. Bone's me...

松质骨是一个由相互连接的板状和杆状结构组成的复杂准随机网络。松质骨不断重塑以适应其所承受的应力（沃尔夫定律）。在骨质疏松症中，骨形成和骨吸收之间的动态平衡被打破，导致骨质流失和结构恶化。骨质流失和结构恶化都会增加骨折风险。骨的力学...

A major challenge in the current computer-aided detection (CAD) of polyps in CT colonography (CTC) is to reduce the number of false-positive (FP) detections while maintaining a high sensitivity level. A pattern-recognition technique based on the use of an artificial neural network (ANN) as a filter, which is called a massive-training ANN (MTANN), has been developed recently for this purpose. The M...

当前CT结肠成像（CTC）中息肉的计算机辅助检测（CAD）面临的主要挑战是在保持高灵敏度的同时减少假阳性（FP）检测数量。为此，最近开发了一种基于人工神经网络（ANN）作为滤波器的模式识别技术，称为大规模训练ANN（MTANN）。该...

Time-difference electrical impedance tomography (tdEIT) requires two data sets measured at two different times. The difference between them is utilized to produce images of time-dependent changes in a complex conductivity distribution inside the human body. Frequency-difference EIT (fdEIT) was proposed to image frequency-dependent changes of a complex conductivity distribution. It has potential ap...

时间差分电阻抗断层成像(tdEIT)需要两个在不同时间测量的数据集。利用它们之间的差异来生成人体内部复电导率分布随时间变化的图像。提出了频率差分电阻抗断层成像(fdEIT)来成像复电导率分布的频率依赖性变化。它具有潜在的应用...

This article discusses the application of sensitivity analysis (SA) in biomedical models. Sensitivity analysis is widely applied in physics, chemistry, economics, social sciences and other areas where models are developed. By assigning a prior probability distribution to each model variable, the SA framework appeals to the posterior probabilities of the model to evaluate the relative importance of...

本文讨论了灵敏度分析（SA）在生物医学模型中的应用。灵敏度分析广泛应用于物理学、化学、经济学、社会科学等开发模型的领域。通过为每个模型变量分配先验概率分布，SA框架利用模型的后验概率来评估相对重要性...

Low noise, high resolution, fast and accurate T1 maps from MRI images of the brain can be performed using a dual flip angle method. However, B1 field inhomogeneity, which is particularly problematic at high field strengths (e.g., 3T), limits the ability of the scanner to deliver the prescribed flip angle, introducing errors into the T1 maps that limit the accuracy of quantitative analyses based on...

低噪声、高分辨率、快速且准确的脑部MRI图像T1图可以通过双翻转角方法获得。然而，B1场不均匀性在高场强（如3T）下尤为突出，限制了扫描仪提供预定翻转角的能力，从而在T1图中引入误差，限制了基于定量分析的准确性...

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