论文标题
使用基于梯度矢量取向的非线性扩散滤波器（GVOF）的正电子发射断层扫描（PET）图像增强，以精确定量放射性浓度
Positron Emission Tomography (PET) image enhancement using a gradient vector orientation based nonlinear diffusion filter (GVOF) for accurate quantitation of radioactivity concentration
论文作者
论文摘要
通过正电子发射断层扫描（PET）准确量化体内放射性示踪剂的吸收，这是一项艰巨的任务，这是由于信噪比低（SNR）和宠物摄像机的空间分辨率不良以及有限的图像采样约束。此外，SNR的病变变化以及对比度以及病变大小的变化使定量更加困难。改进定量的方法之一是通过高斯滤波器（GF）进行重建后过滤。边缘保留双侧过滤器（BF）和非线性扩散滤波器（NDF）是GF的替代方法，可以改善SNR而不会降低图像分辨率。但是，这些边缘保留方法的性能仅适用于高计数和低噪声案例。本文提出了一种新型的基于基于非线性扩散滤波器（GVOF）的基于非线性扩散滤波器（GVOF）的新型参数，对统计波动不敏感（例如，SNR，对比度，大小等）。与原始和其他过滤图像相比，GVOF的对比度和噪声均具有不同级别的对比度和噪声的GVOF方法，其对比度和噪声水平都不同，这表明GVOF方法提供了最高的SNR，CNR（对比度与噪声比率）和分辨率。估计代表直径> 2cm的SUVMAX（最大标准化摄取值）的最大活性的百分比偏差，其中局部体积效应（PVE）可忽略不计为GVOF方法的最低。 GVOF方法还提高了最大强度可重复性。 GVOF防止大小，对比度和SNR变化的鲁棒性使其成为准确诊断和响应评估的合适后过滤方法。此外，它提供准确的定量测量的能力，无论SNR如何，它也可以有效地减少放射性剂量。
To accurately quantify in vivo radiotracer uptake using Positron Emission Tomography (PET) is a challenging task due to low signal-to-noise ratio (SNR) and poor spatial resolution of PET camera along with the finite image sampling constraint. Furthermore, inter lesion variations of the SNR and contrast along with the variations in size of the lesion make the quantitation even more difficult. One of the ways to improve the quantitation is via post reconstruction filtering with Gaussian Filter (GF). Edge preserving Bilateral Filter (BF) and Nonlinear Diffusion Filter (NDF) are the alternatives to GF that can improve the SNR without degrading the image resolution. However, the performance of these edge preserving methods are only optimum for high count and low noise cases. A novel parameter free gradient vector orientation based nonlinear diffusion filter (GVOF) is proposed in this paper that is insensitive to statistical fluctuations (e. g., SNR, contrast, size etc.). GVOF method applied on the PET images collected with the NEMA phantom with varying levels of contrast and noise reveals that the GVOF method provides the highest SNR, CNR (contrast-to-noise ratio) and resolution compared to the original and other filtered images. The percentage bias in estimating the maximum activity representing SUVmax (Maximum Standardized Uptake Value) for the spheres with diameter > 2cm where the partial volume effects (PVE) is negligible is the lowest for the GVOF method. The GVOF method also improves the maximum intensity reproducibility. Robustness of the GVOF against variation in sizes, contrast levels and SNR makes it a suitable post filtering method for both accurate diagnosis and response assessment. Furthermore, its capability to provide accurate quantitative measurements irrespective of the SNR, it can also be effective in reduction of radioactivity dose.
