Division of Imaging and Applied Mathematics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, Maryland 20993, USA.
Med Phys. 2011 Feb;38(2):743-53. doi: 10.1118/1.3533899.
In this study, the authors aim to develop a physical, tissue-mimicking phantom for quantitative evaluation of breast MRI protocols. The objective of this phantom is to address the need for improved standardization in breast MRI and provide a platform for evaluating the influence of image protocol parameters on lesion detection and discrimination. Quantitative comparisons between patient and phantom image properties are presented.
The phantom is constructed using a mixture of lard and egg whites, resulting in a random structure with separate adipose- and glandular-mimicking components. T1 and T2 relaxation times of the lard and egg components of the phantom were estimated at 1.5 T from inversion recovery and spin-echo scans, respectively, using maximum-likelihood methods. The image structure was examined quantitatively by calculating and comparing spatial covariance matrices of phantom and patient images. A static, enhancing lesion was introduced by creating a hollow mold with stereolithography and filling it with a gadolinium-doped water solution.
Measured phantom relaxation values fall within 2 standard errors of human values from the literature and are reasonably stable over 9 months of testing. Comparison of the covariance matrices of phantom and patient data demonstrates that the phantom and patient data have similar image structure. Their covariance matrices are the same to within error bars in the anterior-posterior direction and to within about two error bars in the right-left direction. The signal from the phantom's adipose-mimicking material can be suppressed using active fat-suppression protocols. A static, enhancing lesion can also be included with the ability to change morphology and contrast agent concentration.
The authors have constructed a phantom and demonstrated its ability to mimic human breast images in terms of key physical properties that are relevant to breast MRI. This phantom provides a platform for the optimization and standardization of breast MRI imaging protocols for lesion detection and characterization.
本研究旨在开发一种物理、组织模拟体模，用于定量评估乳腺 MRI 方案。该体模的目的是解决乳腺 MRI 标准化的需求，并提供一个平台来评估图像协议参数对病灶检测和鉴别能力的影响。提出了患者和体模图像特性之间的定量比较。
该体模是由猪油和蛋清混合而成，形成具有独立的脂肪和腺体模拟成分的随机结构。使用最大似然法，分别从反转恢复和自旋回波扫描中估算猪油和蛋清成分的 T1 和 T2 弛豫时间。通过计算和比较体模和患者图像的空间协方差矩阵，对图像结构进行定量检查。通过立体光刻制作一个空心模具并填充掺钆水溶液，来引入一个静态、增强的病灶。
测量的体模弛豫值在 2 个标准差内与文献中的人体值相符，并且在 9 个月的测试中相当稳定。体模和患者数据的协方差矩阵比较表明，体模和患者数据具有相似的图像结构。它们的协方差矩阵在前后方向上的误差范围内相同，在左右方向上的误差范围内约为两个。可以使用主动脂肪抑制协议抑制体模的脂肪模拟材料的信号。还可以包括一个静态、增强的病灶，并能够改变形态和造影剂浓度。
作者已经构建了一个体模，并证明了它在与乳腺 MRI 相关的关键物理特性方面能够模拟人体乳腺图像。该体模为优化和标准化乳腺 MRI 成像方案以进行病灶检测和特征描述提供了一个平台。
