MR∕PET 定量工具：配准、分割、分类和基于 MR 的衰减校正。
MR∕PET quantification tools: registration, segmentation, classification, and MR-based attenuation correction.
机构信息
Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA, USA.
出版信息
Med Phys. 2012 Oct;39(10):6443-54. doi: 10.1118/1.4754796.
PURPOSE
Combined MR∕PET is a relatively new, hybrid imaging modality. A human MR∕PET prototype system consisting of a Siemens 3T Trio MR and brain PET insert was installed and tested at our institution. Its present design does not offer measured attenuation correction (AC) using traditional transmission imaging. This study is the development of quantification tools including MR-based AC for quantification in combined MR∕PET for brain imaging.
METHODS
The developed quantification tools include image registration, segmentation, classification, and MR-based AC. These components were integrated into a single scheme for processing MR∕PET data. The segmentation method is multiscale and based on the Radon transform of brain MR images. It was developed to segment the skull on T1-weighted MR images. A modified fuzzy C-means classification scheme was developed to classify brain tissue into gray matter, white matter, and cerebrospinal fluid. Classified tissue is assigned an attenuation coefficient so that AC factors can be generated. PET emission data are then reconstructed using a three-dimensional ordered sets expectation maximization method with the MR-based AC map. Ten subjects had separate MR and PET scans. The PET with [(11)C]PIB was acquired using a high-resolution research tomography (HRRT) PET. MR-based AC was compared with transmission (TX)-based AC on the HRRT. Seventeen volumes of interest were drawn manually on each subject image to compare the PET activities between the MR-based and TX-based AC methods.
RESULTS
For skull segmentation, the overlap ratio between our segmented results and the ground truth is 85.2 ± 2.6%. Attenuation correction results from the ten subjects show that the difference between the MR and TX-based methods was <6.5%.
CONCLUSIONS
MR-based AC compared favorably with conventional transmission-based AC. Quantitative tools including registration, segmentation, classification, and MR-based AC have been developed for use in combined MR∕PET.
目的
磁共振∕正电子发射断层成像（MR∕PET）组合是一种相对较新的混合成像模式。我们机构安装并测试了一台由西门子 3T Trio MR 和脑 PET 插件组成的人用 MR∕PET 原型系统。该系统目前的设计并未采用传统透射成像来提供经过测量的衰减校正（AC）。本研究旨在开发量化工具，包括用于脑成像的组合 MR∕PET 中的基于 MR 的 AC 进行定量。
方法
所开发的量化工具包括图像配准、分割、分类和基于 MR 的 AC。这些组件被整合到一个用于处理 MR∕PET 数据的单一方案中。分割方法是多尺度的，基于脑 MR 图像的 Radon 变换。该方法旨在对 T1 加权 MR 图像上的颅骨进行分割。开发了一种改进的模糊 C 均值分类方案，用于将脑组织分类为灰质、白质和脑脊液。分类后的组织被赋予一个衰减系数，以便生成 AC 因子。然后，使用基于三维有序集期望最大化方法，根据基于 MR 的 AC 图对 PET 发射数据进行重建。十名受试者分别进行了 MR 和 PET 扫描。使用高分辨率研究断层成像（HRRT）PET 采集了 [(11)C]PIB 的 PET 发射数据。在 HRRT 上，将基于 MR 的 AC 与透射（TX）-基于 AC 进行了比较。在每位受试者的图像上手动绘制了 17 个感兴趣区，以比较基于 MR 和 TX 的 AC 方法之间的 PET 活性。
结果
颅骨分割的重叠率为 85.2±2.6%。十位受试者的衰减校正结果表明，MR 和 TX 方法之间的差异<6.5%。
结论
基于 MR 的 AC 与传统的 TX 基于 AC 相比表现良好。已经开发了包括配准、分割、分类和基于 MR 的 AC 在内的量化工具，用于组合的 MR∕PET。
Zotero 插件