Department of Radiology, Duke University Medical Center, Durham, NC, USA.
Nucl Med Biol. 2010 Feb;37(2):227-35. doi: 10.1016/j.nucmedbio.2009.11.002. Epub 2009 Dec 5.
In this study we proposed and developed a simple attenuation mapping approach based on magnetic resonance imaging (MRI) for the purpose of reconstructing positron emission tomography (PET) images in PET/MRI imaging devices.
After experimental development, an in vivo calibration was performed by whole-body scanning of five beagles on both a PET/CT and an MRI. The attenuation was determined by using an automated segmentation algorithm to segment regions of background, lung, soft tissue and bone, and assigning them values of 0.002, 0.030, 0.098 and 0.130 cm(-1), respectively.
The CT-attenuated and MRI-attenuated PET images had average standardized uptake values (SUVs) that differed by 1-6% for most regions of interest (ROIs). Also, mean relative differences (MRDs) between the images were between 5% and 9% for most regions. The only exception is bone, where the three-region MRI-attenuated PET images had an SUV 10% less on average than the CT-attenuation images, and the MRD averaged 14%. Also, additional segmentation of the bone in the four-region MRI-attenuated PET images reduced the SUV difference to 3% and the MRD to 6%.
Therefore, despite the improvements in the four-region segmentation, the three-region segmentation, without delineation of osseous tissues, produces high-quality images that are sufficient for most expected clinical and research purposes.
在这项研究中，我们提出并开发了一种基于磁共振成像（MRI）的简单衰减映射方法，用于重建正电子发射断层扫描（PET）图像在 PET/MRI 成像设备中。
经过实验开发，在 PET/CT 和 MRI 上对五只比格犬进行全身扫描，进行了体内校准。通过使用自动分割算法来分割背景、肺、软组织和骨骼区域，并分别将它们的值设置为 0.002、0.030、0.098 和 0.130 cm(-1)，来确定衰减。
CT 衰减和 MRI 衰减的 PET 图像在大多数感兴趣区域（ROI）中平均标准化摄取值（SUV）的差异为 1-6%。此外，大多数区域的图像之间的平均相对差异（MRD）在 5%至 9%之间。唯一的例外是骨骼，在那里，三个区域的 MRI 衰减 PET 图像的 SUV 平均比 CT 衰减图像低 10%，MRD 平均为 14%。此外，对四区域 MRI 衰减 PET 图像中的骨骼进行额外的分割，将 SUV 差异降低到 3%，MRD 降低到 6%。
因此，尽管在四区域分割方面有所改进，但不勾画骨组织的三区域分割可以产生高质量的图像，足以满足大多数预期的临床和研究目的。
