基于磁共振成像的躯干正电子发射断层显像/磁共振成像衰减校正：磁共振成像到计算机断层扫描数据映射中的陷阱
MR-based attenuation correction for torso-PET/MR imaging: pitfalls in mapping MR to CT data.
作者信息
Beyer Thomas, Weigert Markus, Quick Harald H, Pietrzyk Uwe, Vogt Florian, Palm Christoph, Antoch Gerald, Müller Stefan P, Bockisch Andreas
机构信息
Department of Nuclear Medicine, University Hospital, Hufelandstr 55, 45122, Essen, Germany.
出版信息
Eur J Nucl Med Mol Imaging. 2008 Jun;35(6):1142-6. doi: 10.1007/s00259-008-0734-0. Epub 2008 Feb 19.
PURPOSE
MR-based attenuation correction (AC) will become an integral part of combined PET/MR systems. Here, we propose a toolbox to validate MR-AC of clinical PET/MRI data sets.
METHODS
Torso scans of ten patients were acquired on a combined PET/CT and on a 1.5-T MRI system. MR-based attenuation data were derived from the CT following MR-CT image co-registration and subsequent histogram matching. PET images were reconstructed after CT- (PET(CT)) and MR-based AC (PET(MRI)). Lesion-to-background (L/B) ratios were estimated on PET(CT) and PET(MRI).
RESULTS
MR-CT histogram matching leads to a mean voxel intensity difference in the CT- and MR-based attenuation images of 12% (max). Mean differences between PET(MRI) and PET(CT) were 19% (max). L/B ratios were similar except for the lung where local misregistration and intensity transformation leads to a biased PET(MRI).
CONCLUSION
Our toolbox can be used to study pitfalls in MR-AC. We found that co-registration accuracy and pixel value transformation determine the accuracy of PET(MRI).
目的
基于磁共振成像的衰减校正（AC）将成为PET/MR联合成像系统的一个组成部分。在此，我们提出一个工具箱，用于验证临床PET/MRI数据集的磁共振AC。
方法
在PET/CT和1.5-T MRI系统上对10名患者进行躯干扫描。基于磁共振的衰减数据是在磁共振-CT图像配准及随后的直方图匹配后从CT数据中获得的。PET图像在基于CT的AC（PET(CT)）和基于磁共振的AC（PET(MRI)）后重建。在PET(CT)和PET(MRI)上估计病灶与背景（L/B）比值。
结果
磁共振-CT直方图匹配导致基于CT和基于磁共振的衰减图像中体素强度平均差异为12%（最大值）。PET(MRI)和PET(CT)之间的平均差异为19%（最大值）。除肺部外，L/B比值相似，在肺部，局部配准不良和强度变换导致PET(MRI)出现偏差。
结论
我们的工具箱可用于研究磁共振AC中的缺陷。我们发现配准精度和像素值变换决定了PET(MRI)的准确性。
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