Accurate PET/MR Quantification Using Time of Flight MLAA Image Reconstruction
Accurate PET/MR Quantification Using Time of Flight MLAA Image Reconstruction
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DOI：
10.1007/s11307-013-0716-x
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发表时间：
2014-08-01
影响因子：
3.1
通讯作者：
Lammertsma, A. A.
中科院分区：
文献类型：
--
作者：
Boellaard, R.;Hofman, M. B. M.;Lammertsma, A. A.
正电子发射断层扫描/磁共振成像(PET/MRI)研究的量化受到基于MR的衰减校正(MR-AC)不准确的阻碍。到目前为止，大多数关于MR-AC的研究都是在没有飞行时间(TOF)的PET/MR系统上进行的。然而，衰减和活动的最大似然重建(MLAA)有可能通过利用TOF来改善MR-AC。本研究的目的是评估MR-AC对TOF-PET/MR系统的PET图像定量的影响，并评估TOF和MLAA(TOF-MLAA)联合使用时的PET准确性。模拟设计用于评估(1)不同TOF窗口(667、500、333和167ps)下MR-AC对PET定量的影响和(2)使用TOF-MLAA来改善PET定量。比较了TOF有序子集期望最大化(OSEM)和使用MR-AC的TOF-MLAA重建与使用基于CT的AC(CT-AC)的TOF-OSEM重建的结果。TOF-OSEM能够将这种偏差降低到-15%，结果更准确，TOF更好。TOF-MLAA能够将偏差降低到5%以内，但代价是图像方差增加了类似40%。TOF-MLAA可以提高PET/MR研究的定量PET准确性。随着TOF性能的提高，预计会有进一步的改进。
Quantification of positron emission tomography/magnetic resonance imaging (PET/MRI) studies is hampered by inaccurate MR-based attenuation correction (MR-AC). To date, most studies on MR-AC have been performed using PET/MR systems without time of flight (TOF). Maximum likelihood reconstruction of attenuation and activity (MLAA), however, has the potential to improve MR-AC by exploiting TOF. The purpose of this study is to assess the impact of MR-AC on PET image quantification for TOF-PET/MR systems and to evaluate PET accuracy when using TOF in combination with MLAA (TOF-MLAA).Simulations were designed to evaluate (1) the impact of MR-AC on PET quantification for different TOF windows (667, 500, 333 and 167 ps) and (2) use of TOF-MLAA for improving PET quantification. TOF-ordered subset expectation maximisation (OSEM) and TOF-MLAA reconstructions using MR-AC were compared with those obtained using TOF-OSEM with computed tomography-based AC (CT-AC).OSEM reconstructions without TOF showed a negative MR-AC-induced bias of -50 % in the bone. TOF-OSEM was able to reduce this bias down to -15 %, with more accurate results for better TOF. TOF-MLAA was able to reduce the bias to within 5 % but at the cost of a similar to 40 % increase in image variance.TOF-MLAA can improve quantitative PET accuracy of PET/MR studies. Further improvements are anticipated with improving TOF performance.