From the Department of Radiology and Biomedical Imaging, UCSF Physics Research Laboratory, University of California, San Francisco, 185 Berry St, Suite 350, San Francisco, CA 94143-0946 (J.Y., N.J., S.C.B., T.A.H., P.E.Z.L., D.V., Y.S.); GE Healthcare, Waukesha, Wis (Y.J.); and Department of Radiology, San Francisco VA Medical Center, San Francisco, Calif (T.A.H.).
Radiology. 2017 Jul;284(1):169-179. doi: 10.1148/radiol.2017161603. Epub 2017 Feb 23.
Purpose To assess the patient-dependent accuracy of atlas-based attenuation correction (ATAC) for brain positron emission tomography (PET) in an integrated time-of-flight (TOF) PET/magnetic resonance (MR) imaging system. Materials and Methods Thirty recruited patients provided informed consent in this institutional review board-approved study. All patients underwent whole-body fluorodeoxyglucose PET/computed tomography (CT) followed by TOF PET/MR imaging. With use of TOF PET data, PET images were reconstructed with four different attenuation correction (AC) methods: PET with patient CT-based AC (CTAC), PET with ATAC (air and bone from an atlas), PET with ATAC (air and tissue from the atlas with patient bone), and PET with ATAC (air and tissue from the atlas without bone). For quantitative evaluation, PET mean activity concentration values were measured in 14 1-mL volumes of interest (VOIs) distributed throughout the brain and statistical significance was tested with a paired t test. Results The mean overall difference (±standard deviation) of PET with ATAC compared with PET with CTAC was -0.69 kBq/mL ± 0.60 (-4.0% ± 3.2) (P < .001). The results were patient dependent (range, -9.3% to 0.57%) and VOI dependent (range, -5.9 to -2.2). In addition, when bone was not included for AC, the overall difference of PET with ATAC (-9.4% ± 3.7) was significantly worse than that of PET with ATAC (-4.0% ± 3.2) (P < .001). Finally, when patient bone was used for AC instead of atlas bone, the overall difference of PET with ATAC (-1.5% ± 1.5) improved over that of PET with ATAC (-4.0% ± 3.2) (P < .001). Conclusion ATAC in PET/MR imaging achieves similar quantification accuracy to that from CTAC by means of atlas-based bone compensation. However, patient-specific anatomic differences from the atlas causes bone attenuation differences and misclassified sinuses, which result in patient-dependent performance variation of ATAC. RSNA, 2017 Online supplemental material is available for this article.
目的 在集成飞行时间（TOF）PET/MR 成像系统中，评估基于图谱的衰减校正（ATAC）对脑正电子发射断层扫描（PET）的患者依赖性准确性。
材料与方法 本机构审查委员会批准的研究中，招募了 30 名经知情同意的患者。所有患者均接受全身氟脱氧葡萄糖 PET/计算机断层扫描（CT）检查，随后进行 TOF PET/MR 成像。使用 TOF PET 数据，采用 4 种不同的衰减校正（AC）方法重建 PET 图像：基于患者 CT 的 AC（CTAC）的 PET、基于图谱空气和骨骼的 AC（ATAC）的 PET、基于图谱空气和组织的 AC（ATAC）的 PET（带有患者骨骼）和基于图谱空气和组织的 AC（ATAC）的 PET（无骨骼）。为了进行定量评估，在整个脑内分布的 14 个 1-mL 感兴趣区（VOI）中测量了 PET 的平均活性浓度值，并使用配对 t 检验进行了统计学意义检验。
结果 与 CTAC 相比，ATAC 的 PET 平均整体差异（±标准差）为-0.69 kBq/mL±0.60（-4.0%±3.2）（P<0.001）。结果具有患者依赖性（范围，-9.3%至 0.57%）和 VOI 依赖性（范围，-5.9 至-2.2）。此外，当不进行 AC 时不包括骨骼，基于图谱的 ATAC 的 PET 整体差异（-9.4%±3.7）明显比基于图谱的 ATAC 的 PET 整体差异（-4.0%±3.2）差（P<0.001）。最后，当使用患者骨骼代替图谱骨骼进行 AC 时，基于图谱的 ATAC 的 PET 整体差异（-1.5%±1.5）比基于图谱的 ATAC 的 PET 整体差异（-4.0%±3.2）改善（P<0.001）。
结论 在 PET/MR 成像中，通过基于图谱的骨骼补偿，ATAC 可实现与 CTAC 相似的定量准确性。然而，来自图谱的患者特定解剖差异会导致骨骼衰减差异和分类错误的窦，从而导致 ATAC 的患者依赖性性能变化。
RSNA，2017 在线补充材料可用于本文。
