基于磁共振和计算机断层扫描衰减校正的正电子发射断层扫描定量在生理组织和病变中的比较：66 例全身正电子发射断层扫描/磁共振研究。
Comparison of Positron Emission Tomography Quantification Using Magnetic Resonance- and Computed Tomography-Based Attenuation Correction in Physiological Tissues and Lesions: A Whole-Body Positron Emission Tomography/Magnetic Resonance Study in 66 Patients.
机构信息
From the *Diagnostic and Interventional Radiology, and †Preclinical Imaging and Radiopharmacy, Laboratory for Preclinical Imaging and Imaging Technology of the Werner Siemens Foundation, Department of Radiology, Eberhard Karls University; ‡Max Planck Institute for Intelligent Systems; and §Nuclear Medicine, Department of Radiology, Eberhard Karls University, Tübingen, Germany.
出版信息
Invest Radiol. 2016 Jan;51(1):66-71. doi: 10.1097/RLI.0000000000000208.
OBJECTIVE
Attenuation correction (AC) in fully integrated positron emission tomography (PET)/magnetic resonance (MR) systems plays a key role for the quantification of tracer uptake. The aim of this prospective study was to assess the accuracy of standardized uptake value (SUV) quantification using MR-based AC in direct comparison with computed tomography (CT)-based AC of the same PET data set on a large patient population.
MATERIALS AND METHODS
Sixty-six patients (22 female; mean [SD], 61 [11] years) were examined by means of combined PET/CT and PET/MR (11C-choline, 18F-FDG, or 68Ga-DOTATATE) subsequently. Positron emission tomography images from PET/MR examinations were corrected with MR-derived AC based on tissue segmentation (PET(MR)). The same PET data were corrected using CT-based attenuation maps (μ-maps) derived from PET/CT after nonrigid registration of the CT to the MR-based μ-map (PET(MRCT)). Positron emission tomography SUVs were quantified placing regions of interest or volumes of interest in 6 different body regions as well as PET-avid lesions, respectively.
RESULTS
The relative differences of quantitative PET values when using MR-based AC versus CT-based AC were varying depending on the organs and body regions assessed. In detail, the mean (SD) relative differences of PET SUVs were as follows: -7.8% (11.5%), blood pool; -3.6% (5.8%), spleen; -4.4% (5.6%)/-4.1% (6.2%), liver; -0.6% (5.0%), muscle; -1.3% (6.3%), fat; -40.0% (18.7%), bone; 1.6% (4.4%), liver lesions; -6.2% (6.8%), bone lesions; and -1.9% (6.2%), soft tissue lesions. In 10 liver lesions, distinct overestimations greater than 5% were found (up to 10%). In addition, overestimations were found in 2 bone lesions and 1 soft tissue lesion adjacent to the lung (up to 28.0%).
CONCLUSIONS
Results obtained using different PET tracers show that MR-based AC is accurate in most tissue types, with SUV deviations generally of less than 10%. In bone, however, underestimations can be pronounced, potentially leading to inaccurate SUV quantifications. In addition, SUV overestimations were found for some lesions close to lung borders. This has to be taken into account when comparing PET/CT- and PET/MR-derived SUVs.
目的
在完全集成的正电子发射断层扫描（PET）/磁共振（MR）系统中，衰减校正（AC）在示踪剂摄取的定量中起着关键作用。本前瞻性研究的目的是评估使用基于 MR 的 AC 与基于 CT 的 AC 在同一 PET 数据集上对大型患者人群进行标准化摄取值（SUV）定量的准确性。
材料与方法
66 例患者（22 例女性；平均[标准差]，61[11]岁）接受了 11C-胆碱、18F-FDG 或 68Ga-DOTATATE 联合 PET/CT 和 PET/MR 检查。从 PET/MR 检查的正电子发射断层扫描图像中，通过基于组织分割的 MR 衍生 AC（PET（MR））进行校正。使用从 PET/CT 获得的基于 CT 的衰减图（μ 图），通过将 CT 非刚性地配准到基于 MR 的μ 图上来校正相同的 PET 数据（PET（MRCT））。在 6 个不同的身体区域以及 PET 阳性病变中分别放置感兴趣区域或感兴趣容积，以定量 PET SUV。
结果
当使用基于 MR 的 AC 与基于 CT 的 AC 时，定量 PET 值的相对差异因评估的器官和身体区域而异。具体而言，PET SUV 的平均（SD）相对差异如下：-7.8%（11.5%），血池；-3.6%（5.8%），脾脏；-4.4%（5.6%）/-4.1%（6.2%），肝脏；-0.6%（5.0%），肌肉；-1.3%（6.3%），脂肪；-40.0%（18.7%），骨骼；1.6%（4.4%），肝病变；-6.2%（6.8%），骨病变；和-1.9%（6.2%），软组织病变。在 10 个肝脏病变中，发现明显大于 5%的高估（高达 10%）。此外，在 2 个骨病变和 1 个靠近肺部的软组织病变中也发现了高估（高达 28.0%）。
结论
使用不同的 PET 示踪剂获得的结果表明，基于 MR 的 AC 在大多数组织类型中是准确的，SUV 偏差通常小于 10%。然而，在骨骼中，可能会出现明显的低估，从而导致不准确的 SUV 定量。此外，在靠近肺边界的一些病变中发现了 SUV 高估。在比较 PET/CT 和 PET/MR 衍生的 SUV 时，这一点必须考虑在内。
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