Hofheinz Frank, Bütof Rebecca, Apostolova Ivayla, Zöphel Klaus, Steffen Ingo G, Amthauer Holger, Kotzerke Jörg, Baumann Michael, van den Hoff Jörg
Helmholtz-Zentrum Dresden-Rossendorf, PET Center, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße, Dresden, Germany.
Department of Radiation Oncology, University Hospital Carl Gustav Carus, Technische Universität, Dresden, Germany.
EJNMMI Res. 2016 Dec;6(1):19. doi: 10.1186/s13550-016-0174-y. Epub 2016 Mar 2.
The standardized uptake value (SUV) is the nearly exclusive means for quantitative evaluation of clinical [18F-]fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) whole body investigations. However, the SUV methodology has well-known shortcomings. In this context, it has been recognized that at least part of the problems can be eliminated if tumor SUV is normalized to the SUV of a reference region in the liver (tumor-to-liver [TLR] ratio). In recent publications, we have systematically investigated the tumor-to-blood SUV ratio (SUR) for normalization of tumor SUVs which in our view offers principal advantages in comparison to TLR. The aim of this study was a comprehensive comparison of TLR and SUR in terms of quantification of tumor lesions.
18F-FDG PET/CT was performed in 424 patients (557 scans) with different tumor entities prior to radio(chemo)therapy. In the PET images, SUVmax of the primary tumor was determined. SUVliver was calculated in the inferior right lobe of the liver. SUVblood was determined by manually delineating the aorta in the low-dose CT. TLR and SUR were computed and scan time corrected to 60 min p.i. (TLRtc and SURtc). Correlation analysis was performed for SUVliver vs. SUVblood, TLR vs. SUR, SUVliver/SUVblood vs. SUVblood,SURtc/TLR vs. SURtc, and SURtc/TLRtc vs. SURtc. Variability of the respective ratios was assessed via histogram analysis. The prognostic value of TLR and TLRtc for distant metastases-free survival (DM) was investigated with univariate Cox regression in a homogeneous subgroup (N = 130) and compared to previously published results for SUV and SURtc.
Correlation analysis revealed a linear correlation of SUVliver vs. SUVblood (R (2)=0.83) and of TLR vs. SURtc (R (2)=0.92). The SUVliver/SUVblood ratio (mean ± s.d.) was 1.47 ± 0.18. For the SURtc/TLR ratio, we obtained 1.14 ± 0.21 and for the SURtc/TLRtc ratio 1.38 ± 0.17. Survival analysis revealed TLR and TLRtc as significant prognostic factors for DM (hazard ratio [HR] = 3.3 and HR = 3, respectively). Both hazard ratios are lower than that of SURtc (HR = 4.1) although this reduction does not reach statistical significance for the given limited group size. HRs of TLR and SURtc are both significantly higher than HR of SUV (HR = 2.2).
Suitability of the liver as surrogate of arterial tracer supply for SUV normalization via TLR computation is limited. Further studies in sufficiently large patient groups are required to better characterize the relative performance of SUV, TLR, and SUR in different settings.
标准化摄取值（SUV）几乎是临床[18F]氟脱氧葡萄糖（18F-FDG）正电子发射断层扫描（PET）全身检查定量评估的唯一手段。然而，SUV方法存在众所周知的缺点。在这种情况下，人们认识到，如果将肿瘤SUV与肝脏参考区域的SUV进行归一化（肿瘤与肝脏[TLR]比值），至少部分问题可以消除。在最近的出版物中，我们系统地研究了肿瘤与血液SUV比值（SUR）用于肿瘤SUV的归一化，我们认为与TLR相比，SUR具有主要优势。本研究的目的是在肿瘤病变定量方面对TLR和SUR进行全面比较。
在424例（557次扫描）患有不同肿瘤实体的患者进行放（化）疗前，进行18F-FDG PET/CT检查。在PET图像中，确定原发肿瘤的SUVmax。计算肝脏右下叶的SUVliver。通过在低剂量CT中手动勾勒主动脉来确定SUVblood。计算TLR和SUR，并将扫描时间校正至注射后60分钟（TLRtc和SURtc）。对SUVliver与SUVblood、TLR与SUR、SUVliver/SUVblood与SUVblood、SURtc/TLR与SURtc以及SURtc/TLRtc与SURtc进行相关性分析。通过直方图分析评估各比值的变异性。在一个同质亚组（N = 130）中，采用单变量Cox回归研究TLR和TLRtc对无远处转移生存（DM）的预后价值，并与先前发表的SUV和SURtc结果进行比较。
相关性分析显示SUVliver与SUVblood呈线性相关（R（2）=0.83），TLR与SURtc呈线性相关（R（2）=0.92）。SUVliver/SUVblood比值（平均值±标准差）为1.47±0.18。对于SURtc/TLR比值，我们得到1.14±0.21，对于SURtc/TLRtc比值为1.38±0.17。生存分析显示TLR和TLRtc是DM的显著预后因素（风险比[HR]分别为3.3和3）。尽管对于给定的有限样本量，这种降低未达到统计学意义，但这两个风险比均低于SURtc的风险比（HR = 4.1）。TLR和SURtc的HR均显著高于SUV的HR（HR = 2.2）。
通过TLR计算将肝脏作为动脉示踪剂供应替代物用于SUV归一化的适用性有限。需要在足够大的患者群体中进行进一步研究，以更好地描述SUV、TLR和SUR在不同情况下的相对性能。
