Test-Retest Variability in Lesion SUV and Lesion SUR in 18F-FDG PET: An Analysis of Data from Two Prospective Multicenter Trials
Test-Retest Variability in Lesion SUV and Lesion SUR in 18F-FDG PET: An Analysis of Data from Two Prospective Multicenter Trials
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DOI：
10.2967/jnumed.117.190736
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发表时间：
2017-11-01
影响因子：
9.3
通讯作者：
van den Hoff, Joerg
中科院分区：
文献类型：
--
作者：
Hofheinz, Frank;Apostolova, Ivayla;van den Hoff, Joerg
近年来，f18 - fdg全身PET对放化疗反应的定量评估引起了越来越多的关注。在大多数已发表的作品中，SUV已被用于此目的。在治疗反应评估的背景下，病变suv的可靠性，特别是其重测稳定性，因此变得至关重要。然而，最近的一项研究表明，suv中存在大量的重测变异性（TRV）。本研究的目的是探讨肿瘤与血液的SUV比（SUR）是否可以改善示踪剂摄取的TRV。方法：73例来自前瞻性多中心试验ACRIN 6678 （n = 34）和MK-0646-008 （n = 539）的晚期非小细胞肺癌患者纳入本研究。所有患者在治疗前两天（时差3.6 +/- 2.1 d，范围1-7 d）接受两次F-18-FDG PET/CT检查。每位患者最多可评估7个肿瘤病变。测定每个病变的SUVmax和SUVpeak值。血SUV被确定为三维主动脉感兴趣区域的平均值，该区域在衰减CT图像上勾画并转移到PET图像上。以肿瘤SUV与血液SUV之比计算sus，并将摄取时间校正至注射后75分钟。TRV量化为1.96乘以SUV与SUR分数对差的均方根偏差。通过考虑R-TRV （TRVSUR/TRVSUV）来检查血液正常化和摄取时间校正的综合效果，R-TRV是反映SUR相对于SUV的TRV降低的比率。R-TRV与数量delta CF =竖条CF - 1竖条的CFmean （delta CFmean）的组平均值差(d)相关，其中CF是将成对suv的个体比率转换为相应的sur的数值因子。通过连续增加阈值δ CFmin并计算δ CFmean和R-TRV对剩余的δ CFmin = δ CFmin的患者/病变亚组进行相关性分析。结果：组平均TRVSUV和TRVSUR分别为32.1和29.0，这相当于与SUV相比，SUR的变异性减少了0.9的R-TRV因子。这种相当边际的改善可以理解为在前瞻性研究组中血液SUV和摄取时间的非典型低受试者内部变异性以及相应的小δ CF值的结果。事实上，随着δ CFmin阈值的增加，亚组分析显示R-TRV与δ CFmean之间存在明显的负相关（Spearman rho = -0.99, P < 0.001），其中δ CFmin = 20%亚组的R-TRV接近0.4，与TRVSUV相比，TRVSUR减少了2倍以上。结论：血液中SUV的变化和摄取时间的变化已被确定为病变SUV中TRV的原因。因此，用SUR代替SUV作为摄取措施可以降低病变摄取测量中的TRV。在临床环境中观察到的血液SUV变异性水平和摄取时间的改善变得实质性。
Quantitative assessment of radio- and chemotherapy response with F-18-FDG whole-body PET has attracted increasing interest in recent years. In most published work, SUV has been used for this purpose. In the context of therapy response assessment, the reliability of lesion SUVs, notably their test-retest stability, thus becomes crucial. However, a recent study demonstrated substantial test-retest variability (TRV) in SUVs. The purpose of the present study was to investigate whether the tumor-to-blood SUV ratio (SUR) can improve TRV in tracer uptake. Methods: 73 patients with advanced non-small cell lung cancer from the prospective multicenter trials ACRIN 6678 (n = 34) and MK-0646-008 (n 5 39) were included in this study. All patients underwent two F-18-FDG PET/CT investigations on two different days (time difference, 3.6 +/- 2.1 d; range, 1-7 d) before therapy. For each patient, up to 7 tumor lesions were evaluated. For each lesion, SUVmax and SUVpeak were determined. Blood SUV was determined as the mean value of a 3-dimensional aortic region of interest that was delineated on the attenuation CT image and transferred to the PET image. SURs were computed as the ratio of tumor SUV to blood SUV and were uptake time-corrected to 75 min after injection. TRV was quantified as 1.96 multiplied by the root-mean-square deviation of the fractional paired differences in SUV and SUR. The combined effect of blood normalization and uptake time correction was inspected by considering R-TRV (TRVSUR/TRVSUV), a ratio reflecting the reduction in the TRV in SUR relative to SUV. R-TRV was correlated with the group-averaged-value difference (d) in CFmean (delta CFmean) of the quantity delta CF = vertical bar CF - 1 vertical bar, where CF is the numeric factor that converts individual ratios of paired SUVs into corresponding SURs. This correlation analysis was performed by successively increasing a threshold value delta CFmin and computing delta CFmean and R-TRV for the remaining subgroup of patients/lesions with delta CF >= delta CFmin. Results: The group-averaged TRVSUV and TRVSUR were 32.1 and 29.0, respectively, which correspond to a reduction of variability in SUR by an R-TRV factor of 0.9 in comparison to SUV. This rather marginal improvement can be understood to be a consequence of the atypically low intrasubject variability in blood SUV and uptake time and the accordingly small delta CF values in the investigated prospective study groups. In fact, subgroup analysis with increasing delta CFmin thresholds revealed a pronounced negative correlation (Spearman rho = -0.99, P < 0.001) between R-TRV and delta CFmean, where R-TRV approximate to 0.4 in the delta CFmin = 20% subgroup, corresponding to a more than 2-fold reduction of TRVSUR compared with TRVSUV. Conclusion: Variability in blood SUV and uptake time has been identified as a causal factor in the TRV in lesion SUV. Therefore, TRV in lesion uptake measurements can be reduced by replacing SUV with SUR as the uptake measure. The improvement becomes substantial for the level of variability in blood SUV and uptake time typically observed in the clinical context.