Cysouw M C F, Golla S V S, Frings V, Smit E F, Hoekstra O S, Kramer G M, Boellaard R
Department of Radiology and Nuclear Medicine, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, De Boelelaan 1117, Amsterdam, the Netherlands.
Department of Thoracic Oncology, Netherlands Cancer Institute, Plesmanlaan 121, Amsterdam, the Netherlands.
EJNMMI Res. 2019 Feb 4;9(1):12. doi: 10.1186/s13550-019-0483-z.
Partial-volume effects generally result in an underestimation of tumor tracer uptake on PET-CT for small lesions, necessitating partial-volume correction (PVC) for accurate quantification. However, investigation of PVC in dynamic oncological PET studies to date is scarce. The aim of this study was to investigate PVC's impact on tumor kinetic parameter estimation from dynamic PET-CT acquisitions and subsequent validation of simplified semi-quantitative metrics. Ten patients with EGFR-mutated non-small cell lung cancer underwent dynamic F-fluorothymidine PET-CT before, 7 days after, and 28 days after commencing treatment with a tyrosine kinase inhibitor. Parametric PVC was applied using iterative deconvolution without and with highly constrained backprojection (HYPR) denoising, respectively. Using an image-derived input function with venous parent plasma calibration, we estimated full kinetic parameters V, K, and k/k (BP) using a reversible two-tissue compartment model, and simplified metrics (SUV and tumor-to-blood ratio) at 50-60 min post-injection.
PVC had a non-linear effect on measured activity concentrations per timeframe. PVC significantly changed each kinetic parameter, with a median increase in V of 11.8% (up to 25.1%) and 10.8% (up to 21.7%) without and with HYPR, respectively. Relative changes in kinetic parameter estimates vs. simplified metrics after applying PVC were poorly correlated (correlations 0.36-0.62; p < 0.01). PVC increased correlations between simplified metrics and V from 0.82 and 0.81 (p < 0.01) to 0.90 and 0.88 (p < 0.01) for SUV and TBR, respectively, albeit non-significantly. PVC also increased correlations between treatment-induced changes in simplified metrics vs. V at 7 (SUV) and 28 (SUV and TBR) days after treatment start non-significantly. Delineation on partial-volume corrected PET images resulted in a median decrease in metabolic tumor volume of 14.3% (IQR - 22.1 to - 7.5%), and increased the effect of PVC on kinetic parameter estimates.
PVC has a significant impact on tumor kinetic parameter estimation from dynamic PET-CT data, which differs from its effect on simplified metrics. However, it affected validation of these simplified metrics both as single measurements and as biomarkers of treatment response only to a small extent. Future dynamic PET studies should preferably incorporate PVC.
Dutch Trial Register, NTR3557 .
部分容积效应通常会导致PET-CT对小病灶的肿瘤示踪剂摄取量估计偏低，因此需要进行部分容积校正（PVC）以实现准确量化。然而，迄今为止，在动态肿瘤PET研究中对PVC的研究很少。本研究的目的是探讨PVC对动态PET-CT采集的肿瘤动力学参数估计以及随后简化半定量指标验证的影响。10例表皮生长因子受体（EGFR）突变的非小细胞肺癌患者在开始使用酪氨酸激酶抑制剂治疗前、治疗7天后和28天后接受了动态F-氟胸苷PET-CT检查。分别使用不进行和进行高约束反投影（HYPR）去噪的迭代反卷积方法应用参数化PVC。使用经静脉母体血浆校准的图像衍生输入函数，我们使用可逆双组织房室模型估计了完整的动力学参数V、K和k/k（BP），并在注射后50 - 60分钟估计了简化指标（标准化摄取值SUV和肿瘤与血液比值）。
PVC对每个时间框架内测量的活性浓度有非线性影响。PVC显著改变了每个动力学参数，在不使用和使用HYPR时，V的中位数分别增加了11.8%（最高达25.1%）和10.8%（最高达21.7%）。应用PVC后，动力学参数估计值与简化指标的相对变化相关性较差（相关性为0.36 - 0.62；p < 0.01）。PVC使简化指标与V之间的相关性分别从SUV的0.82和0.81（p < 0.01）以及肿瘤与血液比值（TBR）的0.81（p < 0.01）增加到0.90和0.88（p < 0.01），尽管差异不显著。部分容积校正PET图像上的勾画导致代谢肿瘤体积中位数减少14.3%（四分位间距为 - 22.1至 - 7.5%），并增加了PVC对动力学参数估计的影响。
PVC对动态PET-CT数据的肿瘤动力学参数估计有显著影响，这与它对简化指标的影响不同。然而，它对这些简化指标作为单次测量以及作为治疗反应生物标志物的验证仅产生了很小的影响。未来的动态PET研究最好纳入PVC。
荷兰试验注册中心，NTR3557 。
