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Abstract：
The normalized distances from the hot spot of radiotracer uptake (SUVmax) to the tumor centroid (NHOC) and to the tumor perimeter (NHOP) have recently been suggested as novel PET features reflecting tumor aggressiveness. These biomarkers characterizing the shift of SUVmax toward the lesion edge during tumor progression have been shown to be prognostic factors in breast and non-small cell lung cancer (NSCLC) patients. We assessed the impact of imaging parameters on NHOC and NHOP, their complementarity to conventional PET features, and their prognostic value for advanced-NSCLC patients. Methods: This retrospective study investigated baseline [18F]FDG PET scans: cohort 1 included 99 NSCLC patients with no treatment-related inclusion criteria (robustness study); cohort 2 included 244 NSCLC patients (survival analysis) treated with targeted therapy (93), immunotherapy (63), or immunochemotherapy (88). Although 98% of patients had metastases, radiomic features including SUVs were extracted from the primary tumor only. NHOCs and NHOPs were computed using 2 approaches: the normalized distance from the localization of SUVmax or SUVpeak to the tumor centroid or perimeter. Bland-Altman analyses were performed to investigate the impact of both spatial resolution (comparing PET images with and without gaussian postfiltering) and image sampling (comparing 2 voxel sizes) on feature values. The correlation of NHOCs and NHOPs with other features was studied using Spearman correlation coefficients (r). The ability of NHOCs and NHOPs to predict overall survival (OS) was estimated using the Kaplan-Meier method. Results: In cohort 1, NHOC and NHOP features were more robust to image filtering and to resampling than were SUVs. The correlations were weak between NHOCs and NHOPs (r ≤ 0.45) and between NHOCs or NHOPs and any other radiomic features (r ≤ 0.60). In cohort 2, the patients with short OS demonstrated higher NHOCs and lower NHOPs than those with long OS. NHOCs significantly distinguished 2 survival profiles in patients treated with immunotherapy (log-rank test, P < 0.01), whereas NHOPs stratified patients regarding OS in the targeted therapy (P = 0.02) and immunotherapy (P < 0.01) subcohorts. Conclusion: Our findings suggest that even in advanced NSCLC patients, NHOC and NHOP features pertaining to the primary tumor have prognostic potential. Moreover, these features appeared to be robust with respect to imaging protocol parameters and complementary to other radiomic features and are now available in LIFEx software to be independently tested by others.
摘要：
从放射性示踪剂摄取热点（SUVmax）到肿瘤质心（NHOC）和肿瘤周长（NHOP）的归一化距离最近已被认为是反映肿瘤侵袭性的新型PET特征。这些表征肿瘤进展期间SUVmax向病变边缘偏移的生物标志物已被证明是乳腺癌和非小细胞肺癌(NSCLC)患者的预后因素。我们评估了成像参数对NHOC和NHOP的影响，它们与传统PET特征的互补性，及其对晚期非小细胞肺癌患者的预后价值。方法：这项回顾性研究调查了基线[18F]FDGPET扫描：队列1包括99例无治疗相关纳入标准的NSCLC患者（稳健性研究）；队列2包括244例接受靶向治疗的NSCLC患者（生存分析）（93），免疫疗法（63），或免疫化疗（88）。虽然98%的患者有转移，包括SUV在内的影像组学特征仅从原发肿瘤中提取.使用2种方法计算NHOC和NHOP:从SUVmax或SUVpeak的定位到肿瘤质心或周边的归一化距离。进行Bland-Altman分析以研究空间分辨率（比较有和没有高斯后滤波的PET图像）和图像采样（比较2个体素大小）对特征值的影响。使用Spearman相关系数（r）研究了NHOC和NHOP与其他特征的相关性。使用Kaplan-Meier方法估计NHOC和NHOP预测总生存期(OS)的能力。结果：在队列1中，NHOC和NHOP特征对图像滤波和重采样比SUV更健壮。NHOC和NHOP之间（r≤0.45）以及NHOC或NHOP与任何其他放射学特征之间（r≤0.60）的相关性较弱。在队列2中，与长OS患者相比，短OS患者表现出更高的NHOC和更低的NHOP。NHOC显着区分接受免疫治疗的患者的2个生存概况(对数秩检验，P<0.01),而NHOPs在靶向治疗(P=0.02)和免疫治疗(P<0.01)亚组中对患者的OS进行了分层。结论：我们的研究结果表明，即使在晚期NSCLC患者中，与原发性肿瘤有关的NHOC和NHOP特征具有预后潜力。此外，这些特征在成像方案参数方面似乎具有鲁棒性,并且与其他影像组学特征互补,现在可在LIFEx软件中获得,由其他人独立测试.
