Patients with metastatic melanoma often receive ¹⁸F-FDG PET/CT scans on different scanners throughout their monitoring period. In this study, we quantified the impact of scanner harmonization on longitudinal changes in PET standardized uptake values using various harmonization and normalization methods, including an anthropomorphic PET phantom. Twenty metastatic melanoma patients received at least two FDG PET/CT scans, each on two different scanners with an average of 4 months (range: 2–8) between. Scans from a General Electric (GE) Discovery 710 PET CT⁻¹ were harmonized to the GE Discovery VCT using image reconstruction settings matching recovery coefficients in an anthropomorphic phantom with bone equivalent inserts and wall-less synthetic lesions. In patient images, SUV_max was measured for each melanoma lesion and time-point. Lesions were classified as progressing, stable, or responding based on pre-defined threshold of 30% change in SUV_max. For comparison, harmonization was also performed using simpler methods, including harmonization using a NEMA phantom, post-reconstruction filtering, reference region normalization of SUV_max, and use of SUV_peak instead of SUV_max. In the 20 patients, 90 lesions across two time-points were available for treatment response assessment. Treatment response classification changed in 47% (42/90) of cases after harmonization with anthropomorphic phantom. Before harmonization, 37% (33/90) of the lesions were classified as stable (changing less than 30% between two time-points), while the fraction of stable lesions increased to 58% (52/90) after harmonization. Harmonization with the NEMA phantom agreed with harmonization with the anthropomorphic phantom in 91% (82/90) of cases. Post-reconstruction filtering agreed with anthropomorphic phantom-based harmonization in 83% (75/90) cases. The utilization of reference regions for normalization or SUV_peak was unable to correct for changes as identified by the anthropomorphic phantom-based harmonization. Overall, PET scanner harmonization has a major impact on individual lesion treatment response classification in metastatic melanoma patients. Harmonization using the NEMA phantom yielded similar results to harmonization using anthropomorphic phantom, while the only acceptable post-reconstruction technique was post-reconstruction filtering. Phantom-based harmonization is therefore strongly recommended when comparing lesion uptake across time-points when the images have been acquired on different PET scanners.

转移性黑色素瘤患者在整个监测期间通常会在不同的扫描仪上接受^18次F-FDG PET / CT扫描。在这项研究中，我们使用多种拟人化和标准化方法（包括拟人化的PET体模），量化了扫描仪协调对PET标准化摄取值纵向变化的影响。20名转移性黑素瘤患者至少接受了两次FDG PET / CT扫描，每一次在两台不同的扫描仪上进行，平均间隔4个月（2-8）。使用图像重建设置将通用电气（GE）Discovery 710 PET CT ^-1的扫描与GE Discovery VCT相协调，该图像重建设置与具有骨骼等效插入物和无壁合成病变的拟人化体模中的恢复系数相匹配。在患者图像中，SUV测量每个黑色素瘤病变和时间点的_最大值。根据预先确定的SUV _max变化30％阈值，将病变分类为进行中，稳定或有反应。为了进行比较，还使用更简单的方法进行了协调，包括使用NEMA体模进行协调，重建后过滤，SUV _max的参考区域归一化以及使用SUV_峰值而不是SUV _max。在这20例患者中，两个时间点的90个病变可用于治疗反应评估。与拟人化体模相协调后，治疗反应分类发生改变的病例占47％（42/90）。统一之前，将37％（33/90）的病变分类为稳定的（在两个时间点之间变化小于30％），而稳定的比例在统一之后增加到58％（52/90）。在91％（82/90）的案例中，与NEMA幻影协调一致与与拟人幻影协调一致。重建后过滤在83％（75/90）的案例中与基于拟人幻影的协调一致。使用参考区域进行归一化或SUV_峰化不能纠正基于拟人幻影的协调所确定的变化。总体而言，PET扫描仪的统一性对转移性黑色素瘤患者的单个病变治疗反应分类具有重大影响。使用NEMA体模进行协调产生的效果与使用拟人体模进行协调产生相似的结果，而唯一可接受的重建后技术是重建后过滤。因此，当在不同的PET扫描仪上采集图像时，比较跨时间点的病变摄取时，强烈建议基于幻影的协调。