Nuclear Medicine and Molecular Imaging Pub Date : 2022-10-11 , DOI: 10.1007/s13139-022-00780-4 Sangkyung Choen 1 , Michael S Kent 1 , Abhijit J Chaudhari 1, 2 , Simon R Cherry 3 , Ana Krtolica 4 , Allison L Zwingenberger 1
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Purpose
We evaluated the kinetics of the hypoxia PET radiotracers, [18F]fluoromisonidazole ([18F]FMISO) and [18F]fluoroazomycin-arabinoside ([18F]FAZA), for tumor hypoxia detection and to assess the correlation of hypoxic kinetic parameters with static imaging measures in canine spontaneous tumors.
Methods
Sixteen dogs with spontaneous tumors underwent a 150-min dynamic PET scan using either [18F]FMISO or [18F]FAZA. The maximum tumor-to-muscle ratio (TMRmax) > 1.4 on the last image frame was used as the standard threshold to determine tumor hypoxia. The tumor time-activity curves were analyzed using irreversible and reversible two-tissue compartment models and graphical methods. TMRmax was compared with radiotracer trapping rate (k3), influx rate (Ki), and distribution volume (VT).
Results
Tumor hypoxia was detected in 7/8 tumors in the [18F]FMISO group and 4/8 tumors in the [18F]FAZA group. All hypoxic tumors were detected at > 120 min with [18F]FMISO and at > 60 min with [18F]FAZA. [18F]FAZA showed better fit with the reversible model. TMRmax was strongly correlated with the irreversible parameters (k3 and Ki) for [18F]FMISO at > 90 min and with the reversible parameter (VT) for [18F]FAZA at > 120 min.
Conclusions
Our results showed that [18F]FAZA provided a promising alternative radiotracer to [18F]FMISO with detecting the presence of tumor hypoxia at an earlier time (60 min), consistent with its favorable faster kinetics. The strong correlation between TMRmax over the 90–150 min and 120–150 min timeframes with [18F]FMISO and [18F]FAZA, respectively, with kinetic parameters associated with tumor hypoxia for each radiotracer, suggests that a static scan measurement (TMRmax) is a good alternative to quantify tumor hypoxia.
中文翻译：
使用动态 PET/CT 成像对患有自发性肿瘤的狗进行缺氧放射性示踪剂 [18F]FMISO 和 [18F]FAZA 的动力学评估
目的
我们评估了缺氧 PET 放射性示踪剂 [18F] 氟米索硝唑 ([18F]FMISO) 和 [18F] 氟偶氮霉素阿拉伯糖苷 ([18F]FAZA) 的动力学，用于检测肿瘤缺氧并评估缺氧动力学参数与静态成像的相关性犬自发性肿瘤的措施。
方法
十六只患有自发性肿瘤的狗使用 [18F]FMISO 或 [18F]FAZA 进行了 150 分钟的动态 PET 扫描。最后一个图像帧上的最大肿瘤肌肉比 (TMR max ) > 1.4 被用作确定肿瘤缺氧的标准阈值。使用不可逆和可逆双组织隔室模型和图形方法分析肿瘤时间-活动曲线。TMR max与放射性示踪剂捕获率 ( k 3 )、流入率 ( K i ) 和分布体积 ( V T ) 进行了比较。
结果
在 [18F]FMISO 组的 7/8 肿瘤和 [18F]FAZA 组的 4/8 肿瘤中检测到肿瘤缺氧。使用[ 18 F]FMISO 在> 120 分钟和使用[ 18 F]FAZA 在> 60 分钟时检测到所有缺氧肿瘤。[18F]FAZA 与可逆模型的拟合度更好。TMR max与 [18F]FMISO 在 > 90 分钟时的不可逆参数（ k 3和K i ）以及在 > 120 分钟时与 [18F]FAZA 的可逆参数（V T ）密切相关。
结论
我们的结果表明，[18F]FAZA 提供了一种有前途的替代放射性示踪剂 [18F]FMISO，可以在更早的时间（60 分钟）检测到肿瘤缺氧的存在，与其有利的更快动力学一致。在 90-150 分钟和 120-150 分钟时间范围内，TMR 最大值与 [18F]FMISO 和 [18F]FAZA 之间的强相关性，以及与每个放射性示踪剂的肿瘤缺氧相关的动力学参数，表明静态扫描测量（ TMR max ) 是量化肿瘤缺氧的一个很好的替代方法。
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