Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin.
Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, Wisconsin.
Int J Radiat Oncol Biol Phys. 2014 Jun 1;89(2):399-405. doi: 10.1016/j.ijrobp.2014.02.016. Epub 2014 Mar 28.
In dose painting, in which functional imaging is used to define biological targets for radiation therapy dose escalation, changes in spatial distributions of biological properties during treatment can compromise the quality of therapy. The goal of this study was to assess the spatiotemporal stability of 2 potential dose painting targets--hypoxia and proliferation--in canine tumors during radiation therapy.
Twenty-two canine patients with sinonasal tumors (14 carcinoma and 8 sarcoma) were imaged before hypofractionated radiation therapy with copper(II)-diacetyl-bis(N4-methylthiosemicarbazone) (Cu-ATSM) positron emission tomography/computed tomography (PET/CT) for hypoxia and 3'-deoxy-3'-(18)F-fluorothymidine (FLT) PET/CT for proliferation. The FLT scans were repeated after 2 fractions and the Cu-ATSM scans after 3 fractions. Midtreatment PET/CT images were deformably registered to pretreatment PET/CT images. Voxel-based Spearman correlation coefficients quantified the spatial stability of Cu-ATSM and FLT uptake distributions between pretreatment and midtreatment scans. Paired t tests determined significant differences between the patients' respective Cu-ATSM and FLT correlations coefficients. Standardized uptake value measures were also compared between pretreatment and midtreatment scans by use of paired t tests.
Spatial distributions of Cu-ATSM and FLT uptake were stable through midtreatment for both sarcomas and carcinomas: the population mean ± standard deviation in Spearman correlation coefficient was 0.88 ± 0.07 for Cu-ATSM and 0.79 ± 0.13 for FLT. The patients' Cu-ATSM correlation coefficients were significantly higher than their respective FLT correlation coefficients (P=.001). Changes in Cu-ATSM SUV measures from pretreatment to midtreatment were histology dependent: carcinomas experienced significant decreases in Cu-ATSM uptake (P<.05), whereas sarcomas did not (P>.20). Both histologies experienced significant decreases in FLT uptake (P<.05).
Spatial distributions of Cu-ATSM were very stable after a few fractions of radiation therapy. FLT spatial distributions were generally stable early in therapy, although they were significantly less stable than Cu-ATSM distributions. Canine tumors had significantly lower proliferative activity at midtreatment than at pretreatment, and they experienced histology-dependent changes in Cu-ATSM uptake.
在剂量描绘中，使用功能成像来定义放射治疗剂量提升的生物学靶标，在治疗过程中生物学特性的空间分布变化可能会影响治疗质量。本研究的目的是评估在放射治疗过程中，两种潜在的剂量描绘靶标（缺氧和增殖）在犬肿瘤中的时空稳定性。
22 例患有鼻窦肿瘤的犬患者（14 例癌和 8 例肉瘤）在接受铜（II）-二乙酰基-双（N4-甲基硫代半卡巴腙）（Cu-ATSM）正电子发射断层扫描/计算机断层扫描（PET/CT）进行缺氧显像和 3'-脱氧-3'-(18)F-氟胸苷（FLT）PET/CT 进行增殖显像之前进行了成像。在接受 2 个分次照射后重复进行 FLT 扫描，在接受 3 个分次照射后进行 Cu-ATSM 扫描。治疗中的 PET/CT 图像通过变形配准到预处理 PET/CT 图像。基于体素的 Spearman 相关系数量化了预处理和治疗中扫描之间 Cu-ATSM 和 FLT 摄取分布的空间稳定性。配对 t 检验确定了患者各自的 Cu-ATSM 和 FLT 相关系数之间的显著差异。还通过配对 t 检验比较了预处理和治疗中扫描之间的标准化摄取值（SUV）测量值。
在肉瘤和癌中，Cu-ATSM 和 FLT 摄取的空间分布在治疗中期都是稳定的：人群平均±标准偏差的 Spearman 相关系数分别为 0.88±0.07（Cu-ATSM）和 0.79±0.13（FLT）。患者的 Cu-ATSM 相关系数明显高于各自的 FLT 相关系数（P=0.001）。从预处理到治疗中，Cu-ATSM SUV 测量值的变化与组织学有关：癌经历了 Cu-ATSM 摄取的显著下降（P<.05），而肉瘤则没有（P>.20）。两种组织学均经历了 FLT 摄取的显著下降（P<.05）。
在接受几次放射治疗后，Cu-ATSM 的空间分布非常稳定。FLT 的空间分布在治疗早期通常是稳定的，尽管它们的稳定性明显低于 Cu-ATSM 分布。犬肿瘤在治疗中期的增殖活性明显低于治疗前，并且它们经历了与组织学相关的 Cu-ATSM 摄取变化。
