¹⁸F-Fluoroazomycin Arabinoside (FAZA) PET/MR as a Biomarker of Hypoxia in Rectal Cancer: A Pilot Study.

IF 2.2 4区医学 Q2 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING Tomography Pub Date : 2024-08-30 DOI:10.3390/tomography10090102

Ur Metser, Andres Kohan, Catherine O'Brien, Rebecca K S Wong, Claudia Ortega, Patrick Veit-Haibach, Brandon Driscoll, Ivan Yeung, Adam Farag

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Abstract

Tumor hypoxia is a negative prognostic factor in many tumors and is predictive of metastatic spread and poor responsiveness to both chemotherapy and radiotherapy. Purpose: To assess the feasibility of using ¹⁸F-Fluoroazomycin arabinoside (FAZA) PET/MR to image tumor hypoxia in patients with locally advanced rectal cancer (LARC) prior to and following neoadjuvant chemoradiotherapy (nCRT). The secondary objective was to compare different reference tissues and thresholds for tumor hypoxia quantification. Patients and Methods: Eight patients with histologically proven LARC were included. All patients underwent ¹⁸F-FAZA PET/MR prior to initiation of nCRT, four of whom also had a second scan following completion of nCRT and prior to surgery. Tumors were segmented using T₂-weighted MR. Each voxel within the segmented tumor was defined as hypoxic or oxic using thresholds derived from various references: ×1.0 or ×1.2 SUVmean of blood pool [BP] or left ventricle [LV] and SUVmean +3SD for gluteus maximus. Correlation coefficient (CoC) between HF and tumor SUVmax/reference SUVmean TRR for the various thresholds was calculated. Hypoxic fraction (HF), defined as the % hypoxic voxels within the tumor volume was calculated for each reference/threshold. Results: For all cases, baseline and follow-up, the CoCs for gluteus maximus and for BP and LV (×1.0) were 0.241, 0.344, and 0.499, respectively, and HFs were (median; range) 16.6% (2.4-33.8), 36.8% (0.3-72.9), and 30.7% (0.8-55.5), respectively. For a threshold of ×1.2, the CoCs for BP and LV as references were 0.611 and 0.838, respectively, and HFs were (median; range) 10.4% (0-47.6), and 4.3% (0-20.1%), respectively. The change in HF following nCRT ranged from (-18.9%) to (+54%). Conclusions: Imaging of hypoxia in LARC with ¹⁸F-FAZA PET/MR is feasible. Blood pool as measured in the LV appears to be the most reliable reference for calculating the HF. There is a wide range of HF and variable change in HF before and after nCRT.

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18F-氟唑霉素阿拉伯苷（FAZA）PET/MR 作为直肠癌缺氧的生物标记物：试点研究。

肿瘤缺氧是许多肿瘤的不良预后因素，预示着转移扩散以及对化疗和放疗的不良反应。目的：评估在新辅助化放疗（nCRT）之前和之后使用 18F-氟唑霉素阿拉伯糖苷（FAZA）PET/MR 对局部晚期直肠癌（LARC）患者的肿瘤缺氧进行成像的可行性。次要目的是比较不同的参考组织和肿瘤缺氧量化阈值。患者和方法：共纳入八名经组织学证实的 LARC 患者。所有患者在接受 nCRT 之前都接受了 18F-FAZA PET/MR 扫描，其中四名患者还在完成 nCRT 后和手术前接受了第二次扫描。使用 T2 加权 MR 对肿瘤进行分段。根据不同参考文献得出的阈值，将分段肿瘤内的每个体素定义为缺氧或缺氧：血池[BP]或左心室[LV]的SUV均值×1.0或×1.2，臀大肌的SUV均值+3SD。计算了不同阈值下 HF 与肿瘤 SUVmax/参考 SUVmean TRR 之间的相关系数（CoC）。计算每个参考值/阈值的缺氧分数（HF），即肿瘤体积内缺氧体素的百分比。结果：在基线和随访的所有病例中，臀大肌以及 BP 和 LV（×1.0）的 CoC 分别为 0.241、0.344 和 0.499，HF 分别为（中位数；范围）16.6%（2.4-33.8）、36.8%（0.3-72.9）和 30.7%（0.8-55.5）。当阈值为 ×1.2 时，作为参考的血压和左心室的 CoC 分别为 0.611 和 0.838，而 HF 分别为（中位数；范围）10.4%（0-47.6）和 4.3%（0-20.1%）。nCRT 后心房颤动的变化范围为 (-18.9%) 至 (+54%)。结论使用 18F-FAZA PET/MR 对 LARC 中的缺氧进行成像是可行的。左心室测得的血池似乎是计算高频的最可靠参考。HF 的范围很广，nCRT 前后 HF 的变化也不尽相同。

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来源期刊

Tomography Medicine-Radiology, Nuclear Medicine and Imaging

CiteScore

2.70

自引率

10.50%

发文量

222

期刊介绍： TomographyTM publishes basic (technical and pre-clinical) and clinical scientific articles which involve the advancement of imaging technologies. Tomography encompasses studies that use single or multiple imaging modalities including for example CT, US, PET, SPECT, MR and hyperpolarization technologies, as well as optical modalities (i.e. bioluminescence, photoacoustic, endomicroscopy, fiber optic imaging and optical computed tomography) in basic sciences, engineering, preclinical and clinical medicine. Tomography also welcomes studies involving exploration and refinement of contrast mechanisms and image-derived metrics within and across modalities toward the development of novel imaging probes for image-based feedback and intervention. The use of imaging in biology and medicine provides unparalleled opportunities to noninvasively interrogate tissues to obtain real-time dynamic and quantitative information required for diagnosis and response to interventions and to follow evolving pathological conditions. As multi-modal studies and the complexities of imaging technologies themselves are ever increasing to provide advanced information to scientists and clinicians. Tomography provides a unique publication venue allowing investigators the opportunity to more precisely communicate integrated findings related to the diverse and heterogeneous features associated with underlying anatomical, physiological, functional, metabolic and molecular genetic activities of normal and diseased tissue. Thus Tomography publishes peer-reviewed articles which involve the broad use of imaging of any tissue and disease type including both preclinical and clinical investigations. In addition, hardware/software along with chemical and molecular probe advances are welcome as they are deemed to significantly contribute towards the long-term goal of improving the overall impact of imaging on scientific and clinical discovery.