背景:胶质瘤是由神经胶质引起的脑肿瘤,中枢神经系统(CNS)的支持组织,并构成最常见的原发性恶性脑肿瘤。胶质瘤根据其在显微镜下的外观从I级到IV级分级。高级别胶质瘤最显著的不良特征之一是缺氧,当氧浓度变得不足以保证正常组织功能时发生的生物现象。由于肿瘤缺氧对患者预后有负面影响,靶向缺氧具有潜在的治疗意义,目前对测量缺氧的成像技术有很大的兴趣。
目的:本综述的目的是提供关于通过正电子发射断层扫描(PET)测量脑肿瘤缺氧的放射性示踪剂的最新证据,最广泛研究的成像方法来量化缺氧。
方法:该综述基于临床前和临床论文,并描述了不同可用放射性示踪剂的验证状态。
结果:迄今为止,[F-18]氟异硝唑([18F]FMISO)仍然是最广泛使用的放射性示踪剂,用于脑肿瘤患者的缺氧成像,但是在过去的二十年中,与其他放射性示踪剂的经验已经扩展。在这些放射性药物可以在临床环境中广泛使用之前,缺氧放射性示踪剂的验证仍在进行且必不可少。
结论:能够可靠地测量和绘制脑肿瘤中不同氧水平的非侵入性成像方法的可用性将为选择可能受益于针对缺氧的定制治疗策略的患者提供关键手段。
BACKGROUND: Gliomas are brain tumours arising from the glia, the supportive tissue of the central nervous system (CNS), and constitute the commonest primary malignant brain tumours. Gliomas are graded from grade I to IV according to their appearance under the microscope. One of the most significant adverse features of high-grade gliomas is hypoxia, a biological phenomenon that develops when the oxygen concentration becomes insufficient to guarantee the normal tissue functions. Since tumour hypoxia influences negatively patient outcome and targeting hypoxia has potential therapeutic implications, there is currently great interest in imaging techniques measuring hypoxia.
OBJECTIVE: The aim of this review is to provide up to date evidence on the radiotracers available for measuring hypoxia in brain tumours by means of positron emission tomography (PET), the most extensively investigated imaging approach to quantify hypoxia.
METHODS: The review is based on preclinical and clinical papers and describes the validation status of the different available radiotracers.
RESULTS: To date, [F-18] fluoromisonidazole ([18F]FMISO) remains the most widely used radiotracer for imaging hypoxia in patients with brain tumours, but experience with other radiotracers has expanded in the last two decades. Validation of hypoxia radiotracers is still on-going and essential before these radiopharmaceuticals can become widely used in the clinical setting.
CONCLUSIONS: Availability of a non-invasive imaging method capable of reliably measuring and mapping different levels of oxygen in brain tumours would provide the critical means of selecting patients that may benefit from tailored treatment strategies targeting hypoxia.