Department of Radiology, Mayo Clinic, Rochester, MNDepartment of Neurology, Mayo Clinic, Rochester, MN; Department of Immunology, Mayo Clinic, Rochester, MN.
Department of Surgical Sciences, Nuclear Medicine, PET and Radiology, Uppsala University, Uppsala Sweden.
Semin Nucl Med. 2020 Nov;50(6):549-561. doi: 10.1053/j.semnuclmed.2020.07.001. Epub 2020 Aug 7.
Perfusion, as measured by imaging, is considered a standard of care biomarker for the evaluation of many tumors. Measurements of tumor perfusion may be used in a number of ways, including improving the visual detection of lesions, differentiating malignant from benign findings, assessing aggressiveness of tumors, identifying ischemia and by extension hypoxia within tumors, and assessing treatment response. While most clinical perfusion imaging is currently performed with CT or MR, a number of methods for PET imaging of tumor perfusion have been described. The inert PET radiotracer O-water PET represents the recognized gold standard for absolute quantification of tissue perfusion in both normal tissue and a variety of pathological conditions including cancer. Other cancer PET perfusion imaging strategies include the use of radiotracers with high first-pass uptake, analogous to those used in cardiac perfusion PET. This strategy produces more visually pleasing high-contrast images that provide relative rather than absolute perfusion quantification. Lastly, multiple timepoint imaging of PET tracers such as F-FDG, are not specifically optimized for perfusion, but have advantages related to availability, convenience, and reimbursement. Multiple obstacles have thus far blocked the routine use of PET imaging for tumor perfusion, including tracer production and distribution, image processing, patient body coverage, clinical validation, regulatory approval and reimbursement, and finally feasible clinical workflows. Fortunately, these obstacles are being overcome, especially within larger imaging centers, opening the door for PET imaging of tumor perfusion to become standard clinical practice. In the foreseeable future, it is possible that whole-body PET perfusion imaging with O-water will be able to be performed in a single imaging session concurrent with standard PET imaging techniques such as F-FDG-PET. This approach could establish an efficient clinical workflow. The resultant ability to measure absolute tumor blood flow in combination with glycolysis will provide important complementary information to inform prognosis and clinical decisions.
灌注成像，通过影像学进行测量，被认为是评估许多肿瘤的标准护理生物标志物。肿瘤灌注的测量可以通过多种方式使用，包括提高病变的视觉检测，区分恶性和良性发现，评估肿瘤的侵袭性，识别肿瘤内的缺血和缺氧，以及评估治疗反应。虽然目前大多数临床灌注成像都是通过 CT 或 MR 进行的，但已经描述了许多用于肿瘤灌注 PET 成像的方法。惰性 PET 示踪剂 O-水 PET 代表了正常组织和各种病理条件（包括癌症）中组织灌注的绝对定量的公认金标准。其他癌症 PET 灌注成像策略包括使用具有高首次通过摄取的放射性示踪剂，类似于用于心脏灌注 PET 的放射性示踪剂。这种策略产生了更具视觉吸引力的高对比度图像，提供了相对而不是绝对的灌注定量。最后，F-FDG 等 PET 示踪剂的多点成像不是专门针对灌注进行优化的，但具有可用性、便利性和报销方面的优势。迄今为止，PET 成像用于肿瘤灌注的常规应用存在多个障碍，包括示踪剂的生产和分布、图像处理、患者身体覆盖范围、临床验证、监管批准和报销以及可行的临床工作流程。幸运的是，这些障碍正在被克服，尤其是在更大的成像中心，为肿瘤灌注的 PET 成像成为标准临床实践打开了大门。在可预见的未来，有可能在单次成像过程中同时进行全身 O-水 PET 灌注成像与 F-FDG-PET 等标准 PET 成像技术，这种方法可以建立一种高效的临床工作流程。测量绝对肿瘤血流与糖酵解相结合的能力将提供重要的补充信息，以告知预后和临床决策。
