Department of Radiology, Charité - Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Augustenburger Platz 1, Berlin 13353, Germany.
Department of Neurosurgery, Charité - Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany; Charité CyberKnife Center, Charité - Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Augustenburger Platz 1, Berlin 13353, Germany; BIH Academy, Clinician Scientist Program, Berlin Institute of Health at Charité - Universitätsmedizin Berlin, Charitéplatz 1, Berlin 10117, Germany.
Cancer Treat Res Commun. 2022;32:100583. doi: 10.1016/j.ctarc.2022.100583. Epub 2022 Jun 3.
Cyberknife robotic radiosurgery (RRS) provides single-session high-dose radiotherapy of brain tumors with a steep dose gradient and precise real-time image-guided motion correction. Although RRS appears to cause more radiation necrosis (RN), the radiometabolic changes after RRS have not been fully clarified. F-FET-PET/CT is used to differentiate recurrent tumor (RT) from RN after radiosurgery when MRI findings are indecisive. We explored the usefulness of dynamic parameters derived from F-FET PET in differentiating RT from RN after Cyberknife treatment in a single-center study population.
We retrospectively identified brain tumor patients with static and dynamic F-FET-PET/CT for suspected RN after Cyberknife. Static (tumor-to-background ratio) and dynamic PET parameters (time-activity curve, time-to-peak) were quantified. Analyses were performed for all lesions taken together (TOTAL) and for brain metastases only (METS). Diagnostic accuracy of PET parameters (using mean tumor-to-background ratio >1.95 and time-to-peak of 20 min for RT as cut-offs) and their respective improvement of diagnostic probability were analyzed.
Fourteen patients with 28 brain tumors were included in quantitative analysis. Time-activity curves alone provided the highest sensitivities (TOTAL: 95%, METS: 100%) at the cost of specificity (TOTAL: 50%, METS: 57%). Combined mean tumor-to-background ratio and time-activity curve had the highest specificities (TOTAL: 63%, METS: 71%) and led to the highest increase in diagnosis probability of up to 16% p. - versus 5% p. when only static parameters were used.
This preliminary study shows that combined dynamic and static F-FET PET/CT parameters can be used in differentiating RT from RN after RRS.
Cyberknife 机器人放射外科（RRS）为脑肿瘤提供单次高剂量放疗，具有陡峭的剂量梯度和精确的实时图像引导运动校正。虽然 RRS 似乎会导致更多的放射性坏死（RN），但 RRS 后的放射代谢变化尚未完全阐明。F-FET-PET/CT 用于在 MRI 结果不确定时，区分放射外科治疗后的复发性肿瘤（RT）与 RN。我们在单中心研究人群中探索了从 Cyberknife 治疗后 F-FET PET 衍生的动态参数在区分 RT 与 RN 中的作用。
我们回顾性地确定了静态和动态 F-FET-PET/CT 用于怀疑 Cyberknife 后 RN 的脑肿瘤患者。对静态（肿瘤与背景比）和动态 PET 参数（时间-活性曲线、达峰时间）进行了定量分析。对所有病变（TOTAL）和脑转移瘤（METS）一起进行了分析。分析了使用 RT 作为截止值的平均肿瘤与背景比>1.95 和达峰时间 20 分钟的 PET 参数的诊断准确性及其各自诊断概率的改善。
14 名患者的 28 个脑肿瘤被纳入定量分析。仅时间-活性曲线提供了最高的敏感性（TOTAL：95%，METS：100%），但特异性较低（TOTAL：50%，METS：57%）。结合平均肿瘤与背景比和时间-活性曲线具有最高的特异性（TOTAL：63%，METS：71%），并导致诊断概率最高增加 16%，p. - 与仅使用静态参数时的 5%，p.相比。
这项初步研究表明，联合使用 F-FET PET/CT 的动态和静态参数可用于区分 RRS 后 RT 与 RN。
