¹⁸F-THK-5351 is a novel radiotracer that demonstrates high binding selectivity and affinity for tau pathology and exhibits better pharmacokinetics in the living brain than previous THK tau probes. The aim of the present study was to estimate the radiation dose of ¹⁸F-THK-5351 in humans and to compare the clinical radiation dosimetry results to estimations published previously with preclinical data. Methods: Serial whole-body PET/CT imaging was performed for 240 min on 12 healthy volunteers after injecting ¹⁸F-THK-5351 (mean administered activity, 377.8 ± 14.0 MBq; range, 340–397 MBq). The bladder and gallbladder were delineated on PET images, and the other organs were delineated on CT images. Voided urine activity was recorded. The decay-corrected and normalized ¹⁸F-THK-5351 activity of 15 source-organ regions as a function of time was entered into the OLINDA/EXM software to calculate the effective dose for each subject following the medical internal radiation dosimetry schema. Results: Overall, the ¹⁸F-THK-5351 injection was well tolerated. The highest mean initial uptake at 10 min after injection was in the liver (11.4% ± 2.0%), lung (5.7% ± 2.1%), intestine (3.4% ± 0.8%), and kidney (1.4% ± 0.3%). The highest mean absorbed dose of radiation was in the gallbladder wall (242.2 ± 105.2 μGy/MBq), upper large intestine (90.0 ± 15.8 μGy/MBq), small intestine (79.5 ± 13.8 μGy/MBq), and liver (55.8 ± 6.1 μGy/MBq). The resultant whole-body effective dose was 22.7 ± 1.3 μSv/MBq. Conclusion: Our results suggest that a routine injection of 370 MBq of ¹⁸F-THK-5351 would lead to an estimated effective dose of 8.4 mSv; hence, ¹⁸F-THK-5351 has a radiation burden similar to that of other commonly used clinical tracers. Our findings in humans were compatible with recently published preclinical dosimetry data extrapolated from mice.

¹⁸ F-THK-5351是一种新型放射性示踪剂，与以前的THK tau探针相比，它对tau病理学表现出高结合选择性和亲和力，并且在活脑中表现出更好的药代动力学。本研究的目的是评估人体内¹⁸ F-THK-5351的辐射剂量，并将临床辐射剂量测定结果与先前发表的具有临床前数据的估计值进行比较。方法：对12名健康志愿者进行了^18次注射后，对其进行了连续的全身PET / CT成像240分钟F-THK-5351（平均给药活性，377.8±14.0 MBq；范围：340-397 MBq）。在PET图像上描绘了膀胱和胆囊，在CT图像上描绘了其他器官。记录了尿活动的无效。将15个源器官区域的经衰变校正和归一化的¹⁸ F-THK-5351活性随时间变化输入OLINDA / EXM软件，以按照医学内部辐射剂量学方案计算每个受试者的有效剂量。结果：总体来说，这¹⁸F-THK-5351注射液耐受良好。注射后10分钟的最高平均初始摄取量是在肝脏（11.4％±2.0％），肺（5.7％±2.1％），肠（3.4％±0.8％）和肾脏（1.4％±0.3％）中。辐射的平均吸收最高剂量在胆囊壁（242.2±105.2μGy/ MBq），大肠上部（90.0±15.8μGy/ MBq），小肠（79.5±13.8μGy/ MBq）和肝脏（55.8±6.1） μGy/ MBq）。最终的全身有效剂量为22.7±1.3μSv/ MBq。结论：我们的结果表明，常规注射370 MBq的¹⁸ F-THK-5351将导致估计的有效剂量8.4 mSv。因此，¹⁸F-THK-5351的辐射负荷与其他常用的临床示踪剂相似。我们在人类中的发现与最近从小鼠推断的临床前剂量学数据兼容。