Krieger Korbinian, Pyka Thomas, Mingels Clemens, Sari Hasan, Gjedde Albert, Rominger Axel, Cumming Paul
Department of Nuclear Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
Center for Radiopharmaceutical Sciences, Department of Chemistry and Applied Biology, ETH Zurich, Zurich, Switzerland.
EJNMMI Res. 2025 Jul 22;15(1):90. doi: 10.1186/s13550-025-01279-7.
The large neutral amino acid [F]fluoroethoxy-L-tyrosine ([F]FET) is a popular tracer for detection and staging of intracranial tumors by positron emission tomography (PET). While its high tumoral uptake reflects over-expression of the L-type amino acid transporter (LAT1), there is little knowledge about the kinetics of [F]FET uptake in healthy brain tissue, owing to the limited PET data in healthy volunteers, and to the requirement of an arterial input function for compartmental analysis. To address this, we used long axial field-of-view (LAFOV) dynamic 40-min recordings of 28 post-operative patients with intracranial tumors to undertake parametric brain mapping relative to an image-derived arterial input function (IDIF) obtained from the aorta. We averaged the individual parametric maps to obtain estimates of the physiological uptake relatively unaffected by individual residual lesions and resections, and tested simplified single-frame methods for quantitation.
The analyses yielded estimates of regional unidirectional blood-brain clearance K (0.00825-0.0244 ml g min), net blood-brain clearance K (0.00448-0.00913 ml g min), and equilibrium distribution volume V (0.126-0.495 ml g), where the lowest values depict white matter, and the highest values cerebellum. In our test of a simplified quantitation of [F]FET uptake from single frame recordings, i.e., Gjedde-Patlak multilinear graphic analyses of K at five min post-injection and K at 40 min post injection, results were in good agreement with the analyses from the dynamic recordings (< 10% error).
Compartmental analysis results for [F]FET uptake in extra-tumoral human brain regions are in accord with the few prior reports, mainly obtained in experimental animals, and support the use of single frame quantitation. Present findings in relatively healthy brain should inform the interpretation of pathological [F]FET uptake in tumors.
大中性氨基酸[F]氟乙氧基-L-酪氨酸（[F]FET）是一种通过正电子发射断层扫描（PET）检测和分期颅内肿瘤的常用示踪剂。虽然其在肿瘤中的高摄取反映了L型氨基酸转运体（LAT1）的过表达，但由于健康志愿者的PET数据有限，以及进行房室分析需要动脉输入函数，因此对[F]FET在健康脑组织中的摄取动力学了解甚少。为了解决这个问题，我们对28例颅内肿瘤术后患者进行了40分钟的长轴视野（LAFOV）动态记录，以相对于从主动脉获得的图像衍生动脉输入函数（IDIF）进行参数化脑图谱分析。我们对个体参数图进行平均，以获得相对不受个体残留病变和切除术影响的生理摄取估计，并测试了简化的单帧定量方法。
分析得出区域单向血脑清除率K（0.00825-0.0244 ml g min）、净血脑清除率K（0.00448-0.oo913 ml g min）和平衡分布容积V（0.126-0.495 ml g）的估计值，其中最低值代表白质，最高值代表小脑。在我们对单帧记录中[F]FET摄取的简化定量测试中，即注射后5分钟和注射后40分钟的K的Gjedde-Patlak多线性图形分析，结果与动态记录的分析结果高度一致（误差<10%）。
[F]FET在肿瘤外人类脑区摄取的房室分析结果与少数先前的报告一致，这些报告主要是在实验动物中获得的，并支持单帧定量的使用。相对健康脑的当前研究结果应有助于解释肿瘤中病理性[F]FET摄取情况。
