Abstract
52
Objectives We aimed at presenting a first human dosimetry for 68Ga-NODAGA-RGDyK, visualizing the integrin ανβ3 thanks to its peptide motif Arg-Gly-Asp (RGD). The ανβ3 integrin plays an essential role regulating tumor growth, local invasiveness and metastatic potential, and it is highly expressed on activated endothelial cells during angiogenesis.
Methods NODAGA-RGDyK(cyclic) was radiolabeled with the eluate of a 68Ge→68Ga generator using an automatic processor unit (PharmTracer). Five male patients (aged 66±8 y) scheduled to undergo endarterectomy were included and underwent low-dose, whole-body PET/CT scans at 10 min, 1 h 10 min and 2 h post i.v. injection of 200 MBq 68Ga-NODAGA-RGDyK. The 68Ga-NODAGA-RGDyK biodistribution was derived from 68Ga activity concentration measured in 13 CT-delineated regions (thyroid, lungs, heart, liver, spleen, stomach, kidneys, urinary bladder, red bone marrow, pancreas, large intestine, small intestine and whole-body). Mono-exponential fit was used to derive time-integrated activity for OLINDA/EXM dosimetry assessment using a 30-min cycle for urinary bladder voiding.
Results The average Effective Dose (ED) for men was 0.015 [95%CI 0.013-0.016] mSv/MBq, while the Effective Dose Equivalent (EDE) was 0.018 [0.016-0.019] mSv/MBq). The highest organ absorbed doses were in the kidneys, small intestine and urinary bladder wall (0.055, 0.037, 0.036 mGy/MBq, respectively). In women, estimated ED and EDE were 0.020 and 0.024 mSv/MBq, leading to human ED and EDE of 0.017 and 0.021 mSv/MBq, respectively.
Conclusions This first-in-man dosimetry study led to an ED of 3.4 mSv for a 200 MBq injection of 68Ga-NODAGA-RGDyK. This is very close to what had previously been extrapolated from mice biokinetics data (Nuklearmedizin 2011;50:225-33).