Purpose: 4-(3S)-3-[5-(2-[18F]-fluoroethoxy)pyridin-3-yl]-3-[({(3R)-1-[3-(piperidin-4-yl)propanoyl]-piperidin-3-yl}carbonyl)amino]propanoic acid ([18F]GP1) is a radiotracer developed for targeted imaging of activated platelet glycoprotein IIb/IIIa receptors with positron emission tomography/computed tomography (PET/CT) in acute thromboembolism. We evaluated here radiation dosimetry of [18F]GP1 in humans.
Procedures: We studied 30 subjects (10 with deep vein thrombosis, 10 with pulmonary embolism, and 10 with arterial thromboembolism) who had signs or symptoms of acute thromboembolism, and were confirmed to have thromboembolic foci by imaging studies. Dynamic whole-body PET/CT images were acquired for up to 140 min after injection of 250 MBq of [18F]GP1. Radiation absorbed dose and effective dose were calculated using the OLINDA/EXM software.
Results: [18F]GP1 PET images showed high initial uptake of the tracer in the heart, spleen, kidney, and liver. [18F]GP1 activity was cleared by hepatobiliary and urinary excretion. The organ receiving the highest radiation absorbed dose (mGy/MBq) was the urinary bladder (0.0884 ± 0.0458), followed by upper large intestine (0.0498 ± 0.0189), small intestine (0.0454 ± 0.0166), and kidneys (0.0350 ± 0.0231). The effective dose (mSv/MBq) was 0.0212 ± 0.0027 (ICRP 103). ED was not significantly different between the three disease groups (p = 0.94). A 45-minute voiding reduced the urinary bladder wall radiation dose to 0.0495 ± 0.0140 mGy/MBq, and effective dose (ICRP 103) to 0.0186 ± 0.0030.
Conclusions: [18F]GP1 has favorable radiation dosimetry profile for clinical PET/CT imaging. The ED is comparable to commonly used 18F PET tracers.
Keywords: Platelet activation; Positron emission tomography; Radiation dosimetry; Thromboembolism; [(18)F]GP1.
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