Quantitative analysis and parametric imaging of 18F-FPRGD and 18F-FPPRGD2 kinetics in breast cancer xenografts using a compartmental model

Wednesday, October 26, 2011 — Poster Session III
10:00 a.m. – Noon	Natcher Conference Center	NIBIB	IMAG-11

Authors

• N Guo
• L Lang
• H Gao
• G Niu
• DO Kiesewetter
• Q Xie
• X Chen

Abstract

Non-invasive PET imaging with radiolabeled RGD peptides for αvβ3 integrin targeting has become an important tool for tumor diagnosis and treatment monitoring in both pre-clinical and clinical studies. We have applied kinetic modeling to improve understanding of the molecular processes and tracer pharmacokinetics of 18F-labeled RGD peptide monomer 18F-FP-c(RGDyK) (denoted as 18F-FPRGD) and dimer 18F-FP-E[c(RGDyK)]2 (denoted as 18F-FPPRGD2). MDA-MB-435 tumor-bearing mice underwent PET imaging. Sixty-min dynamic PET scans were acquired with tail-vein injection of ~3.7 MBq (100 μCi) radiotracer (18F-FPRGD, 18F-FPPRGD2, or 18F-FPRAD) under isoflurane anesthesia. A reversible three-compartment model was applied for kinetic analysis in this study. The rates of perfusion into tissue (K1), clearance from plasma (k2), specific binding (k3) and dissociation (k4) were determined. Some combination of parameters were also calculated, such as binding potential (Bp = k3/k4) that reflects the binding affinity, and volume of distribution (Vd = K1/k2(1+k3/k4)) that reflects the tissue-to-plasma concentration ratio. The pharmacokinetics of both monomeric and dimeric RGD peptide tracers was compared and the RGD dimers showed significantly higher binding affinity than the monomer analogs. Kinetic parameters were demonstrated to be valuable and may allow more sensitive and detailed quantification than simple SUV analysis for tumor diagnosis and therapy response monitoring.

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