INTRODUCTION: Although the first polyphosphonates were already introduced in the early 1970s, mechanisms involved in uptake still remain speculative. The present work aimed to establish a new method to rate the influence of various factors on the uptake and to evaluate new bone-seekers on these bone compartments. METHODS: Radioactive-labelled diphosphonates and [(18)F]-fluoride were added to a vial containing hydroxyapatite (HA), collagen, or amorphous calcium phosphate (ACP) in 3 ml of Hanks' Balanced Salt Solution (HBSS). After incubation, these suspensions were filtered, the radioactivity was measured in the gamma-counter, and the percentage of irreversibly bound radioactivity was calculated. RESULTS: Kinetic experiments revealed uptake increase over time for [(99m)Tc]-MDP and [(18)F]-fluoride on various amounts of matrix. After 120 min, static studies on HA yielded: [(99m)Tc]-EDTMP < [(188)Re]-/Re-EDTMP < [(99m)Tc]-/11 microl Re-EDTMP < [(99m)Tc]-/In-EDTMP < [(99m)Tc]-/15 microl Re-EDTMP < nca [(188)Re]-EDTMP < [(111)In]-/Re-EDTMP < [(111)In]-EDTMP < [(111)In]-/In-EDTMP < [(99m)Tc]-DPD < [(99m)Tc]-/80 microl Re-EDTMP < [(99m)Tc]-EDTMP "boiled" < [(99m)Tc]-/150 microl Re-EDTMP < [(153)Sm]-EDTMP < [(99m)Tc]-/11 microl Re-EDTMP "boiled" < [(18)F]-ions < [(99m)Tc]-MDP. Collagen showed very low uptake. Reincubation experiments suggest that bone tracers are irreversibly bound. CONCLUSION: The presented method is rapid and feasible to examine the adsorption of radioactive-labelled substances on bone components. Correlations between our findings and published in vivo data support the application as a simple model.
INTRODUCTION: Although the first polyphosphonates were already introduced in the early 1970s, mechanisms involved in uptake still remain speculative. The present work aimed to establish a new method to rate the influence of various factors on the uptake and to evaluate new bone-seekers on these bone compartments. METHODS: Radioactive-labelled diphosphonates and [(18)F]-fluoride were added to a vial containing hydroxyapatite (HA), collagen, or amorphous calcium phosphate (ACP) in 3 ml of Hanks' Balanced Salt Solution (HBSS). After incubation, these suspensions were filtered, the radioactivity was measured in the gamma-counter, and the percentage of irreversibly bound radioactivity was calculated. RESULTS: Kinetic experiments revealed uptake increase over time for [(99m)Tc]-MDP and [(18)F]-fluoride on various amounts of matrix. After 120 min, static studies on HA yielded: [(99m)Tc]-EDTMP < [(188)Re]-/Re-EDTMP < [(99m)Tc]-/11 microl Re-EDTMP < [(99m)Tc]-/In-EDTMP < [(99m)Tc]-/15 microl Re-EDTMP < nca [(188)Re]-EDTMP < [(111)In]-/Re-EDTMP < [(111)In]-EDTMP < [(111)In]-/In-EDTMP < [(99m)Tc]-DPD < [(99m)Tc]-/80 microl Re-EDTMP < [(99m)Tc]-EDTMP "boiled" < [(99m)Tc]-/150 microl Re-EDTMP < [(153)Sm]-EDTMP < [(99m)Tc]-/11 microl Re-EDTMP "boiled" < [(18)F]-ions < [(99m)Tc]-MDP. Collagen showed very low uptake. Reincubation experiments suggest that bone tracers are irreversibly bound. CONCLUSION: The presented method is rapid and feasible to examine the adsorption of radioactive-labelled substances on bone components. Correlations between our findings and published in vivo data support the application as a simple model.
Authors: Stefan Toegel; Oskar Hoffmann; Wolfgang Wadsak; Dagmar Ettlinger; Leonhard-Key Mien; Karoline Wiesner; Joseph Nguemo; Helmut Viernstein; Kurt Kletter; Robert Dudczak; Markus Mitterhauser Journal: Eur J Nucl Med Mol Imaging Date: 2006-01-17 Impact factor: 9.236