Preliminary evaluation of a polyethyleneglycol-stabilized manganese-substituted hydroxylapatite as an intravascular contrast agent for MR angiography
✍ Scribed by Kofi Adzamli; Richard B. Dorshow; Michael R. Hynes; Debiao Li; Dennis L. Nosco; Max D. Adams
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 902 KB
- Volume
- 7
- Category
- Article
- ISSN
- 1053-1807
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✦ Synopsis
Abstract
A blood‐persistent particulate paramagnetic contrast agent has been formulated via size stabilization of manganese‐substituted hydroxylapatite by a polyethylene glycol (PEG) bearing a terminal diphosphonate. At high PEG surface densities (35–40 mol %), particles with mean diameter 8 ± 2 nm were obtained. Relaxivities of autoclaved samples (at 20 MHz proton Lamor frequency) were R1 = 18.7 ± .8 mM^−1^ sec^−1^ and R2 = 22.3 ± .7 mM^−1^ sec^−1^. The formulation persisted in rabbit blood with a biphasic clearance profile. Halflives (with amplitudes in parenthesis) were 4 ± 1 minutes (55%), and 49 ± 3 minutes (45%), respectively, for the two phases. A dose of 40 μmol Mn/kg body weight enhanced the signal from rabbit vasculature for more than 45 minutes on MR angiograms. Thus, PEG‐modified MnHA particles may find use as T1 agents for MR angiography.