PVP‐coated Gd‐grafted nanodiamonds as a novel and potentially safer contrast agent for in vivo MRI

Abstract

Purpose Testing the potential use of saline suspension of polyvinylpyrrolidone (PVP)‐coated gadolinium(Gd)‐grafted detonation nanodiamonds (DND) as a novel contrast agent in MRI. Methods Stable saline suspensions of highly purified de‐agglomerated Gd‐grafted DND particles coated by a PVP protective shell were prepared. T 1 and T 2 proton relaxivities of the suspensions with varying gadolinium concentration were measured at 8 Tesla. A series of ex vivo (phantom) and in vivo dynamic scans were obtained in 3 Tesla MRI using PVP‐coated Gd‐grafted DND and gadoterate meglumin in equal concentrations of gadolinium, and then T 1 ‐weighted hyperintensity was compared. Results The proton relaxivities of PVP‐coated Gd‐grafted DND were found to be r 1 = 15.9 ± 0.8 s −1 mM −1 and r 2 = 262 ± 15 s −1 mM −1 , respectively, which are somewhat less than those for uncoated Gd‐grafted DND but still high enough. Ex vivo MRI evaluation of PVP‐coated Gd‐grafted DND results with a dose‐dependent T 1 ‐weighted hyperintensity with a significant advantage over the same for gadoterate meglumin. The same was found when the 2 contrast agents were tested in vivo. Conclusion The novel MRI contrast agent — saline suspensions of PVP‐coated Gd‐grafted DND — provides significantly higher signal intensities than the common tracer gadoterate meglumin, therefore increasing its potential for a safer use in clinics.