Comparative analysis of metallic nanoparticles as exogenous soft tissue contrast for live in vivo micro-computed tomography imaging of avian embryonic morphogenesis.

Abstract

Gestationally survivable congenital malformations arise during mid-late stages of development that are inaccessible in vivo with traditional optical imaging for assessing long-term abnormal patterning. MicroCT is an attractive technology to rapidly and inexpensively generate quantitative three-dimensional (3D) datasets but requires exogenous contrast media. Here we establish dose-dependent toxicity, persistence, and biodistribution of three different metallic nanoparticles in day 4 chick embryos. We determined that 110-nm alkaline earth metal particles were nontoxic and persisted in the chick embryo for up to 24 hr postinjection with contrast enhancement levels at high as 1,600 Hounsfield units (HU). The 15-nm gold nanoparticles persisted with x-ray attenuation higher than that of the surrounding yolk and albumen for up to 8 hr postinjection, while 1.9-nm particles resulted in lethality by 8 hr. We identified spatial and temporally heterogeneous contrast enhancement ranging from 250 to 1,600 HU. With the most optimal 110-nm alkaline earth metal particles, we quantified an exponential increase in the tissue perfusion vs. distance from the dorsal aorta into the flank over 8 hr with a peak perfusion rate of 0.7 μm(2) /s measured at a distance of 0.3 mm. These results demonstrate the safety, efficacy, and opportunity of nanoparticle based contrast media in live embryos for quantitative analysis of embryogenesis. Developmental Dynamics 245:1001-1010, 2016. © 2016 Wiley Periodicals, Inc.