Implant Imaging: Perspectives of Nuclear Imaging in Implant, Biomaterial, and Stem Cell Research

Abstract

Until now, very few efforts have been made to specifically trace, monitor, and visualize implantations, artificial organs, and bioengineered scaffolds for tissue engineering in vivo. While mainly X-Ray, CT, and MRI methods have been used for this purpose, the applications of more sensitive, quantitative, specific, radiotracer-based nuclear imaging techniques remain a challenge. As the need for biomaterials increases, so does the need for research tools to evaluate host responses. PET (positron emission tomography) and SPECT (single photon emission computer tomography) techniques are promising tools for the clinical translation of such regenerative medicine and tissue engineering efforts. These tracer-based methods offer unique and inevitable support, providing specific, quantitative, visual, non-invasive feedback on implanted biomaterials, devices, or transplanted cells. PET and SPECT can improve and accelerate these studies through biocompatibility, inertivity, and immune-response evaluations over long investigational periods at high sensitivities with low limits of detection. The wide range of radiopharmaceuticals, the newly developed specific bacteria, and the inflammation of specific or fibrosis-specific tracers as well as labeled individual nanomaterials can represent new, valuable tools for implant research. This review aims to summarize the opportunities of nuclear-imaging-supported implant research, including bone, fibrosis, bacteria, nanoparticle, and cell imaging, as well as the latest cutting-edge pretargeting methods.

Preparation and PET/CT imaging of implant directed 68Ga-labeled magnetic nanoporous silica nanoparticles

“…Dynamic PET and SPECT acquisition allows the registration of organ uptake values, ex vivo biodistribution, and pharmacokinetic parameters of labeled nanovesicles, including blood clearance and excretion times. Thus, although the method recommends special radiochemical apparatus and has obvious limitations (limited tracking time depending on selected radioisotope), hybrid PET/CT imaging systems combined with radiolabeled nanoparticles for targeted drug delivery offer a unique way to evaluate quantitatively the whole body distribution and the anatomical information regarding the NP-accumulation in targeted tissues [ 38 , 44 , 45 ].…”