title: X-ray imaging of poly(ethylene glycol) hydrogels without contrast agents.
abstract: Hydrogels have shown promise for a number of tissue engineering applications. However, their high water content results in little or no image contrast when using conventional X-ray imaging techniques. X-ray imaging techniques based on phase-contrast have shown promise for biomedical application due to their ability to provide information about the X-ray refraction properties of samples. Nonporous and porous poly(ethylene glycol) hydrogels were synthesized and imaged using a synchrotron light source employing a silicon analyzer crystal and an X-ray energy of 40-keV. Data were acquired at 21 angular analyzer positions spanning the range of -5 to 5 μrad. Images that depict the projected X-ray absorption, refraction, and ultra-small-angle scatter (USAXS) properties of the hydrogels were reconstructed from the measurement data. The poly(ethylene glycol) hydrogels could be discerned from surrounding water and soft tissue in the refraction image but not the absorption or USAXS images. In addition, the refraction images of the porous hydrogels have a speckle pattern resulting in increased image texture in comparison to nonporous hydrogels. To our knowledge, this is the first study to show that X-ray phase-contrast imaging techniques can identify and provide detail on hydrogel structure without the addition of contrast agents.
authors.affiliation: Department of Biomedical Engineering, Illinois Institut e of Technology, Chicago, Illinois 60616, USA. brey@iit.edu
authors.forename: Eric M
authors.initials: EM
authors.lastname: Brey
authors.forename: Alyssa
authors.initials: A
authors.lastname: Appel
authors.forename: Yu-Chieh
authors.initials: YC
authors.lastname: Chiu
authors.forename: Zhong
authors.initials: Z
authors.lastname: Zhong
authors.forename: Ming-Huei
authors.initials: MH
authors.lastname: Cheng
authors.forename: Holger
authors.initials: H
authors.lastname: Engel
authors.forename: Mark A
authors.initials: MA
authors.lastname: Anastasio
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry / Q000528:radiation effects; D003287:Contrast Media / Q000737:chemistry / Q000494:pharmacology*; D020100:Hydrogels / Q000528:radiation effects; D021621:Imaging, Three-Dimensional / Q000379:methods; D008962:Models, Theoretical; D011092:Polyethylene Glycols / Q000737:chemistry*; D019736:Prostheses and Implants; D011859:Radiography / Q000379:methods*; D053838:Scattering, Small Angle; D023822:Tissue Engineering / Q000379:methods; D014961:X-Ray Diffraction / Q000379:methods; D014965:X-Rays
chemical_list: D001672:Biocompatible Materials; D003287:Contrast Media; D020100:Hydrogels; D011092:Polyethylene Glycols