title: MRI of regular-shaped cell-encapsulating polyhedral microcontainers.
abstract: We devised cubic and pyramidal microcontainers for cell encapsulation. While the cube is easier to manipulate, the pyramid offers a higher surface area-to-volume ratio and may therefore provide the encapsulated cells with increased access to nutrients. To discern the microcontainers' implant location and environment, and to aid in image-guided therapy, we showed noninvasive detection of microcontainers using MRI. Diamagnetic microcontainers were imaged using the radio frequency (RF) shielding effect, with negative contrast localized to the interior of the microcontainers. For applications in which it is difficult to distinguish the microcontainers from other hypointensities, positive contrast can be used to discern them. We showed positive-contrast MRI of a diamagnetic microcontainer. To image microcontainers that are smaller than the spatial resolution of MRI, we performed in vivo negative-contrast MRI of a ferromagnetic microcontainer. As opposed to the diamagnetic microcontainer, the ferromagnetic microcontainer created a region of MRI contrast several times larger than the microcontainer's dimensions.
authors.affiliation: Department of Radiology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75235, USA. barjorg@yahoo.com
authors.forename: Barjor
authors.initials: B
authors.lastname: Gimi
authors.forename: Dmitri
authors.initials: D
authors.lastname: Artemov
authors.forename: Timothy
authors.initials: T
authors.lastname: Leong
authors.forename: David H
authors.initials: DH
authors.lastname: Gracias
authors.forename: Zaver M
authors.initials: ZM
authors.lastname: Bhujwalla
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques / Q000295:instrumentation* / Q000379:methods; D045744:Cell Line, Tumor; D017690:Cell Transplantation / Q000295:instrumentation* / Q000379:methods; D003287:Contrast Media; D007089:Image Enhancement / Q000295:instrumentation* / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D008297:Male; D051379:Mice; D016513:Mice, SCID; D008863:Microspheres; D011471:Prostatic Neoplasms / Q000473:pathology*
chemical_list: D003287:Contrast Media