title: In vivo multicolor molecular MR imaging using diamagnetic chemical exchange saturation transfer liposomes.
abstract: A variety of (super)paramagnetic contrast agents are available for enhanced MR visualization of specific tissues, cells, or molecules. To develop alternative contrast agents without the presence of metal ions, liposomes were developed containing simple bioorganic and biodegradable compounds that produce diamagnetic chemical exchange saturation transfer MR contrast. This diamagnetic chemical exchange saturation transfer contrast is frequency-dependent, allowing the unique generation of "multicolor" images. The contrast can be turned on and off at will, and standard images do not show the presence of these agents. As an example, glycogen, L-arginine, and poly-L-lysine were encapsulated inside liposomes and injected intradermally into mice to image the lymphatic uptake of these liposomes. Using a frequency-dependent acquisition scheme, it is demonstrated that multicolor MRI can differentiate between different contrast particles in vivo following their homing to draining lymph nodes. Being nonmetallic and bioorganic, these diamagnetic chemical exchange saturation transfer liposomes form an attractive novel platform for multicolor imaging in vivo.
authors.affiliation: F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland 21205, USA.
authors.forename: Guanshu
authors.initials: G
authors.lastname: Liu
authors.forename: Matthew
authors.initials: M
authors.lastname: Moake
authors.forename: Yah-el
authors.initials: YE
authors.lastname: Har-el
authors.forename: Chris M
authors.initials: CM
authors.lastname: Long
authors.forename: Kannie W Y
authors.initials: KW
authors.lastname: Chan
authors.forename: Amanda
authors.initials: A
authors.lastname: Cardona
authors.forename: Muksit
authors.initials: M
authors.lastname: Jamil
authors.forename: Piotr
authors.initials: P
authors.lastname: Walczak
authors.forename: Assaf A
authors.initials: AA
authors.lastname: Gilad
authors.forename: George
authors.initials: G
authors.lastname: Sgouros
authors.forename: Peter C M
authors.initials: PC
authors.lastname: van Zijl
authors.forename: Jeff W M
authors.initials: JW
authors.lastname: Bulte
authors.forename: Michael T
authors.initials: MT
authors.lastname: McMahon
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D003124:Colorimetry / Q000379:methods*; D003287:Contrast Media / Q000493:pharmacokinetics; D008081:Liposomes / Q000493:pharmacokinetics*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D051379:Mice; D008810:Mice, Inbred C57BL; D057054:Molecular Imaging / Q000379:methods*; D009374:Neoplasms, Experimental / Q000378:metabolism* / Q000473:pathology*
chemical_list: D003287:Contrast Media; D008081:Liposomes