title: In vivo MRI visualization of release from liposomes triggered by local application of pulsed low-intensity non-focused ultrasound.
abstract: The work aimed at developing a MRI-guided protocol for the visualization of the release of material entrapped in liposomes stimulated by the local application of pulsed low-intensity non-focused ultrasound (pLINFU). The task was achieved by formulating liposomes filled up with the clinically approved paramagnetic agent gadoteridol, because the release of the agent from the nanovesicles is accompanied by a significant MRI signal enhancement. The protocol was validated in vivo on mice-bearing subcutaneous syngeneic B16 melanoma and i.v. injected with the paramagnetic liposomes. Upon exposing tumor to pLINFU (3MHz, insonation time 2min, duty cycle 50%) few minutes after liposomes injection, a signal enhancement of ca. 35% was detected. The effective release of the agent was confirmed by the strong enhancement measured in kidneys calyx and bladder due to the rapid renal excretion of the agent released in the tumor.
  
  
  BACKGROUND
  In this paper, a pulsed low-intensity non-focused ultrasound-based technique was used to release a paramagnetic MRI contrast agent from liposomes, demonstrating the feasibility of this triggered release system in a mouse melanoma model for future research applications.
authors.affiliation: Department of Molecular Biotechnology and Health Sciences, Molecular Imaging Center, University of Torino, Torino, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Rizzitelli
authors.affiliation: Department of Molecular Biotechnology and Health Sciences, Molecular Imaging Center, University of Torino, Torino, Italy; Center for Preclinical Imaging, University of Torino, Colleretto Giacosa (TO), Italy.
authors.forename: Pierangela
authors.initials: P
authors.lastname: Giustetto
authors.affiliation: Department of Molecular Biotechnology and Health Sciences, Molecular Imaging Center, University of Torino, Torino, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Boffa
authors.affiliation: Department of Molecular Biotechnology and Health Sciences, Molecular Imaging Center, University of Torino, Torino, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Delli Castelli
authors.affiliation: Department of Molecular Biotechnology and Health Sciences, Molecular Imaging Center, University of Torino, Torino, Italy.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Cutrin
authors.affiliation: Department of Molecular Biotechnology and Health Sciences, Molecular Imaging Center, University of Torino, Torino, Italy; Center for Preclinical Imaging, University of Torino, Colleretto Giacosa (TO), Italy.
authors.forename: Silvio
authors.initials: S
authors.lastname: Aime
authors.affiliation: Department of Molecular Biotechnology and Health Sciences, Molecular Imaging Center, University of Torino, Torino, Italy; Center for Preclinical Imaging, University of Torino, Colleretto Giacosa (TO), Italy. Electronic address: enzo.terreno@unito.it.
authors.forename: Enzo
authors.initials: E
authors.lastname: Terreno
mesh_terms: D003287:Contrast Media / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry*; D008279:Magnetic Resonance Imaging / Q000379:methods*
chemical_list: D003287:Contrast Media; D008081:Liposomes
keywords: Drug release; Liposomes; MRI; Theranosis; Ultrasound