title: Ultrashort echo time (UTE) imaging of receptor targeted magnetic iron oxide nanoparticles in mouse tumor models.
abstract: OBJECTIVE
  The purpose of this study was to investigate an ultrashort echo time (UTE) imaging approach for improving the detection of receptor targeted magnetic nanoparticles in cancer xenograft models using positive contrast.
  
  
  METHODS
  Iron oxide nanoparticle (IONP) conjugated with tumor targeting ligands were prepared. A 3D UTE gradient echo sequence with the shortest TE of 0.07 msec was evaluated on a 3T magnetic resonance imaging (MRI) scanner using IONP solution, cancer cells bound with targeted IONPs and orthotopic human pancreatic, and breast cancer mouse models administered tumor targeting IONPs. A simulation was performed to analyze contrast-to-noise ratios (CNR) of UTE images and subtraction of the images obtained UTE and longer TE (SubUTE). T2-weighted imaging and T2 relaxometry mapping were applied for comparison and validation.
  
  
  RESULTS
  UTE and SubUTE images showed positive contrast in pancreatic tumors accumulated with EGFR targeted ScFvEGFR-IONPs and mammary tumors accumulated with uPAR targeted ATF-IONPs. The positive contrast observed in UTE images was consistent with the negative contrast observed in the T2-weighted images. A flip angle of 10° and a maximal possible TE for the second echo are suitable for SubUTE imaging.
  
  
  CONCLUSIONS
  UTE imaging is capable of detecting tumor targeted IONPs in vivo with positive contrast in molecular MRI applications.
authors.forename: Liya
authors.initials: L
authors.lastname: Wang
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Zhong
authors.forename: Weiping
authors.initials: W
authors.lastname: Qian
authors.forename: Jing
authors.initials: J
authors.lastname: Huang
authors.forename: Zehong
authors.initials: Z
authors.lastname: Cao
authors.forename: Qiqi
authors.initials: Q
authors.lastname: Yu
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Lipowska
authors.forename: Run
authors.initials: R
authors.lastname: Lin
authors.forename: Andrew
authors.initials: A
authors.lastname: Wang
authors.forename: Lily
authors.initials: L
authors.lastname: Yang
authors.forename: Hui
authors.initials: H
authors.lastname: Mao
mesh_terms: D000818:Animals; D003287:Contrast Media; D005260:Female; D064593:Heterografts; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D008325:Mammary Neoplasms, Experimental / Q000175:diagnosis*; D051379:Mice; D057054:Molecular Imaging / Q000379:methods*; D009368:Neoplasm Transplantation; D010190:Pancreatic Neoplasms / Q000175:diagnosis*; D019047:Phantoms, Imaging; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D058185:Magnetite Nanoparticles