title: Positive contrast visualization of SPIO-labeled pancreatic islets using echo-dephased steady-state free precession.
abstract: OBJECTIVE
  MRI has recently been introduced as a promising method of monitoring the transplanted pancreatic islets labelled with superparamagnetic iron oxide (SPIO). However, the traditional [Formula: see text]-weighted approach frequently yields ambiguous results because of the negative contrast of the SPIO particles on the background of other body components. This obstacle could be overcome with the use of a novel method known as echo-dephased steady state free precession (SSFP), generating positive contrast in the presence of paramagnetic material.
  
  
  METHODS
  In phantoms, we achieved exact localisation and clear positive contrast visualisation of human SPIO labelled islets. Using the proposed method we demonstrated the ability to detect even a single pancreatic islet against a homogeneous background.
  
  
  RESULTS
  In vivo experiments in rats confirmed reliable and accurate localisation of transplanted SPIO labelled islets.
  
  
  CONCLUSIONS
  The echo-dephased SSFP technique could successfully visualise SPIO-labelled human and rat pancreatic islets yielding a positive contrast.
authors.affiliation: Center for Applied Medical Imaging, Siemens Corporation, Corporate Research, Baltimore, MD, USA.
authors.forename: S
authors.initials: S
authors.lastname: Patil
authors.forename: D
authors.initials: D
authors.lastname: Jirák
authors.forename: F
authors.initials: F
authors.lastname: Saudek
authors.forename: M
authors.initials: M
authors.lastname: Hájek
authors.forename: K
authors.initials: K
authors.lastname: Scheffler
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000494:pharmacology; D005260:Female; D052203:Ferrosoferric Oxide / Q000494:pharmacology; D006801:Humans; D007515:Islets of Langerhans / Q000000981:diagnostic imaging* / Q000187:drug effects; D008279:Magnetic Resonance Imaging / Q000295:instrumentation; D008280:Magnetics; D019047:Phantoms, Imaging; D011859:Radiography; D051381:Rats
chemical_list: D003287:Contrast Media; D052203:Ferrosoferric Oxide