title: Positive Contrast MRI Techniques for Visualization of Iron-Loaded Hernia Mesh Implants in Patients.
abstract: OBJECTIVE
  In MRI, implants and devices can be delineated via susceptibility artefacts. To discriminate susceptibility voids from proton-free structures, different positive contrast techniques were implemented. The purpose of this study was to evaluate a pulse sequence-based positive contrast technique (PCSI) and a post-processing susceptibility gradient mapping algorithm (SGM) for visualization of iron loaded mesh implants in patients.
  
  
  METHODS
  Five patients with iron-loaded MR-visible inguinal hernia mesh implants were examined at 1.5 Tesla. A gradient echo sequence (GRE; parameters: TR: 8.3ms; TE: 4.3ms; NSA:2; FA:20°; FOV:350mm²) and a PCSI sequence (parameters: TR: 25ms; TE: 4.6ms; NSA:4; FA:20°; FOV:350mm²) with on-resonant proton suppression were performed. SGM maps were calculated using two algorithms. Image quality and mesh delineation were independently evaluated by three radiologists.
  
  
  RESULTS
  On GRE, the iron-loaded meshes generated distinct susceptibility-induced signal voids. PCSI exhibited susceptibility differences including the meshes as hyperintense signals. SGM exhibited susceptibility differences with positive contrast. Visually, the different algorithms presented no significant differences. Overall, the diagnostic value was rated best in GRE whereas PCSI and SGM were barely "sufficient".
  
  
  CONCLUSIONS
  Both "positive contrast" techniques depicted implanted meshes with hyperintense signal. SGM comes without additional acquisition time and can therefore be utilized in every patient.
authors.affiliation: Department of Diagnostic and Interventional Radiology, RWTH University Hospital Aachen, Aachen, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Ciritsis
authors.affiliation: Department of Diagnostic and Interventional Radiology, RWTH University Hospital Aachen, Aachen, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Truhn
authors.affiliation: Department of Diagnostic and Interventional Radiology, RWTH University Hospital Aachen, Aachen, Germany.
authors.forename: Nienke L
authors.initials: NL
authors.lastname: Hansen
authors.affiliation: Department of General, Visceral and Transplant Surgery, RWTH University Hospital Aachen, Aachen, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Otto
authors.affiliation: Department of Diagnostic and Interventional Radiology, RWTH University Hospital Aachen, Aachen, Germany.
authors.forename: Christiane K
authors.initials: CK
authors.lastname: Kuhl
authors.affiliation: Department of Diagnostic and Interventional Radiology, RWTH University Hospital Aachen, Aachen, Germany.
authors.forename: Nils A
authors.initials: NA
authors.lastname: Kraemer