title: In vivo MRI visualization of mesh shrinkage using surgical implants loaded with superparamagnetic iron oxides.
abstract: BACKGROUND
  Prosthetic mesh implants are widely used in hernia surgery. To show long-term mesh-related complications such as shrinkage or adhesions, a precise visualization of meshes and their vicinity in vivo is important. By supplementing mesh fibers with ferro particles, magnetic resonance imaging (MRI) can help to delineate the mesh itself. This study aimed to demonstrate and quantify time-dependent mesh shrinkage in vivo by MRI.
  
  
  METHODS
  Polyvinylidenfluoride (PVDF) meshes with incorporated superparamagnetic iron oxides (SPIOs) were implanted as an abdominal wall replacement in 30 rats. On days 1, 7, 14, or 21, MRI was performed using a gradient echo sequence with repetition time (TR)/echo time (TE) of 50/4.6 and a flip angle of 20°. The length, width, and area of the device were measured on axial, coronal, and sagittal images, and geometric deformations were assessed by surgical explantation.
  
  
  RESULTS
  In all cases, the meshes were visualized and their area estimated by measuring the length and width of the mesh. The MRI presented a mean area shrinkage in vivo of 13% on day 7, 23% on day 14, and 23% on day 21. Postmortem measurements differed statistically from MRI, with a mean area shrinkage of 23% on day 7, 28% on day 14, and 30% on day 21. Ex vivo measurements of shrinkage showed in vivo measurements to be overestimated approximately 8%. Delineation of the mesh helped to show folding or adhesions close to the intestine.
  
  
  CONCLUSIONS
  Loading of surgical meshes with SPIOs allows their precise visualization during MRI and guarantees an accurate in vivo assessment of their shrinkage. The authors' observation clearly indicates that shrinkage in vivo is remarkably less than that shown by illustrated explantation measurements. The use of MRI with such meshes could be a reliable technique for checking on proper operation of implanted meshes and showing related complications, obviating the need for exploratory open surgical revision.
authors.affiliation: Department of Surgery, University Hospital, RWTH Aachen University, 52074, Aachen, Germany. nkuehnert@ukaachen.de
authors.forename: Nicolas
authors.initials: N
authors.lastname: Kuehnert
authors.forename: Nils A
authors.initials: NA
authors.lastname: Kraemer
authors.forename: Jens
authors.initials: J
authors.lastname: Otto
authors.forename: Hank C W
authors.initials: HC
authors.lastname: Donker
authors.forename: Ioana
authors.initials: I
authors.lastname: Slabu
authors.forename: Martin
authors.initials: M
authors.lastname: Baumann
authors.forename: Christiane K
authors.initials: CK
authors.lastname: Kuhl
authors.forename: Uwe
authors.initials: U
authors.lastname: Klinge
mesh_terms: D000818:Animals; D004867:Equipment Design; D046449:Hernia, Abdominal / Q000601:surgery; D058085:Iron Compounds; D008279:Magnetic Resonance Imaging; D008297:Male; D011145:Polyvinyls / Q000627:therapeutic use; D019736:Prostheses and Implants; D051381:Rats; D017207:Rats, Sprague-Dawley; D013526:Surgical Mesh / Q000592:standards*; D005465:Fluorocarbon Polymers
chemical_list: D058085:Iron Compounds; D011145:Polyvinyls; C024865:polyvinylidene fluoride; D005465:Fluorocarbon Polymers