title: Initial in vivo experience with a novel type of MR-safe pushable coils for MR-guided embolizations.
abstract: OBJECTIVE
  Conventional detachable embolization coils are made from platinum or stainless steel and may thus be a magnetic resonance (MR) safety hazard because of resonant device heating. The objective of this experimental study was to assess the feasibility of MR-guided embolization procedures with a novel type of nonmetallic and, therefore, intrinsically MR-safe pushable coil.
  
  
  METHODS
  The embolization coils are made from a polymer and coated with a hydrogel, which expands during contact with liquids. Magnetic resonance-guided embolizations were performed in 6 healthy domestic pigs by deploying up to 3 polymer pushable coils via an active tracking catheter under real-time magnetic resonance imaging monitoring. To assess the renal perfusion deficit induced by the coil embolization, intra-arterial 3-dimensional contrast-enhanced magnetic resonance angiography (3D ce-MRA) data sets were acquired before and every 5 minutes after coil placement until complete vessel occlusion.
  
  
  RESULTS
  The MR-guided embolizations were successful in 5 of the 6 animals. The 3D ce-MRA data sets indicated first perfusion deficits within 2 to 40 minutes after coil deployment. Complete vessel occlusion was achieved after 6 to 53 minutes. In 1 animal, no perfusion defect could be detected. Because our experiments were designed as a preliminary proof-of-concept study, different sizes and numbers of all-polymer hydrocoils were deployed at different anatomical positions, making the drawing of correlation between the size/number of deployed coils and the occlusion efficiency difficult. The all-polymer hydrocoils did not induce any artifacts on the MR images, either in the real-time MR images, which were recorded during the embolization, or in the subsequently acquired 3D ce-MRA images.
  
  
  CONCLUSIONS
  Our results demonstrated that the novel all-polymer and intrinsically MR-safe pushable hydrocoils may become a promising tool for MR-guided embolization procedures.
authors: Department of Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany. a.homagk@dkfz.de
authors: Ann-Kathrin
authors: AK
authors: Homagk
authors: Reiner
authors: R
authors: Umathum
authors: Michael
authors: M
authors: Bock
authors: Peter
authors: P
authors: Hallscheidt
mesh_terms: D000818:Animals; D001807:Blood Vessel Prosthesis; D004621:Embolization, Therapeutic / Q000295:instrumentation* / Q000379:methods*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D053783:Magnetic Resonance Imaging, Interventional / Q000295:instrumentation* / Q000379:methods*; D010865:Pilot Projects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015607:Stents; D013552:Swine