title: Polymer film-nanoparticle composites as new multimodality, non-migrating breast biopsy markers.
abstract: OBJECTIVE
  To develop a breast biopsy marker that resists fast and slow migration and has permanent visibility under commonly used imaging modalities.
  
  
  METHODS
  A polymer-nanoparticle composite film was prepared by embedding superparamagnetic iron oxide nanoparticles and a superelastic Nitinol wire within a flexible polyethylene matrix. MRI, mammography, and ultrasound were used to visualize the marker in agar, ex vivo chicken breast, bovine liver, brisket, and biopsy training phantoms. Fast migration caused by the "accordion effect" was quantified after simulated stereotactic, vacuum-assisted core biopsy/marker placement, and centrifugation was used to simulate accelerated long-term (i.e., slow) migration in ex vivo bovine tissue phantoms.
  
  
  RESULTS
  Clear marker visualization under MRI, mammography, and ultrasound was observed. After deployment, the marker partially unfolds to give a geometrically constrained structure preventing fast and slow migration. The marker can be deployed through an 11G introducer without fast migration occurring, and shows substantially less slow migration than conventional markers.
  
  
  CONCLUSIONS
  The polymer-nanoparticle composite biopsy marker is clearly visible on all clinical imaging modalities and does not show substantial migration, which ensures multimodal assessment of the correct spatial information of the biopsy site, allowing for more accurate diagnosis and treatment planning and improved breast cancer patient care.
  
  
  CONCLUSIONS
  Polymer-nanoparticle composite biopsy markers are visualized using ultrasound, MRI, and mammography. Embedded iron oxide nanoparticles provide tuneable contrast for MRI visualization. Permanent ultrasound visibility is achieved with a non-biodegradable polymer having a distinct ultrasound signal. Flexible polymer-based biopsy markers undergo shape change upon deployment to minimize migration. Non-migrating multimodal markers will help improve accuracy of pre/post-treatment planning studies.
authors.affiliation: Departments of Biomedical Engineering and Chemistry, Boston University, 590 Commonwealth Ave., Boston, MA, 02215, USA.
authors.forename: Jonah A
authors.initials: JA
authors.lastname: Kaplan
authors.affiliation: Departments of Biomedical Engineering and Chemistry, Boston University, 590 Commonwealth Ave., Boston, MA, 02215, USA. mgrin@bu.edu.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Grinstaff
authors.affiliation: Department of Radiology, Boston University School of Medicine, 820 Harrison Ave, FGH 3, Boston, MA, 02118, USA. bnbloch@bu.edu.
authors.forename: B Nicolas
authors.identifier: http://orcid.org/0000-0001-8040-159X
authors.initials: BN
authors.lastname: Bloch
mesh_terms: D000818:Animals; D001707:Biopsy, Needle / Q000379:methods; D001940:Breast / Q000473:pathology*; D001943:Breast Neoplasms / Q000473:pathology*; D002417:Cattle; D005260:Female; D006801:Humans; D061705:Image-Guided Biopsy; D008099:Liver; D008279:Magnetic Resonance Imaging / Q000295:instrumentation; D058185:Magnetite Nanoparticles; D008327:Mammography / Q000295:instrumentation; D064847:Multimodal Imaging; D019047:Phantoms, Imaging; D011108:Polymers; D011200:Poultry; D013525:Surgical Instruments; D016217:Ultrasonography, Mammary
chemical_list: D058185:Magnetite Nanoparticles; D011108:Polymers
keywords: Breast Biopsy; Breast Biopsy Marker; Breast Cancer; Core Needle Biopsy; Image-Guided Biopsy