title: Development of an MRI/x-ray/ultrasound compatible marker for pre-operative breast tumour localization.
abstract: This paper describes an in vitro investigation into the composition, structure and development of an magnetic resonance imaging (MRI), ultrasound (US) and x-ray imaging compatible marker for breast tumour localization. The marker is composed of 0.4-0.6 mm glass and iron-containing aluminium microspheres suspended in a gelatin matrix. The final form of the marker is a cylindrical shape 7 mm long with 2.05 mm diameter to facilitate delivery through a 12 gauge biopsy needle. To get optimal reflectivity for the US contrast, the glass microsphere concentration was found to be 40% by weight. US contrast is independent of marker orientation and the cylindrical shape made its US signal appearance distinctive thus ensuring confident identification. To control the MRI contrast, iron content was varied to generate a clear and local susceptibility signal void to reflect the marker position. Optimal iron content was found to be 52 microg iron which produced a clear signal void in spoiled gradient recalled MR images. The appearance of the susceptibility artefact is determined by the marker's shape, orientation and echo time. The final marker produces a dark artefact in MRI while appears as a clear hyperintense structure with acoustic shadowing in US images. The x-ray image showed the marker as a radio-opaque structure. This in vitro study demonstrates that the marker forms an alternative to traditional wire localization currently used for breast surgical procedures and creates new opportunities for US guided surgical procedures.
authors.affiliation: Imaging Research, Sunnybrook and Women's College Health Sciences Centre, University of Toronto, Toronto, Ontario M4N 3M5, Canada.
authors.forename: Yangmei
authors.initials: Y
authors.lastname: Li
authors.forename: Jianxiong
authors.initials: J
authors.lastname: Wang
authors.forename: Claire
authors.initials: C
authors.lastname: Holloway
authors.forename: Donald B
authors.initials: DB
authors.lastname: Plewes
mesh_terms: D000535:Aluminum; D000818:Animals; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging; D002645:Chickens; D003300:Copper; D005780:Gelatin; D005898:Glass; D007501:Iron; D008279:Magnetic Resonance Imaging / Q000295:instrumentation; D008327:Mammography / Q000295:instrumentation; D008863:Microspheres; D019047:Phantoms, Imaging; D016217:Ultrasonography, Mammary / Q000295:instrumentation; D014965:X-Rays
chemical_list: D003300:Copper; D005780:Gelatin; D000535:Aluminum; D007501:Iron