title: Technical Note: Development of a combined molecular breast imaging/ultrasound system for diagnostic evaluation of MBI-detected lesions.
abstract: OBJECTIVE
  The purpose of this study was to perform a pilot evaluation of an integrated molecular breast imaging/ultrasound (MBI/US) system designed to enable, in real-time, the registration of US to MBI and diagnostic evaluation of breast lesions detected on MBI.
  
  
  METHODS
  The MBI/US system was constructed by modifying an existing dual-head cadmium zinc telluride (CZT)-based MBI gamma camera. The upper MBI detector head was replaced with a mesh panel, which allowed an ultrasound probe to access the breast. An optical tracking system was used to monitor the location of the ultrasound transducer, referenced to the MBI detector. The lesion depth at which ultrasound was targeted was estimated from analysis of previously acquired dual-head MBI datasets. A software tool was developed to project the US field of view onto the current MBI image. Correlation of lesion location between both modalities with real-time MBI/US scanning was confirmed in a breast phantom model and assessed in 12 patients with a breast lesion detected on MBI.
  
  
  RESULTS
  Combined MBI/US scanning allowed for registration of lesions detected on US and MBI as validated in phantom experiments. In patient studies, successful registration was achieved in 8 of 12 (67%) patients, with complete registration achieved in seven and partial registration achieved in one patient. In 4 of 12 (37%) patients, lesion registration was not achieved, partially attributed to uncertainty in lesion depth estimates from MBI.
  
  
  CONCLUSIONS
  The MBI/US system enabled successful registration of US to MBI in over half of patients studied in this pilot evaluation. Future studies are needed to determine if real-time, registered US imaging of MBI-detected lesions may obviate the need to proceed to more expensive procedures such as contrast-enhanced breast MRI for diagnostic workup or biopsy of MBI findings.
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, MN, USA.
authors.forename: Michael K
authors.initials: MK
authors.lastname: O'Connor
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, MN, USA.
authors.forename: Melissa M
authors.initials: MM
authors.lastname: Morrow
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, MN, USA.
authors.forename: Thuy
authors.initials: T
authors.lastname: Tran
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, MN, USA.
authors.forename: Carrie B
authors.initials: CB
authors.lastname: Hruska
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, MN, USA.
authors.forename: Amy L
authors.initials: AL
authors.lastname: Conners
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, MN, USA.
authors.forename: Katie N
authors.initials: KN
authors.lastname: Hunt
mesh_terms: D001941:Breast Diseases / Q000000981:diagnostic imaging; D066264:Datasets as Topic; D004867:Equipment Design; D005260:Female; D006801:Humans; D008875:Middle Aged; D008953:Models, Anatomic; D057054:Molecular Imaging / Q000295:instrumentation* / Q000379:methods; D064847:Multimodal Imaging / Q000295:instrumentation* / Q000379:methods; D061848:Optical Imaging / Q000295:instrumentation / Q000379:methods; D019047:Phantoms, Imaging; D010865:Pilot Projects; D012984:Software; D016217:Ultrasonography, Mammary / Q000295:instrumentation* / Q000379:methods
keywords: breast cancer; cadmium zinc telluride (CZT); molecular breast imaging (MBI); ultrasound