title: Initial characterization of a dedicated breast PET/CT scanner during human imaging.
abstract: We have constructed a dedicated breast PET/CT scanner capable of high-resolution functional and anatomic imaging. Here, we present an initial characterization of scanner performance during patient imaging.
  
  
  METHODS
  The system consisted of a lutetium oxyorthosilicate-based dual-planar head PET camera (crystal size, 3 x 3 x 20 mm) and 768-slice cone-beam CT. The position of the PET heads (separation and height) could be adjusted for varying breast dimensions. For scanning, the patient lay prone on a specialized bed and inserted a single pendent breast through an aperture in the table top. Compression of the breast as used in mammography is not required. PET and CT systems rotate in the coronal plane underneath the patient sequentially to collect fully tomographic datasets. PET images were reconstructed with the fully 3-dimensional maximum a posteriori method, and CT images were reconstructed with the Feldkamp algorithm, then spatially registered and fused for display. Phantom scans were obtained to assess the registration accuracy between PET and CT images and the influence of PET electronics and activity on CT image quality. We imaged 4 women with mammographic findings highly suggestive of breast cancer (breast imaging reporting and data system, category 5) in an ongoing clinical trial. Patients were injected with (18)F-FDG and imaged for 12.5 min per breast. From patient data, noise-equivalent counting rates and the singles-to-trues ratio (a surrogate for the randoms fraction) were calculated.
  
  
  RESULTS
  The average registration error between PET and CT images was 0.18 mm. PET electronics and activity did not significantly affect CT image quality. For the patient trial, biopsy-confirmed cancers were visualized on dedicated breast PET/CT on all patient scans, including the detection of ductal carcinoma in situ in 1 case. The singles-to-trues ratio was found to be inversely correlated with breast volume in the field of view, suggesting that larger breasts trend toward increased noise-equivalent counting rates for all other things equal.
  
  
  CONCLUSIONS
  Scanning of the uncompressed breast with dedicated breast PET/CT can accurately visualize suspected lesions in 3 dimensions.
authors.affiliation: Department of Biomedical Engineering, UC Davis, Davis, California, USA. slbowen@ucdavis.edu
authors.forename: Spencer L
authors.initials: SL
authors.lastname: Bowen
authors.forename: Yibao
authors.initials: Y
authors.lastname: Wu
authors.forename: Abhijit J
authors.initials: AJ
authors.lastname: Chaudhari
authors.forename: Lin
authors.initials: L
authors.lastname: Fu
authors.forename: Nathan J
authors.initials: NJ
authors.lastname: Packard
authors.forename: George W
authors.initials: GW
authors.lastname: Burkett
authors.forename: Kai
authors.initials: K
authors.lastname: Yang
authors.forename: Karen K
authors.initials: KK
authors.lastname: Lindfors
authors.forename: David K
authors.initials: DK
authors.lastname: Shelton
authors.forename: Rosalie
authors.initials: R
authors.lastname: Hagge
authors.forename: Alexander D
authors.initials: AD
authors.lastname: Borowsky
authors.forename: Steve R
authors.initials: SR
authors.lastname: Martinez
authors.forename: Jinyi
authors.initials: J
authors.lastname: Qi
authors.forename: John M
authors.initials: JM
authors.lastname: Boone
authors.forename: Simon R
authors.initials: SR
authors.lastname: Cherry
authors.forename: Ramsey D
authors.initials: RD
authors.lastname: Badawi
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000175:diagnosis*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation*; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique / Q000295:instrumentation*; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*
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