title: Photoacoustic imaging of breast microcalcifications: a preliminary study with 8-gauge core-biopsied breast specimens.
abstract: BACKGROUND
  We presented the photoacoustic imaging (PAI) tool and to evaluate whether microcalcifications in breast tissue can be detected on photoacoustic (PA) images.
  
  
  METHODS
  We collected 21 cores containing microcalcifications (n = 11, microcalcification group) and none (n = 10, control group) in stereotactic or ultrasound (US) guided 8-gauge vacuum-assisted biopsies. Photoacoustic (PA) images were acquired through ex vivo experiments by transmitting laser pulses with two different wavelengths (700 nm and 800 nm). The presence of microcalcifications in PA images were blindly assessed by two radiologists and compared with specimen mammography. A ratio of the signal amplitude occurring at 700 nm to that occurring at 800 nm was calculated for each PA focus and was called the PAI ratio.
  
  
  RESULTS
  Based on the change of PA signal amplitude between 700 nm and 800 nm, 10 out of 11 specimens containing microcalcifications and 8 out of 10 specimens without calcifications were correctly identified on blind review; the sensitivity, specificity, accuracy, positive predictive and negative predictive values of our blind review were 90.91%, 80.0%, 85.71%, 83.33% and 88.89%. The PAI ratio in the microcalcification group was significantly higher than that in the control group (the median PAI ratio, 2.46 versus 1.11, respectively, P =  .001). On subgroup analysis in the microcalcification group, neither malignant diagnosis nor the number or size of calcification-foci was proven to contribute to PAI ratios.
  
  
  CONCLUSIONS
  Breast microcalcifications generated distinguishable PA signals unlike breast tissue without calcifications. So, PAI, a non-ionizing and non-invasive hybrid imaging technique, can be an alternative in overcoming the limitations of conventional US imaging.
authors.affiliation: Department of Radiology and Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Ga Ram
authors.initials: GR
authors.lastname: Kim
authors.affiliation: Sogang Institute of Advanced Technology, Sogang University, Seoul, Republic of Korea; Interdisciplinary Program of Integrated Biotechnology, Seoul, Republic of Korea.
authors.forename: Jeeun
authors.initials: J
authors.lastname: Kang
authors.affiliation: Department of Radiology and Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Jin Young
authors.initials: JY
authors.lastname: Kwak
authors.affiliation: Sogang Institute of Advanced Technology, Sogang University, Seoul, Republic of Korea; Interdisciplinary Program of Integrated Biotechnology, Seoul, Republic of Korea.
authors.forename: Jin Ho
authors.initials: JH
authors.lastname: Chang
authors.affiliation: Department of Surgery, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Seung Il
authors.initials: SI
authors.lastname: Kim
authors.affiliation: Department of Radiology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Ji Hyun
authors.initials: JH
authors.lastname: Youk
authors.affiliation: Department of Radiology and Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Hee Jung
authors.initials: HJ
authors.lastname: Moon
authors.affiliation: Department of Radiology and Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Min Jung
authors.initials: MJ
authors.lastname: Kim
authors.affiliation: Department of Radiology and Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Eun-Kyung
authors.initials: EK
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D062005:Biopsy, Large-Core Needle; D001940:Breast / Q000473:pathology*; D001941:Breast Diseases / Q000473:pathology*; D001943:Breast Neoplasms / Q000473:pathology*; D002114:Calcinosis / Q000473:pathology*; D003952:Diagnostic Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008875:Middle Aged; D061088:Photoacoustic Techniques / Q000379:methods*; D055815:Young Adult