title: Ex vivo estimation of photoacoustic imaging for detecting thyroid microcalcifications.
abstract: BACKGROUND
  The aim of this study was to evaluate the diagnostic utility of PAI at detecting thyroid microcalcifications at 700 nm laser wavelengths.
  
  
  METHODS
  This study included 36 resected samples in 18 patients. To evaluate the PA manifestation of microcalcifications in PAI, gray level histogram and co-occurrence matrix (COM) texture parameters were extracted from the 3 fixed ROI US and PA images, respectively, per sample. We compared the textural parameters obtained from specimen PAIs between samples with punctate microcalcifications on specimen radiography and those without microcalcifications.
  
  
  RESULTS
  On specimen US, the mean value (2748.4 ± 862.5) of samples with microcalcifications on specimen radiography was higher than that (1961.9 ± 780.2) of those without microcalcifications (P = 0.007). However, there were no significant differences in textural parameters obtained from specimen PAIs between samples with punctate microcalcifications on specimen radiography and those without when applying both the mean value of the three slices of thyroid specimens and the value of the thyroid specimen slice which had the highest value of the mean values in specimen US.
  
  
  CONCLUSIONS
  PAI did not show significant PA contrast on thyroid microcalcifications indicating that the experimental setup and protocols should be enhanced, e.g., method of complete blood rejection from ex vivo specimens, the multi-wavelength spectroscopic PA imaging method which can solely extract the PA signal from microcalcifications even with high spectral interferences, or PA imaging with narrower slice thickness using 2-dimensional array transducer, etc.
authors.affiliation: Department of Electronics Engineering, Sogang University, Seoul, Korea.
authors.forename: Jeeun
authors.initials: J
authors.lastname: Kang
authors.affiliation: Department of Surgery, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Woong Youn
authors.initials: WY
authors.lastname: Chung
authors.affiliation: Department of Surgery, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Sang-Wook
authors.initials: SW
authors.lastname: Kang
authors.affiliation: Department of Pathology, Severance Hospital, Yonsei University, College of Medicine, Seoul, Korea.
authors.forename: Hyeong Ju
authors.initials: HJ
authors.lastname: Kwon
authors.affiliation: Yonsei University, College of Medicine, Seoul, Korea.
authors.forename: Jaeheung
authors.initials: J
authors.lastname: Yoo
authors.affiliation: Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Eun-Kyung
authors.initials: EK
authors.lastname: Kim
authors.affiliation: Department of Electronics Engineering, Sogang University, Seoul, Korea; Interdisciplinary Program of Integrated Biotechnology, Sogang University, Seoul, South Korea.
authors.forename: Jin Ho
authors.initials: JH
authors.lastname: Chang
authors.affiliation: Department of Electronics Engineering, Sogang University, Seoul, Korea.
authors.forename: Tai-Kyong
authors.initials: TK
authors.lastname: Song
authors.affiliation: Department of Surgery, The Catholic University of Korea, Seoul, South Korea.
authors.forename: Sohee
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Jin Young
authors.initials: JY
authors.lastname: Kwak
mesh_terms: D000328:Adult; D002114:Calcinosis / Q000175:diagnosis* / Q000000981:diagnostic imaging; D003952:Diagnostic Imaging / Q000379:methods; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D061088:Photoacoustic Techniques / Q000379:methods*; D011859:Radiography; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013961:Thyroid Gland / Q000000981:diagnostic imaging / Q000473:pathology*