title: Fiber-needle swept-source optical coherence tomography system for the identification of the epidural space in piglets.
abstract: BACKGROUND
  Epidural needle insertion is traditionally a blind technique whose success depends on the experience of the operator. The authors describe a novel method using a fiber-needle-based swept-source optical coherence tomography (SSOCT) to identify epidural space.
  
  
  METHODS
  An optical fiber probe was placed into a hollow 18-gauge Tuohy needle. It was then inserted by an experienced anesthesiologist to continuously construct a series of two-dimensional SSOCT images by mechanically rotating the optical probe. To quantify this observation, both the average SSOCT signal intensities and their diagnostic potentials were assessed. The insertions were performed three times into both the lumbar and thoracic regions of five pigs using a paramedian approach.
  
  
  RESULTS
  A side-looking SSOCT is constructed to create a visual image of the underlying structures. The image criteria for the identification of the epidural space from the outside region were generated by the analysis of a training set (n = 100) of ex vivo data. The SSOCT image criteria for in vivo epidural space identification are high sensitivity (0.867 to 0.965) and high specificity (0.838 to 0.935). The mean value of the average signal intensities exhibits statistically significant differences (P < 0.01) and a high discriminatory capacity (area under curve = 0.88) between the epidural space and the outside tissues.
  
  
  CONCLUSIONS
  This is the first study to introduce a SSOCT fiber probe embedded in a standard epidural needle. The authors anticipate that this technique will reduce the occurrence of failed epidural blocks and other complications such as dural punctures.
authors.affiliation: From the Institute of Biophotonics (W.-C.K., M.-C.K.), Biophotonics and Molecular Imaging Research Center (W.-C.K.), National Yang-Ming University, Taipei, Taiwan; and Department of Anesthesiology, Taipei Veterans General Hospital and School of Medicine (W.-N.T., M.-Y.T., C.-K.T.), and Institute of Bioengineering (W.-N.T., Y.C.), National Yang-Ming University, Taipei, Taiwan.
authors.forename: Wen-Chuan
authors.initials: WC
authors.lastname: Kuo
authors.forename: Meng-Chun
authors.initials: MC
authors.lastname: Kao
authors.forename: Kuang-Yi
authors.initials: KY
authors.lastname: Chang
authors.forename: Wei-Nung
authors.initials: WN
authors.lastname: Teng
authors.forename: Mei-Yung
authors.initials: MY
authors.lastname: Tsou
authors.forename: Yin
authors.initials: Y
authors.lastname: Chang
authors.forename: Chien-Kun
authors.initials: CK
authors.lastname: Ting
mesh_terms: D000818:Animals; D004824:Epidural Space / Q000000981:diagnostic imaging*; D005336:Fiber Optic Technology / Q000295:instrumentation / Q000379:methods*; D009339:Needles; D055100:Optical Fibers; D011859:Radiography; D013552:Swine; D041623:Tomography, Optical Coherence / Q000295:instrumentation / Q000379:methods*