title: Optical coherence tomography as a method to identify parathyroid glands.
abstract: OBJECTIVE
  The identification of parathyroid glands can be a major problem in parathyroid surgery. The purpose of this study was to evaluate the feasibility of optical coherence tomography (OCT) in distinguishing between parathyroid tissue, thyroid tissue, lymph nodes, and adipose tissue.
  
  
  METHODS
  Ex vivo OCT images as well as histological sections were generated from parathyroid glands, thyroid tissue, lymph nodes and fat in order to define significant morphologic differences between these entities. As a second step all OCT images were separately evaluated by two blinded investigators and later compared to the corresponding histology. Sensitivity and specificity of OCT in distinguishing between the different tissues were determined. To assess the interobserver agreement, κ coefficients were calculated from the ratings of each investigator for each OCT image seen.
  
  
  RESULTS
  A total of 320 OCT images from 32 patients undergoing thyroid surgery, parathyroidectomy or lymphadenectomy were compared with the corresponding histology. The sensitivity and specificity in distinguishing parathyroid tissue from the other entities was 84% (second investigator: 82%) and 94% (93%) respectively. Unweighted κ using four diagnostic categories was 0.97 (95% CI, 0.94-0.99) showing substantial agreement between both investigators.
  
  
  CONCLUSIONS
  OCT is highly sensitive in distinguishing between parathyroid tissue, thyroid tissue, lymph nodes and adipose tissue. These ex vivo results should be confirmed by using OCT imaging intraoperatively.
authors.affiliation: Department of Surgery, Ludwig Maximilians University Munich, Innenstadt Medical Campus, Nussbaumstrasse 20, 80336, Munich, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Ladurner
authors.forename: Klaus K J
authors.initials: KK
authors.lastname: Hallfeldt
authors.forename: Norah
authors.initials: N
authors.lastname: Al Arabi
authors.forename: Herbert
authors.initials: H
authors.lastname: Stepp
authors.forename: Susanna
authors.initials: S
authors.lastname: Mueller
authors.forename: Julia K S
authors.initials: JK
authors.lastname: Gallwas
mesh_terms: D000273:Adipose Tissue; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008198:Lymph Nodes; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010280:Parathyroid Glands; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D013961:Thyroid Gland; D041623:Tomography, Optical Coherence; D055815:Young Adult
keywords: OCT; parathyroid gland; parathyroid surgery