title: Optical coherence tomography in the diagnosis of actinic keratosis-A systematic review.
abstract: BACKGROUND
  Optical coherence tomography (OCT) is a real-time non-invasive imaging tool, introduced in dermatology in the late 1990s. OCT uses near-infrared light impulses to produce images which can be displayed in cross-sectional and en-face mode. The technique has been used to image skin diseases especially non-melanoma skin cancer including actinic keratosis (AK). Morphological characteristics of AK can be visualized in OCT images and can be used for diagnosis as well as disease monitoring.
  
  
  METHODS
  A systematic review of original papers on AK and OCT was performed on 31.03.16 and 24.10.16 in the major databases Pubmed, MEDLINE, EMBASE, Cochrane and Svemed. Through database search and other sources, we identified 1366 titles of which 21 studies met the inclusion criteria and were used for further investigation.
  
  
  RESULTS
  16/16 Conventional OCT (cross-sectional images) studies described disruption of layers consistent with absence of normal layered architecture in the skin. Thickened epidermis was found in 14/16 studies and white (hyperreflective) streaks and dots were described in 11/16 studies. In High-definition optical coherence tomography (HD-OCT) images disarranged epidermis (cross-sectional images) along with an atypical honeycomb pattern (en-face images) was found in 5/5 studies and well-demarcated dermo-epithelial junction (DEJ) (cross-sectional images) was described in 3/5 studies.
  
  
  CONCLUSIONS
  Several morphological characteristics of AKs were identified using Conventional OCT and HD-OCT. It is suggested that these may be used in the diagnosis of AK. Additional validation is however required to establish consensus on the optimal diagnostic criteria.
authors.affiliation: Department of Dermatology, Zealand University Hospital, Roskilde, Denmark; Health Sciences Faculty, University of Copenhagen, Denmark. Electronic address: kebf@regionsjaelland.dk.
authors.forename: K B E
authors.initials: KBE
authors.lastname: Friis
authors.affiliation: Department of Dermatology, Zealand University Hospital, Roskilde, Denmark; Health Sciences Faculty, University of Copenhagen, Denmark.
authors.forename: L
authors.initials: L
authors.lastname: Themstrup
authors.affiliation: Department of Dermatology, Zealand University Hospital, Roskilde, Denmark; Health Sciences Faculty, University of Copenhagen, Denmark.
authors.forename: G B E
authors.initials: GBE
authors.lastname: Jemec
mesh_terms: D019317:Evidence-Based Medicine; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D055623:Keratosis, Actinic / Q000000981:diagnostic imaging* / Q000473:pathology*; D015995:Prevalence; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012867:Skin / Q000000981:diagnostic imaging* / Q000473:pathology*; D041623:Tomography, Optical Coherence / Q000379:methods*
keywords: Actinic keratosis; Dermatology; High-definition optical coherence tomography; Non-invasive imaging; Non-melanoma skin cancer; Optical coherence tomography