title: Optical coherence tomography of actinic keratoses and basal cell carcinomas - differentiation by quantification of signal intensity and layer thickness.
abstract: BACKGROUND
  Previous studies have shown that actinic keratoses (AKs) and basal cell carcinomas (BCCs) can be diagnosed by optical coherence tomography (OCT) based on morphological characteristics. There is a lack of systematic studies that give standardized information on signal intensity and layer thickness of AKs and BCCs.
  
  
  OBJECTIVE
  The aim of this study was to find out if AKs and BCCs can be objectively diagnosed through standardized measurement of signal intensity and layer thickness and to use OCT as a non-invasive objective method for the diagnosis and evaluation of AKs and BCCs. Additionally, tumour and skin layer thickness were investigated in correlation with histology.
  
  
  METHODS
  In this experimental study, 301 lesions (188 BCCs and 113 AKs) of 125 patients were clinically as well as dermoscopically diagnosed and investigated with OCT before therapy. Normal perilesional skin served as control.
  
  
  RESULTS
  It is possible to differentiate BCCs and AKs from normal skin in OCT due to the decrease of local signal intensity in affected skin layers in relation to adjacent healthy skin. In AKs, a strong thickness increase of the stratum corneum and epidermis compared to normal skin were observed. For the distinction between AKs and BCCs, a drop of signal intensity in the dermis of AKs towards BCCs and a thicker epidermis of AKs in contrast to BCCs were registered. All results are statistically highly significant (P < 0.0001). Besides, a strong correlation of tumour and skin layer thickness of BCCs and AKs in OCT with histology was found.
  
  
  CONCLUSIONS
  Through standardized measurement of signal intensity and layer thickness, BCCs and AKs can be objectively diagnosed and distinguished from each other with OCT. This will further improve the use of OCT as a non-invasive objective method for the diagnosis and treatment monitoring of these diseases.
authors.affiliation: Department of Dermatology and Allergology, General Hospital Augsburg, Augsburg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Schuh
authors.affiliation: Department of Dermatology and Allergology, General Hospital Augsburg, Augsburg, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Kaestle
authors.affiliation: Department of Dermatology and Allergology, Ludwig-Maximilian University of Munich, Munich, Germany.
authors.forename: E C
authors.initials: EC
authors.lastname: Sattler
authors.affiliation: Department of Dermatology and Allergology, General Hospital Augsburg, Augsburg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Welzel
mesh_terms: D002280:Basal Cell Carcinoma / Q000175:diagnosis*; D006801:Humans; D055623:Keratosis, Actinic / Q000175:diagnosis*; D041623:Tomography, Optical Coherence / Q000379:methods*