title: Inter-device size variation of small choroidal nevi measured using stereographic projection ultra-widefield imaging and optical coherence tomography.
abstract: OBJECTIVE
  Our purpose was to compare the tumor sizes of small choroidal nevi using ultra-widefield imaging (UWF) and different optical coherence tomography systems.
  
  
  METHODS
  Thirteen choroidal nevi were measured using automatic and manual segmentation techniques, including enhanced depth imaging spectral-domain optical coherence tomography (EDI-SDOCT) and 1050 nm swept source OCT (SSOCT), to compare to measurements obtained using the Optos projection ultra-widefield fundus (UWF) imaging technique. Segmentation artifacts were evaluated for all 13 cases, alongside an additional 12 choroidal nevi, using SSOCT.
  
  
  RESULTS
  In tumor eyes, segmentation artifacts for the choroid-sclera interface were found in 42 % of SSOCT scans. EDI-SDOCT can underestimate tumor dimensions and differs up to -8.41 % compared to UWF imaging and by 1.25 % compared to SSOCT cases. The horizontal length of the nevi showed an average difference between EDI-SDOCT and SSOCT of ± 9.38 %. Measured markers showed an average difference in length of ± 12.51 %. The average tumor thickness showed a difference of ± 11.47 %. Comparisons between EDI-SDOCT/UWF, SSOCT/EDI-SDOCT, and marker EDI-SDOCT/SSOCT showed significant mean differences of -122 μm (CI: -212 to -31 μm, p = 0.013), 134 μm (CI: 65-203 μm, p = 0.0012), and -193 μm (CI: -345 to -41 μm, p = 0.017), whereas SSOCT/UWF showed no significant difference with a measurement of 13 μm (CI: -69-95 μm, p = 0.74).
  
  
  CONCLUSIONS
  Automatic segmentation of nevi requires much caution, because a choroidal tumor can trigger many artifacts. It would be beneficial to monitor choroidal nevi using the same type of OCT technology, because a tumor is displayed differently.
authors.affiliation: Department of Ophthalmology, OCTlab, University of Basel, Mittlere Strasse 91, CH-4056, Basel, Switzerland. info@dr-maloca.ch.
authors.forename: Peter
authors.initials: P
authors.lastname: Maloca
authors.affiliation: Department of Ophthalmology, OCTlab, University of Basel, Mittlere Strasse 91, CH-4056, Basel, Switzerland.
authors.forename: Cyrill
authors.initials: C
authors.lastname: Gyger
authors.affiliation: Department of Ophthalmology, OCTlab, University of Basel, Mittlere Strasse 91, CH-4056, Basel, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Schoetzau
authors.affiliation: Department of Ophthalmology, OCTlab, University of Basel, Mittlere Strasse 91, CH-4056, Basel, Switzerland.
authors.forename: Pascal W
authors.initials: PW
authors.lastname: Hasler
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002830:Choroid Neoplasms / Q000473:pathology*; D003952:Diagnostic Imaging; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D009508:Nevus, Pigmented / Q000473:pathology*; D015588:Observer Variation; D041623:Tomography, Optical Coherence
keywords: Choroid; Nevus; Optical coherence tomography; Widefield imaging