title: Ultra-Short-Term Reproducibility of Speckle-Noise Freed Fluid and Tissue Compartmentalization of the Choroid Analyzed by Standard OCT.
abstract: OBJECTIVE
  We measured reproducibility of speckle-noise freed fluid and tissue compartmentalization of the choroid (choroidal angiography and tissue characterization).
  
  
  METHODS
  This study included 26 eyes of 13 healthy females: 13 were used for repeated measurements and 13 were used for side comparison. A semiautomated algorithm removed speckle-noise with structure preservation.
  
  
  RESULTS
  Intraclass correlation (ICC), with respect to reproducibility of the method, showed an ICC for choroidal fluid inner space analysis (FISA) of 95.15% (90.01-98.24). The ICC of tissue inner space analysis (TISA) was 99.75% (99.47-99.91). The total choroid ratio (TCR), calculated from volumes of tissue to vessels, showed an ICC of 88.84% (78.28-95.82). Comparison of eyes (left to right) showed a difference for FISA of 0.033 (95% confidence interval [CI] -0.0018-0.0680,P= 0.063), TISA -0.118 (CI -0.2373-0.0023,P= 0.055), and TCR -0.590 (CI -0.9047 to -0.2754,P= 0.004). The ICC for FISA and TISA showed a trend in the difference comparing left and right eyes; however, TCR showed a significant difference between the eyes in the measured area (P< 0.001). Mean overall FISA was 0.58 mm3(range, 0.25-0.98 mm3, SD = 0.14). Mean TISA was 3.45 mm3(range, 2.38-5.0 mm3, SD 0.072). Mean TCR was 6.13 (overall range, 3.93-10.2, SD = 1.34).
  
  
  CONCLUSIONS
  Differences in choroidal layers between subjects were found mainly due to alterations in choroidal tissue. Reproducibility of speckle-noise freed choroidal angiography appeared excellent.
  
  
  CONCLUSIONS
  Speckle noise is a granular "noise" that appears in a wide range of medical imaging methods as ultrasonography, magnetic resonance, computer tomography, or optical coherence tomography (OCT). Findings from basic science about speckle noise were translated into a novel, medical image postprocessing application that can separate signal from speckle noise with structure preservation with high reproducibility and enhance medical imaging.
authors.affiliation: Department of Ophthalmology, University of Basel, Basel, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Maloca
authors.affiliation: Department of Ophthalmology, University of Basel, Basel, Switzerland.
authors.forename: Cyrill
authors.initials: C
authors.lastname: Gyger
authors.affiliation: Department of Biomedical Statistics, University of Basel, Basel, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Schoetzau
authors.affiliation: Department of Ophthalmology, University of Basel, Basel, Switzerland.
authors.forename: Pascal W
authors.initials: PW
authors.lastname: Hasler
keywords: angiography; choroid; imaging; optical coherence tomography; speckle noise; tissue