  We apply three optical coherence tomography (OCT) image analysis techniques
to extract morphometric information from OCT images obtained on peripheral
nerves of rat. The accuracy of each technique is evaluated against histological
measurements accurate to +/-1 um. The three OCT techniques are: 1) average
depth resolved profile (ADRP); 2) autoregressive spectral estimation (AR-SE);
and, 3) correlation of the derivative spectral estimation (CoD-SE). We
introduce a scanning window to the ADRP technique which provides transverse
resolution, and improves epineurium thickness estimates - with the number of
analysed images showing agreement with histology increasing from 2/10 to 5/10
(Kruskal-Wallis test, {\alpha} = 0.05). A new method of estimating epineurium
thickness, using the AR-SE technique, showed agreement with histology in 6/10
analysed images (Kruskal-Wallis test, {\alpha} = 0.05). Using a tissue sample
in which histology identified two fascicles with an estimated difference in
mean fibre diameter of 4 um, the AR-SE and CoD-SE techniques both correctly
identified the fascicle with larger fibre diameter distribution but incorrectly
estimated the magnitude of this difference as 0.5um. The ability of OCT signal
analysis techniques to extract accurate morphometric details from peripheral
nerve is promising but restricted in depth by scattering in adipose and neural
tissues.

Tissues and Organs