Feature Of The Week 12/4/11: Researchers in Hannover Germany Utilize OCT to Measure Skin Swelling Along Percutaneous Implants
Researchers from the Leibniz University of Hannover (LUH), Laser Zentrum Hannover (LZH), and the Hannover Medical School (MHH) used OCT to measure skin swelling along percutaneous implants. An undistortion technique is proposed to compensate for the refractive distortions .
Optical Coherence Tomography is a non invasive imaging modality recently used for taking high resolution optical biopsies of layered tissue structures such as the epidermis and the retina.
As the OCT system captures optical distances rather than geometrical distances, the optical properties of the tissue introduce distortions into the OCT images. Therefore, model based image undistortion is an important step for further image processing.
Here, OCT was applied in an animal study enabling high resolution repetitive biopsies at one animal at different time points instead of lethal biopsies at different animals at each time point. The particular objective of this study is the morphometric analysis of the skin adjacent to a percutaneous implant situated in the lateral abdominal region of a hairless but immunocompetent mouse to draw conclusions on its biocompatibility.
This paper proposes an approach for fully automatic segmentation of high resolution 3D Fourier-domain OCT and refractive undistortion. The determination of the refractive index is facilitated by the geometry of the implant which consists of a percutaneous pin (3mm diameter and 5mm length) anchored beneath the dermis by a flat disc shaped base which is visible in OCT.
Estimation of the skin surface in the 3D space from several OCT B-scans is done using a Markov random field approach. The distorted implant base is segmented using a refractive distortion model and the previously segmented skin surface for parameter estimation in order to match the distorted implant base best to the a priori known shape of the undistorted base contour. The segmented model is finally used for refractive image undistortion.
Several experiments including model verification on a gluedrop phantom and a quantitative evaluation of our algorithm compared to manual segmentation by experts are done (see slides).
For more information, please see our Project Page and recent publications below [1, 2]. Courtsey Oliver Muller.
 Müller et al., “Model Based 3D Segmentation and OCT Image Undistortion of Percutaneous Implants”, MICCAI 2011, Lecture Notes in Computer Science (LNCS), Springer Berlin / Heidelberg, 6893, 454-462 (2011).
 Donner et al., "In vivo optical coherence tomography of percutaneous implants in hairless mice", Proc. SPIE 7554, 75540S (2010).