The use of optical coherence tomography (OCT) as a monitoring tool in the growth of human fibroblasts cells in collagen-based constructs is investigated. Rat-tail tendon type-1 collagen based gels mixed with human fibroblasts were prepared and incubated. Fixed samples were then imaged using OCT, and subsequently cross-sectioned and analysed
microscopically. The concentration of cells in samples under different contraction dynamics was investigated using analysis of the OCT images. Results show clear differences in scattering intensity as a consequence of cell concentration in both OCT images and micrographs.
The ability to delineate structural information in medical images is important for accurate diagnoses and will often depend on how the image is presented. Various methods of signal and image processing have been explored to improve this process across a wide range of medical imaging techniques. We present the application of chromatic analysis, a measurement technique developed for colorimetry applications, for signal processing of optical coherence tomography (OCT) images in human tissue. In particular, specific characteristics in the optical signal relating to various structural features are identified using chromatic filters and this information is used to process the OCT image. The technique was developed using mathematically simulated OCT signals and the applied to experimental OCT images of human tissue biopsy samples of the oesophagus. In the processed images, reflecting surfaces are highlighted and background noise is reduced to improve image interpretation.
In conventional optical coherence tomography (OCT) the resolution of the image is dependant on the spectral width and center wavelength of the light source. We investigate whether the application of chromatic analysis techniques and Gaussian peak fitting can provide an improved resolution to OCT images. OCT signals were simulated mathematically and analyzed to observe interference effects in the signal when considering two surfaces separated by less than the coherence length of the source. Chromatic analysis was then applied to identify the component interferograms within the signal. The peaks of these component interferograms were then found by fitting Gaussian peaks to the signal. Images of air wedges and onion slices were analyzed and improved resolution was shown in both cases. This work shows the potential for the use of chromatic techniques in improving the resolution of OCT images in tissue.
Virtual environment technologies, such as helmet-mounted displays (HMDs), are challenged by problems involving time delay--the time between an input to a system, and its corresponding output. An experiment was conducted to evaluate two methods of time delay compensation--algorithmic prediction and perceptual adaptation--during a time-delayed, head- slaved tracking task using an HMD. Predictive algorithms attempt to compensate for time delays by predicting future head position in order to update images effectively in the HMD. Perceptual adaptation refers to the ability of humans to adapt to the time delay by modifying their tracking strategies. Subjects were assigned to either a perceptual adaptation or algorithmic prediction condition, and participated in four experimental sessions during which they attempted to center a reticle over a moving circular target using a HMD. Tracking performance was evaluated in terms of RMS error, and the adequacy of the adaptation and prediction solutions was evaluated by several comparisons of tracking efficiency within and between sessions. Results indicated that the algorithmic prediction solution was superior to the perceptual adaptation solution for compensating for the effects of time delay in a head-slaved tracking task.