Detection of esophageal disease in current clinical practice is limited to visualization of macroscopic epithelial morphology. In this work, we investigate high resolution autofluorescence imaging under ultra violet excitation to visualize microscopic epithelial changes related to disease progression using a bench top prototype microscope. The approach is based on the hypothesis that UV excitation light can only penetrate the superficial layer of cells resulting in autofluorescence images of the epithelial layer without using an additional image sectioning approach. The experiments were performed using ex vivo human esophagus biopsy specimens. The results indicate that cellular morphology information related to disease progression is attainable without tissue preparation.

The autofluorescence under ultraviolet excitation arising from normal squamous and columnar esophageal mucosa is investigated using multispectral microscopy. The results suggest that the autofluorescence signal arises from the superficial tissue layer due to the short penetration depth of the ultraviolet excitation. As a result, visualization of esophageal epithelial cells and their organization can be attained using wide-field autofluorescence microscopy. Our results show tryptophan to be the dominant source of emission under 266 nm excitation, while emission from NADH and collagen are dominant under 355 nm excitation. The analysis of multispectral microscopy images reveals that tryptophan offers the highest image contrast due to its non-uniform distribution in the sub-cellular matrix. This technique can simultaneously provide functional and structural imaging of the microstructure using only the intrinsic tissue fluorophores.

We report the diagnostic ability of ultraviolet (UV)-excited autofluorescence (AF) excitation-emission matrix (EEM) spectroscopy associated with parallel factor (PARAFAC) analysis for differentiating cancer from normal nasopharyngeal tissue. A bifurcated fiber-optic probe coupled with an EEM system was used to acquire tissue AF EEMs using excitation wavelengths between 260 and 400 nm, and emission collection between 280 and 500 nm. A total of 152 AF EEM landscapes were acquired from 13 normal and 16 nasopharyngeal carcinoma (NPC) thawed ex vivo tissue samples from 23 patients. PARAFAC was introduced for curve resolution of individual AF EEM landscapes associated with the endogenous tissue constituents. The significant factors were further fed to a support vector machine (SVM) and cross-validated to construct diagnostic algorithms. Both the EEM intensity landscapes and the PARAFAC model revealed tryptophan, collagen, and elastin to be the three major endogenous fluorophores responsible for the AF signal from normal and NPC tissues. The EEM intensity distribution and PARAFAC factors suggest an increase of tryptophan and a decrease of collagen and elastin in NPC tissues compared to the normal. The classification results obtained from the PARAFAC-SVM modeling yielded a diagnostic accuracy of 94.7% (sensitivity of 95.0% (76/80); specificity of 94.4% (68/72)) for normal and NPC tissue differentiation. This study suggests that UV-excited AF EEM spectroscopy integrated with PARAFAC algorithms has the potential to provide clinical diagnostics of early onset and progression of NPC.

Abstract:We investigate a microscope design that offers high signal sensitivity and hyperspectral imaging capabilities and allows for implementation of various optical imaging approaches while its operational complexity is minimized. This system utilizes long working distance microscope objectives that enable for off-axis illumination of the tissue thereby allowing for excitation at any optical wavelength and nearly eliminating spectral noise from the optical elements. Preliminary studies using human and animal tissues demonstrate the feasibility of this approach for real-time imaging of intact tissue microstructures using autofluorescence and light scattering imaging methods.2

-Objective: The purpose of this manuscript is to compute skin strain data from a flexed biological limb, using portable, inexpensive, and easily-available resources. Methods: We apply and evaluate this approach on a person with bi-lateral transtibial amputations, imaging left and right residual limbs in extended and flexed knee postures. We map 3D deformations to a flexed biological limb using freeware and a simple point-and-shoot camera. Mean principal strain, maximum shear strain, as well as lines of maximum, minimum, and non-extension are computed from 3D digital models to inform directional mappings of the strain field for an unloaded residual limb. Index Terms-skin strain, lines of non-extension, wearable technology.