Greater understanding of tympanic membrane (TM) biomechanics has the potential to guide future advances in medical
technology related to its surgical repair (myringoplasty). The pars tensa of the TM is a composite structure with two
collagen fiber layers that provide the main scaffolding for the TM. The external layer is arranged in an approximately
radial configuration, and the other is arranged in an approximately circumferential configuration. A more detailed
knowledge of collagen fiber orientation and volume fraction could greatly improve existing mechanical simulations of
the TM. To address this, we employed multiphoton microscopy (MPM) imaging of the TM in two modalities: second
harmonic generation (SHG) and two-photon fluorescence (TPF). The unique spectral signature of SHG allows selective
imaging of collagen fibers. TPF also produces images of fibrillar-type collagen but lacks the specificity of SHG. Both
the SHG and TPF images show patterns of collagen organization in the TM that match expected results with respect to
both orientation and size. Through MPM, we intend to accurately determine the collagen fiber layer thickness, density,
and orientation as a function of radial position and quadrant location.
Optical coherence tomography (OCT) is an evolving noninvasive imaging modality and has been used to image the larynx during surgical endoscopy. The design of an OCT sampling device capable of capturing images of the human larynx during a typical office based laryngoscopy examination is discussed. Both patient's and physician's movements were addressed. In vivo OCT imaging of the human larynx is demonstrated. Though the long focal length limits the lateral resolution of the image, the basement membrane can still be readily distinguished. Office-based OCT has the potential to guide surgical biopsies, direct therapy, and monitor disease. This is a promising imaging modality to study the larynx.
Stenotic, collapsed, and flow-restricted tracheal airways may result from blunt trauma, chronic infection, and the prolonged endotracheal intubation. This pilot investigation characterizes the degree of shape change produced by Ho:YAG laser (λ=2.12 μm) irradiation of rabbit and pig trachea tissue as a function of laser dosimetry and application protocol. Force displacement curves were generated using fresh lagomorph and porcine tracheal cartilage rings secured in a modified single beam cantilever geometry. These specimens were then irradiated for varying amounts of time and power with the objective of straightening these curved specimens. The degree of shape change was documented photographically. Force and surface temperature were monitored. Confocal microscopy was then used in combination a vital staine (“live-dead assay”) to determine the level of viability of straightened cartilage for selected exposure time-power pairs. Laser Cartilage Reshaping of the trachea may provide a new method to treat severe tracheal injuries without the need for classic open surgical techniques. This pilot investigation is the first step toward demonstrating the feasibility of this technique. Long-term, the design of stents combined with laser irradiation may provide a means to alter tracheal shape.