Beside the good image quality with the confocal laser scanning microscope (HRTII) and the Rostock Cornea Module
(RCM), this technology can not be used to investigate the human larynx in vivo. To accomplish this, a rigid custom-made
endoscope (KARL STORZ GmbH & Co. KG; Tuttlingen Germany) was developed. A connector was developed to
connect the scanner head of the HRTII to the rigid endoscope. With the connector, the starting plane can be set manually.
To achieve optical sectioning of the laryngeal tissue (80 μm per volume scan), the scanning mechanism of the HRTII
needs to be activated using a foot switch. The devices consisting of the endoscope, HRTII, and the connector supply
images of 400 x 400 μm and reach average penetration depths of 100-300 μm (λ/4 plate of the scanner head of the
HRTII was removed). The lateral and axial resolutions are about 1-2 μm and 2 μm, respectively. In vivo rigid confocal
endoscopy is demonstrated with an acquisition time for a volume scan of 6 s. The aim of this study was to differentiate
pre-malignant laryngeal lesions from micro-invasive carcinoma of the larynx. 22 patients with suspicious lesions of the
true vocal cords were included. This pilot study clearly demonstrates the possibility to detect dysplastic cells close to the
basal cell layer and within the subepithelial space in lesions with small leukoplakia (thin keratin layer). These findings
may have an impact on microlaryngoscopy to improve the precision for biopsy and on microlaryngoscopic laser surgery
of the larynx to identify the margins of the pre-malignant lesion.
Early detection of cancerous lesions of the larynx may be the best method of improving patient quality of life and
survival rates. New in-vivo technologies may be of great clinical relevance in improving the accuracy of sampling during
microlaryngeal surgery. Optical coherence tomography (OCT) is an optical imaging technique that clearly identifies
basement membrane violation caused by laryngeal cancer. With a microscope-based spectral domain OCT (SD-OCT) we
reached in vivo a fairly accurate assessment of benign and dysplastic laryngeal lesions.
Recent improvements in OCT technology have led to the development of high-speed OCT systems displaying millions
of pixels per second. These systems allow non-contact real-time imaging of large sections of laryngeal tissue.
Polarization contrast OCT (PS-OCT) may provide additional information about the lamina propria of the true vocal cord
because of the birefringence of connective tissue.
We present microscope-based high-speed SD-OCT images with and without polarization contrast and 3D volumes of
selected laryngeal pathologies in order to demonstrate our current concepts for the intended intraoperative application.
High-speed SD-OCT and polarization contrast can also be complemented by our recently developed rigid confocal
endoscopic system to obtain cellular and sub-cellular information about the tissue. Further perspectives will be
An optical coherence tomography study for imaging the round window niche and the promontorium tympani
Tympanosclerosis may involve the tympanic membrane, the ossicles, and the oval and round window niche,
respectively. The surgical treatment of the obliterated oval window niche is most challenging. Beside stapesplasty,
vibroplasty coupling the floating mass transducer (FMT) onto the round window niche and into a new, so-called third
window is indicated. In the latter situation, drilling a hole into the promontorium is necessary to couple the FMT close to
the membranous endosteum. Damage of the membranous inner ear must be avoided. The question was whether OCT is
useful to identify the endosteum and to provide microanatomical information of the round window niche. OCT was
carried out on human temporal bone preparations, in which a third window was drilled leaving the membranous labyrinth
and the fluid-filled inner ear intact and the overhang of the round window niche was removed. An especially equipped
operating microscope with integrated OCT prototype (spectral-domain-OCT) was used. The OCT images and 3D
reconstructions demonstrate the usefulness of OCT to measure the drilling cavity, to visualize the inner ear structures,
and to obtain microanatomical information of the round and oval window niche. These findings may have an impact on
stapes surgery, on cochlea implantation, and on vibroplasty coupling the FMT onto the round and third window. OCTguided
drilling allows for more precise identification of the intact inner ear.
To assess the potential use of optical coherence tomography (OCT) in cochlear implant surgery, OCT was applied in human temporal bones before cochleostomy. The question was whether OCT might provide information about the cochlear topography, especially about the site of the scala tympani. OCT was carried out on human temporal bone preparations, in which the cochleostomy was performed leaving the membranous labyrinth and the fluid-filled inner ear intact. A specially equipped operating microscope with integrated OCT prototype was used. Spectral-domain (SD)-OCT was used for all investigations. On all scans, OCT supplied information about inner ear structures, such as scala tympani, scala vestibuli while the membranous labyrinth was still intact. In the fresh temporal bone the scala media, basilar membrane and the Reissner's membrane were identified. This OCT study clearly documents the possibility to identify inner ear structures, especially the scala tympani without opening its enveloping membranes. These findings may have an impact on cochlear implant surgery, especially as an orientation guide to localize the scala tympani precisely before opening the fluid filled inner ear.