Endoscopic measurement of nasal septum perforations.

BACKGROUND: Nasal septum perforations (NSP) have many uncomfortable symptoms for the patient and a highly negative impact on quality of life. NSPs are closed using patient-specific implants or surgery. Implants are created either under anesthesia using silicone impressions or using 3D models from CT data. Disadvantages for patient safety are the increased risk of morbidity or radiation exposure. MATERIALS AND METHODS: In the context of otorhinolaryngologic surgery, we present a gentle approach to treating NSP with a new image-based, contactless, and radiation-free measurement method using a 3D endoscope. The method relies on image information only and makes use of real-time capable computer vision algorithms to compute 3D information. This endoscopic method can be repeated as often as desired in the clinical course and has already proven its accuracy and robustness for robotic-assisted surgery (RAS) and surgical microscopy. We expand our method for nasal surgery, as there are additional spatial and stereoperspective challenges. RESULTS: After measuring 3 relevant parameters (NSP extension: axial, coronal, and NSP circumference) of 6 patients and comparing the results of 2 stereoendoscopes with CT data, it was shown that the image-based measurements can achieve comparable accuracies to CT data. One patient could be only partially evaluated because the NSP was larger than the endoscopic field of view. CONCLUSION: Based on the very good measurements, we outline a therapeutic procedure which should enable the production of patient-specific NSP implants based on endoscopic data only.

[Endoscopic measurement of nasal septum perforations. German version]. / Endoskopische Vermessung von Nasenseptumdefekten.

BACKGROUND: Nasal septum perforations (NSP) have many uncomfortable symptoms for the patient and a highly negative impact on quality of life. NSPs are closed using patient-specific implants or surgery. Implants are created either under anesthesia using silicone impressions or using 3D models from CT data. Disadvantages for patient safety are the increased risk of morbidity or radiation exposure. MATERIALS AND METHODS: In the context of otorhinolaryngologic surgery, we present a gentle approach to treating NSP with a new image-based, contactless, and radiation-free measurement method using a 3D endoscope. The method relies on image information only and makes use of real-time capable computer vision algorithms to compute 3D information. This endoscopic method can be repeated as often as desired in the clinical course and has already proven its accuracy and robustness for robotic-assisted surgery (RAS) and surgical microscopy. We expand our method for nasal surgery, as there are additional spatial and stereoperspective challenges. RESULTS: After measuring 3 relevant parameters (NSP extension: axial, coronal, and NSP circumference) of 6 patients and comparing the results of 2 stereoendoscopes with CT data, it was shown that the image-based measurements can achieve comparable accuracies to CT data. One patient could be only partially evaluated because the NSP was larger than the endoscopic field of view. CONCLUSION: Based on the very good measurements, we outline a therapeutic procedure which should enable the production of patient-specific NSP implants based on endoscopic data only.

Evaluating the didactic value of 3D visualization in otosurgery.

INTRODUCTION: Improvements of surgical visualization add value to the quality of clinical routine and offer the opportunity to improve surgical education of medical staff. The aim of this study was to determine whether otorhinolaryngology trainees gain additional comprehension of the anatomical structures and the surgical site when 3D visualization is used. METHODS: Data were collected from ENT trainees of microsurgical courses of the middle ear, inner ear and lateral skull base at four university ENT departments (Charité (Berlin), Martin Luther University Halle-Wittenberg (Halle/Saale), Ludwig Maximilian University (Munich) and Rostock University Medical Center). Participants were asked to complete a questionnaire assessing the subjective value of identical surgical field visualization in 3D for surgeon and observer. RESULTS: A total of 112 participants completed the questionnaire. The majority of participants stated a high additional value of 3D visualization compared to 2D visualization, with 75% fully agreeing to the statement that 3D visualization of the surgical field is superior to perceive the anatomical topography and structures compared to 2D representation. Participants encouraged the storage of data in online learning platforms. CONCLUSION: The results show that 3D visualization with identical imaging for surgeon and observer is a useful tool in teaching of microsurgery. It addresses perception of anatomical topography and structures as well as conception of the surgical workflow.

Surgical Guidance for Removal of Cholesteatoma Using a Multispectral 3D-Endoscope.

We develop a stereo-multispectral endoscopic prototype in which a filter-wheel is used for surgical guidance to remove cholesteatoma tissue in the middle ear. Cholesteatoma is a destructive proliferating tissue. The only treatment for this disease is surgery. Removal is a very demanding task, even for experienced surgeons. It is very difficult to distinguish between bone and cholesteatoma. In addition, it can even reoccur if not all tissue particles of the cholesteatoma are removed, which leads to undesirable follow-up operations. Therefore, we propose an image-based method that combines multispectral tissue classification and 3D reconstruction to identify all parts of the removed tissue and determine their metric dimensions intraoperatively. The designed multispectral filter-wheel 3D-endoscope prototype can switch between narrow-band spectral and broad-band white illumination, which is technically evaluated in terms of optical system properties. Further, it is tested and evaluated on three patients. The wavelengths 400 nm and 420 nm are identified as most suitable for the differentiation task. The stereoscopic image acquisition allows accurate 3D surface reconstruction of the enhanced image information. The first results are promising, as the cholesteatoma can be easily highlighted, correctly identified, and visualized as a true-to-scale 3D model showing the patient-specific anatomy.

Influence of Airflow Rate and Stimulus Concentration on Olfactory Event-Related Potentials (OERP) in Humans.

Although the association between odor concentration and olfactory event-related potential (OERP) has been studied, less is known about the influence of airflow on OERP. The aim of this study was to investigate the influence of airflow rate and stimulus concentration on OERP in humans. Electroencephalogram data were collected from young healthy volunteers (n = 17) in separate sessions where 2-phenylethanol (PEA) was delivered in the following conditions: 8 L/min 50% v/v, 8 L/min 30% v/v, 4 L/min 100% v/v, and 4 L/min 60%v/v. Odor concentrations are referred to the %v/v achieved with air dilution and was not measured in the nose. Odor intensity ratings were recorded immediately after stimulus presentation. Data recorded at 5 electrodes (Fz, Cz, Pz, C3, and C4) were pooled and analyzed using both time-domain averaging and single-trial time-frequency domain approaches. Higher airflow rate significantly increased intensity ratings (F = 10.98, P < 0.01), and improved the signal-to-noise-ratio (F = 5.42, P = 0.025). Results from time-frequency analysis showed higher concentration versus lower concentration increased brain oscillations in the slow frequency band (1-3 Hz) at 0-600 ms; while higher airflow rates versus lower airflow rate increased theta-band oscillations (300-600 ms and 5-9 Hz) and decreased delta-band oscillations at 900-1500 ms after stimulus onset. In conclusion, compared to stimulus concentration, airflow rate was associated with improved OERP quality and more pronounced responses. The results suggest that intensity ratings and OERP are strongly related to the steepness of stimulus onset. High airflow rates are suggested for odor delivery in order to record OERP.

Duration of deafness impacts auditory performance after cochlear implantation: A meta-analysis.

OBJECTIVE: Hearing loss is a highly disabling condition. Cochlear implantation is an established remedy if conventional hearing aids have failed to alleviate the level of disability. Unfortunately, cochlear implant (CI) performance varies dramatically. This study aims to examine the effects of duration of deafness (DoD) prior to cochlear implantation and the postoperative duration of implant experience with resulting hearing performance in postlingually deaf patients. METHODS: A systematic literature review and two meta-analyses were conducted using the search terms cochlear implant AND duration deafness. Included studies evaluate the correlation between the DoD and auditory performance after cochlear implantation using monosyllabic and sentence tests. Correlation coefficients were determined using Pearson's correlation and Spearman rho. RESULTS: A total of 36 studies were identified and included data on cochlear implantations following postlingual deafness and postoperative speech testing of hearing outcomes for 1802 patients. The mean age ranged from 44 to 68 years with a DoD of 0.1 to 77 years. Cochlear implant use varied from 3 months to 14 years of age. Speech perception, which was assessed by sentence and monosyllabic word perception, was negatively correlated with DoD. Subgroup analyses revealed worse outcomes for longer DoD and shorter postoperative follow-up. CONCLUSION: DoD is one of the most important factors to predict speech perception after cochlear implantation in postlingually deaf patients. The meta-analyses revealed a negative correlation between length of auditory deprivation and postoperative sentence and monosyllabic speech perception. Longer DoD seems to lead to worse CI performance, whereas more experience with CI mitigates the effect.

Validation of two techniques for intraoperative hyperspectral human tissue determination.

Purpose: Hyperspectral imaging (HSI) is a non-contact optical imaging technique with the potential to serve as an intraoperative computer-aided diagnostic tool. Our work analyzes the optical properties of visible structures in the surgical field for automatic tissue categorization. Approach: Building an HSI-based computer-aided tissue analysis system requires accurate ground truth and validation of optical soft tissue properties as these show large variability. We introduce and validate two different hyperspectral intraoperative imaging setups and their use for the analysis of optical tissue properties. First, we present an improved multispectral filter-wheel setup integrated into a fully digital microscope. Second, we present a novel setup of two hyperspectral snapshot cameras for intraoperative usage. Both setups are operating in the spectral range of 400 up to 975 nm. They are calibrated and validated using the same database and calibration set. Results: For validation, a color chart with 18 well-defined color spectra in the visual range is analyzed. Thus the results acquired with both settings become transferable and comparable to each other as well as between different interventions. On patient data of two different otorhinolaryngology procedures, we analyze the optical behaviors of different soft tissues and show a visualization of such different spectral information. Conclusion: The introduced calibration pipeline for different HSI setups allows comparison between all acquired spectral information. Clinical in vivo data underline the potential of HSI as an intraoperative diagnostic tool and the clinical usability of both introduced setups. Thereby, we demonstrate their feasibility for the in vivo analysis and categorization of different human soft tissues.

Determination of the optical properties of cholesteatoma in the spectral range of 250 to 800 nm.

Cholesteatoma of the ear can lead to life-threatening complications and its only treatment is surgery. The smallest remnants of cholesteatoma can lead to recurrence of this disease. Therefore, the optical properties of this tissue are of high importance to identify and remove all cholesteatoma during therapy. In this paper, we determine the absorption coefficient µ a and scattering coefficient µ s ' of cholesteatoma and bone samples in the wavelength range of 250 nm to 800 nm obtained during five surgeries. These values are determined by high precision integrating sphere measurements in combination with an optimized inverse Monte Carlo simulation (iMCS). To conserve the optical behavior of living tissues, the optical spectroscopy measurements are performed immediately after tissue removal and preparation. It is shown that in the near-UV and visible spectrum clear differences exist between cholesteatoma and bone tissue. While µ a is decreasing homogeneously for cholesteatoma, it retains at the high level for bone in the region of 350 nm to 580 nm. Further, the results for the cholesteatoma measurements correspond to published healthy epidermis data. These differences in the optical parameters reveal the future possibility to detect and identify, automatically or semi-automatically, cholesteatoma tissue for active treatment decisions during image-guided surgery leading to a better surgical outcome.

Determination of optical properties of human tissues obtained from parotidectomy in the spectral range of 250 to 800 nm.

The optical properties of human tissues are an important parameter in medical diagnostics and therapy. The knowledge of these parameters can encourage the development of automated, computer-driven optical tissue analysis methods. We determine the absorption coefficient µa and scattering coefficient µs' of different tissue types obtained during parotidectomy in the wavelength range of 250 to 800 nm. These values are determined by high precision integrating sphere measurements in combination with an optimized inverse Monte Carlo simulation. To conserve the optical behavior of living tissues, the optical spectroscopy measurements are performed immediately after tissue removal. Our study includes fresh samples of the ear, nose, and throat (ENT) region, as muscle tissue, nervous tissue, white adipose tissue, stromal tissue, parotid gland, and tumorous tissue of five patients. The measured behavior of adipose corresponds well with the literature, which sustains the applied method. It is shown that muscle is well supplied with blood as it features the same characteristic peaks at 430 and 555 nm in the absorption curve. The parameter µs' decreases for all tissue types above 570 nm. The accuracy is adequate for the purposes of providing µa and µs' of different human tissue types as muscle, fat, nerve, or gland tissue, which are embedded in large complex structures such as in the ENT area. It becomes possible for the first time to present reasonable results for the optical behavior of human soft tissue located in the ENT area and in the near-UV, visual, and near-infrared areas.

Olfactory and Gustatory Dysfunction in Patients With Autoimmune Encephalitis.

Objective: To test the hypothesis that olfactory (OF) and gustatory function (GF) is disturbed in patients with autoimmune encephalitides (AE). Methods: The orthonasal OF was tested in 32 patients with AE and 32 age- and sex-matched healthy controls (HC) with the standardized Threshold Discrimination Identification (TDI) score. This validated olfactory testing method yields individual scores for olfactory threshold (T), odor discrimination (D), and identification (I), along with a composite TDI score. The GF was determined by the Taste Strip Test (TST). Results: Overall, 24/32 (75%) of patients with AE, but none of 32 HC (p < 0.001) had olfactory dysfunction in TDI testing. The results of the threshold, discrimination and identification subtests were significantly reduced in patients with AE compared to HC (all p < 0.001). Assessed by TST, 5/19 (26.3%) of patients with AE, but none of 19 HC presented a significant limitation in GF (p < 0.001). The TDI score was correlated with the subjective estimation of the olfactory capacity on a visual analog scale (VAS; rs = 0.475, p = 0.008). Neither age, sex, modified Rankin Scale nor disease duration were associated with the composite TDI score. Conclusions: This is the first study investigating OF and GF in AE patients. According to unblinded assessment, patients with AE have a reduced olfactory and gustatory capacity compared to HC, suggesting that olfactory and gustatory dysfunction are hitherto unrecognized symptoms in AE. Further studies with larger number of AE patients would be of interest to verify our results.

Research platform for medical device development to simplify translation to the market.

New regulations for medical products complicate research projects for new application fields and translation of innovative product ideas to refundable medical products becomes a high economic risk. All this demands for a CE-marked platform, which offers the possibility to access the recorded data online or even directly the hardware during research applications, to bridge the gap. This paper describes how a CE-marked medical product can be extended by different interfaces to enable basic research or simplify first proof-of-concept studies thus optimizing prototype development in research projects, simplifying the documentation process and reducing the risk for market access.