4K Video-Laryngoscopy and Video-Stroboscopy: Preliminary Findings.

INTRODUCTION: 4K video is a new format. At 3840 × 2160 resolution, it has 4 times the resolution of standard 1080 high definition (HD) video. Magnification can be done without loss of resolution. This study uses 4K video for video-stroboscopy. MATERIAL AND METHOD: Forty-six patients were examined by conventional video-stroboscopy (digital 3 chip CCD) and compared with 4K video-stroboscopy. The video was recorded on a Blackmagic 4K cinema production camera in CinemaDNG RAW format. The video was played back on a 4K monitor and compared to standard video. Pathological conditions included: polyps, scar, cysts, cancer, sulcus, and nodules. RESULTS: Successful 4K video recordings were achieved in all subjects using a 70° rigid endoscope. The camera system is bulky. The examination is performed similarly to standard video-stroboscopy. Playback requires a 4K monitor. As expected, the images were far clearer in detail than standard video. Stroboscopy video using the 4K camera was consistently able to show more detail. Two patients had diagnosis change after 4K viewing. CONCLUSION: 4K video is an exciting new technology that can be applied to laryngoscopy. It allows for cinematic 4K quality recordings. Both continuous and stroboscopic light can be used for visualization. Its clinical utility is feasible, but usefulness must be proven.

Microscopic OCT imaging with focus extension by ultrahigh-speed acousto-optic tunable lens and stroboscopic illumination.

We develop high-resolution optical coherence tomography (OCT) system with high-speed acousto-optic tunable lens. Stroboscopic pulsed illumination is used for the first time to perform time-resolved OCT imaging with acousto-optic tunable focusing. The operation of ultrahigh-speed tunable acousto-optic lens is demonstrated theoretically and experimentally. Focal position tuning at MHz frequency range is experimentally shown in the imaging system leading to OCT images with extended depth of focus. Imaging with active optical elements is helpful for improvement of photon collection efficiency, depth of focus and enhancement of the image quality.

Optical lock-in particle tracking in optical tweezers.

We demonstrate a lock-in particle tracking scheme in optical tweezers based on stroboscopic modulation of an illuminating optical field. This scheme is found to evade low frequency noise sources while otherwise producing an equivalent position measurement to continuous measurement. This was demonstrated to yield up to 20 dB of noise suppression at both low frequencies (< 1 kHz), where low frequency electronic noise was significant, and around 630 kHz where laser relaxation oscillations introduced laser noise. The setup is simple, and compatible with any trapping optics.

Stroboscopic white-light interferometry of vibrating microstructures.

We describe a LED-based stroboscopic white-light interferometer and a data analysis method that allow mapping out-of-plane surface vibration fields in electrically excited microstructures with sub-nm amplitude resolution for vibration frequencies ranging up to tens of MHz. The data analysis, which is performed entirely in the frequency domain, makes use of the high resolution available in the measured interferometric phase data. For demonstration, we image the surface vibration fields in a square-plate silicon MEMS resonator for three vibration modes ranging in frequency between 3 and 14 MHz. The minimum detectable vibration amplitude in this case was less than 100 pm.

Imaging velocities of a vibrating object by stroboscopic sideband holography.

We propose here to combine sideband holography with stroboscopic illumination synchronized with the vibration of an object. By sweeping the optical frequency of the reference beam such a way the holographic detection is tuned on the successive sideband harmonic ranks, we are able to image the instantaneous velocities of the object. Since the stroboscopic illumination is made with an electronic device, the method is compatible with fast (up to several MHz) vibration motions. The method is demonstrated with a vibrating clarinet reed excited sinusoidally at 2 kHz, and a stroboscopic illumination with cyclic ratio 0.15. Harmonic rank up to n = ± 100 are detected, and a movie of the instantaneous velocities is reported.

[Stroboscopy findings: a comparison of flexible CCD-videostroboscopy and rigid stroboscopy]. / Stroboskopie-Befunde: Flexible CCD-Videostroboskopie und klassische Lupenstroboskopie im Vergleich.

OBJECTIVE: After exclusion of morphologic laryngeal alterations by laryngoscopy the prospective study compared stroboscopy findings using a flexible distal charge-coupled device chip-optic (CCD-optic) and a rigid 70° - or 90° -laryngoscope. MATERIAL AND METHODS: 52 patients with functional dysphonia and 47 candidates for speech therapy education were checked with both examination methods. The stroboscopy results were rated randomized and pseudonymized by 3 experts assessed by a study protocol according to the European laryngological society basic protocol 2001. RESULTS: The interrater-reliability was moderate to good. Using the flexible videolaryngoscopy less gaging, less supraglottic contraction during phonation, more often a complete glottal closure and more often a normal mucosal wave movement were found. CONCLUSION: To get an optimal endoscopy result the combination of rigid laryngoscopy and flexible videolaryngoscopy and -stroboscopy will be recommended. Because of the variety of stroboscopic findings for the diagnosis of functional dysphonia additional the case history and functional voice examinations are necessary.

Correlation of Glottic Gap and Voice Impairment in Presbyphonia.

OBJECTIVE/HYPOTHESIS: The objective of this study was to investigate the glottic gap area as a significant marker for the severity of presbyphonia as it relates to patient-reported outcome measures (Voice Handicap Index-10 [VHI-10]) and stroboscopic findings. STUDY DESIGN: Retrospective case-control study conducted in an academic tertiary voice center. METHODS: Patients seen at a tertiary voice clinic who were diagnosed with presbyphonia without other organic laryngeal pathology from January 2014 to December 2017 were included. Clinical data and laryngeal videostroboscopy videos were collected. Still images at the point of vocal process approximation during adduction were captured, and the glottic gap area was measured using ImageJ. These were compared to a control cohort. Correlations were made using Wilcoxon rank sum test, Mann-Whitney U test, and Pearson correlation coefficients. RESULTS: Thirty-three patients were included. Inter-rater reliability of glottic area measurement was strong (intraclass correlation coefficient = 0.73, P < .001). Compared to controls, presbyphonia patients had a larger glottic gap area (P < .001) and greater open-phase quotient on laryngeal videostroboscopy (P < .001). Larger glottic gap area did not correlate with patient-reported vocal function as measured by VHI-10 (P = .79) and did not correlate with presence of secondary muscle tension dysphonia (P = .99). In the presbyphonia cohort, the glottic gap area did not correlate with age (P = .29). CONCLUSIONS: Glottic gap area at the point of vocal process approximation during phonation can be reliably measured. Patients with presbyphonia have a larger glottic gap area and greater open-phase quotient on stroboscopy, but these do not correlate with patient-reported voice impairment or the presence of secondary muscle tension dysphonia (MTD). These data suggest that dysphonia severity in presbyphonia is not fully explained by a glottic gap or secondary MTD alone. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:1594-1598, 2021.

From Voice Clinic to Operating Room: Are We Out of Tune?

INTRODUCTION: To determine the consistency and accuracy of preoperative diagnosis in the voice clinic with intraoperative diagnosis and to suggest a standardized laryngeal examination protocol in the UK that is supported by evidence-based findings. METHOD: From January 2011-September 2014, 164 patients were referred to the Multidisciplinary Team voice clinic and diagnosed with laryngeal pathology that required phonosurgery. The visualization (videostrobolaryngoscopy) in clinic was performed using either rigid laryngoscope or a video-naso-laryngoscope. Intraoperatively, laryngeal visualization and surgical procedure was conducted using Storz Aida HD system, 10-mm rigid laryngoscope 0° or 5-mm rigid laryngoscope 0°/30° and a Zeiss S7 microscope. RESULTS: Of the 164 patients seen in the multidisciplinary voice clinic, 86 clinic diagnoses were confirmed intraoperatively (52.4%), 15 patients had the diagnosis confirmed intraoperatively with additional lesion found (9.1%). The clinic diagnosis changed intraoperatively in 63 cases (38.4%). 61 (37.2%) patients seen in the voice clinic were diagnosed with cyst, in 39.3% the diagnosis was confirmed intraoperatively with 5 cases (8.2%) having an additional diagnosis. Twenty (12.2%) patients were diagnosed with polyps, with 80% confirmation intraoperatively; 3 patients (10%) had an additional diagnosis. CONCLUSION: Videolaryngostroboscopy imaging of the larynx provides an outpatient tool for accurately diagnosing more than 50% of laryngeal pathologies when interpreted by multidisciplinary voice clinicians. However direct laryngeal examination under general anesthesia remains the gold standard when obtaining accurate diagnoses of laryngeal pathology. Patients diagnosed with nonorganic voice disorders should be considered for direct laryngoscopy under general anesthetic should they fail to respond to conservative management.

Stroboscopic fluorescence lifetime imaging.

We report a fluorescence lifetime imaging technique that uses the time integrated response to a periodic optical excitation, eliminating the need for time resolution in detection. A Dirac pulse train of variable period is used to probe the frequency response of the total fluorescence per pulse leading to a frequency roll-off that is dependent on the relaxation rate of the fluorophores. The technique is validated by demonstrating wide-field, realtime, lifetime imaging of the endocytosis of inorganic quantum dots by a cancer cell line. Surface charging of the dots in the intra-cellular environment produces a switch in the fluorescence lifetime from approximately 40 ns to < 10 ns. A temporal resolution of half the excitation period is possible which in this instance is 15 ns. This stroboscopic technique offers lifetime based imaging at video rates with standard CCD cameras and has application in probing millisecond cell dynamics and in high throughput imaging assays.

The ciliary beat frequency of middle ear mucosa in children with chronic secretory otitis media.

The chronic secretory otitis media (CSOM) is a common disease in children. Its cardinal symptoms are recurrent middle ear effusions and conductive hearing loss. Until today, the pathophysiological mechanism of this disease remains unknown. The correlation with adenoids and tubal dysfunction during childhood seems to be obvious, but the origin of middle ear effusions still has to be clarified. It is known that the CSOM affects the mucociliary system in several ways. In order to find out more about these correlations, the ciliary beat frequency was examined in 123 samples of infantile middle ear mucosa suffering from CSOM. Samples were surveyed using a stroboscopic microscopy method. The results of this study showed a significant decrease of ciliary beat frequency (CBF) to an average of 7.4 s(-1) in children with a CSOM. The healthy group of control showed a frequency of 10.1 s(-1). The measured CBF dataset was correlated with microbiological findings. We found a typical bacterial profile in nearly all the cases that were examined but were unable to find a specific bacterium decreasing CBF. This study provides evidence for the diminution of CBF in cases of CSOM in comparison to a healthy control group. Our findings emphasize the importance of stopping the vicious circle of recurrent effusions by paracentesis or grommet insertion.

Does flexible videostroboscopy compare with rigid videostroboscopy in the assessment of the neoglottis? A preliminary report.

OBJECTIVE: To evaluate rigid and flexible stroboscopy of the neoglottis. STUDY DESIGN: Prospective pilot study set at a tertiary level Head & Neck Unit. PARTICIPANTS: Twenty-four patients recruited. All had undergone a total laryngectomy and were voicing using a Blom-singer valve. All had stroboscopic evaluation of their neoglottis using flexible and rigid endoscopes. MAIN OUTCOME MEASURES: A rating form was devised based on six parameters with clear definitions. Secondary measures included ability to tolerate the procedure and completeness of the rating form for each parameter using the two systems. RESULTS: There was good reliability between individual raters for the assessment of each system based on Spearman Rho correlation. Importantly, two-thirds of the patients were unable to tolerate the rigid videostroboscopy managed flexible videostroboscopy. Correlation between rigid and flexible videostroboscopy was poor for both raters. Flexible systems picked up more mucosal waves and allowed further analysis of the mucosal wave pattern. CONCLUSIONS: To our knowledge, this is the first study to demonstrate that fibreoptic videstroboscopy is as good as rigid videostroboscopy in the assessment of the neoglottis. In fact, flexible videostroboscopy should be routinely used, as it is better tolerated and allows a more detailed analysis of the neoglottis.

Preliminary evaluation of stroboscopy system using multiple light sources for observation of pathological vocal fold oscillatory pattern.

OBJECTIVES: Laryngostroboscopy is used to check the oscillatory patterns of the vocal folds. However, the use of one single flash timing cannot give a clear view of abnormal vocal fold oscillations that have multiple fundamental frequencies. Visualization of such complex vocal fold movements will be helpful in the diagnosis of diplophonia, a pathological condition in which the vocal folds produce multiple tones at the same time. METHODS: We developed a new stroboscopy-based technique using multiple light-emitting diodes (LEDs) and image analysis. Specific flash timings for each LED, suitable for accurate visualization, were determined on a computer according to an algorithm based on frequency analysis. The image analysis extracted the necessary parts of the captured images to yield a clear slow-motion view of the oscillations. The series of visualization procedures took advantage of the narrow-spectrum light property of LEDs, thereby yielding a degradation-free picture. RESULTS: Feasibility tests using a mechanical vocal fold model demonstrated that this computer-assisted system allows observation of the pathological oscillatory patterns as one single video. They would not be clearly visualized by conventional stroboscopy. CONCLUSIONS: Because of its relatively simple use and inexpensive construction, the proposed technique can become one potential option for clinical assessment of pathological vocal fold oscillations.

Real-time Simultaneous DKG and 2D DKG Using High-speed Digital Camera.

INTRODUCTION: For the evaluation of voice disorders, direct observation of vocal cord vibration is important. Among the various methods, laryngeal videostroboscopy (LVS) is widely used, but it was not a true image because it collects images from different cycles. In contrast, high-speed videoendoscopy and videokymography have much higher frame rates and can assess functional and mobility disorders. OBJECTIVE: The purpose of the study is to describe real-time, simultaneous digital kymography (DKG), two-dimensional scanning (2D) DKG, and multi-frame (MF) LVS system using a high-speed digital camera, and identify the efficacy of this system in evaluating vibratory patterns of pathologic voice. METHODS: The pattern of vocal fold vibration was evaluated in a vocally healthy subject and in subjects with vocal polyp, vocal nodules, vocal cord scar, and vocal cord paralysis. We used both quantitative (left-right phase symmetry, amplitude symmetry index) and qualitative (anterior-posterior phase symmetry) parameters for assessment of vocal fold vibration. RESULTS: Our system could record videos within seconds and required relatively little memory. The speed of replay in the DKG, 2D DKG, MF LVS, and high-speed videoendoscopy was controllable. The number of frame per cycle with MF LVS was almost the same as the fundamental frequency. CONCLUSION: Our system can provide images of various modalities simultaneously in real time and analyze morphological and functional vibratory patterns. It can be possible to provide a greater level of information for the diagnosis and treatment of vibratory disorders.

A Preliminary Quantitative Comparison of Vibratory Amplitude Using Rigid and Flexible Stroboscopic Assessment.

STUDY OBJECTIVE: The purpose of this study was to establish preliminary, quantitative data on amplitude of vibration during stroboscopic assessment in healthy speakers with normal voice characteristics. Amplitude of vocal fold vibration is a core physiological parameter used in diagnosing voice disorders, yet quantitative data are lacking to guide the determination of what constitutes normal vibratory amplitude. METHODS/STUDY DESIGN: Eleven participants were assessed during sustained vowel production using rigid and flexible endoscopy with stroboscopy. Still images were extracted from digital recordings of a sustained /i/ produced at a comfortable pitch and loudness, with F0 controlled so that levels were within ±15% of each participant's comfortable mean level as determined from connected speech. Glottal width (GW), true vocal fold (TVF) length, and TVF width were measured from still frames representing the maximum open phase of the vibratory cycle. To control for anatomic and magnification differences across participants, GW was normalized to TVF length. GW as a ratio of TVF width was also computed for comparison with prior studies. RESULTS: Mean values and standard deviations were computed for the normalized measures. Paired t tests showed no significant differences between rigid and flexible endoscopy methods. Interrater and intrarater reliability values for raw measurements were found to be high (0.89-0.99). CONCLUSIONS: These preliminary quantitative data may be helpful in determining normality or abnormality of vocal fold vibration. Results indicate that quantified amplitude of vibration is similar between endoscopic methods, a clinically relevant finding for individuals performing and interpreting stroboscopic assessments.

Stroboscopy as a research instrument: development of a perceptual evaluation tool.

Laryngeal stroboscopy is arguably the most important clinical tool for the evaluation and treatment of patients with voice disorders. Unfortunately, at present, laryngeal stroboscopy is strictly a clinical tool and has no definitive use in the area of voice research. The limitation with laryngeal stroboscopy is the subjective nature of the interpretation of the video examination. A video stroboscopy research tool was developed using 10 stroboscopic parameters selected from the literature and clinical practice. The stroboscopy research tool was validated with the results of 18 reviewers using the instrument to rate 21 unique "cases" and 6 repeated "cases." The results of this video perceptual analysis study identified which parameters were the most robust and reliable across a wide range of reviewers and validated power analysis curves for future similar research. Furthermore, findings from this study revealed that a greater than 80% intra-rater reliability is the preferred method for the selection of a valid and reliable reviewer. Future research using this instrument will most likely increase the reliability and utility of the instrument with the use of prestudy reviewer training and/or the use of video examples to serve as anchors or external references.

The feasibility of rigid stroboscopy in children.

OBJECTIVE: Voice disorders in children are common but ways of their analysis are limited. We conducted a prospective feasibility study of rigid stroboscopy in children. METHODS: All children referred for voice analysis during the years 2002-2003 were evaluated including subjective perception of voice, voice recording, flexible or rigid laryngoscopy and stroboscopy. Children were prepared by an explanation and visual demonstration. Local anesthesia was introduced through inhalation of Lidocaine (2%) solution prior to examination. Stroboscopy was performed either by a 70 degrees rigid laryngoscope or by a 3.0 mm fiberoptic-flexible endoscope. RESULTS: Forty-two children were analyzed. Rigid stroboscopy was feasible in 31 children of whom 7 were under 10 years of age. Short phonation time (7), gag reflex (6), impaired view due to high and posteriorly inclined epiglottis (4) were the main reasons of failure. CONCLUSIONS: Standard telescopic stroboscopy can be safely and effectively implemented in the majority of children over 10 years of age.

Three-dimensional vibrometry of the human eardrum with stroboscopic lensless digital holography.

The eardrum or tympanic membrane (TM) transforms acoustic energy at the ear canal into mechanical motions of the ossicles. The acousto-mechanical transformer behavior of the TM is determined by its shape, three-dimensional (3-D) motion, and mechanical properties. We have developed an optoelectronic holographic system to measure the shape and 3-D sound-induced displacements of the TM. The shape of the TM is measured with dual-wavelength holographic contouring using a tunable near IR laser source with a central wavelength of 780 nm. 3-D components of sound-induced displacements of the TM are measured with the method of multiple sensitivity vectors using stroboscopic holographic interferometry. To accurately obtain sensitivity vectors, a new technique is developed and used in which the sensitivity vectors are obtained from the images of a specular sphere that is being illuminated from different directions. Shape and 3-D acoustically induced displacement components of cadaveric human TMs at several excitation frequencies are measured at more than one million points on its surface. A numerical rotation matrix is used to rotate the original Euclidean coordinate of the measuring system in order to obtain in-plane and out-of-plane motion components. Results show that in-plane components of motion are much smaller (<20%) than the out-of-plane motions' components.

Blood flow velocity measured using the Retinal Function Imager predicts successful ranibizumab treatment in neovascular age-related macular degeneration: early prospective cohort study.

PURPOSE: Anti-VEGF treatment has a potent vasoconstrictive effect. Early changes of retinal blood flow velocity (RBFV) measured using the Retinal Function Imager (RFI) combined with indicators of vascular status may help in predicting the visual outcome 1 month post injection in patients with neovascular age-related macular degeneration (nvAMD) under ranibizumab treatment. To develop a simple prediction model based on the change in RBFV 3 days post injection and indicators of a patient's vascular status to assess the probability of a successful visual outcome 1 month post injection. METHODS: RBFV measured using RFI were prospectively collected pre-injection and 3 days post injection in 18 eyes of 15 patients. Indicators of vascular status (history of hypertension, diabetes mellitus without retinal affection, and smoking) were assessed by medical history. By univariate analyses, parameters associated with visual outcome were weighted (-1 to 6 points). A multivariate logistic regression model with the categorized visual outcome parameter (≥0 letters gained after 1 month) as the dependent variate and the sum score as the independent variate (continuous scale) was used to estimate the score value-specific probabilities of letters gained ≥0 1 month post injection. RESULTS: The indicators of vascular status negatively influenced the likelihood of a letter gain ≥0 whereas an increase in the arterial RBFV strongly increased it. The area under the receiver operating characteristics curve for these parameters investigated was 0.71 (95% CI: 0.43-1.00). CONCLUSION: Changes in the arterial RBFV following 3 days after ranibizumab injection combined with three indicators of the vascular status identified nvAMD patients with favorable visual outcome accurately.

Development of laryngeal video stroboscope with laser marking module for dynamic glottis measurement.

Physicians clinically use laryngeal video stroboscope as an auxiliary instrument to test glottal diseases, and read vocal fold images and voice quality for diagnosis. As the position of vocal fold varies in each person, the proportion of the vocal fold size as presented in the vocal fold image is different, making it impossible to directly estimate relevant glottis physiological parameters, such as the length, area, perimeter, and opening angle of the glottis. Hence, this study designs an innovative laser projection marking module for the laryngeal video stroboscope to provide reference parameters for image scaling conversion. This innovative laser projection marking module to be installed on the laryngeal video stroboscope using laser beams to project onto the glottis plane, in order to provide reference parameters for scaling conversion of images of laryngeal video stroboscope.