Distal chip versus fiberoptic laryngoscopy using endoscopic sheaths: diagnostic accuracy and image quality

Evaluating the Quality of Rigid Optic Videolaryngoscopy Image Taken Through Dental Protection Cap and Its Feasibility as Additional Barrier Method Against COVID-19

Videolaryngoscopy screening is essential to help assessing human larynx. The use of 70° optical fiber in association with image recording by analog or digital cameras is one of the methods adopted to perform this examination. Endoscopic exams can contaminate the equipment with several microorganisms. The pandemic caused by the new coronavirus reinforces the importance of developing efficient barrier methods to be adopted in videolaryngoscopy procedures. Although dental intraoral camera covers are a barrier method authorized by Brazilian health organs, it has not yet been used in videolaryngoscopy examinations. The aim of the current longitudinal, individualized, single-blind, prospective, self-controlled, and accurate study is to evaluate the quality of images generated through, and confidence level of, diagnosis based on videolaryngoscopy performed with intraoral dental camera equipped with disposable protection cap and connected to 70° rigid laryngoscope in vocally healthy individuals. Videolaryngoscopy examinations based on 70° rigid optics were performed in 13 euphonic and asymptomatic volunteers at an otorhinolaryngology specialist clinic; only 1 patient was excluded from the study. Images were taken with, and without, disposable intraoral dental camera protection cap; high-grade disinfection protocol was applied between examinations. Recorded videos were randomly distributed in a single-blind manner in order to be evaluated by four otorhinolaryngologists, who answered a questionnaire comprising three questions. Statistical analysis was used to compare groups - which were defined by the use, or not, of protection cap - based on Wilcoxon nonparametric test. Statistical significance was set at 5% with 95% confidence interval. There was no statistically significant difference in image quality between examinations performed with, and without, protection cap (P= 0.646) or in the diagnosis confidence level of examinations performed with, or without, the barrier method. The use of disposable protection cap on intraoral dental camera did not significantly change the quality of images taken through videolaryngoscopy performed with 70° rigid optics in vocally healthy patients.

Influence of edge enhancement applied in endoscopic systems on sharpness and noise

SIGNIFICANCE

Flexible endoscopes are essential for medical internal examinations. Digital endoscopes are connected to a video processor that can apply various operations to enhance the image. One of those operations is edge enhancement, which has a major impact on the perceived image quality by medical professionals. However, the specific methods and parameters of this operation are undisclosed and the arbitrary units to express the level of edge enhancement differ per video processor.

AIM

Objectively quantify the level of edge enhancement from the recorded images alone, and measure the effect on sharpness and noise

APPROACH

Edge enhancement was studied in four types of flexible digital ear nose and throat endoscopes. Measurements were performed using slanted edges and gray patches. The level of edge enhancement was determined by subtracting the step response of an image without edge enhancement from images with selected settings of edge enhancement and measuring the resulting peak-to-peak differences. These values were then normalized by the step size. Sharpness was characterized by observing the normalized modulation transfer function (MTF) and computing the spatial frequency at 50% MTF. The noise was measured on the gray patches and computed as a weighted sum of variances from the luminance and two chrominance channels of the pixel values.

RESULTS

The measured levels were consistent with the level set via the user interface on the video processor and varied typically from 0 to 1.3. Both sharpness and noise increase with larger levels of edge enhancement with factors of 3 and 4 respectively.

CONCLUSIONS

The presented method overcomes the issue of vendors expressing the level of edge enhancement each differently in arbitrary units. This allows us to compare the effects, and we can start exploring the relationship with the subjectively perceived image quality by medical professionals to find substantiated optimal settings.

Diagnostic accuracy of flexible fiberoptic laryngoscopy: experience from a tertiary health institution in Nigeria

BACKGROUND

Flexible fibreoptic laryngoscopy (FFL) is a technique of laryngeal visualization. The instrument (flexible laryngoscope) is relatively scarce in resource challenged countries. Where available, it is a useful compliment to the armamentarium of clinical tools at the disposal of the otolaryngologist. We evaluated the diagnostic value of flexible fibreoptic laryngoscope in a tertiary health institution in Nigeria. And we hypothesized that its diagnostic precision is comparable to direct laryngoscopy.

METHODS

This is a retrospective study of records of 360 patients referred for FFL at the ENT clinic. Sensitivity and specificity of FFL for laryngeal lesions were determined using direct laryngoscopy (DL) as the gold standard.

RESULTS

Of the 360 FFL reports studied, 336 additionally underwent DL. FFL findings in 311 (92.6%) cases were comparable with that of DL. FFL had a good detection rate for vocal cord palsy (sensitivity 100%, specificity 80.7%). Pick-up rate for vocal nodules, polyps, papillomatosis and palsy were statistically equal for FFL and DL (p value = 0.96). Diagnostic accuracy of FFL was good for supraglottic (sensitivity 100%, specificity 88.0%) and glottic (sensitivity 100%, specificity 92.3%) tumours; relatively lower for subglottic (sensitivity 83.3%; specificity 100%) and transglottic (sensitivity 80.0%, specificity 100%) tumours; and least for tumours involving more than on subsites (sensitivity 50%, specificity 100%).

CONCLUSION

The sensitivity and specificity of FFL were not the same for all endo-laryngeal lesions; yet, the overall diagnostic accuracy of FFL is comparable with DL. Clinicians should be mindful of this variability to optimize its application.

Detection of Aspiration, Penetration, and Pharyngeal Residue During Flexible Endoscopic Evaluation of Swallowing (FEES): Comparing the Effects of Color, Coating, and Opacity

The aim of this study was to assess the effects of color, coating, and opacity on the detection of aspiration, penetration, and residue during flexible endoscopic evaluations of swallowing (FEES). Thirty dysphagic adults underwent FEES while swallowing five 5 mL thin liquid boluses (1 × each, randomized): white water, blue water, white milk, blue milk, and barium water. To assess the effects of color, blue milk was compared to white milk. To assess the effects of coating, barium, white water, and white milk were compared to each other. To assess the effects of opacity, blue milk was compared to blue water. Videos were blindly analyzed and judged for the presence of pharyngeal residue, penetration, and aspiration. Repeated measures analyses were used to assess differences in the frequency of detection across bolus types. Pharyngeal residue was detected more frequently for liquids that were blue, had a coating effect, or were opaque (p < 0.05) when compared to liquids that were white, did not have a coating effect, or were translucent, respectively. Penetration and aspiration were detected more frequently for liquids that had a coating effect (p < 0.05), but not for liquids that were colored blue or opaque (p > 0.05). Coating appears to be the most important factor detecting thin liquid residue, penetration, and aspiration during FEES. Given these findings, standardized use of boluses that possess a coating effect (e.g., white-dyed water or barium) is highly recommended to enhance the sensitivity of identifying impairments in swallowing safety and efficiency during FEES.

Differences in the diagnostic value between fiberoptic and high definition laryngoscopy for the characterisation of pharyngeal and laryngeal lesions: A multi-observer paired analysis of videos

OBJECTIVES

High definition laryngoscopy (HDL) could lead to better interpretation of the pharyngeal and laryngeal mucosa than regularly used fiberoptic laryngoscopy (FOL). The primary aim of this study is to quantify the diagnostic advantage of HDL over FOL in detecting mucosal anomalies in general, in differentiating malignant from benign lesions and in predicting specific histological entities. The secondary aim is to analyse image quality of both laryngoscopes.

DESIGN

Retrospective paired analysis with multiple observers evaluating endoscopic videos simulating daily clinical practice.

SETTING

A tertiary referral hospital.

PARTICIPANTS

In 36 patients, both FOL and HDL videos were obtained. Six observers were provided with additional clinical information, and 36 FOL and HDL videos were evaluated in a randomised order.

MAIN OUTCOME MEASURES

Sensitivity, specificity, positive and negative predictive value and diagnostic accuracy of observers using both flexible laryngoscopes were calculated for detection of mucosal lesions in general and uncovering malignant lesions. Sensitivities were calculated for prediction of specific histological entities. Image quality (scale 1-10) was assessed for both flexible laryngoscopes.

RESULTS

HDL reached higher sensitivity compared to FOL for detection of mucosal abnormalities in general (96.0% vs 90.4%; P = .03), differentiating malignant from benign lesions (91.7% vs 79.8%; P = .03) and prediction of specific histological entities (59.7% vs 47.2%; P < .01). Image quality was judged better with HDL in comparison with FOL (mean: 8.4 vs 5.4, P < .01).

CONCLUSIONS

HDL is superior to FOL in detecting mucosal anomalies in general, malignancies and specific histological entities. Image quality is considered as superior using HDL compared to FOL.

The effect of endoscopic sheaths on visualization in distal chip and fiberoptic laryngoscopy

Endoscopic sheaths covering the laryngoscope are advised to prevent cross contamination, but might hamper visualization as the most important tool in the diagnostic approach of laryngeal disease. We evaluated whether endoscopic sheaths change image quality and diagnostic accuracy of flexible distal chip laryngoscopy (DCL) and flexible fiberoptic laryngoscopy (FOL). Twelve healthy volunteers underwent a flexible laryngoscopy using a distal chip and a fiberoptic laryngoscope with and without endoscopic sheaths, and in this way 48 images were collected. To determine diagnostic accuracy, the 48 images were mixed with images of 40 patients. All images were randomly shown to four experts in the field of laryngology and head and neck oncology. Observers were asked to validate image quality, choose a diagnosis, and express their confidence level of that diagnosis. Image quality was validated better in DCL as compared to FOL (p < 0.05) both with or without endoscopic sheaths. Endoscopic sheaths worsened image quality in DCL (p < 0.05) but not in FOL. No differences were observed between DCL and FOL with or without endoscopic sheaths in diagnostic accuracy (79-89%). Confidence levels (7.7-8.1) were comparable in DCL and FOL and not influenced by endoscopic sheaths. Image quality in DCL is superior to FOL, but significantly hampered by the use of endoscopic sheaths. In FOL the image quality is already low and not further diminished by endoscopic sheaths.