Virtual Laryngoscopy Research Articles

Expert consensus on difficult airway assessment.

Identifying a potentially difficult airway is crucial both in anaesthesia in the operating room (OR) and non-operation room sites. There are no guidelines or expert consensus focused on the assessment of the difficult airway before, so this expert consensus is developed to provide guidance for airway assessment, making this process more standardized and accurate to reduce airway-related complications and improve safety. Seven members from the Airway Management Group of the Chinese Society of Anaesthesiology (CSA) met to discuss the first draft and then this was sent to 15 international experts for review, comment, and approval. The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) is used to determine the level of evidence and grade the strength of recommendations. The recommendations were revised through a three-round Delphi survey from experts. This expert consensus provides a comprehensive approach to airway assessment based on the medical history, physical examination, comprehensive scores, imaging, and new developments including transnasal endoscopy, virtual laryngoscopy, and 3D printing. In addition, this consensus also reviews some new technologies currently under development such as prediction from facial images and voice information with the aim of proposing new research directions for the assessment of difficult airway. This consensus applies to anesthesiologists, critical care, and emergency physicians refining the preoperative airway assessment and preparing an appropriate intubation strategy for patients with a potentially difficult airway.

Positive Predictive Value of Computed Tomography Virtual Laryngoscopy in Detecting Laryngeal Carcinoma Taking Histopathology as Gold Standard

Background: Computed tomography virtual laryngoscopy (CTVL) is favored diagnostic tool in detecting laryngeal carcinoma because it delivers excellent temporal and spatial resolution. Objective: To determine the positive predictive value of computed tomography virtual laryngoscopy in detecting laryngeal carcinoma taking histopathology as gold standard. Methods: A cross sectional survey was conducted at department of Radiology, Mayo Hospital Lahore. The completion of study was done in six months [Feb 16, 2019 till Aug 16, 2019]. After obtaining approval from ethical committee and informed consent from subjects, 64 subjects were included in the study who presented in the Department of the Radiology having carcinoma of larynx on CTVL and then sent to department of ENT of mayo hospital, where they underwent direct laryngoscopy and afterwards biopsy obtained sent to the department of histopathology. All the subjects undergoing CT scan examination on the CT machine of hospital. Contrast injection was given to all subjects undergoing CT scan, through power injector at the rate of 4ml per min and dosage of 0.1ml/kg. Same machine was used to conduct all CT scans and was inferred through same radiologist and all the histopathology was performed by same pathologist to exclude bias. Results: The mean age of patients was 44.38 ± 9.57 years with minimum and maximum age as 22 and 60 years. There were 47(73.4%) male and 17(26.6%) female cases. On histopathology the laryngeal carcinoma was diagnosed in 56(87.5%) of the cases while it was negative in 8(12.5%) of the cases. On CT the laryngeal carcinoma was diagnosed in 59(92.2%) of the cases while it was negative in 5(7.8%) of the cases. The Positive Predictive Value of CT was 89.83%, while its sensitivity was 94.64%, specificity was 25.00%, negative predictive value was 40.00% and diagnostic accuracy was 85.94%. Conclusion: Through the findings of this study it is concluded that positive predictive value of computed tomography virtual laryngoscopy is high (89.83%) in detecting laryngeal carcinoma taking histopathology as gold standard. CT is a precise and non-invasive imaging method in detecting laryngeal carcinoma.

Diagnostic Accuracy of Fiber Optic Laryngoscopy

Background: Laryngeal examination of patients with hoarseness is essential to diagnose a wide range of pathologies. Laryngeal visualization has progressed from simple indirect mirror examination to virtual laryngoscopy with flexible fiber optic laryngoscope as an acceptable option. This study was done to determine the diagnostic accuracy of fiber optic laryngoscopy in patients with hoarseness.Material and Methods: This cross-sectional comparative study included a sample of 155 participants, of both genders, aged 20 to 60 years with hoarseness of at least 1 month duration. Participants were recruited through non probability consecutive sampling technique from ENT department, Sir Ganga Ram Hospital Lahore, Pakistan over a period of six months (October 2015 to March 2016). Patients fulfilling the selection criteria were subjected to Fiber Optic Laryngoscopy (FOL) under local anesthesia followed by Direct Laryngoscopy (DL) under general anesthesia and findings recorded. Data was collected, tabulated and analyzed using SPSS 17. Diagnostic value of FOL versus DL was calculated with frequency, percentage, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV).Results: Out of 155 participants, 48.39 % (75) were males and 51.61 % (80) females, with mean age of 31 ± 9.54 years. Assessment of diagnostic accuracy of fiber optic laryngoscopy taking direct laryngoscopy as criterion standard showed an accuracy of 80.65% with 89.19% sensitivity, 77.96% specificity, 55.93% PPV, and 95.83% NPV.Conclusions: Fiber optic laryngoscopy is an excellent tool for the diagnosis of hoarseness, with a diagnostic accuracy of 80.65%.

Utility of 64 multislice CT-virtual laryngoscopy in presurgical planning of laryngeal and hypopharyngeal carcinomas

ObjectiveTo evaluate the utility of 64-multislice CT with virtual laryngoscopy in diagnosis and pre-therapeutic planning of laryngeal and hypopharyngeal carcinomas in comparison with conventional laryngoscopy. Patients and methodsForty patients with laryngeal and hypopharyngeal carcinomas were subjected to 64-multislice CT examinations with multiplanar reformation and CT-virtual laryngoscopy. The results were compared with those of direct and indirect laryngoscopy. Multiple variables like primary subsite of the mass, invasion of anterior commissure, posterior commissure and subglottic extension of mass were analyzed and the Chi-square test was used to study the association between each 2 variables. ResultsExcellent correlation was found between direct laryngoscopy and CTVL in detection and localization of primary subsite of laryngeal carcinomas. A statistically significant difference existed between both modalities in favor of CTVL in identifying subglottic extension, anterior and posterior commissures invasion (P⩽0.001) as well as in evaluating the hidden areas of the hypopharynx. Direct endoscopy was more valuable, however in identifying mucosal surface irregularities and vocal cord involvement diagnosed as cord fixation(P⩽0.001). ConclusionVirtual laryngoscopy is a noninvasive and reliable technique that in combination with axial and MPR CT images is valuable in staging and pretherapeutic planning of laryngeal/hypopharyngeal carcinomas. It is not an alternative to conventional laryngoscopy but may assist direct endoscopy without causing additional radiation exposure or discomfort to the patient.

Virtual intubation training at a remote military site.

To provide medical support to the far forward battlefield, training in advanced medical technologies is essential for military healthcare providers. To meet this challenge, the use of modern video communication technologies and novel medical devices can be implemented. This study demonstrates the combined use of modern video conferencing technology and video laryngoscopy equipment in the virtual laryngoscopy training of deployed military medical personnel.

Detection of laryngeal tumors and tumoral extension by multislice computed tomography-virtual laryngoscopy (MSCT-VL)

Virtual endoscopy is becoming a widely used non-invasive clinical diagnostic tool. The present study was designed to compare the sensitivity and specificity of the conventional endoscopy and virtual laryngoscopy with respect to laryngeal masses. A total of 38 patients (20 males, 18 females, mean age 61 years) with the complaint of hoarseness were included in the study. Laryngeal mucosa, lumen and mass pathology were evaluated initially by direct endoscopy and then by virtual laryngoscopy during multislice CT of the larynx. Histopathologic evaluation of the masses was also made. The main pathology of the patients was found to be laryngeal masses (60% of patients, one mass for each patient), which were polyps (n = 8), papilloma (n = 4) and carcinoma (n = 11) according to histopathologic evaluation. Retrospective evaluation of 6 lesions detected in virtual but not in conventional laryngoscopy resulted with the finding of viscous-dense mucous secretion. On the contrary, three lesions detected by conventional laryngoscopy could not be detected by virtual evaluation. A total of six patients were evaluated and considered as normal both by conventional and virtual laryngoscopic examinations. Sensitivity of the virtual laryngoscopy was 88% (23/26) while its specificity was only 50% (6/12). Positive and negative predictive values were 79% (23/29) and 66% (6/9), respectively. Accuracy of the virtual laryngoscopy was 76% (29/38). Virtual laryngoscopy is not an alternative to conventional laryngoscopy but may assist direct endoscopy without causing additional radiation exposure or discomfort to the patient. The three-dimensional contribution to interpretation of the results and subsequent manipulation of the data can be used for educational and surgical purposes.

Cone Beam Computed Tomography: An Innovative Tool for Airway Assessment

Improvements in airway imaging technology provide the potential for an improved understanding of airway pathology and upper airway mechanics. We present here a preliminary report on the applicability of cone beam computed tomography technology in conjunction with multidimensional digital analysis for the purposes of clinical airway management. The use of this technology for airway imaging in anesthesiology has not been reported. Traditional skeletal and soft tissue images as well as distance and volume measurements were obtained without difficulty. Three-dimensional image reconstructions as well as "virtual laryngoscopy" were achieved with resulting excellent image quality, suggesting a broad range of possibilities for upper airway examination and analysis. A modified Muller test with volumetric rendering of the airway passages under baseline and negative pressure conditions was also performed, made possible as a result of the system's short (9 s) scanning times. We believe that cone beam computed tomography technology offers an additional dimension to airway evaluation that has considerable potential.

Virtual Laryngoscopy: a Noninvasive Tool for the Assessment of Laryngeal Tumor Extent

Present a clinical application of virtual laryngoscopy (VL) in the assessment of laryngeal tumor and its extent. CT data from two subjects are acquired for this preliminary study. One subject is a healthy volunteer and the other is a patient with laryngeal tumor. The laryngeal framework and upper airway are reconstructed using CT data, which allows for computer-aided internal and external anatomical views and interactive fly-through. These CT data are reconstructed into 0.5 mm slice images, resulting in a total of 200-300 image slices. An advanced commercial visualization software (AMIRA) is used for 3D image segmentation, reconstruction and surface rendering of laryngeal anatomical structures. The 3D laryngeal framework and upper airway are reconstructed for both the tumor patient and the healthy subject. The conventional views of the reconstructed vocal folds are compared with those obtained from fiber-optic laryngoscope. Additionally, unique views of the vocal folds obtained from retrograde visualization and fly-through are presented, which are not possible to obtain using conventional endoscope imaging. The segmented anatomical model and the tumor from the patient's CT images were displayed individually to show the distribution of the tumor and its extent as well as spatial and contextual relationships to the larynx and airway anatomical structures. This study demonstrated the potential application of VL as a noninvasive clinical diagnostic tool for the assessment of laryngeal tumor and its extent. Our preliminary results demonstrated that the VL may provide valuable insights for the diagnosis and treatment planning for laryngeal and airway tumors. The noninvasive VL may complement the invasive laryngoscopic examinations for the staging of tumors and follow-ups on surgical interventions.

System and method for performing a three-dimensional virtual examination of objects, such as internal organs

Methods for generating a three-dimensional visualization image of an object, such as an internal organ, using volume visualization techniques are provided. The techniques include a multi-scan imaging method; a multi-resolution imaging method; and a method for generating a skeleton of a complex three dimension object. The applications include virtual cystoscopy, virtual laryngoscopy, virtual angiography, among others.

Virtual versus Conventional Laryngeal Endoscopy

We have evaluated the capacity of virtual laryngoscopy and conventional laryngoscopy conducted with a rigid or flexible instrument to visualize laryngeal structures in 64 patients with normal endoluminal anatomy. Virtual laryngoscopy allowed total visualization of laryngeal structures, including those that could not be reached by a flexible instrument. There was good correlation between virtual laryngoscopy and "real" images, indicating satisfactory diagnostic accuracy (p < .05). Although virtual laryngoscopy does not provide histologic data, it is a fast and noninvasive technique that can be added to and integrated with conventional laryngoscopy, and it can be an alternative in cases in which conventional laryngoscopy is difficult, contraindicated, or impossible. It is particularly useful for the study of laryngeal narrow spaces and in the visualization of subglottic regions and of other more restricted areas (inferior tonsil region, posterior surface of the epiglottis, glossoepiglottic vallecula, Morgagni's ventricle, anterior commissure).

Virtual laryngoscopy—preliminary experience

Purpose: Computed tomographic virtual laryngoscopy is a non-invasive radiological technique that allows visualisation of intra-luminal surfaces by three-dimensional reconstruction of air/soft tissue interfaces. It is particularly useful when the patient cannot tolerate clinical examination, when infection, neoplasm or congenital defects compromise the lumen and for assessment of the sub-glottic region. We have performed virtual laryngoscopy on patients referred because of upper airway symptoms, and compared the findings with those at conventional laryngoscopy. Materials and methods: Axial scans were obtained using a Toshiba Xpress helical scanner. Virtual laryngoscopy was then performed on a workstation using Toshiba “Fly-thru” software and was completed within 5 min. Results: Pathology included vocal cord nodules, laryngeal cysts, Reinke's oedema, laryngeal neoplasms and leukoplakia. Conclusions: Virtual laryngoscopy displays anatomical detail comparable to conventional endoscopy. Impassable obstructions are no hindrance and all viewing directions are possible. It is especially useful for providing views of the larynx from below.

Update on the etiology, diagnosis, and treatment of vocal fold nodules, polyps, and cysts

Innovative otolaryngologists, speech language pathologists, and voice scientists have continued to advance our understanding of the etiology, diagnosis, and treatment of vocal fold nodules, polyps, and cysts. This article reviews the recent publications over the past 3 years with respect to these advances. Support for the notion that benign vocal fold lesions arise from phonatory trauma and vocal misuse continues to become evident. Changes in the molecular characteristics of the lamina propria in these lesions are beginning to be understood. For diagnostic purposes, the use of innovative technology such as ultrasonography and virtual laryngoscopy is being explored. Continued support for behavior modification as a primary treatment modality for benign vocal fold lesions has been published, and refinements in technical aspects of laryngeal microsurgery persist. Finally, outcomes studies have demonstrated improvements in vocal disability with both behavioral and surgical interventions. Clinical and basic research has furthered our understanding of benign vocal fold lesions and has expanded our diagnostic and therapeutic armamentarium for patients with dysphonia arising from these lesions.

Virtual laryngoscopy and multiplanar reformats with multirow detector CT for detection and grading of upper airway stenosis

A controlled trial was performed to compare non-invasive multislice CT (virtual laryngoscopy, axial CT slices, coronal and sagittal reformats) in the detection and grading of upper airway stenosis with fiberoptic laryngoscopy. Multislice CT and fiberoptic laryngoscopy were used to examine 111 upper airway sections (supraglottis, glottis, subglottis, trachea) in 29 patients. CT data were acquired on a multirow detector CT (collimation 4 x 1 mm, reconstruction interval 1 mm, IV contrast) and postprocessing was performed using multiplanar reformatted images (MPR) and virtual laryngoscopy. All CT methods accurately detected upper airway stenosis (accuracy was 96 % for virtual laryngoscopy and MPR and 94 % for axial CT-slices). Correlation of fiberoptic and virtual laryngoscopy (r = 0.94) for grading of stenosis was closer than with sagittal reformats (r = 0.80), coronal reformats (r = 0.72), and axial CT slices (r = 0.57). Even high grade stenosis could be passed with virtual laryngoscopy that was impassable for fiberoptic laryngoscopy. Virtual laryngoscopy enabled better assessment of stenosis as compared to reading of axial CT slices or MPR. Virtual laryngoscopy is complementary to fiberoptic laryngoscopy and should be combined with axial CT slices and MPR readings for evaluation of the surrounding structures.

The potential of virtual laryngoscopy in the assessment of vocal cord lesions.

Virtual laryngoscopy is a useful adjunctive radiological tool in the assessment of laryngeal lesions. A total of 10 patients requiring direct laryngoscopy for the investigation of laryngeal lesions underwent preoperative virtual laryngoscopy using three-dimensional reconstruction of two-dimensional computerized tomography (CT) images. All lesions were correctly diagnosed on virtual laryngoscopy before direct laryngoscopy. Its main advantages are that it does not require general anaesthesia, it allows three-dimensional visualization of the airway beyond areas of narrowing and it gives a highly accurate representation of vocal cord lesions, both in terms of definition and spatial representation. Its disadvantages are that it does not provide histology, it requires an air-mucosa interface to produce an image and it cannot identify functional lesions of the vocal cords.

Feasibility studies of virtual laryngoscopy by CT and MRI-from data acquisition, image segmentation, to interactive visualization

Virtual endoscopy concept has been applied to study the larynx, as well as other hollow organs in recent years, assuming a clean lumen. In this work, we investigated the feasibility of virtual laryngoscopy by (1) studying currently available imaging protocols, (2) developing a suitable image segmentation method, and (3) constructing art efficient visualization system. By utilizing helical computed tomography (CT), the images for laryngeal volume can be obtained during a breath hold with 0.3 mm resolution. A fast pulse sequence using 1.5 T magnetic resonance (MR) imager can achieve 1 mm resolution within few minutes. The gain in tissue contrast on MR images is at the cost of resolution, and motion artifacts must be considered during image segmentation. A first-order Lagrange interpolation was applied to mitigate the reduced resolution, as well as partial volume effect and noise on the MR images. An automatic segmentation algorithm was adapted to extract the wall volume of the larynx. The algorithm considers local voxel property and classifies voxels based on the local property in the KL (Karhunen-Loeve) space. A visualization system was constructed for examining the mucosa and wall geometry with anatomical references in three dimensions. It navigates inside the lumen, as well as outside the larynx interactively with capability of inspecting and zooming into the regions of interest. It can also cut the larynx in any orientation to open the whole volume for viewing the entire inner surface. The procedure was tested on 2 volunteers and 2 patients. The segmentation performed consistently for all the studies and showed to be relatively insensitive to mild respiratory motion artifacts in the MR images. Image processing was accomplished within a few minutes on PC and low-end SGI platforms. These studies demonstrated the feasibility of virtual laryngoscopy for diagnosis of laryngeal abnormalities.

2D and 3D visualisation of head and neck tumours from spiral-CT data

Purpose: This paper intends to demonstrate the possibilities of two- and three-dimensional visualisation methods from spiral-CT data sets in the head and neck region and demonstrates their value based on various studies. Material and methods: The scanner was a Somatom PLUS 4 (Siemens, Forchheim/Germany). The patients were scanned using a slice thickness of 3 mm and a table feed of 5 mm (pitch 1,6). The images were reconstructed with an increment of 1 mm. Contrast agent (150 ml) was applied intravenously with a flow of 2.5 ml/s and a start delay of 80 s. In one study the start delay was 20 s in order to visualise the carotid arteries (extracranial aneurysm). Volumetric data sets were postprocessed with ‘Vitrea’ and ‘VoxelView’ (Vital Images) volume rendering software on a Silicon Graphics O2 workstation (virtual laryngoscopy). Multiplanar reformation and colour-coded 3D-reconstruction were done on a Prominence workstation (Siemens/Forchheim/Germany). Results: In every region of the head and neck MPRs are useful as additional planes (with the exception of the hypopharynx and the larynx), SSDs are always useful if there is extensive bony destruction (skull, spine, skeleton larynx). Colour-coded three-dimensional reformations may be done for extensive tumours and before multi-specialty surgery. Perspective volume rendering is already in use for virtual endoscopy of the paranasal sinuses and the virtual laryngoscopy. In temporal bone evaluation, perspective volume rendering is a new and promising method of the future to assess the inner ear. Summary: Two- and three-dimensional displays are used to visualise pathological findings in their topographic relation to anatomical leading structures. Thus, the radiologist can point out to the clinician the pathological findings by some essential images without having to demonstrate all axial slices.

High-resolution virtual laryngoscopy based on spiral CT data

This pilot study investigated the feasibility and clinical value of high-resolution virtual real-time laryngoscopy based on helical CT data sets. Nine patients with laryngeal pathology (three with tumors of the vocal cords, two laryngeal carcinomas, one with invasion of the larynx by thyroid carcinoma and six subglottic stenoses) underwent examination by helical CT at a collimation of 1 mm. Following acquisition, the images were processed at a workstation with standard visualization software, such that virtual endoscopy (VE) in real time was possible. The images were then compared with the findings of conventional endoscopy. Because of swallowing artifacts, reconstruction failed in 2 of 12 patients. None of the carcinomas of the vocal cords was recognized at VE or in the cross-sectional CT images. VE provided the correct diagnosis in 8 of 12 cases (laryngeal tumors, subglottic stenoses). Virtual laryngoscopy is capable of simulating the visual findings of endoscopy in cases of laryngeal tumors and subglottic stenoses. Small tumors of the vocal cords are not adequately visualized. The major problem affecting results is motion artifacts resulting from involuntary swallowing.