Giriraj K. Sharma

Long-range Fourier domain optical coherence tomography of the pediatric subglottis

BACKGROUND Acquired subglottic stenosis (SGS) most commonly results from prolonged endotracheal intubation and is a diagnostic challenge in the intubated child. At present, no imaging modality allows for in vivo characterization of subglottic microanatomy to identify early signs of acquired SGS while the child remains intubated. Fourier domain optical coherence tomography (FD-OCT) is a minimally invasive, light-based imaging modality which provides high resolution, three dimensional (3D) cross-sectional images of biological tissue. We used long-range FD-OCT to image the subglottis in intubated pediatric patients undergoing minor head and neck surgical procedures in the operating room. METHODS A long-range FD-OCT system and rotary optical probes (1.2mm and 0.7mm outer diameters) were constructed. Forty-six pediatric patients (ages 2-16 years) undergoing minor upper airway surgery (e.g., tonsillectomy and adenoidectomy) were selected for intraoperative, trans-endotracheal tube FD-OCT of the subglottis. Images were analyzed for anatomical landmarks and subepithelial histology. Volumetric image sets were rendered into virtual 3D airway models in Mimics software. RESULTS FD-OCT was performed on 46 patients (ages 2-16 years) with no complications. Gross airway contour was visible on all 46 data sets. Twenty (43%) high-quality data sets clearly demonstrated airway anatomy (e.g., tracheal rings, cricoid and vocal folds) and layered microanatomy of the mucosa (e.g., epithelium, basement membrane and lamina propria). The remaining 26 data sets were discarded due to artifact, high signal-to-noise ratio or missing data. 3D airway models were allowed for user-controlled manipulation and multiplanar airway slicing (e.g., sagittal, coronal) for visualization of OCT data at multiple anatomic levels simultaneously. CONCLUSIONS Long-range FD-OCT produces high-resolution, 3D volumetric images of the pediatric subglottis. This technology offers a safe and practical means for in vivo evaluation of lower airway microanatomy in intubated pediatric patients. Ultimately, FD-OCT may be applied to serial monitoring of the neonatal subglottis in long-term intubated infants at risk for acquired SGS.

Intraoperative long range optical coherence tomography as a novel method of imaging the pediatric upper airway before and after adenotonsillectomy

BACKGROUND/OBJECTIVES While upper airway obstruction is a common problem in the pediatric population, the first-line treatment, adenotonsillectomy, fails in up to 20% of patients. The decision to proceed to surgery is often made without quantitative anatomic guidance. We evaluated the use of a novel technique, long-range optical coherence tomography (LR-OCT), to image the upper airway of children under general anesthesia immediately before and after tonsillectomy and/or adenoidectomy. We investigated the feasibility of LR-OCT to identify both normal anatomy and sites of airway narrowing and to quantitatively compare airway lumen size in the oropharyngeal and nasopharyngeal regions pre- and post-operatively. METHODS 46 children were imaged intraoperatively with a custom-designed LR-OCT system, both before and after adenotonsillectomy. These axial LR-OCT images were both rendered into 3D airway models for qualitative analysis and manually segmented for quantitative comparison of cross-sectional area. RESULTS LR-OCT images demonstrated normal anatomic structures (base of tongue, epiglottis) as well as regions of airway narrowing. Volumetric rendering of pre- and post-operative images clearly showed regions of airway collapse and post-surgical improvement in airway patency. Quantitative analysis of cross-sectional images showed an average change of 70.52mm(2) (standard deviation 47.87mm(2)) in the oropharynx after tonsillectomy and 105.58mm(2) (standard deviation 60.62mm(2)) in the nasopharynx after adenoidectomy. CONCLUSIONS LR-OCT is an emerging technology that rapidly generates 3D images of the pediatric upper airway in a feasible manner. This is the first step toward development of an office-based system to image awake pediatric subjects and thus better identify loci of airway obstruction prior to surgery.

In vivo cross-sectional imaging of the phonating larynx using long-range Doppler optical coherence tomography

Diagnosis and treatment of vocal fold lesions has been a long-evolving science for the otolaryngologist. Contemporary practice requires biopsy of a glottal lesion in the operating room under general anesthesia for diagnosis. Current in-office technology is limited to visualizing the surface of the vocal folds with fiber-optic or rigid endoscopy and using stroboscopic or high-speed video to infer information about submucosal processes. Previous efforts using optical coherence tomography (OCT) have been limited by small working distances and imaging ranges. Here we report the first full field, high-speed, and long-range OCT images of awake patients’ vocal folds as well as cross-sectional video and Doppler analysis of their vocal fold motions during phonation. These vertical-cavity surface-emitting laser source (VCSEL) OCT images offer depth resolved, high-resolution, high-speed, and panoramic images of both the true and false vocal folds. This technology has the potential to revolutionize in-office imaging of the larynx.

A Novel Device for Measurement of Subglottic Stenosis in 3 Dimensions During Suspension Laryngoscopy

IMPORTANCE A challenge in treating subglottic stenosis is assessment of airway caliber before and after management. At present, surgeons lack a simple, efficient, and precise method of measuring subglottic stenosis intraoperatively. We present a novel, easily reproducible tool for measurement of the diameter, location, and length of subglottic stenosis during suspension laryngoscopy. METHODS AND OBSERVATIONS A set of 5 Kirschner wires (30-cm length and 1.6-mm diameter) were bent 90° at both ends to produce a series of 10 short ends designed to measure airway diameter (0.3- to 2.1-cm length with 2-mm intervals). Short, bent ends of the measuring sticks were designed to measure airway diameter. Hash marks at 2-mm intervals were created along the long axis of the measuring sticks to measure subglottic stenosis length and location relative to the vocal cords. The measuring stick was tested in 10 adult patients undergoing suspension microlaryngoscopy for endoscopic treatment of subglottic stenosis between September 2012 and July 2013. The accuracy of the measuring stick was evaluated using an airway phantom. The measuring stick enabled easy and precise quantification of subglottic stenosis diameter (82.5% agreement with reference; interobserver agreement, r = 0.995; P < .001), length (72.5%; r = 0.995; P < .001) and location during suspension laryngoscopy. CONCLUSIONS AND RELEVANCE The measuring stick is inexpensive and simple to construct. It allows for safe, accurate, and practical measurement of subglottic stenosis diameter, length, and location during suspension laryngoscopy.

Long-Range Optical Coherence Tomography of the Neonatal Upper Airway for Early Diagnosis of Intubation-related Subglottic Injury.

RATIONALE Subglottic edema and acquired subglottic stenosis are potentially airway-compromising sequelae in neonates following endotracheal intubation. At present, no imaging modality is capable of in vivo diagnosis of subepithelial airway wall pathology as signs of intubation-related injury. OBJECTIVES To use Fourier domain long-range optical coherence tomography (LR-OCT) to acquire micrometer-resolution images of the airway wall of intubated neonates in a neonatal intensive care unit setting and to analyze images for histopathology and airway wall thickness. METHODS LR-OCT of the neonatal laryngotracheal airway was performed a total of 94 times on 72 subjects (age, 1-175 d; total intubation, 1-104 d). LR-OCT images of the airway wall were analyzed in MATLAB. Medical records were reviewed retrospectively for extubation outcome. MEASUREMENTS AND MAIN RESULTS Backward stepwise regression analysis demonstrated a statistically significant association between log(duration of intubation) and both laryngeal (P < 0.001; multiple r(2) = 0.44) and subglottic (P < 0.001; multiple r(2) = 0.55) airway wall thickness. Subjects with positive histopathology on LR-OCT images had a higher likelihood of extubation failure (odds ratio, 5.9; P = 0.007). Longer intubation time was found to be significantly associated with extubation failure. CONCLUSIONS LR-OCT allows for high-resolution evaluation and measurement of the airway wall in intubated neonates. Our data demonstrate a positive correlation between laryngeal and subglottic wall thickness and duration of intubation, suggestive of progressive soft tissue injury. LR-OCT may ultimately aid in the early diagnosis of postintubation subglottic injury and help reduce the incidences of failed extubation caused by subglottic edema or acquired subglottic stenosis in neonates. Clinical trial registered with www.clinicaltrials.gov (NCT 00544427).

Quantitative Evaluation of Adult Subglottic Stenosis Using Intraoperative Long-range Optical Coherence Tomography.

Objectives: To determine the feasibility of long-range optical coherence tomography (LR-OCT) as a tool to intraoperatively image and measure the subglottis and trachea during suspension microlaryngoscopy before and after endoscopic treatment of subglottic stenosis (SGS). Methods: Long-range optical coherence tomography of the adult subglottis and trachea was performed during suspension microlaryngoscopy before and after endoscopic treatment for SGS. The anteroposterior and transverse diameters, cross-sectional area (CSA), distance from the vocal cords, and length of the SGS were measured using a MATLAB software. Pre-intervention and postintervention airway dimensions were compared. Three-dimensional volumetric airway reconstructions were generated using medical image processing software (MIMICS). Results: Intraoperative LR-OCT imaging was performed in 3 patients undergoing endoscopic management of SGS. Statistically significant differences in mean anteroposterior diameter (P < .01), transverse diameter (P < .001), and CSA (P < .001) were noted between pre-intervention and postintervention data. Three-dimensional airway models were viewed in cross-sectional format and via virtual “fly through” bronchoscopy. Conclusions: This is the first report of intraoperative LR-OCT of the subglottic and tracheal airway before and after surgical management of SGS in humans. Long-range optical coherence tomography offers a practical means to measure the dimensions of SGS and acquire objective data on the response to endoscopic treatment of SGS.

Analysis and digital 3D modeling of long-range fourier-domain optical coherence tomography images of the pediatric subglottis

In neonatal and pediatric patients who require long-term endotracheal intubation, the subglottic mucosa is most susceptible to injury from the endotracheal tube. At present, there is no diagnostic modality to identify early signs of subglottic mucosal pathology. Fourier-domain optical coherence tomography (FD-OCT) is a minimally-invasive imaging modality which acquires high-resolution, 3D cross-sectional images of biological tissue. FD-OCT of the neonatal and pediatric airways was conducted to evaluate subglottic microanatomy and histopathologic changes associated with prolonged intubation. FD-OCT of the larynx, subglottis and proximal trachea was conducted in pediatric and neonatal patients. OCT image sets were analyzed by anatomic categorization (airway level), tissue segmentation and mucosa micrometry in MATLAB. Subsequently, OCT data sets were rendered into digital 3D airway models in Mimics software. We report original methods for subglottic OCT image processing and analysis.

Solid Variant of Aneurysmal Bone Cyst of the Temporal Bone

Objectives: Aneurysmal bone cysts (ABC) are benign, rapidly growing osteolytic lesions. Solid variant of ABC (SVABC) is a rare subtype of ABC that has not been reported in the temporal bone. Methods: We report the case of a 6-year-old boy presenting with a slowly enlarging bony protuberance over the right zygomatic/malar eminence region. Computed tomography and magnetic resonance imaging demonstrated a 2.6 × 5.8 × 5.1 cm temporal bone mass involving the right mastoid, petrous, and temporal squamosal calvarium, with extradural intracranial extension to the middle cranial fossa. Results: The patient underwent preoperative embolization of feeder arteries followed by combined neurosurgical and neurotologic resection. Histopathology revealed characteristic ABC features with interspersed areas of intralesional osteoid formation. Conclusion: Solid variant of ABCs are rare lesions of the skull base that present a diagnostic challenge given their unique radiographic and histologic features. Thorough cytogenetic evaluation is warranted to rule out potential malignant secondary causes. Early surgical resection is essential due to the risk of intracranial extension. This is the first report of ABC of any type with concurrent involvement of the squamous, mastoid, and petrous portions of the temporal bone and the first report of SVABC of the temporal bone.

Evaluation of the American College of Surgeons Thyroid and Parathyroid Ultrasound Course: Results of a Web-Based Survey

The American College of Surgeons Thyroid and Parathyroid Ultrasound Skills‐Oriented Course (TPUSC) was designed to teach surgeons how to interpret and perform office‐based head and neck ultrasound (HNUS). The objective of this study was to survey attendees of the TPUSC to evaluate the usefulness of the course, to track surgeon performed HNUS practice patterns, and to help identify potential roadblocks to incorporation of HNUS into a surgeons practice.

Is Nebulized Lidocaine Adequate Topical Anesthesia for Diagnostic Transnasal Tracheoscopy

Objectives: To evaluate if nebulized 4% lidocaine alone provides adequate laryngopharyngeal anesthesia for office-based diagnostic transnasal tracheoscopy (TNT). Methods: A retrospective chart review (January 2011 to June 2014) and a prospective case series (July 2014 to December 2014) of patients who underwent diagnostic TNT were performed at a university voice and swallowing center. TNT cases were categorized by method of topical laryngopharyngeal anesthesia: nebulized 4% lidocaine and 4% lidocaine drip (phase I) and nebulized 4% lidocaine only (phase II). Results: TNT was performed a total of 59 times on 38 patients. Eleven (69%) of 16 phase I TNT procedures involved significant patient discomfort and severe cough following the lidocaine drip. Forty-two (98%) of 43 phase II TNT procedures were completed comfortably; 1 case required additional anesthesia by lidocaine drip. Retrospectively, 100% (n = 8) of patients who underwent both phase I and phase II TNTs were noted to prefer anesthesia with nebulizer alone. In a prospective case series of 14 phase II TNT cases, 6 (86%) of 7 patients who previously underwent phase I TNT reported preference for anesthesia with nebulizer alone. Conclusions: Nebulized lidocaine appears to provide sufficient laryngopharyngeal anesthesia for diagnostic TNT. It is preferred by patients over laryngeal drip.