Quantitative Evaluation of Subglottic Stenosis Using Ultrashort Echo Time MRI in a Rabbit Model

Abstract

Objective/Hypothesis: To assess the ability of ultra-short echo time (UTE)-MRI to detect subglottic stenosis (SGS) and evaluate response to balloon dilation. To correlate measurements from UTE-MRI with endotracheal-tube (ETT)-sizing and to investigate whether SGS causes change in airway dynamics.Study Design: Animal research study. Methods: Eight adult New-Zealand white rabbits were used as they approximate neonatal airway-size. The airways were measured using ETT-sizing and 3D UTE-MRI at baseline, 2 weeks post-cauterization induced SGS injury, and post-balloon dilation treatment. UTE-MR images were acquired to determine airway anatomy and motion. Airways were segmented from MR images. Cross-sectional area (CSA), major and minor diameters (D major and D minor ), and eccentricity were measured.Results: Post-injury CSA at SGS was significantly reduced (mean 38%) compared to baseline (P = .003) using UTE-MRI. ETT-sizing correlated significantly with MRI-measured CSA at the SGS location (r = 0.6; P < .01), particularly at the post-injury timepoint (r = 0.93; P < .01). Outer diameter from ETT-sizing (OD) correlated significantly with D major (r = 0.63; P < .01) from UTE-MRI at the SGS location, especially for the post-injury timepoint (r = 0.91; P < .01). Mean CSA of upper trachea did not change significantly between end-expiration and end-inspiration at any timepoint (all P > .05). Eccentricity of the upper trachea increased significantly post-balloon dilation (P < .05).Conclusions: UTE-MRI successfully detected SGS and treatment response in the rabbit model, with good correlation to ETT-sizing. Balloon dilation increased CSA at SGS, but not to baseline values. SGS did not alter dynamic motion for the trachea in this rabbit model; however, tracheas were significantly eccentric post-balloon dilation. UTE-MRI can detect SGS without sedation or ionizing radiation and may be a non-invasive alternative to ETT-sizing.

Bronchopulmonary dysplasia from chest radiographs to magnetic resonance imaging and computed tomography: adding value

“…Magnetic resonance imaging has been used to noninvasively investigate airway abnormalities such as tracheobronchomalacia and subglottic stenosis in neonates and animal models of neonates [101][102][103]. Retrospective respiratory gating of UTE MRI, the same sequence that evaluates the lung parenchyma, simultaneously allows measurement of 3-D dynamic changes in lumen size [74].…”

Utilizing a Functional Lumen Imaging Probe for Evaluation of the Pediatric Airway, A Pilot Study

“…Non-invasive methods that utilize radiographic studies, including computed tomography and magnetic resonance imaging, have been demonstrated accuracy in detection and quantification of subglottic stenosis. [11][12][13] 3D airway reconstructions of the airway based on endoscopic video evaluation have been shown to be reliable strategies in both phantom airway modeling, as well as ex-vivo animal experiments. [14][15][16] However, these processes can be time consuming, may subject patients to ionizing radiation, and do not provide intraoperative feedback.…”

“…Currently, the standard method of evaluating subglottic stenosis described by Myer et.al 4 is limited by its single dimensionality; it does not provide other important information, such as the location or length of stenosis. Non‐invasive methods that utilize radiographic studies, including computed tomography and magnetic resonance imaging, have been demonstrated accuracy in detection and quantification of subglottic stenosis 11–13 . 3D airway reconstructions of the airway based on endoscopic video evaluation have been shown to be reliable strategies in both phantom airway modeling, as well as ex‐vivo animal experiments 14–16 .…”