Magnetic resonance imaging of the larynx in the pediatric population: A systematic review

Observation of Anatomical Structures in the Human Larynx Using Micro-Computed Tomography with Lugol's Solution Enhancement

Histological and naked-eye dissections are frequently used to investigate human anatomy. However, limitations of conventional methods include tissue damage and difficulty in observing structures, rendering findings limited. Micro-computed tomography (micro-CT) allows for a three-dimensional observation with whole-mount staining for contrast enhancement. A precise anatomical understanding of the larynx is essential for both the medical and surgical fields; however, the larynx is difficult to dissect because of its minuscule and complex structures. Therefore, we aimed to clarify the detailed anatomy of the larynx using micro-CT. The study was conducted on twelve specimens of cadavers using Lugol-based-contrast micro-CT. Using Lugol-micro-CT, relevant information on human structures was obtained. Consequently, we successfully employed the Lugol-micro-CT technique in the analysis of specific human soft tissue structures that are challenging to analyze using conventional methods.

Guidelines for magnetic resonance imaging in pediatric head and neck pathologies: a multicentre international consensus paper

The use of standardized imaging protocols is paramount in order to facilitate comparable, reproducible images and, consequently, to optimize patient care. Standardized MR protocols are lacking when studying head and neck pathologies in the pediatric population. We propose an international, multicenter consensus paper focused on providing the best combination of acquisition time/technical requirements and image quality. Distinct protocols for different regions of the head and neck and, in some cases, for specific pathologies or clinical indications are recommended. This white paper is endorsed by several international scientific societies and it is the result of discussion, in consensus, among experts in pediatric head and neck imaging.

The value of 1.5T MRI in the evaluation of vocal fold mobility in patients with goiter

The laryngoscopic examination remains the gold standard in the perioperative evaluation of the mobility of the vocal folds in patients with goiter. During the COVID-19 pandemic, many medical procedures, including laryngoscopy are optimized in terms of epidemiological safety. Therefore, it seems deeply justified to implement methods like i.e. ultrasound or MRI which can provide the diagnostic information usually obtained via laryngoscopic examination.

Aim of the study

To determine the value of dynamic MRI examination in the 1.5 T field in the assessment of the mobility of vocal folds in patients with goiter compared to healthy people and in relation to ultrasound examinations and routine laryngoscopy.

Materials and methods

35 healthy volunteers and 44 patients with goiter were subjected to videolaryngoscopy, dynamic examinations of the vocal folds during respiration and phonation using ultrasound and the MRI sequences: generic gradient echo (GRE) and true fast imaging with steady-state precession (TRUFI). The qualitative and quantitative data were analyzed, i.e. the angles of deviation from the midline of the vocal folds and the area of the right and left rima glottidis compartments.

Results

No statistically significant differences were found between the groups of healthy volunteers and patients with goiter in the values of the angles of deviation of the vocal folds with the use of ultrasound and two MRI dynamic sequences - GRE and TRUFI. There were also no statistically significant differences in the areas of the rima glottidis compartments between these two groups with the use of two MRI dynamic sequences - GRE and TRUFI. Among the analyzed parameters, the maximum size of each rima glottidis compartment was the only one to show features of sexual dimorphism and was significantly higher in men (GRE p < 0.001 and TRUFI p = 0.001). There was no correlation between the size of the minimum and maximum rima glottidis compartment and the total volume of the thyroid lobes in patients with goiter for the GRE and TRUFI sequences.

Conclusions

MRI is a promising tool for the objective assessment of the mobility of the vocal folds in patients with goiter, as well as for the qualification for treatment and monitoring its effects. It is particularly important during an epidemiological emergency due to its safety compared to laryngoscopy. The presence of the goiter and its volume do not limit the possibility of performing dynamic imaging studies of the vocal folds and do not affect the surface area of the glottis.

High-resolution magnetic resonance and mass spectrometry imaging of the human larynx

High-resolution, noninvasive and nondestructive imaging of the subepithelial structures of the larynx would enhance microanatomic tissue assessment and clinical decision making; similarly, in situ molecular profiling of laryngeal tissue would enhance biomarker discovery and pathology readout. Towards these goals, we assessed the capabilities of high-resolution magnetic resonance imaging (MRI) and matrix-assisted laser desorption/ionisation-mass spectrometry (MALDI-MS) imaging of rarely reported paediatric and adult cadaveric larynges that contained pathologies. The donors were a 13-month-old male, a 10-year-old female with an infraglottic mucus retention cyst and a 74-year-old female with advanced polypoid degeneration and a mucus retention cyst. MR and molecular imaging data were corroborated using whole-organ histology. Our MR protocols imaged the larynges at 45-117 μm² in-plane resolution and capably resolved microanatomic structures that have not been previously reported radiographically-such as the vocal fold superficial lamina propria, vocal ligament and macula flavae; age-related tissue features-such as intramuscular fat deposition and cartilage ossification; and the lesions. Diffusion tensor imaging characterised differences in water diffusivity, primary tissue fibre orientation, and fractional anisotropy between the intrinsic laryngeal muscles, mucosae and lesions. MALDI-MS imaging revealed peptide signatures and putative protein assignments for the polypoid degeneration lesion and the N-glycan constituents of one mucus retention cyst. These imaging approaches have immediate application in experimental research and, with ongoing technology development, potential for future clinical application.

Structure and Function of the Vocal Cords after Airway Reconstruction on Magnetic Resonance Imaging

Objectives/Hypothesis

Dysphonia is a common problem at long‐term follow‐up after airway surgery for laryngotracheal stenosis (LTS) with major impact on quality of life. Dysphonia after LTS can be caused by scar tissue from initial stenosis along with anatomical alterations after surgery. There is need for a modality to noninvasively image structure and function of the reconstructed upper airways including the vocal cords to assess voice outcome and possible treatment after LTS. Our objective was to correlate vocal cord structure and function of patients after airway reconstruction for LTS on static and dynamic magnetic resonance imaging (MRI) to voice outcome.

Study Design

Prospective cohort study.

Methods

Voice outcome was assessed by voice questionnaires ((pediatric) Voice Handicap Index (p)VHI)) and the Dysphonia Severity Index (DSI). Postsurgical anatomy, airway lumen, and vocal cord thickness and movement on multiplanar static high‐resolution MRI and dynamic acquisitions during phonation was correlated to voice outcome.

Results

Forty‐eight patients (age 14.4 (range 7.5–30.7) years) and 11 healthy volunteers (15.9 (8.2–28.8) years) were included. Static MRI demonstrated vocal cord thickening in 80.9% of patients, correlated to a decrease in DSI (expected odds 0.75 [C.I. 0.58–0.96] P = .02). Dynamic MRI showed impaired vocal cord adduction during phonation in 61.7% of patients, associated with a lower DSI score (0.65 [C.I. 0.48–0.88] P = .006).

Conclusions

In LTS patients, after airway reconstruction MRI can safely provide excellent structural and functional detail of the vocal cords correlating to DSI, with further usefulness expected from technical refinements. We therefore suggest MRI as a tool for extensive imaging during LTS follow‐up.

Level of evidence

3 Laryngoscope, 131:E2402–E2408, 2021

MRI of the upper airways in children and young adults: the MUSIC study

RATIONALE

Paediatric laryngotracheal stenosis (LTS) is often successfully corrected with open airway surgery. However, respiratory and vocal sequelae frequently remain. Clinical care and surgical interventions could be improved with better understanding of these sequelae.

OBJECTIVE

The objective of this cross-sectional study was to develop an upper airway MRI protocol to obtain information on anatomical and functional sequelae post-LTS repair.

METHODS

Forty-eight patients (age 14.4 (range 7.5-30.7) years) and 11 healthy volunteers (15.9 (8.2-28.8) years) were included. Spirometry and static and dynamic upper airway MRI (3.0 T, 30 min protocol) were conducted. Analysis included assessment of postoperative anatomy and airway lumen measurements during static and dynamic (inspiration and phonation) acquisitions.

MAIN RESULTS

Good image quality without artefacts was achieved for static and dynamic images in the majority of MRIs. MRI showed vocal cord thickening in 80.9% of patients and compared with volunteers, a significant decrease in vocal cord lumen area (22.0 (IQR 17.7-30.3) mm² vs 35.1 (21.2-54.7) mm², p=0.03) but not cricoid lumen area (62.3±27.0 mm² vs 66.2±34.8 mm², p=0.70). Furthermore, 53.2% of patients had an A-frame deformation at site of previous tracheal cannula, showing lumen collapse during inspiration. Dynamic imaging showed incomplete vocal cord abduction during inspiration in 42.6% and incomplete adduction during phonation in 61.7% of patients.

CONCLUSIONS

Static and dynamic MRI is an excellent modality to non-invasively image anatomy, tissue characteristics and vocal cord dynamics of the upper airways. MRI-derived knowledge on postsurgical LTS sequelae might be used to improve surgery.

Magnetic resonance imaging of the larynx in the pediatric population: A systematic review

BACKGROUND

Magnetic Resonance Imaging (MRI) techniques to image the larynx have evolved rapidly into a promising and safe imaging modality, without need for sedation or ionizing radiation. MRI is therefore of great interest to image pediatric laryngeal diseases. Our aim was to review MRI developments relevant for the pediatric larynx and to discuss future imaging options.

METHODS

A systematic search was conducted to identify all morphological and diagnostic studies in which MRI was used to image the pediatric larynx, laryngeal disease, or vocal cords.

RESULTS

Fourteen articles were included: three studies on anatomical imaging of the larynx, two studies on Diffusion Weighted Imaging, four studies on vocal cord imaging and five studies on the effect of anaesthesiology on the pediatric larynx. MRI has been used for pediatric laryngeal imaging since 1991. MRI provides excellent soft tissue contrast and good visualization of vascular diseases such as haemangiomas. However, visualization of cartilaginous structures, with varying ossification during childhood, and tissue differentiation remain challenging. The latter has been partly overcome with diffusion weighted imaging (DWI), differentiating between benign and malignant masses with excellent sensitivity (94-94.4%) and specificity (91.2-100%). Vocal cord imaging evolved from static images focused on vocal tract growth to dynamic images able to detect abnormal vocal cord movement.

CONCLUSION

MRI is promising to evaluate the pediatric larynx, but studies using MRI as diagnostic imaging modality are scarce. New static and dynamic MR imaging techniques could be implemented in the pediatric population. Further research on imaging of pediatric laryngeal diseases should be conducted.