Comparison of four MR carotid surface coils at 3T

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.

A 12-channel flexible receiver coil for accelerated tongue imaging

Objective

MRI of the tongue requires acceleration to minimise motion artefacts and to facilitate real-time imaging of swallowing. To accelerate tongue MRI, we designed a dedicated flexible receiver coil.

Materials and methods

We designed a flexible 12-channel receiver coil for tongue MRI at 3T and compared it to a conventional head-and-neck coil regarding SNR and g-factor. Furthermore, two accelerated imaging techniques were evaluated using both coils: multiband (MB) diffusion-tensor imaging (DTI) and real-time MRI of swallowing.

Results

The flexible coil had significantly higher SNR in the anterior (2.1 times higher, P = 0.002) and posterior (2.0 times higher, P < 0.001) parts of the tongue, while the g-factor was lower at higher acceleration. Unlike for the flexible coil, the apparent diffusion coefficient (P = 0.001) and fractional anisotropy (P = 0.008) deteriorated significantly while using the conventional coil after accelerating DTI with MB. The image quality of real-time MRI of swallowing was significantly better for hyoid elevation (P = 0.029) using the flexible coil.

Conclusion

Facilitated by higher SNR and lower g-factor values, our flexible tongue coil allows faster imaging, which was successfully demonstrated in MB DTI and real-time MRI of swallowing.

Electronic supplementary material

The online version of this article (10.1007/s10334-019-00824-5) contains supplementary material, which is available to authorized users.