Clinical Applications of Oral and Laryngeal Ultrasonography: From Anatomy to Treatment Planning

Ra-Gyoung Yoon¹, Dong Han Kim²

​

^{1 Korea University Ansan Hospital, Korea, Republic of}

^{2 Nowon Eulji Medical Center, Eulji University, Korea, Republic of}

Overview

• Oral cavity US
• Techniques
• Normal sonographic appearance
• Clinical cases in pathological conditions

• Laryngeal US
• Technical considerations
• Normal sonographic laryngeal anatomy
• Dynamic vocal cord evaluation
• Clinical cases in pathological conditions

Oral Cavity Ultrasonography

• Technical considerations
• A high-frequency linear (5–12-MHz) transducer
• A small-footprint linear array ("hockey-stick") transducer (7–15 MHz)

• Superior spatial resolution for superficial structures (0.3-0.5mm)
• Effective visualization of the mucosal-submucosal interface
• Clear delineation of muscles
• Adequate penetration depth (3-4 cm) for most oral pathologies

Oral Cavity

Oral Cavity Ultrasonography

• The hockey-stick transducer
• Provides high-resolution anatomy of the mucosa, submucosa, and muscular layers (intrinsic and extrinsic tongue muscles)
• Aiding in differential diagnosis
• Characterization of inflammatory or non-neoplastic conditions
• Identifying minor salivary gland tumors
• Assessment of tumor thickness and depth of invasion in oral squamous cell carcinoma

🡺 Aiding TNM staging and surgical planning

​

Oral Cavity

Oral Cavity Ultrasonography

• Ultra-high frequency ultrasound (UHFUS)
• Recently introduced ultrasonographic technique (30-100 MHz)
• Providing high spatial resolution (pixel size as small as 30 µm)
• Tongue, buccal mucosa, gingiva, lip mucosa can be scanned

​

Izzetti R et al. Dentomaxillofac Radiol. 2020;49(7):20190318

Filiform papillae

Oral Cavity

Hockey-stick transducer

Mucosa

– Thin superficial hypoechoic line (white arrow)

​

Submucosa

– Linear hyperechoic layer (yellow arrow)

Intrinsic Muscles

Identified according to their fiber orientation

​

- Superficial longitudinal (red arrow)

- Transverse muscles (blue arrow)

Anatomy and Normal US Appearance of Tongue

Linear transducer

Oral Cavity

Lesion Characterization – Glandular hypertrophy

Linear transducer US evaluation

Unilateral sublingual salivary gland hypertrophy

US Findings

- Isoechoic to the normal sublingual gland

- No evidence of disruption of normal tissue

19/M

CT

MRI

Oral Cavity

Lesion Characterization - Oral Lichen Planus

• Reticular oral lichen planus

- Thick hypoechoic oral mucosa with increased vascularity

• Erosive oral lichen planus

- Hypoechoic area with irregular margins (ulceration), showing irregularity of the interface between mucosa and submucosa

• Plaque-like oral lichen planus

- Markedly hypoechoic area inside the hypoechoic mucosal layer

[Izzetti R et al. Skin Res Technol. 2020;26:200-204]

Oral Cavity

• Malignancies show:
• Hypoechoic, heterogeneous mass with irregular/spiculated margins
• Disruption of normal tissue planes
• Infiltration into deeper muscular layers

​

​

Lesion Characterization - Malignancy

Linear transducer US findings of tongue squamous cell carcinoma

MRI

Oral Cavity

Applications of US in Oncology

• Measurement of tumor thickness (TT) in oral cavity squamous cell carcinoma (SCC)
• High degree of reliability with histological measurements for TT
• Consistency ratio = 91.4 % to 98.2 %

​

​

• US can be more accurate than CT or MRI when used for preoperative assessment for tongue cancer
• US can detect lesions that are undetectable by CT or MRI because of dental artifact

​

​

Baek CH et al. Otolaryngol Head Neck Surg. 2008;139:805-810.

Nair AV et al. Indian J Radiol Imaging. 2018;28:140-145.

Songra AK et al. Int J Oral Maxillofac Surg. 2006;35:324-331.

Caprioli S et al. Int J Environ Res Public Health. 2022;19:14900.

Nogami S et al. Oral Sci Int 2022;19:24–30

Oral Cavity

Tumor Thickness Assessment

Nogami S et al. Oral Sci Int 2022;19:24–30

MR, US and histopathological findings (H&E staining) before the biopsy

MR, US and histopathological findings (H&E staining) after the biopsy

Oral Cavity

Applications of US in Oncology

• Measurement of depth of invasion (DOI) in oral cavity SCC
• Stronger correlation between mriDOI and pDOI than that between usDOI and pDOI

​

• Robust correlation between usDOI and pDOI

​

​

• US better determines the DOI in T1 lesions
• Tumors with a DOI up to 10 mm (pT1-2 tumors)
• Intraoral US is more accurate than MRI
• MRI tends to overestimate DOI

​

• MRI remains the most accurate method for T3 lesions

​

​

Iida Y et al. Laryngoscope 2018;128:2778–2782

Nilsson, O. et al. Laryngoscope Investig Otolaryngol. 2022;5;1448-1455

Noorlag R et al. Oral Oncol 2020;110:104895

Rocchetti F et al. Oral Surg Oral Med Oral Pathol Oral Radiol 2021;131:130–138.

Caprioli S et al. Cancers (Basel) 2023;15: 17

Nilsson, O. et al. Laryngoscope Investig Otolaryngol. 2022;5;1448-1455

Oral Cavity

Depth of Invasion Assessment

Example measurements of mobile tongue squamous cell carcinoma on:

MRI (COR CE-T1WI), depth of invasion 11 mm

US, depth of invasion 10 mm. Tumor is hypoechoic in comparison with the normal echogenic tongue musculature.

​

Histologic depth of invasion after surgery 12 mm

[US - Linear transducer]

COR CE-T1WI

Ax CE-T1WI

Oral Cavity

Applications of US in Oncology

• Ultrasound-assisted resection of oral tongue cancer
• US-assisted surgery for T1/ T2 tumors could improve the deep resection margins
• Significant improvement in the US-assisted resections, 55% clear deep margins vs 15% in conventional resections

​

• 76.5% of the US-assisted resections had clear deep margins

​

​

Nilsson O et al. Acta Otolaryngol. 2022;142(9-12):743-748.

[US-assisted surgery measuring the deep resection margin]

• Black arrow - deep tumor border

de Koning KJ et al. Oral Oncol. 2022;133:106023.

Nilsson O et al. Acta Otolaryngol. 2022;142(9-12):743-748.

Oral Cavity

Laryngeal Ultrasonography

• Technical Considerations
• A high-frequency linear (5–12-MHz) transducer
• Patient positioning with slight neck extension
• Examination during quiet respiration and phonation
• The air-tissue interface can create strong reflections

Larynx

Anatomy and Normal US Appearance of Larynx

(A) At the level of the epiglottis

Thyrohyoid (TH) and sternohyoid (SH) muscles

Thyrohyoid membrane (white arrows)

Preepiglottic space (*)

Hypoechoic epiglottis (yellow arrows)

(B-C) At the level of the cricothyroid and inferior thyroid laminae with partially adducted vocal cord state

Vocal cords (white arrows)

Anterior commissure (yellow arrow)

False vocal cord (*)

Arytenoid cartilage (blue arrows)

(B)

Larynx

Clinical Applications of US for Larynx

• Detecting minor invasion of laryngeal subsites for accurate T staging of laryngeal SCC
• Real-time dynamic assessment of vocal cord mobility for functional evaluation
• Guidance for fine-needle aspiration or core needle biopsy

​

Larynx

Real-time Dynamic Vocal Cord Evaluation

Vocal cord mobility assessment of right vocal cord palsy patient

​

Dynamic ultrasound at the vocal cord level demonstrates preserved mobility of the left vocal cord during both abduction and adduction.

In contrast, the right vocal cord remains fixed in a paramedian position during phonation, indicating impaired mobility.

​

The axial contrast-enhanced CT image demonstrates a heterogeneously enhancing nodule in the right thyroid lobe, protruding posteriorly.

Abduction

Adduction

Axial CT

Larynx

Applications of US in Oncology

(A-B) CT and MRI indicate invasion of the paraglottic space by laryngeal cancer (*).

(C) Equivalent right paramedian transverse plane US.

There is a focal invasion of the inner cortex of the thyroid cartilage (arrows).

No definite tumor extension beyond the outer cortex of the thyroid cartilage was

identified.

🡪 T3 stage

Glottic cancer extension assessment on US

Larynx

Applications of US in Oncology

(A-B) CT indicate fungating mass in the right aryepiglottic fold and vallecular

​

(C-D) Equivalent transverse and longitudinal plane US.

There is no definite tumor extension beyond the pre-epiglottic space

🡪 T2 stage

​

Supraglottic cancer assessment on US

(A)

(B)

(C)

(D)

Larynx

Applications of US in Oncology

• Assessment of subsite invasion in laryngeal SCC
• High concordance rate between US and CT (86.4%–100%)
• US more frequently demonstrated invasion of the inner cortex of the thyroid cartilage than CT (40.9% vs. 22.7%)

​

• US shows higher sensitivity for the detection of overall thyroid cartilage invasion than CT (US; 98% vs CT; 91%)
• The specificity of US was higher than that of CT for the evaluation of paraglottic space invasion

​

US can depict each layer of unossified thyroid cartilage from the inner cortex to the outer cortex

Ahn D et al. Auris Nasus Larynx. 2022;49(5):868-874

Dhoot NM et al. J Ultrasound 2017;20:205–11.

Xia CX at al. Br J Radiol 2013;86:20130343

Larynx

Applications of US in Oncology

• Assessment of T staging in laryngeal SCC
• US accuracy: 82.9% ~ 83.3%
• Limitations of US
• Upstaging or underestimation of the tumor size
• Fails to depict the boundaries of the entire tumor
• Masked by ossified thyroid cartilage, hyoid bone, or endolaryngeal air

​

Concurrent use of US for thyroid cartilage and/or when the invasion is ambiguous or inconclusive on CT

​

Ahn D et al. Auris Nasus Larynx. 2022;49(5):868-874

Larynx

Conclusion

• Ultrasonography can offer complementary information in oral and laryngeal assessment
• High-resolution anatomical visualization enables precise evaluation of subtle or minor changes
• Complements CT and MRI for tumor staging by detecting subtle mucosal and submucosal changes
• Dynamic evaluation provides functional information

​

• Radiologists should be familiar with US anatomy and its clinical applications, and consider its expanding role in head and neck imaging.

References

1. Izzetti R, Vitali S, Aringhieri G, Oranges T, Dini V, Nisi M, Graziani F, Gabriele M, Caramella D. Discovering a new anatomy: exploration of oral mucosa with ultra-high frequency ultrasound. Dentomaxillofac Radiol. 2020;49(7):20190318.
2. Beale T, Twigg VM, Horta M, Morley S. High-Resolution Laryngeal US: Imaging Technique, Normal Anatomy, and Spectrum of Disease. Radiographics. 2020;40(3):775-790.
3. Cergan R, Dumitru M, Vrinceanu D, Neagos A, Jeican II, Ciuluvica RC. Ultrasonography of the larynx: Novel use during the SARS-CoV-2 pandemic (Review). Exp Ther Med. 2021;21(3):273.
4. Ahn D, Kwak JH, Lee GJ, Sohn JH. Ultrasonography for masses of the pharynx and larynx and assessment of laryngeal squamous cell carcinoma. Auris Nasus Larynx. 2022;49(5):868-874.
5. Lo WC, Chang CM, Cheng PC, Wen MH, Wang CT, Cheng PW, Liao LJ. The Applications and Potential Developments of Ultrasound in Oral Cancer Management. Technol Cancer Res Treat. 2022;21:15330338221133216.
6. Di Stasio D, Romano A, Montella M, Contaldo M, Petruzzi M, Hasan I, Serpico R, Lucchese A. Quantitative Ultrasound Analysis of Oral Mucosa: An Observational Cross-Sectional Study. Applied Sciences. 2022; 12(14):6829.
7. Nilsson O, Knutsson J, Landström FJ, Magnuson A, von Beckerath M. Ultrasound-assisted resection of oral tongue cancer. Acta Otolaryngol. 2022;142(9-12):743-748.
8. Nilsson, O., Knutsson, J., Landström, F. J., Magnuson, A., and von Beckerath, M. 2022. Ultrasound accurately assesses depth of invasion in T1-T2 oral tongue cancer. Laryngoscope Investig Otolaryngol. 7, 5, 1448-1455.
9. Russo A, Patanè V, Fusco L, Faggioni L, Boschetti CE, Santagata M, Neri E, Cappabianca S, Reginelli A. Reliability of Ultrasonographic Assessment of Depth of Invasion and Tumor Thickness in Intraoral Mucosa Lesions: A Preliminary Experience. J Clin Med. 2024;13(9):2595.
10. Esperouz F, Caponio VCA, Santarelli A, Ballini A, Lo Muzio L, Ciavarella D, Lo Russo L. Are we ready to use ultrasounds in the clinical assessment of depth of invasion and tumor thickness in oral squamous cell carcinoma? Results from a systematic review, meta-analysis and trial sequential analysis. Oral Oncol. 2024 ;159:107104.
11. Baek CH, Son YI, Jeong HS, Chung MK, Park KN, Ko YH, Kim HJ. Intraoral sonography-assisted resection of T1-2 tongue cancer for adequate deep resection. Otolaryngol Head Neck Surg. 2008;139(6):805-10.
12. Nair AV, Meera M, Rajamma BM, Anirudh S, Nazer PK, Ramachandran PV. Preoperative ultrasonography for tumor thickness evaluation in guiding management in patients with early oral tongue squamous cell carcinoma. Indian J Radiol Imaging. 2018;28(2):140-145.
13. Songra AK, Ng SY, Farthing P, Hutchison IL, Bradley PF. Observation of tumour thickness and resection margin at surgical excision of primary oral squamous cell carcinoma--assessment by ultrasound. Int J Oral Maxillofac Surg. 2006;35(4):324-31.
14. Caprioli S, Casaleggio A, Tagliafico AS, Conforti C, Borda F, Fiannacca M, Filauro M, Iandelli A, Marchi F, Parrinello G, Peretti G, Cittadini G. High-Frequency Intraoral Ultrasound for Preoperative Assessment of Depth of Invasion for Early Tongue Squamous Cell Carcinoma: Radiological-Pathological Correlations. Int J Environ Res Public Health. 2022;19(22):14900.
15. Nogami S, Yamauchi K, Kitamura J, Miyashita H, Kojima I, Kouketsu A, et al. The accuracy of ultrasound and magnetic resonance imaging for estimating thickness of oral tongue squamous cell carcinoma and influence of biopsy on those findings. Oral Sci Int 2022;19(1):24–30
16. Iida Y, Kamijo T, Kusafuka K, Omae K, Nishiya Y, Hamaguchi N, et al. Depth of invasion in superficial oral tongue carcinoma quantified using intraoral ultrasonography. Laryngoscope 2018;128(12):2778–82.
17. Rocchetti F, Tenore G, Montori A, Cassoni A, Cantisani V, Di Segni M, et al. Preoperative evaluation of tumor depth of invasion in oral squamous cell carcinoma with intraoral ultrasonography: A retrospective study. Oral Surg Oral Med Oral Pathol Oral Radiol 2021;131(1):130–8
18. Noorlag R, Klein Nulent TJW, Delwel VEJ, Pameijer FA, Willems SM, de Bree R, et al. Assessment of tumour depth in early tongue cancer: Accuracy of MRI and intraoral ultrasound. Oral Oncol 2020;110:104895
19. Dhoot NM, Choudhury B, Kataki AC, Kakoti L, Ahmed S, Sharma J. Effectiveness of ultrasonography and computed tomography in assessing thyroid cartilage invasion in laryngeal and hypopharyngeal cancers. J Ultrasound 2017;20:205–11
20. Xia CX, Zhu Q, Zhao HX, Yan F, Li SL, Zhang SM. Usefulness of ultrasonography in assessment of laryngeal carcinoma. Br J Radiol 2013;86:20130343.