imaging of the larynx goalsdistribute.cmetoronto.ca/mim1202/1002-1030-bartlett-the... ·...

10/09/2012

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Imaging of the Larynx

Eric S. Bartlett, MPH MD

www.HeadAndNeckRad.com

Assistant ProfessorNeuroradiology, Head and Neck DivisionJoint Department of Medical ImagingDepartment of Otolaryngology—Head and Neck SurgeryUniversity of TorontoPrincess Margaret Hospital

Goals:

• Describe basic function of larynx

• Define the role of imaging

• Review anatomy

• Identify squamous cell carcinoma (SCCa) & pitfalls.

• Introduction: Function / Embryology / Role of imaging

• Imaging Methods

• Anatomy: Larynx (& Hypopharynx)

• SCCa and Pitfalls.



• Imaging Methods




Preface:

Why consider the larynx and hypopharynx together?

Duplexed structures

Introduction • Function• Embryology• Role of Imaging

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• Larynx:

– Phonation

– Maintenance of the airway

– Protection against aspiration.

Function:

1. Introduction

• Larynx:

– 2 distinct portions separated at laryngeal ventricle:

• Supraglottic larynx: primitive buccopharyngeal anlage*

– Lush lymphatic system

• Glottic and Subglottic larynx: tracheobronchial buds

– Sparse lymphatics.

Embryology:

1. Foregut2. Stomach3. Hindgut4. Midgut5. Pharyngeal gut6. Esophagus7. Tracheobronchial diverticulum8. Buccopharyngeal membrane9. Cloacal membrane10. Stomodeum11. Cloaca12. Gallbladder13. Liver14. Pancreas15. Vitelline duct16. Allantois

http://www.embryo.chronolab.com/digestive.htm

*

1. Introduction

• Larynx:

– Endolaryngeal mucosa is readily visualized:

• Indirect with mirror

• Direct with endoscope

• If inconclusive, direct exam under anesthesia, biopsy

• >95% of malignancies are squamous cell carcinoma (SCCa)

The Role of Imaging:

1. Introduction

• Larynx:

– Pathology often identified relatively early due to:

• Changes in phonation (hoarseness)

• Breathing difficulties (stridor, dyspnea)

• Aspiration

• Hemoptysis

• Odynophagia (painful / difficult swallowing)

• Referred otalgia


1. Introduction

• Vagus nerve (CN 10): pyriform sinus

• Larynx:

– Radiologist:

• Sub-mucosal / deep soft tissue extension of disease (pre-epiglottic space, paraglottic space, etc)

• Cartilage involvement

• Extralaryngeal extension of disease

• Staging of the neck (nodal status).


1. Introduction


• Imaging Methods




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Imaging • CT• MRI

• Preferred modality (available, fast, higher res)

• Total IV contrast = 105 cc, 2-stage bolus

– 1st bolus: 50 cc at 1.5 cc/sec

– 2nd bolus: 55 cc at 1.5 cc/sec, approx. 130 seconds after start of 1st bolus

– SCAN: total of 160 seconds delay

Contrast-Enhanced CT:

2. Imaging Methods

• Above orbits through clavicles, 2 mm slices

Carina

2. Imaging Methods


• Reformats:

– Axial along the plane of the glottis, 1 mm slices.

2. Imaging Methods

Standard AxialGlottic Reformats


• Reformats:

– 2mm Coronal and Sagittal (essential).

2. Imaging Methods


• Limited application for larynx / hypopharynx

– Usually poor quality images due to motion from breathing, swallowing, secretions

MRI:

2. Imaging Methods

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• Imaging Methods




Anatomy • Larynx

• (Hyopharynx)

Anatomy—Larynx:

• Cartilages

• Endolarynx― Supraglottis

― Glottis

― Subglottis

Anatomy—Larynx:

• Cartilages


― Glottis

― Subglottis

Laryngeal Cartilages:

Cricoid

Cricothyroid Ligament

Inf. Horn Thyroid Cart.

Thyroid Cartilage

Arytenoid Cartilage

Corniculate Cartilage

Sup. Horn Thyroid Cart.

Thyrohyoid Membrane

Hyoid Bone

EpiglottisAnterior Posterior

3. Anatomy Larynx / Hypopharynx

• Thyroid Cartilage:– Largest laryngeal cartilage,

shields larynx

– Superior cornua attach to thyrohyoid ligament

– Inferior cornua articulate medially with cricoid cartilage


Posterior View


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• Cricoid Cartilage:– Only complete ring in larynx;

provides structural integrity

– “Signet ring”;

• anterior arch = band

• posterior lamina = signet

– Lower border = junction of larynx and trachea

– Conservative surgical therapy will not be successful if tumor present within the cricoid


PosteriorAnterior


• Arytenoid Cartilage:– Paired pyramidal cartilages

– Sit on top of posterior cricoid cartilage lamina

– Most in supraglottis; vertical height spans the ventricle

– Vocal* and muscular*processes are at level of true vocal cord

– Superior process at false cord


*

*

Posterior View




Hyoid BoneThyroid CartilageArytenoid CartilageCricoid Cartilage

• Cartilages


― Glottis

― Subglottis


Anatomy—Larynx:

Larynx

• Supraglottic

• Glottic

• Subglottic

Hyoid Bone

Thyroid Cartilage

Cricoid Cartilage


Supraglottic LarynxFalse Vocal Cord

Aryepiglottic Fold

Pre-epiglottic Fat


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Glottis

True Vocal Cord

Arytenoid Cartilage

Cricoid

Paraglottic Fat Stripe

Thyroarytenoid Muscle

Anterior Commissure

Posterior Commissure


Subglottic Larynx

Thyroid Cartilage

Cricoid


• Hyoid bone to inferior cricoid cartilage

• 3 Regions:

– Posterior wall

– Pyriform sinus

– Post-cricoid


Anatomy—Hypopharynx:Hypopharynx

• Posterior Wall

• Pyriform Sinus

• Post-Cricoid

Hyoid Bone

Thyroid Cartilage

Cricoid Cartilage

Trachea

Transverse Arytenoid muscle


Hypopharynx

• Posterior Wall

• Pyriform Sinus

• Post-Cricoid

Mucosa overlying the posterior confluence of

the aryepiglottic folds


Imaging Anatomy

CT of the Larynx and Hypopharynx

Transverse and Oblique Arytenoid Muscles

Supraglottic Larynx

Pyriform Sinus

Posterior Wall

Posterior confluence of the Aryepiglottic

Folds


For a review of the axial CT anatomy of the Larynx, please visit us on-line at:www.headandneckrad.com

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• Imaging Methods




SCCa & Pitfalls

• Larynx• (Hypopharynx)

Duplexed structures

SCCa Risk Factors:• Smoking• Alcohol ingestion

4. SCCa and Pitfalls

• Tumor extension:

– Superior to Inferior: Transglottic

– Anterior / Lateral: Extralaryngeal

– Posterior: Anterior hypopharyngeal wall

• Cartilage:

– Thyroid cartilage has variable calcification / ossification that can mimic tumor invasion when asymmetric.

– Look for paraglottic fat.

SCCa and Pitfalls: Larynx


• Tumor extension:

– Anterior: larynx (thyroarytenoid and cricothyroid tunnels)

– Posterior: pre-vertebral space (invasion = non-surgical)

– Lateral: around posterior thyroid cartilage; >180 involvement of the ICA / CCA = non surgical.

• Distant metastasis

SCCa and Pitfalls: Hypopharynx


Supraglottic SCCa:


1/2

70-y.o. female with 15-month history of “laryngitis” with

pain and hoarseness.

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Supraglottic SCCa:

2/2


Glottic SCCa:60-y.o. male with 5-month

history of hoarseness.

1/2


Glottic SCCa:

2/2


Subglottic SCCa:59-y.o. male with 5 month history of dysphonia; laryngoscopy showed an exophytic mass just inferior to the anterior Commissure

1/4

Trachea


Subglottic SCCa:

2/4


Trachea

Subglottic SCCa:

3/4


Trachea

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Subglottic SCCa:

4/4


Extra-laryngeal SCCa:

1/1


Widened Thyro-Arytenoid Tunnel:

Crico-thyroid Tunnel 1/1

Thyro-arytenoid Tunnel


SCCa: AE Fold + Transverse Arytenoid:70-y.o. female with dysphagia and dysphonia. 50 pack-

year smoker and moderate alcohol drinker. No otalgia.

1/3


2/3

SCCa: AE Fold + Transverse Arytenoid:


Normal thyro-arytenoid tunnel

3/3

SCCa: AE Fold + Transverse Arytenoid:


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Goals, revisited:

• Describe basic function of larynx

• Define the role of imaging

• Review anatomy

• Identify squamous cell carcinoma (SCCa) & pitfalls.

HeadAndNeckRadwww.headandneckrad.com

• Site dedicated to Head and Neck Radiology education and research• Free access• Features:

• Anatomy• Lectures• Interactive Tutorials• ‘Case of the Month’• Protocols and Imaging Policies• Research• Links• Monthly Newsletter

Eric S Bartlett, MPH MD & Eugene Yu, MD

Thank You!

Eric S. Bartlett, MPH MD

www.HeadAndNeckRad.com

Assistant ProfessorUniversity of Toronto Joint Department of Medical ImagingNeuroradiology, Head and Neck DivisionDepartment of Otolaryngology, Head and Neck SurgeryPrincess Margaret Hospital

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