The Nuts and Bolts of Head and Neck Tumor

Evaluation

Colin McKnight, Kelly Malloy, Amanda Corey, Ashok Srinivasan

Presentation Number: eEdE-126

Disclosures

NONE

Purpose

To review the key imaging features that are crucial

to patient management as discussed in head and

neck tumor boards.

Approach

Various teaching points are critical to the radiologist’s ability to provide

useful and relevant insight into the pertinent imaging findings in a head

and neck tumor board case.

Topics covered include:

-Lymph nodal stations in the neck

-Accepted ranges for normal size in neck lymph nodes at different levels

-When is a lymph node morphologically abnormal?

-Where to look for the ‘unknown primary’

-What are ‘orphan’ lymph nodes?

-How is carotid artery encasement determined?

-Importance of TNM staging

Discussion

Lymph nodal stations in the neck:

How to divide the neck into different lymph nodal stations

Level I: All nodes above the hyoid bone, below the

mylohyoid muscle, and anterior to a line drawn through

the posterior edge of the submandibular gland.

Level IA: Lie between the medial margins of the anterior

bellies of the digastric muscles.

Level IB: Lie posterior and lateral to the medial edge of

the anterior belly of the digastric muscle, and anterior to

a line drawn between the posterior surface of the

submandibular glands.

II

I

V

II

I

V

IBIA

Discussion

Lymph nodal stations in the neck:

How to divide the neck into different lymph nodal stationsLevel II: Lie from the skull base, at the lower level of the

bony margin of the jugular fossa, to the level of the lower

body of the hyoid bone. Level II nodes lie anterior to a line

drawn through the posterior edge of the sternocleidomastoid

muscle and posterior to a line through the posterior edge of

the submandibular gland.

Level IIA: Lie anterior, lateral, or medial to the jugular vein; or

lie posterior to the internal jugular vein and are inseparable

from the vein.

Level IIB: Lie posterior to the internal jugular vein and have a

fat plane separating the nodes and the vein.

II

I

V

II

I

V

IIA

IIB

Discussion

Lymph nodal stations in the neck:

How to divide the neck into different lymph nodal stations

Level III: Lie between the level of the

lower body of the hyoid bone and the

lower margin of the cricoid cartilage arch,

anterior to the posterior edge of the

sternocleidomastoid muscle and lateral to

the common/internal carotid artery.

III

V

VI

III

IV

II

Discussion

Lymph nodal stations in the neck:

How to divide the neck into different lymph nodal stations

Level IV: Lie between the level of the lower

margin of the cricoid cartilage arch and the

level of the clavicle. These are located

anterior to the posterior edge of the

stenocleidomastoid muscle and the

posterolateral edge of the anterior scalene

muscle and are located lateral to the

common carotid artery.

IV

V

VI

III

IV

II

Discussion

Lymph nodal stations in the neck:

How to divide the neck into different lymph nodal stations

III

V

VILevel V: Extend from the skull base to the level of the clavicle.

Level VA: Lie between the levels of the skull base and the

bottom of the cricoid arch. These nodes are situated posterior to

a transverse line drawn on each axial scan through the posterior

edge of the sternocleidomastoid muscle.

Level VB: Lie between the axial level of the bottom of the cricoid

arch and the level of the clavicle. Level VB nodes lie posterior

and lateral to an oblique line through the posterior edge of the

sternocleidomastoid muscle and the posterolateral edge of the

anterior scalene muscle.

IV

V

VI

Discussion

Lymph nodal stations in the neck:

How to divide the neck into different lymph nodal stations

III

V

VIIV

V

VI

Level VI: Lie inferior to the lower body of the hyoid bone, superior to the top of the manubrium, and between the medial

margins of the left and right common carotid arteries or the internal carotid arteries.

Discussion

Lymph nodal stations in the neck:

How to divide the neck into different lymph nodal stations

Level VII: Lie caudal to the top of the manubrium in the

superior mediastinum, between the medial margins of the

left and right common carotid arteries. These nodes

extend caudally to the level of the innominate vein.

VII

Discussion

Accepted ranges for normal size in neck lymph nodes at different

levels:

AJR 1992 158(5):961-969

-Nodal size criteria can be used when nodes are homogenous and

clearly delineated.

-Upper limit for short axis is 11 mm for jugulodigastric lymph nodes and

10 mm for all other nodes.

-Upper limit for greatest nodal diameter is 1.5 cm for jugulodigastric,

submandibular and submental nodes, and 1 cm for all other nodes.

-Retropharyngeal node <8mm

Discussion

Accepted ranges for normal size in neck lymph nodes at different

levels:

AJR 1992 158(5):961-969

There is an error rate of  ≈  10 - 20% if using size criteria alone.

The long to short axis ratio has also been proposed to help evaluate

enlarged nodes in the setting of head and neck SCC.

When nodes have a ratio of >2 (ie long and flat) 95% are benign. When

the ratio is less than 2 (i.e. rounder) then a similar proportion where

malignant.

Discussion

When is a lymph node morphologically abnormal?

Rounded

(long-short axis ratio <2)

Low density or cystic

(internal low attenuation

without thick rim)

Discussion

When is a lymph node morphologically abnormal?

Necrotic Calcified

E.g., papillary thyroid cancer

metastases, tuberculosis

Internal low T1 signal with

peripheral thick rim of

enhancement

Pericapsular infiltration implies

worse prognosis

Extracapsular spread

Discussion

Where to look for the ‘Unknown Primary’:

Where is the primary tumor?

Metastatic lymph node

Discussion

Where to look for the ‘Unknown Primary’:

Look at:

1. Nasopharynx

2. Oropharynx –

(Base of tongue/palatine tonsil)

3. Supraglottic larynx

4. Pyriform sinus

5. Thyroid gland

Occasionally none is seen on CT.

Next step…

PET CT

Primary SCC in palatine tonsillar fossa

DiscussionWhat are ‘Orphan’ Lymph Nodes?

Lymph nodes in the face and retropharyngeal region that do

not fit into the nodal stations from I-VIIWith permission from Radiology 1993; 188(3):695-700.

DiscussionZygomatic group lymph nodes:

T2 T1 Post

Recurrent SCC in right cheek

Discussion

Parotid space mass. Where are the nodes?

While the retropharyngeal lymph node is apparent on the T2W

image, it is easier to appreciate on the diffusion image

Discussion

One more:

Zygomatic lymph node

Discussion

-Do not forget retropharyngeal lymph

nodes.

-These are probably the most

commonly missed lymph nodes in the

neck

-Look for asymmetry, as well as

displacement of the carotid artery

Discussion

How is carotid encasement determined?

-Determined by calculating degree of

circumferential contact around the carotid artery by

tumor

>270 degrees considered threshold for

encasement

-Makes the tumor inoperable

-Increases risk of carotid blowout

Shows 3600 involvement

suggestive of encasement

Discussion

Importance of TNM staging:

1. Dictates prognosis

2. Treatment is based on staging

T1 – T2: Single modality: surgery vs radiation therapy

T3 – T4: Combination of both

T4: Can be locally advanced, may not do surgery

Discussion

Importance of TNM staging:

Laryngeal Cancer:

Discussion

Importance of TNM staging:

Laryngeal Cancer:

-Invades paraglottic fat

-Was clinically staged as T2

-Upstaged to T3 based on CT

Normal

paraglottic fat

Effaced

paraglottic fat

Discussion

-Lesion involves supraglottis, glottis, subglottis

-Lesion is transglottic

-While this remains T3, the surgical approach is

changed

Importance of TNM staging:

Subglottic

involvement

Discussion

Nasopharyngeal cancer staging:

-Invasion of the medial pterygoid: Upstaged to T4 based on imaging

Discussion

Nasopharyngeal cancer staging:

-Also, there is an involved retropharyngeal lymph node

-Skull base invasion, if present, would reflect T3 disease

-Invasion of longus colli muscle: While not in TNM staging, implies worse prognosis

-Intracranial extension would qualify as T4 disease

Discussion

Nasopharyngeal cancer staging:

Discussion

Squamous cell cancer staging:

Invasion of the genioglossus and hyoglossus:

Extrinsic tongue muscle invasion is T4 disease

MRI Confirms invasion

Discussion

Squamous cell cancer staging:

Another patient with invasion of posterior genioglossus indicating T4 disease; the

normal muscle on the left is depicted as well

Patient with pyriform sinus cancer shows loss of fat planes on CT with the prevertebral muscle. If truly involved, this would be T4 disease.

MRI is a better modality for making this assessment and shows no convincing extension into the muscles. At surgery, the muscle was free from tumor.

Discussion

Squamous cell cancer staging:

Normal fat plane of separation

DiscussionRemember Perineural Spread

Right Parotid acinic cell CA with perineural spread

along the facial nerve involving multiple segments.

The genu of the facial nerve …And the IAC

Note anterior spread from genu to involve the greater superfical petrosal nerve

that reached up to the pterygopalatine fossa and also retrogradely involve the maxillary N.

Discussion

Utility of fat suppression imaging:

Separating fatty atrophy from tumor

Increased conspicuity of primary tumor borders after contrast

administration

“Revealing” small lesions including perineural spread surrounded by

fat

Discussion

Fatty denervation versus tumor

Fat sat imaging helpful

because fat is abundant in the

neck.

Fat sat imaging reveals fatty denervation in the right tongue from hypoglossal nerve

palsy. Clinically diagnosed as bulky tongue lesion

T1 + Without Fat saturation T1 + With Fat saturation

Right neck SCC

Perineural spread along V3 nerve is seen much more conspicuously with fat saturation (Sometimes subtle

enhancement such as this can be seen only after fat saturation)

Discussion

Summary

Knowing the imaging pearls and pitfalls in head and neck tumors

is crucial to making a difference to patient management

Contact: cmcknig@med.umich.edu

Bibliography

1. Som PM, Curtin HD, Mancuso AA. Imaging-based nodal classification for evaluation of

neck metastatic adenopathy. AJR 2000; 174(3):837-844.

2. Som PM. Detection of metastasis in cervical lymph nodes: CT and MRI criteria and

differential diagnosis. AJR 1992; 158(5):961-969.

3. Tart RP, Mukherji SK, Avio AJ, Stringer SP, Mancuso AA. Facial lymph nodes: normal

and abnormal CT appearance. Radiology 1993; 188(3):695-700.