the value of mri in imaging malignant head and neck tumours

The Value of MRI in Imaging Malignant Head andNeck Tumours

Astrid Schneider, Rosemarie ForstnerUniversitatsinstitut fur Radiologie, Salzburger Landeskrankenanstalten, Paracelsus Private Medical University Salzburg, Salzburg,Austria

Correspondence to:Astrid Schneider, M.D.Universitatsinstitut fur Radiologie, Salzburger Landeskrankenanstalten, Paracelsus Private Medical University Salzburg, MuellnerHauptstrasse 48, 5020 Salzburg, AustriaTel/fax: ++43/662/4482; E-mail: [email protected]

Key words: MRI, head and neck cancer, laryngeal cancer, hypopharyngeal cancer, oropharyngeal cancer.

Summary

Magnetic resonance imaging (MRI) plays an important

role in pre-treatment assessment of tumours of the head

and neck region. Because of its excellent soft tissue

contrast it renders pivotal information in staging and

serves as a basis for surgery planning or primary chemo-

and/or radiotherapy. Primary tumours are best seen on

T2WI with fat saturation or contrast-enhanced images.

Morphologic criteria used for lymph node imaging

depend on size and shape, and thus MRI is limited in

differentiation of normal size malignant nodes or hyper-

plastic benign nodes. Necrosis is a more specific sign of

malignancy.In this review, imaging technique and imag-

ing of tumours in the head and neck region in general

and for specific areas are covered with the emphasis on

MR imaging features of the primary tumours and their

spread including perineural and lymphatic dissemination.

Uncooperative or claustrophobic patients, however,

should undergo staging by computerized tomography

instead of MRI.

Introduction

Naso-, oro- and hypopharyngeal carcinoma, and cancers

of the larynx and the paranasal sinuses account for the

most common malignancies in the head and neck area.

Rare tumours include: lymphoepithelial carcinoma, non-

Hodgkin lymphoma, Hodgkin lymphoma, melanomas

and tumours originating in the salivary glands such

as mucoepidermoid carcinoma and adenoid-cystic

carcinoma (1).

Pharyngeal and laryngeal tumours are associated with

consumption of alcohol and tobacco, whereas in case of

paranasal sinus cancer the exposure to organic

fibres found in the wood, shoe and textile industry is

relevant (2, 27).

In the United States, oral cavity and pharynx cancer

ranges ninth in the list of cancers in males (3).

Imaging technique

In the assessment of a suspected cancer in the head and

neck region magnetic resonance imaging (MRI) should be

performed using thin-slice sections. Slice thickness

of 3–5 mm is performed, applying T1, T2 and T1-

gadolinium (GD)-DTPA in the axial and coronal planes,

with sagittal sections added in paramidline lesions involv-

ing the tongue, lips and anterior floor of the mouth.

Fat saturation (FS) MRI is considered to improve the

detection and delineation of head and neck lesions,

because of the abundance of fat and the complex

anatomy of the head and neck (4). Disadvantages of FS

MRI, such as uneven fat suppression in a large field of

view and in areas with sharp changes in anatomy,

increase in susceptibility artefacts around air-containing

structures and low signal-to-noise ratio are outweighed

by the advantage of increased and superior contrast

(5, 6).

Contrast-enhanced FS T1-weighted images offer com-

plementary information on the precise characterization of

complex tumours such as vascularization, tumour necrosis,

perineural tumour spread and meningeal infiltration (7). FS

T2-weighted images offer better contrast between tumours

and adjacent muscle, fat and mucosa as compared with

contrast-enhanced FS T1-weighted images (8).

Imaging features

Primary tumours

Malignant head and neck tumours commonly present as

diffuse or focal mucosal thickening or as an expansile soft

tissue mass (9). The lesions present mostly as hypointese to

isointense (relative to muscles) on T1-weighted images and

remain hypointense or moderately hyperintense on

T2-weighted images (9) (Fig. 1).

In general, on T2WI signal of cancers is less intense than

that of normal adenoid tissue; but often this difference in

signal intensity is not sufficient to confidently differentiate

2/2007 n IMAGING DECISIONS

between a carcinoma and normal adenoids. Contrast

enhancement improves the assessment of the internal

architecture of the tumour, and moderate to intense

enhancement on Gd-enhanced images is seen. Most

tumours are best depicted on FS T2WI and on contrast-

enhanced FS T1WI (6).

Lymph node metastases

On computerized tomography (CT) and MR morphologic

criteria including size, homogeneity, shape, margins of

lymph node and the presence of necrosis determine

whether a node is abnormal. Metastatic nodes are often

large, round in shape, have a necrotic centre and

have ill-defined margins with stranding of the surrounding

fat.

The most commonly used size criteria for suspected

malignancy in a lymph node is a short axis diameter of

8 mm or more. In the carotid triangle, lymph nodes of

up to 10 mm can be reactive. The roundness index

(longitudinal- to transverse diameter ratio) is a valuable

tool for predicting malignancy. A roundness index of

greater than 2 indicates reactive nodes in 84% and an

index of less than 1.5 predicts metastatic disease in 71%

(10–12).

Lymph nodes are best depicted on T1WI signal as

isointense to the muscle and surrounded by hyperintense

fat. On T2WI they appear hyperintense with focal central

hyperintensity in the case of necrosis. Contrast-enhanced

T1FS facilitates the depiction of lymph node metastases as

enhancing lesions. Furthermore, contrast media allows best

detection of necrosis with a central area of lower signal

intensity and a periphery with enhancing higher signal

intensity on T1-weighted images (13). Unfortunately,

mildly enlarged metastatic lymph nodes cannot be differ-

entiated from hyperplastic nodes, and metastases in normal

size lymph nodes cannot be diagnosed by MRI unless they

show necrosis (Fig. 2).

Perineural spread

Perineural spread implies tumour extension to non-

contiguous areas along the endoneurium or perineurium

(14). Tumour extension typically occurs in a centripetal

fashion towards the brain but also centrifugal growing at

branch points is possible. For example, tumour that has

extended intracranially along a trigeminal branch may

extend centrifugally back out of the skull along another

division of the trigeminal nerve (15).

Imaging findings of perineural tumour spread include

foraminal enlargement and destruction, obliteration of fat

planes, nerve enlargement, nerve enhancement, neuro-

pathic atrophy, convexity of the lateral cavernous sinus

wall and replacement of the trigeminal subarachnoid

cistern with soft tissue (16).

Nasopharyngeal carcinoma

Nasopahryngeal cancer (NPC) typically originates in the

fossa of Rosenmueller. Patients remain asymptomatic for a

(a)

(b)

(c)

j Fig. 1. (a) T1, (b) T2 fat saturation, (c) contrast-enhanced T1. A mass (arrow) in the right tonsillar regionis seen which is isointense in T1 (a), moderately hyperin-tense in T2 (b) and shows an inhomogeneous contrastenhancement after intravenous gadolinium (c). A centralfocus of necrosis is inhomogeneous and contains small fociof low SI corresponding to air.

4 n M R I I N I M A G I N G M A L I G N A N T H E A D A N D N E C K T U M O U R S

IMAGING DECISIONS n 2/2007

relatively long time, as this is a clinically occult site (17). As

a result, more than 90% of the patients present with locally

and/or regionally advanced disease. Bone erosion into the

skull base with or without impairment of cranial nerves is

common at diagnosis.

Focal or diffuse thickening of the nasopharyngeal

mucosa and cervical lymphadenopathy are the most

common presentation of nasopharyngeal carcinomas in

imaging. In MRI these lesions appear mostly hypointense-

to-isointense on T1WI, hypointense-to-moderately hyper-

intense on T2WI (Fig. 3), and show moderate-to-intense

enhancement on contrast-enhanced sequences (9).

NPC can penetrate the tough pharyngobasilar fascia

extending from the top of the constrictor pharyngis superior

muscle to the skull base because of its locally aggressive

nature. It can also directly breach the foramen of Morgagni

in the pharyngobasilar fascia, a gap in the upper ventral

pharyngobasilar fascia through which the Eustachian tube

and the levator veli palatine muscle extend. NPC can also

expand to the pharyngeal muscles and rapidly spread to the

parapharyngeal, retropharyngeal and masticator spaces.

Invasion of the skull base usually occurs through the

skull base mostly via the foramen lacerum and the neural

foramina of the middle cranial fossa floor. Further tumour

extension can involve the orbit, cavernous sinus (Fig. 4)

and even the brain stem (9).

MRI appears to be superior to CT in the assessment of

tumour invasion into soft tissue and bony structures, in

identification of pharyngobasilar fascia obliteration,

invasion of the skull base and in imaging lymph

node metastases to the carotid and retropharyngeal

spaces (18).

(a)

(b)

(c)

j Fig. 2. Lymph node metastasis (arrow) in coronal T-1weighted (a) and transaxial T2-weighted image with fatsaturation (b) in oropharyngeal cancer. In the left mandibularangle an enlarged lymph node with slightly irregularcontours is seen. The central necrosis (small arrow) is bestappreciated on the contrast-enhanced image (c). Necrosisin a lymph node is a sign suggestive of malignancy.

j Fig. 3. Small epipharyngeal cancer (arrow). On theT2-weighted image slight asymmetry with demonstration ofa mildly hyperintese lesion in the lateral wall of theepipharynx is seen, which is located posterior to the torustubarius.

M R I I N I M A G I N G M A L I G N A N T H E A D A N D N E C K T U M O U R S n 5


Cancers of the oropharynx and buccal cavity

Buccal cavity cancer can arise from the buccal floor, the

mobile portion of the tongue, the cheek, the palate and the

gingival crest. Lesions of the oropharynx arise in the lateral

wall (tonsillar fossa, anterior and posterior fauces, palatine

tonsil, glosso-palatine sulcus), the anterior wall (base of the

tongue, valleculae), superior wall (antero-inferior surface of

the soft palate, free edge of the palate and uvula) and

posterior wall (19) (Fig. 5).

Cancer of the base of the tongue is associated with the

worst prognosis because of its fairly minor clinical symp-

toms it is often detected late. Clinical appearance can be

ulcers or masses that do not heal, dental changes or poorly

fitting dentures, and in some cases, referred otalgia. Lip

and tongue caners present as exophytic or ulcerative

lesions often associated with pain (2). Contrast-enhanced

MRI shows homogeneously or inhomogeneously enhanc-

ing lesions (Fig. 6).

A combination of contrast-enhanced T1WI and T2-

weighted images defines the depth of infiltration into the

intrinsic musculature, into the floor of the mouth,

parapharyngeal space or other adjacent structures. Partic-

ularly palate tumours tend to spread perineurally via the

pterygoideal and pterygopalatine fossa (20). Tumours of

the floor of the mouth, the lower lip and the chin can also

follow the inferior alveolar nerve, and tumours of the

tongue can extend along the lingual nerve to reach the

cavernous sinus (21).

Hypopharyngeal carcinoma

Hypopharyngeal carcinoma originates on the mucosal

surface of hypopharynx. The most common subsite is the

pyriform sinus from where posterolateral tumour spread

into cervical soft tissues with erosion of ipsilateral thyroid

cartilage may occur.

Further sites are the post-cricoid region with a tendency

for infiltration anteriorly into the larynx, and inferiorly into

the cervical oesophagus and the posterior hypopharyngeal

wall with infiltration posteriorly into the retropharyngeal

space, the prevertebral space and laterally into cervical soft

tissues.

MRI findings include a mass with low-to-intermediate

T1 signal, low-to-moderate hyperintense SI on T2WI and

intermediate-to-high signal intensity on T2 and T2FSWI,

and a commonly heterogeneous enhancement after GD-

contrast (22) (Fig. 7). Signs suggestive of cartilage invasion

are an inhomogeneous signal loss of normally hyperin-

tense cartilage tissue in T1WI with high SI on T2WI or

T2FS (23).

(a)

(b)

j Fig. 4. At time of diagnosis non-operable tumour (arrow)infiltrating left and right sinus cavernosus, axial (a) andcoronal (b) contrast-enhanced T1 fat saturation.

j Fig. 5. Oropharyngeal cancer in a T2-weighted image.A cancer of 1.5 cm in size (long arrow) is seen as a solidmildly hyperintese, well-delineated lesion in the lateralaspect of the oropharynx. A left cervical lymph nodemetastasis (short arrow) displays inhomogeneous signalas a result of necrosis.



Laryngeal cancer

Anatomically, laryngeal cancer is divided into supraglottic,

glottic and subglottic types.

Supraglottic laryngeal cancer presents as a moderately

enhancing, infiltrating mass of the epiglottis, aryepiglottic

fold or false vocal cord, often associated with adenopathy

suggesting malignancy on imaging (24) (Fig. 8).

At time of diagnosis glottic laryngeal cancer tends to be

usually small. It typically presents as an invasive or

exophytic homogeneously enhancing mass arising from

the mucosal surface of the glottic larynx and is located

commonly at the true vocal cord level (24).

Infraglottic laryngeal cancer can either spread anteri-

orly through the cricothyroid membrane into the thyroid

gland, posteriorly into the cricoid cartilage and oesoph-

agus, inferior into the tracheal lumen and cartilaginous

rings or cephalad to invade the true vocal cords and

supraglottis.

In differentiating glottic from hypopharyngeal tumours

the modified Valsalva manoeuvre, which consists of an

expiration against the resistance of the closed glottis,

may be useful. Phonation manoeuvres are also useful

when the exact location of a laryngeal tumour remains

undefined following a quiet respiration examination

because the true and false vocal cords are not clearly

depicted (25).

For the assessment of glottic carcinomas CT seems

superior to MRI because of the shorter acquisition time

and thinner slice sections. Other laryngeal tumours,

however, are better visualized in MRI (26). Functional

MRI images, such as Valsalva¢s manoeuvre and phonation

studies may also be performed in MRI by using ultrafast

sequences and increase the diagnostic performance of MRI

in this area (26).

(a)

(b)

(c)

j Fig. 6. Oropharyngeal carcinoma originating from thefloor of the mouth (arrow). In the left lateral aspect of thefloor of the mouth a band-like lesion is seen which displacelow SI on T1WI (a), high SI on T2WI (b) and moderatepredominantly homogeneous contrast enhancement (c).There is no evidence of bony destruction of the mandibularbone.

j Fig. 7. On a coronal T1WI a large bilateral cancer(arrows) is seen which is demonstrated as a solid coat-likelesion extending from the hypopharynx to the epipharynx.



Paranasal sinus cancer

Risk factors for developing paranasal sinus cancer are

exposure to thorotrast, chromium, nickel, isopropyl oils,

organic fibres found in the wood, shoe and textile indus-

tries and possibly formaldehyde. Further predisposing

factors are tobacco smoke, exposure to human papilloma

viruses (HPV) and chronic sinusits. The most common

symptoms include facial or dental pain, nasal obstruction

and epistaxis (27).

Locally advanced lesions in the ethmoid sinus may

extend into the anterior cranial fossa via the cribriform

plate or into the orbit through the lamina papyracea. From

sphenoid sinus, disease may directly extend through the

lateral bony wall into the cavernous sinus. It can also

invade the middle cranial fossa directly or via the

infraorbital nerve. Affected patients may complain of

diplopia, blured vision, proptosis, paresthesias in the

distribution of the trigeminal nerve or trismus if the

pterygoid muscles are invaded (27). The typical finding in

imaging includes a solid, moderately enhancing lesion

originating from the paranasal sinus with associated

aggressive bone destruction in advanced cases (Fig. 9).

In T1WI, paranasal sinus cancer presents as an inter-

mediate signal mass; areas of intratumoural haemorrhage

may show a high T1 signal. The T2-weighted images show

intermediate-to-high signal compared with musculature.

T2WI allows differentiation of the high SI in sinus

obstructed secretions from the tumour which displays

lower SI. Contrast enhancement is typically heterogenous

mild-to-moderate. For the assessment of subtle bone

destruction complementary thin section CT are useful (27).

Staging

Head and neck tumours are staged according to

the Tumour Node Metastasis (TNM) system. This

(a)

(b)

j Fig. 8. Supraglottic laryngeal cancer (arrow). Axial T2WIwith fat saturation (FS) (a) and coronal contrast-enhancedT1WI with FS (b) demonstrate bilateral thickening of theepiglottis. On (a), the cancer is slightly inhomogeneous andslightly hyperintense. On (b), it is less enhancing comparedwith the surrounding structures.

(a)

(b)

j Fig. 9. Squamous cell carcinoma of the left maxillarysinus in coronal T1 (a) and axial T2WI with fat saturation (b).A soft tissue mass fills the left maxillary sinus. In the medialaspect it extends to the nasal cavity (a) (long arrow). In thelateral posterior aspect it grows continuously into thepterygopalatine fossa (b) (short arrow). Bony destruction isseen on (b).



classification takes into account the size of the tumour, the

depth of penetration and invasion of adjacent organs. It

also describes lymph node involvement and spread to

distant organs (28).

In head and neck malignancies the tumour stage at the

time of diagnosis is strongly related to the localization of

the primary tumour. Because of early symptoms larynx

carcinomas and as a result of its visibility oropharyngeal

malignancies are mostly diagnosed in early stages (T1/T2).

In contrast, carcinomas of the epipharynx and hypophar-

ynx become typically clinically symptomatic in advanced

stages (T3/T4).

In up to 50%, these tumours are accompanied by lymph

node metastases at time of diagnosis (Fig. 10).

The lowest probability of metastases show laryngeal

carcinomas and high rates can be found in oro- and

hypopharyngeal carcinomas (29). Just T1 tumours show a

low risk for nodal metastases. Tumour grading is also an

important predictor for metastases. Hence well-differenti-

ated carcinomas almost never show contralateral lymph

node metastases or metastases larger than 6 cm in size (29).

In the pre-operative assessment, staging by CT and MRI

is widely used for treatment stratification including surgery

planning and treatment with radiotherapy and/or chemo-

therapy. The advantage of MRI compared with CT is its

superior soft tissue contrast. However, if the patient is not

able to cooperate or unable to lie still CT should be

performed because of its shorter acquisition time and

reduction of movement artefacts. MRI is also a valuable

tool in pre-operative planning of tumours in the nasophar-

ynx and oropharynx, particularly when dental artefacts are

present. It is also valuable in sinunasal or epiphayrynx

cancers to diagnose skull base invasion or in suspected

perineural invasion (9). However, CT is still irreplaceable

for detection of subtle cortical erosion. However, for bone

marrow invasion MR is more sensitive than CT (30).

References

1. Schantz Sessions RB, Harrison LB, Forastiere AA. Cancer of the head

and neck. In: De Vita VT, Hellman S, Rosenberg SA (eds) Cancer

Principles and Practice of Oncology, vol. 1. Lippincott Williams and

Wilkins, Philadeplphia, 2001; 797–906.

2. Stenson KM, Brockstein BE, Chung TDK: Overview of Head and

Neck Cancer. http://www.uptodate, 2007.

3. American Cancer Society Inc., Surveillance Research. American

Cancer Society, Inc., 2007.

4. Tien RD, Hesselink JR, Chu PK et al. Improved detection and

delineation of head and neck lesions with fat suppression spin-echo

MR imaging. AJNR 1991; 12: 19–24.

5. Lau KY, Kan WK, Sze WM et al. Magnetic resonance for T-staging

of nasopharyngeal carcinoma – the most informative pair of

sequences. Jpn J Clin Oncol 2004; 34: 171–175.

6. Tien RD, Robbins KT. Correlation of clinical, surgical, pathologic,

and MR fat suppression results for head and neck cancer. Head Neck

1992; 14: 278–284.

7. Su CY, Lui CC. Perineural invasion of the trigeminal nerve in

patients with nasopharyngeal carcinoma: imaging and clinical corre-

lations. Cancer 1996; 78: 2063–2069.

8. Dubin MD, Teresi LM, Bradley WG et al. Conspicuity of tumors of

the head and neck on fat-suppressed MR images: T2-weighted fast-

spin-echo versus contrast-enhanced T1-weighted conventional spin-

echo sequences. AJR – Am J Roentgenol 1995; 164: 1213–1221.

9. Chin SC, Fatterpekar G, Chen CY et al. MR imaging of diverse

manifestations of nasopharyngeal carcinomas. AJR 2003; 180:

1715–1722.

10. Solbiati L, Rizzatto G. Ultrasound of Superficial Structures. Churchill

Livingstone, Edinburgh, 1995.

11. Solbiati L, Arsizio B, Rizzatto G et al. High-resolution sonography of

cervical lymph nodes in head and neck cancer: criteria for differen-

tiation of reactive versus malignant nodes. Radiology 1988; 169: 113.

12. Gritzmann N, Hollerweger A, Macheiner P et al. Sonography of soft

tissue masses of the neck. J Clin Ultrasound 2002; 30: 356–373.

13. Barakos JA, Dillon WP, Chew WM. Orbit, skull base, and pharynx:

contrast enhanced fat suppression MR imaging. Radiology 1991; 179:

191–198.

14. Caldemeyer KS, Mathews VP, Righi PD et al. Imaging features and

clinical significance of perineural spread or extension of head and

neck tumors. RadioGraphics 1998; 18: 97–110.

15. Parker GD, Harnsberger HR. Clinical-radiologic issues in perineural

tumor spread of malignant diseases of the extracranial head and neck.

RadioGraphics 1991; 11: 383–399.

16. Laine FJ, Braun IF, Jensen ME, Nadel L, Som PM. Perineural tumor

extension through the foramen ovale: evaluation with MR imaging.

Radiology 1990; 174: 65–71.

(a)

(b)

j Fig. 10. Extensive lymph node metastasis (long arrow)at the time of diagnosis caused by a left hypopharyngealcarcinoma [short arrow in (b)] seen on transaxial T1WI (a)and coronal contrast-enhanced T1WI with fat saturation (b).



17. Leong JL, Fong KW, Low WK. Factors contributing to delayed

diagnosis in nasopharyngeal carcinoma. J Laryngol Otol 1999; 113:

633–636.

18. Sakata K, Hareyama M, Tamakawa M et al. Prognostic factors of

nasopharynx tumors investigated by MR imaging and the value of

MR imaging in the newly published TNM staging. Int J Radiat Oncol

Biol Phys 1999; 43: 273–278.

19. Weber AL, Romo L, Hashimi S. Malignant tumors of the oral cavity

and oropharynx: clinical, pathologic, and radiologic evaluation.

Neuroimaging Clin N Am 2003; 13: 443–464.

20. Czerny C, Formanek M. Maligne tumoren des pharynx. Radiologe

2000; 40: 625–631.

21. Matzko J, Becker DG, Phillips CD. Obliteration of fat planes by

perineural spread of squamous cell carcinoma along the inferiour

alveolar nerve. AJNR 1994; 15: 1843–1845.

22. Cure J. SCCa hypopharyngeal III-3. In: Harnsberger HC, Wiggins

RH, Hudgins PA (eds) Diagnostic Imaging Head and Neck. Amirsys

Inc, Salt Lake City, UT, 2004; 32–35.

23. Vogl TJ, Balzer J, Mack M, Steger W. Hypopharynx und larynx. In:

Radiologische Differentialdiagnostik in der Kopf-Hals-Region. Thi-

eme Verlag, 1998; 311–329.

24. Wiggins RH. SCCa, larynx, supraglottic/glottic/subglottic III-3. In:

Harnsberger HC, Wiggins RH, Hudgins PA (eds) Diagnostic

Imaging Head and Neck. Amirsys Inc, Salt Lake City, UT, 2004;

18–27.

25. Henrot P, Blum A, Toussaint B et al. Dynamic maneuvers in local

staging of head and neck malignancies with current imaging tech-

niques: principles and clinical applications. RadioGraphics 2003; 23:

1201–1213.

26. Held P, Langnickel R, Breit A. CT and MRI in tumors of the

hypopharynx and larynx – comparison of methods with reference to

rapid and ultrafast MR pulse sequences. Laryngorhinootologie 1994;

73: 59–64.

27. Michel MA. Squamous cell carcinoma, Sinonasal II-2. In: Harns-

berger HC, Wiggins RH, Hudgins PA (eds) Diagnostic Imaging Head

and Neck. Amirsys Inc, Salt Lake City, UT, 2004; 82–85.

28. TNM Classification Help, Manual for Cancer Staging. http://

cancerstaging.blogspot.com.

29. Remmert S, Rottmann M, Reichenbach M et al. Lymphknotenme-

tastasierung bei Kopf-Hals-Tumoren. Laryngo-Rhino-Otol 2001; 80:

27–35.

30. Bensimon JL, Buthiau D, Herbreteau D. Cancer of the nasopharynx.

In: Buthiau D, Khayat D (eds) CT and MRI in Oncology, chap. 11.

Springer, 1998; 113–116.

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the value of mri in imaging malignant head and neck tumours

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