Imaging of nasopharyngeal carcinoma

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Imaging of nasopharyngeal carcinoma

• ATTIA M, KOUKI S, LANDOULSI M,BOUGUERRA S,AROUSY,
  BOUJEMAA H, BEN ABDALLAH N.

HEAD AND NECK HN 21
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INTRODUCTION

• Nasopharyngeal carcinoma is a non-lymphomatous,
  squamous-cell carcinoma that occurs in the
  epithelial lining of the nasopharynx.
• This neoplasm shows varying degrees of
  differentiation and is frequently seen at the
  pharyngeal recess (Rosenmüllers fossa)
  posteromedial to the medial crura of the
  eustachian tube opening in the nasopharynx.
• Many histological entities exist from Squamous
  Cell Carcinoma (SCC) to the more frequent
  Undifferentiated Carcinoma of the Nasopharyngeal
  Type (UCNT), and these entities share endemic
  areas throughout the world

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• the disease occurs with much greater frequency in
  southern China, northern Africa, and Alaska.
• While NPC may occur at any age, it has a bimodal
  distribution with the first peak of occurrence in
  the 1525 years age range and the second peak in
  the fourth to fifth decade.
• EBV infection is clearly associated with NPC.

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• The symptomatology is variable and misleading.
• The diagnosis is  based on endoscopy  biopsy.
• The imaging has an interest in
• The diagnosis (fossa of Rosenmüller  )
• The staging of the tumor.
• The post therapeutic surveillance.
• The aims of our study are to -Remind the normal
  radioanatomy.- Know the main routes of
  extension.- State the purpose of imaging during
  the post treatmentmonitoring .

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Normal anatomy

• The nasopharynx is a mucosal lined,
  tubular-shaped midline structure which
  constitutes the superior extendt of the airway.
• Its cranial border is limited by the skull
  base(sphenoid sinus and clivus)
• The posterior margin of the nasopharynx extends
  to the prevertebral muscles and soft tissues.
• Anteriorly, the nasopharynx freely communicates
  with the nasal cavity through the posterior
  choane.
• Laterally it abuts the pyramidal- shaped
  parapharyngeal spaces.

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Normal anatomy

• The rigid and tough pharyngobasilar fascia
  provides structural support for the nasopharynx.
• The fascia forms a three-sided curtain which
  opens anteriorly toward the nasal cavity.
• Superiorly, the fascia is fixed to the skull base
  from the pterygoid plates to the carotid canal.
• Lateraly it is adherent to the cartilaginous
  portion of the eustachian tube.
• It forms a closed and resistant barrier
• The sinus of Morgagni is the only defect through
  which the eustachian tube and the levator veli
  palatini muscle pass.

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• As a result of the close proximity of the foramen
  lacerum and foramen ovale to the sinus of
  Morgagni and eustachian tube there exists a
  potential pathway for the spread of disease to
  cranial cavity.

the foramen ovale
the foramen lacerum
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Radioanatomy
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Radioanatomy
nasopharynx
Rosenmullers fossa
T2 weighted image
T1 weighted image
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Radioanatomy
nasopharynx
T2 weighted image
CT image
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Extension pathways.

• The nasopharyngeal tumor may extend straight
  up to the base of the skull, down to the
  oropharynx and to the nasal cavities forward.

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Extension pathways

• Lateral to the pharyngobasilar fascia, the
  nasopharynx is bounded by four spaces which are
  divided by three layers of deep cervical fascia.
• These include the masticator (infratemporal
  fossa), the parapharyngeal, the carotid and the
  parotid spaces.
• Lateral deviation and or infiltration of the
  parapharyngeal fat are sensitive indicators of
  the spread of nasopharyngeal disease.

Dark pharyngobasilar fascia. Blue
parapharyngeal space. Green the masticator
space. Red the carotid space.
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Imaging techniques
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Computed tomography

• Advantages
• Detecting bone erosion and cervical lymph node.
• Limits
• Analysing the peripharyngeal spaces and
  perinervous extension.

• Performing exam
• Extending from the skull base to the thoracic
  inlet
• ( cervical adenopathy)
• Thin slices ( 1-3mm)
• intravenous contrast enhancement ( 2cc/Kg)

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MRI

• Technique
• Exploration in the three plans of the space in
  T1, T2 andT1 gadolinium / - FatSat.
•  Advantages
• - Extension to the skull base.Extension to the
  deep face spaces .
• - Perinervous and perivascular extension.

• limits
• Claustrophobia.
• Metallic components

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TNM classification

• T1 Tumor confined to the nasopharynx.
• T2 Extension to T2a nasal cavity and
  / or oropharynx, T2b parapharyngeal space.
• T3 Extension bone and / or sinuses.
• T4 intracranial extension, cranial
  nerves, the hypopharynx, withinfratemporal
  fossa and / or the orbit.

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TNM classification

• N0 No regional metastatic ADP.
•  N1  metastatic (s) unilateral (s)
  ADP (s), ltor equal to 6 cm, above
  the supraclavicular fossa.(NB ADP located in
  the midline are consideredipsilateral). N2
   metastatic bilateral ADPltor equal to 6 cm in the
  largest dimension, above the supraclavicular
  fossa. N3  metastatic (s) ADP (s) N3Agt 6 cm
  , N3b at the supraclavicular fossa.
• M M0 no metastases, M1 metastases.Distant
  metastases   bones, liver, lung, pleura

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Results

• 5 patients were evaluated with MRI before and
  after contrast material.
• 10 patients with advanced stages had CT tomgrpahy
  with intravenous contrast enhancement.
• MRI is most efficient for local staging
  especially in stage 1 and 2 (TNM classification)
  which correspond to 5 patients in our study.
• Computed tomography is performing to determinate
  bone extension and metastatic locations (liver,
  lung) in 10 patients with advanced stage tumors.

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T1 tumor
Blunning of left fossa of Rosenmuller and
enlargement of levator palatini muscle
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T2a tumor
nasopharyngeal tumor with oropharyngeal extension
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T2b tumor
nasopharyngeal tumor with parapharyngeal extension
throuugh pharyngobasilar fascia
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T4 tumor
nasopharyngeal tumor with infratemporal
fossa extension
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T4 tumor
Coronal computed tomography showing bony
involvement of the sphenoid sinus and
intracranial extension
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DISCUSSION

• Computed tomography and MRI have respective
  specific advantages and disadvantages.
• MR seems to provide a more accurate evaluation of
  the extent of the primary tumor in fact, MR is
  able to identify as retropharyngeal nodes
  findings previously misdiagnosed on CT as
  oropharyngeal or parapharyngeal invasion.
• Moreover, it provides new pieces of information
  such as the infiltration of long muscles of the
  neck and pterygoid muscles that, in most cases,
  cannot be clearly imaged with CT according to
  some authors, MR can also detect cavernous sinus
  and early perineural invasion.

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DISCUSSION

• The advantages of CT over MR in imaging bone
  details, especially when the bone contains little
  or no fat marrow, are well known.
• This suggests that CT should continue to be part
  of the pretherapeutic workup whenever the base of
  skull involvement is suspected or possible, but
  not clearly detected with MR. In fact, upstaging
  leads to a substantial change of treatment volume
  and may hint that a locally aggressive treatment
  should be delivered.
• As far as follow-up is concerned, the basic
  clinical question of differentiating between
  postradiation changes and recurring tumor seems
  to be less often uncertain with MR than with CT.
• Therefore, MR, even if not a panacea, may be the
  preferred modality. However, the cases with
  subtle bone erosions or cortical defects on
  staging CT are probably best followed up with
  this modality.

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DISCUSSION

• FOLOW UPMRI   once a year during 5 years and
  then every 5 years
• Goals - evaluate tumor response to treatment-
  Tracking early recurrence (T4 60recurrence at
  10 years)-Guiding biopsies

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Conclusion

• The imaging constitutes a key element in the
  diagnostic and therapeutic care of the
  nasopharyngeal carcinoma. 
• It aims at determining exactly the point of
  departure and the extension of the tumor in order
  to establish the classification
  tumor-nodes-metastases and to specify the fields
  of the irradiation.

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References

• Staging and follow-up of nasopharyngeal
  carcinoma magnetic resonance imaging versus
  computerized tomography.
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• Cancer du nasopharynx. F Cohen, O Monnet, F
  Casalonga, A Jacquier, V Vidal, JM Bartoli et G
  Moulin. J Radiol 200889956-67.
• Current understanding and management of
  nasopharyngeal carcinoma. Tomokazu Yoshizaki and
  al. Auris Nasus Larynx 39 (2012) 137144