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X-ray of Mastoids

While we have more sophisticated radiological techniques of examination of the mastoids, the ability to read an X-ray of mastoid is a must for the undergraduate students of the medicine. While describing an X-ray in ENT or Otorhinolaryngology, you need to comment on these points:

  1. Plain or Contrast
  2. Regions: Mastoid, Nose and PNS or Soft-tissue neck
  3. View: AP, lateral, other views of mastoid x-rays
  4. Important anatomical landmarks
  5. Pathological findings
  6. Diagnosis

And when reading an X-ray of mastoid, never forget to comment on the following points:

  1. Type of pneumatization: cellular (well pneumatized), acellular (sclerotic), diploetic
  2. Position of: dural plate, sinus plate
  3. Presence of bone destruction
  4. Presence of mastoid cavity
  5. Presenc of choleasteatoma

The adult temporal bone is made up of squamous, mastoid, petrous and tympanic parts. The standard projections for the radiographic examination of mastoid include:

Temporal bone X-rays

  1. Law’s view (15º lateral oblique): Sagittal plane of the skull is parallel to the film and X-ray beam is projected 15 degrees cephalocaudal
  2. Schuller’s or Rugnstrom view (30º lateral oblique): Similar to Law’s view but cephalocaudal beam makes an angle of 30 degrees instead of 15 degrees
  3. Stenver’s view (Axio-anterior oblique posterior): Facing the film and head slightly flexed and rotated to 45 degrees to the opposite of side under examination and X-ray beam is angulated 14 degrees caudad
  4. Towne’s view (30º Fronto-occipital axial): Anteroposterior view with 30 degrees tilt from above and in front
  5. Transorbital view (Anteroposterior or Posteroanterior): AP or PA view with orbito-meatal line perpendicular to the film and the X-ray beam also perpendicular to the film.
  6. Submentovertical view (Full axial): Chin raised and neck hyperextended until orbito-meatal line is parallel to the film and the beam is projected at right angles to the film from submental area
  7. Other views: Mayer’s view, Owen’s view, Chause III view
AP view mastoid

Transorbital view: (4) EAC, (12) Mastoid air cells, (13) Mastoid process, (19) Cochlea, (20) IAC, (21) Orbital rim, (29) Vestibule, (30) Base of skull 

Notes on Schuller’s view:

In schuller’s view, there is superimposition of External Acoustic Meatus (EAC) and Internal Acoustic Meatus (IAM) due to the angulation of the X-ray beam. This angulation is provided to separate the right and left mastoid. This angulation also displaces the arcuate eminence of the petrous bone downward showing the key area i.e. antrum and upper part of attic area which is not clearly seen in the Law’s view. This is how, Schuller’s view differs from the Law’s view.

Lateral oblique mastoid

Schuller’s view (1) Root of zygomatic process, (2) Condyle of mandible, (3) TMJ, (7) Malleus, 8 (Incus), (12) Mastoid air cells, (14) Lateral sinus plate, (15) Dural plate, (25) Petrous apex

X-ray projection Structures seen Clinical applications
Schuller’s view EAC superimposed on IAC
Mastoid air cells
Tegmen
Lateral sinus plate
Condyle of mandible
Sino-dural angle
Attico-antral region (Key area)
Extent of pneumatization (compare both sides)
Destruction of intercellular septa (mastoiditis)
Location of sinus plate (position of sigmoid sinus) & tegmen
Cholesteatoma
Longitudinal fracture of petrous pyramid
Towne’s view Both side temporal bone
Arcuate eminence
Superior semicircular canal
Mastoid antrum
IAC, tympanic cavity, cochlea
EAC
Acoustic neuroma
Apical petrositis
Towne's view mastoid

Towne’s view

Some radiological signs in mastoid conditions:

1. Normal: Cellular (80%)/Bilaterally acellular (20%) – If cellular, mastoid cells are seen extending beyond sinus plate and tegmen

2. Acute mastoiditis: Diffuse haziness or clouding of mastoid air cells, destruction of intercellular septa (loss of trabecular pattern) and the lateral sinus plate appears more prominent

Chronic mastoiditis

Sclerotic mastoid

3. Chronic mastoiditis: Diffuse sclerosis of cellular mastoid and prominence of periantral triangle

4. Cholesteatomas: Cholesteatomas are radiolucent and can only be diagnosed if they erode bone. An erosion of mastoid antrum is seen as an area of translucency in a sclerotic mastoid.

Bony erosion

Cholesteatoma

Notes on Citelli’s or Sinodural angle:

Citelli’s angle or sinodural angle is the angle between the sinus plate and the dural plate. This angle is acute in primary sclerosis but obtuse in secondary sclerosis i.e. Chronic Suppurative Otitis Media (CSOM).

Differential diagnoses of Mastoid cavity:

Mastoid cavity differentials

  1. Choleasteatoma: cavity has smooth margins and is surrounded by a rim of sclerosis
  2. Granulation cavity: cavity shows hairline appearance
  3. Operated cavity: history of mastoid surgery, cavity shows irregular margin (due to osteogenesis) and sclerosis is absent
  4. Metastases
  5. Multiple myeloma
  6. TB mastoiditis
  7. Eosinophilic granuloma
  8. Large antral cells



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This entry was posted by on December 1, 2013 at 11:30 am and filed under Medical Students category.

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