Sialography

Dr Ian Bickle et al.

Sialography is the imaging of the salivary glands, most commonly the parotid gland.  The salivary ducts are conventionally examined fluoroscopically with high sensitivity, though cross-sectional imaging with CT or MR sialography have also been described.

  • suspected sialolithiasis or salivary duct obstruction
  • suspected sialadenitis to identify ductal strictures or sialectasis in chronic inflammatory disorders and autoimmune diseases

There are three types:

  • conventional/fluoroscopic sialography (with or without digital subtraction)
  • CT sialography (ultrafast technique)
  • MR sialography

By and large ultrasound, and if required sialography, is the preferred choice of investigation in ductal pathologies. Ultrasound of the parotid glands is a useful adjunct, readily available, noninvasive and cheaper option, in cases of sialolithiasis.

Technique of conventional sialography
  • control images are taken with the patient supine to assess for radio-opaque calculi
    • lateral oblique and anteroposterior views
    • using tongue depressors for submandibular
  • the patient may be asked to suck on a lemon or secretory stimulant for 2-3 minutes before sialography
    • to make the salivary duct opening conspicuous for cannulation
  • symptomatic parotid or submandibular duct cannulated
    • 21 gauge catheter for Stensen's duct
      • located adjacent to crown of second upper molar in buccal mucosa
    • 24 or 27 gauge for Wharton's duct
      • at the base of frenulum of the tongue
  • up to 2 mL of water soluble contrast is instilled
  • care should be taken not to introduce air into the salivary ducts
    • can simulate a ductal calculus
Advantages
  • higher spatial resolution for superior diagnostic elucidation ( when the procedure is successfully achieved) with accurate delineation of second and third order branches.
  • enables therapeutic approach in sialoendoscopy for removal of sialiths, retrograde displacement of sialiths to relieve acute obstruction, and to dilate strictures.
Disadvantages
  • invasive procedure
  • substantial failure rate of procedure (especially submandibular sialography) due to cannulation problems, lack of skill, lack of patient compliance, pain, etc
  • radiation exposure
  • contrast media exposure with risk of allergic reaction.
Technique of CT sialography

The procedure is same as conventional sialogram, after which the patient is positioned in a CT in neutral supine position and multiplanar data acquisition allows for 3D reconstruction. Also intravenous contrast can be administered for better soft tissue assessment especially for parotid masses. In the 1970s and 80s when this technique was first introduced, slower CT scans called for delayed ductal emptying, for which atropine was given.

Advantages
  • assessement of other glands possible
  • better diagnosis of parenchymal pathology, excellent visualisation of deep lobe, and better substraction options
  • no special positioning required
Disadvantages
  • intravenous atropine is required to minimise run-off of contrast and impair ductal clearance, in some cases
  • radiation exposure
  • invasive procedure
Technique of MR sialography

MRI sialography is a fairly sensitive and reliable method of evaluating the salivary glands. Fast acquisition heavy T2 weighted sequences (e.g. RARE, CISS, FISP as used in MRCP and MR urography) brighten intraluminal fluid and display ductal morphology adequately with no requirement to inject contrast in the ducts. MR contrast administered intravenously is a useful adjunct. 

Advantages
  • rapid acquistion
  • non-invasive
  • assessement of other glands possible
  • excellent delineation of parenchymal pathology
  • no special positioning required
  • because no cannulation is required, risk of airbubbles simulating intraductal calculi is minimised
Disadvantages
  • general MRI contraindications, e.g. pacemakers, implants, claustophobia
  • dental fillings, implants, bridges, etc can cause image impairment
  • only first and second order branches can be delineated.
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Article information

rID: 47235
System: Head & Neck
Tag: refs
Synonyms or Alternate Spellings:
  • Sialogram

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Cases and figures

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    Case 1: normal CT sialography
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    Case 2: submandibular duct stone on fluroscopy
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    Case 3: fistula on sialotomography
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    MR sialography sh...
    Case 4: parotid duct strictures on MR sialography
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    Case 5: chronic recurrent sialodenitis
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    Case 6: obstructed parotid duct on MR sialogram
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