Other imaging modalities Flashcards
What are the 3 salivary glands
- parotid
- submandibular
- sublingual
Where does the parotid sit
Sits in the periauricular region
Extends to angle of the mandible
Crosses masseter into buccal fat pad
Where is the orifice of the parotid
into buccal mucosa adjacent to first and second molars
How many lobes does the parotid gland have
Has a superficial + a deep lobe which sits medially
What is the predominant acini in the parotid gland
serous
Where does the submandibular gland sit
In the inferior border of the mandible
Sits lingual to the mandible in the submandibular fossa
What type of acini does the submandibular gland have
mixed
What type of acini does the sublingual gland have
mucous mainly
What are indications for imaging of salivary glands
- obstruction
- dry mouth
- swelling
What can cause obstructions of the salivary glands
- mucous plugs
- dry mouth
- swelling
What are salivary stones also known as
sialoliths
Where are mucous pligs most common
- Mucous obstructions are more common in the parotid glands despite it having mainly serous acini, cause is unknown
How can a neoplastic mass cause destruction
Benign/malignant tumour preventing saliva from entering the oral cavity
Why do we image for a dry mouth
Sjogren changes have a very characteristic appearance on an ultrasound
Why is ultrasound used on salivary glands
o The salivary glands are superficially positioned in exception of the deep lobe of the parotid which is hidden deep to the ramus and is not viewed on an ultrasound
o Can assess the parenchymal pattern, vascularity, ductal dilatation or neoplastic masses
o Can give a sialagogue (i.e citric acid) to aid salivary flow which will allow better visualisation of dilated ducts as at rest, dilatation is minimal
Why is ultrasound beneficial
does not utilise ionising radiation
How does ultraound work
- It uses high frequency sound waves which are not audible
- The sound waves have a short wavelength which are not transmittable through air and require a coupling agent to help sound waves get to tissues
- A gel is used to transmit the sound waves to the tissue
- Various body tissues conduct sound differently and some tissues absorb sound waves while other reflect them and the density of the tissues dictate the speed at which the echoes return
What is an ultrasound image called
a sonogram
What results in a black image
ultrasound
- When the sound waves easily travel through uniform substances such as water then no echoes are generated which results in a black image
What results in a white/grey image
ultrasound
When the sound waves encounter a tissue that absorbs/transmits the sound, a wave is reflected back to the probe which results in a white/gray image depending on the intensity of the reflection
What is the imaging protocol for salivary glands
- Ultrasound (due to no ionising radiation)
- Plain film (mandibular true occlusal) – especially if a submandibular stone is suspected
- Sialography
What are the signs and symptoms of obstructive disease
salivary gland
o Symptoms at mealtimes due to increase in saliva production close to mealtimes
o Prandial swelling and pain
o Bad taste (salty)
o Thick saliva
o Dry mouth
What is the aetiology of obstructive disease
salivary gland
o Sialolith or mucous plug
o 80% of salivary stones associated with submandibular gland
o 80% of submandibular stones are radiopaque
What would we expect to see on the ultrasound when obstruction is present
o Would expect to see ductal dilatation anterior to the obstruction
o Salivary stone will appear white as the stone is hyperechoic