Other Imaging Modalities - Ultrasounds Flashcards
(36 cards)
Why do we image salivary glands?
- Obstructions:
-mucous plugs
-salivary stones (sialoliths)
-neoplasia - Dry mouth (sjogrens has a characteristic presentation on an ultrasound)
- swellings
Why is ultrasound good for salivary glands?
- glands are superficially positioned (apart from the deep lobe of the parotid)
- can assess parenchymal pattern, vascularity, ductal dilation or neoplastic masses
- Can give sialogogue (i.e. citric acid) to aid salivary flow and get better visualisation of dilated ducts on US
If a salivary gland has increased vascularity, what is likely?
That it is inflamed
Describe ultrasounds.
-no ionising radiation
-high frequency sound waves
-sound waves have a short wave length which are not transmittable through air and require coupling agent ot help sound waves get into tissues (the gel that is used)
What is the imagine protocol for salivary gland obstruction?
Ultrasound then a plain film (mandibular true occlusal) then sialography (depends on what first 2 show)
Note: if you are a GDP and think there is a salivary stone can do a plain film then refer for ultrasound if negative
Symptoms of obstructive salivary disease?
-‘meal time symptoms’ so prandial swelling and pain (eating/thinking about eating get presure and pain over salivary gland)
-‘rush of saliva into mouth’ which is salty/bad taste and thicker in consistency
-dry mouth
What is the aetiology of salivary gland obstruction?
Either sialolith (salivary stone) or mucous plug
Most sialoliths are associated with what gland?
80% associated with submandibular gland
Are sialoliths normally radiopaque or radiolucent? What does this mean for imaging?
80% are radiopaque so should be picked up on plain film images
What sialoliths are better seen with ultrasounds?
Mucous ones
What is sialography?
-Injection of iodinated radiographic contrast into salivary duct (via duct oriface) to look for obstruction or stictures
-no LA required
-very small volume of contrast injected (1-1.5ml)
Sialography can be done with what radiographic views?
Either panoramic (used at GDH), skull views or fluroscoptic approach
What are the indications for sialography?
-looking for obstruction or stricture (narrowing) of salivary duct which could be leading meal time symtpoms
-planning for access for interventional procedures (basket retrieval of stones or baloon dilation of ductal strictures)
What are the risk of sialography?
-discomfort
-swelling
-infection (if any infection present it will be pushed further into gland so if any signs of infections it should be postponed and AB’s prescribed)
-allergy to contrast (very rare but MRI is alternative as no contrast required)
What are the normal findings of a sialography?
-parotid gland ‘tree in Winter’
-submandibular ‘bush in winter’
If there are acinar changes, how will the sialography look? What changes might cause this?
‘snow-storm’ appearance
Advanced sjogrens or advanced chronic inflamamtion
How many images need to be taken with sialography? When/what are the images that need to be taken?
2
1st = contrast phase with the cannula in place
2nd = during emptying phase with time delay
What is the purpose of taking an image during the emptying phase?
Because allows the gland to work and produce saliva to excrete contrast
If there is still a lot of contrast after 5 mins etc then can indicate a problem
Technical considerations for sialography?
-don’t overfill gland
-if use too small a cannula get contrast into mouth sitting on floor of mouth
-air in contrast syringe can lead to air locules that can be misdiagnosed as stones
When are interventional procedures done for salivary glands?
-not done routinely in Scotland
-is an option in some cases rather than surgical removal of stone via incision (when not possible) or extra-oral removal of salivary gland (is too severe in the case)
What interventional option is ther to try and remove stones? What is the problem with this?
Attempt to dilate strictures (narrowing) of the duct and break up the stones
Can required multiple attempts and stenting to keep the duct patent (prevent closure)
Sometimes not possible due to extent of scarring from chronic infection
What is the selection criteria for stone removal?
1-stone must be mobile
2-stone must be located within lumen on main duct distal to posterior body of mylohyoid (SMG)
3-stone should be dital to hilum or at anterior border of the gland (parotid)
4-duct should be patent and wide enough to allow passage of the stone
US for dry mouth typically done in pts with suspected Sjogren’s. The findings from the US used in correlation with what other investigations/clinical findings?
-blood tests (auto-antibodies)
-Schirmer test
-Sialometry
-Labial gland biopsy
In US for Sjogrens you are looking for what?
-atrophy
-heterogeneous parenchymal pattern (leopard print)
-hypoeachoic (darker)
-fatty infiltration)
Note: chance for MALT lymphoma to develop so have frequent scans
