Other Imaging Modalities Flashcards
Why do we need to image salivary glands?
Obstruction
- Via mucous plugs
- Via salivary stones (sialoliths)
- Via neoplasia
Dry Mouth to exclude sjogrens syndrome
Swelling
Why is ultrasound good for salivary sound imaging?
- Glands are superficially positioned (apart from deep lobe of parotid which is hidden deep in ramus)
- Can assess parenchymal pattern, vascularity, ductal dilation or neoplastic masses
- Can give a sialagogue to aid salivary flow to allow better visualisation of structures
What is Ultrasound?
- No ionising radiation to create images
- High frequency sound waves (not heard audibly)
- Sound waves have short wave length which not transmittable through air (require coupling agent to create imaging)
What is the imaging protocol for salivary gland obsruction?
- Ultrasound
- Plain film (true mandibular occlusal)
- Sialography
What symptoms will pts complain of if there is obstructive disease present?
- Meal time symptoms
- Prandial swelling and pain
- Rush of saliva into mouth
- Bad taste
- Thick saliva
- Dry mouth
What is the aetiology of obstructive disease?
- Unusually a sialolith or mucous plug
- 80% sialoliths ass with submandibular gland
- 80% submandibular stones radiopaque
Describe what you see in this radiograph
- Presence of two large submandibular sialolith extending from duct orifice to mandibular molars
What is Sialography?
- Very small vol of Injection of iodinated radiographic contrast into salivary duct to look for obstruction
- Done with either Panoramic, skull views of fluroscopic approach
What are the indications of sialography?
- Looking for obstruction or stricture(narrowing) of salivary duct which could be leading meal time symptoms
- Planning for access for interventional procedures (basket retrieval of stones or endoscopy)
What are some risks of Sialography>
- Discomfort
- Swelling
- Infection
- Allergy to contract (very rare) can use MRI as alternative
What is the procedure of Sialography?
- Locate duct orifice
- Dilate duct
- Cannula placed into duct
- Inject contrast and take radiographs
- Remove canula and allow for excretion of injection
- Take 2 images - contact phase and emptying phase
What are normal findings of sialograph?
- Parotid gland ‘tree in winter’
- Submandibular ‘bush in winter’ (more rounded)
- If acinar changes ‘snow storm appearance’
Describe this contrast image finding
- Sialography procedure or right submandibular gland
- See the contrast thoughout the duct and see a blockage about 80% of way through
- The salivary stone is being passed through the duct causing temp obstruction
Describe what this sialography procedure contrast radiograph is showing
- Right submandibular gland
- Slight subtle obstructions where red pointer is likely to be mucous plugs
- Stricture of duct towards end
- Duct dilatation towards genome
- Filling defect shows in duct
Describe what is happening in this sialography radiograph
- Narrowing of duct in left submandibular gland
- Showing complete stricture and closure of duct due to salivary stone
- No gland being contrasted due to stricture closure
What are some technical considerations for sialography?
- Contrast into oral cavity
- Air bubbles in the tubing
- Over filling ‘blushing’
What are the treatment options of salivary stones? - Not routinely done in Scotland
- Surgical removal of stone via incision of EO removal salivary gland
- Dilate strictures via stent
What selection criteria for stone removal?
- Stone must be mobile
- Stone should be located within lumen on main duct duct distal to posterior border of mylohyoid
- Stone should be distal to hilum or at anterior border of gland (parotid)
- Duct should be patent and wide to allow passage of stone
Pt has dry mouth and you suspect sjogrens disease what other investigations can be used to diagnose?
- Blood tests (autoantibodies)
- Schirmer test
- Sialometry
- Labial gland biopsy
When suspected sjogrens what ultrasound findings are we looking for?
- Atrophy
- Heterogenous parenchymal pattern (leopard print)
- Hypoechoic (darker)
- Fatty inflitration
What is a Scintiscan?
- Injection of radioactive Technetium 99m
- Assesses how well the glands are working via uptake
What are the ultrasound findings of benign tumour?
- Well defined
- Encapsulated
- Peripheral vascularity
- No lymphadenopathy
What are the ultrasound findings of malignant tumours?
- Irregular margins
- Poorly defined
- Increased / tortuous internal vascularity
- Lymphadenopathy
When is MRI useful in obstructive disease?
- Pre surgical assessment and deep margiins of lesions that can’t be seen on ultrasound
- Do before a biopsy
When would you do extra tests for minor salivary glands?
- Image if enlarged or pathological
- Ultrasound if superficial
- MRI if deeper or poss bony inolvement
Do minor or major salivary glands have higher chance of malignancy?
- Minor salivary glands have higher chance if pathological
Why is MRI used for TMJ imaging?
- Can see the disc using MRI
- Determine if with or without reduction and which direction the disc moves in relation to the condyle
Compare the use of CT vs MRI
- MRI no radiation dose to pt
- MRI scan takes longer
- More contraindications for MRI including pacemakers, cochlear implants and claustrophobic
- MRI better for assessing perineural spread, bone invasion via bone marrow change, soft tissue characterists of lesion
