Other Imaging Modalities

Question 1

Why might we want to image the salivary glands?

Answer 1

1. Obstruction
2. Dry mouth
3. Swellings

Question 2

What type of obstructions can occur in salivary glands?

Answer 2

• mucous plugs
• salivary stones
• neoplasia

Question 3

Label the glands shown on this image from top to bottom:

Answer 3

1. Parotid
2. Submandibular
3. Sublingual

Question 4

What is a good option for imaging the salivary glands?

Answer 4

Ultrasound

Question 5

Why is ultrasound a good option for imaging salivary glands?

Answer 5

• Glands are superficially positioned
• Can give a sialogogue to aid saliva flow to allow better visualisation of ducts

Question 6

What can we assess about salivary glands with ultrasound?

Answer 6

• parenchymal pattern
• vascularity
• ductal dilatation
• neoplastic masses

Question 7

What is ultrasound?

Answer 7

High frequency sound waves (cannot be heard audibly)
- no radiation

Question 8

What is the imaging protocol order for salivary gland obstruction?

Answer 8

• ultrasound
• plain film (mandibular true occlusal)
• sialography

Question 9

What might be indicative that a patient is suffering from obstructive disease of salivary gland?

Answer 9

• swelling and pain during meals
• bad taste
• thick saliva
• dry mouth

Question 10

What is usually the cause/aetiology of obstructive salivary gland disease?

Answer 10

Sialolith or mucous plug

Question 11

What is a sialolith?

Answer 11

Sialolithiasis is a crystallopathy where a calcified mass or ‘sialolith’ forms within a salivary gland, usually in the duct of the submandibular gland
- these are radiopaque

Question 12

What is sialography?

Answer 12

Injection of iodinated radiographic contrast into salivary duct to look for obstruction
- 1.0 - 1.5ml of liquid injected

Question 13

When is sialography indicated?

Answer 13

• looking for obstruction or stricture of salivary duct which could be leading meal time symptoms
• planning for access for interventional procedures (eg retrieval of stones)

Question 14

What risks are associated with Sialography?

Answer 14

• discomfort
• swelling
• infection
• allergy to iodine contrast injection

Question 15

How could the normal finding of an imaged parotid gland be described?

Answer 15

‘tree in winter’

Question 16

How could the normal finding of an imaged submandibular gland be described?

Answer 16

‘bush in winter’

Question 17

What would this salivary gland imaging suggest?

Answer 17

Gland obstructions
- ‘snow storm appearance’

Question 18

Why should you always take at least 2 images when performing Sialography?

Answer 18

So you can image:
- contrast phase with cannula in place
- emptying phase with time delay

Allows gland to work and produce saliva to excrete contrast

Question 19

What is the selection criteria for salivary stone removal?

Answer 19

1. Stone must be mobile
2. Stone should be located within lumen on main duct distal to posterior border of mylohyoid
3. Stone should be distal to hilus or at anterior border of gland
4. Duct should be patent & wide to allow passage of stone

Question 20

What should be used alongside Sialometry to diagnose Sjogrens Syndrome?

Answer 20

• blood test (anti-Ro anti-La)
• Schirmer test
• labial gland biopsy

Question 21

When investigating for Sjogrens syndrome with ultrasound imaging of glands, what are you looking for?

Answer 21

• Atrophy
• Heterogeneous parenchymal pattern (leopard print)
• Hypoechoic (darker)
• Fatty infiltration

Question 22

What is a Scintiscan?

Answer 22

Injection of radioactive Technetium 99m into glands to assess how they work
- uptake into glands if working well

Question 23

If neoplasia is suspected after ultrasound imaging of salivary glands, what should be done?

Answer 23

Biopsy
- fine needle aspiration for cytopathological diagnosis
- core biopsy for tissue histopathological diagnosis

Question 24

What are the features of a benign tumour?

Answer 24

• well defined margins
• encapsulated
• peripheral vascularity (not internal)
• no lymphadenopathy

Question 25

What are the features of a malignant tumour?

Answer 25

• irregular margins
• poorly defined
• increased internal vascularity
• lymphadenopathy

Question 26

If an MRI of salivary gland is required, should it be done before or after biopsy?

Answer 26

Before
- if done after scarring from biopsy may complicate image

Question 27

When imaging bones, what techniques are routinely used?

Answer 27

CBCT or CT

Question 28

What is CBCT?

Answer 28

Low dose multi-planar imaging
- images made up of isotropic voxels
- look at images in 3 planes (axial, coronal & sagittal)

Question 29

How do CBCT and CT differ?

Answer 29

Question 30

what is the dose range of a CBCT?

Answer 30

11-1025 uSv

Question 31

What is the dose of an intra-oral plain image?

Answer 31

0.3-21.6uSv

Question 32

What pathology can be seen on this radiographic image?

Answer 32

Osteonecrosis/MRONJ

Question 33

What pathology can be seen on this CBCT image?

Answer 33

Osteonecrosis/MRONJ

Question 34

Is imaging always required for patients with TMD?

Answer 34

Myofascial
- no imaging required

Internal derangement
- MRI gold standard

Degenerative
- CBCT

Question 35

How can internal derangement of TMJ be viewed?

Answer 35

Disc visualised on MRI
- need to view in para-sagittal (along short axis of condyle) and para-coronal (along long axis of condyle)