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My BDS4 > Radiology - Other Imaging modalities > Flashcards

Radiology - Other Imaging modalities Flashcards

1
Q

Where is the parotid duct orifice located?

A

adjacent to the upper 1st/2nd permanent molar in the buccal mucosa

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2
Q

Where is the submandibular duct orifice located?

A

Adjacent to the lingual frenum

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3
Q

Where is the sublingual duct orifice located?

A

Adjacent to the lingual frenum

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4
Q

Why do we image salivary glands? (3)

A
  1. Obstruction;
    * Mucous plugs
    * Stones (sialoliths)
    * Neoplastic mass – benign or malignant
  2. Dry mouth
    * Sjogrens syndrome associated changes - characteristic US appearance
  3. Swelling
    * Neoplastic
    * Infection
    * Mumps or other viral infection
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5
Q

Where are mucous plug obstructions more commonly found?

A

parotid gland

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6
Q

Why are ultrasounds used to image salivary glands? (3)

A
  • Superficially positioned in the face (However Struggle to see the deep lobe as it wraps around the medial surface of the ramus)
  • it can Assess parenchymal Pattern changes:
  • Vascularity
  • Ductal dilatation
  • Neoplastic masses
  • Can use to give a Sialogogue
  • Stimulates saliva and improves imaging of dilated ducts (increased dilation)
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7
Q

What does ductal dilatation usually indicate?

A

obstruction

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8
Q

Briefly describe how ultrasounds work.

A

Uses high freq soundwaves (short waves) which are transmitted through tissues via a coupling agent (can’t transmit through air – must use gel)

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9
Q

What does hyperechoic mean on an US?

A

whiter areas

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10
Q

What does hypoechoic mean on an US?

A

darker areas

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11
Q

What is a bend in the salivary ducts called?

What is the implication of this?

A

hilum

stones can become obstructed here

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12
Q

What is the first line imaging method for the salivary gland?
why is this first line?

A

Ultrasound
- no radiation dose to px

(however in practice you may use a mandibular true occlusal for submandibular/sublingual areas as a first line since US may not be readily available)

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13
Q

What are the symptoms of obstructive disease of the salivary glands? (5)

A
  • Mealtime symptoms (Thinking about or eating)
  • Pressure
  • Prandial Pain over salivary gland
  • Prandial swelling
  • Rush of saliva into the mouth once swelling gone (salty and thicker)
  • Dry mouth
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14
Q

What are the symptoms of obstructive disease of the salivary glands? (5)

A
  • Mealtime symptoms (Thinking about or eating)
  • Pressure
  • Prandial Pain over salivary gland
  • Prandial swelling
  • Rush of saliva into the mouth once swelling gone (salty and thicker)
  • Dry mouth
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15
Q

What can cause obstructive disease of the salivary glands? (2)

A

Stones

mucous plugs

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16
Q

Why is the full ductal structure examined if a px is suspected/found to have salivary stones?

A

if a px has one salivary stone they likely have others elsewhere in the ductal system

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17
Q

What does posterior shadowing of the duct indicate?

A

There is a calcification present within the duct

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18
Q

What salivary stones can be assessed on an OPT? (2)

A

anterior parotid stones

submandibular stones

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19
Q

What is Sialography?

A

Where iodinated radiographic contrast is Injected through the ductal orifice into the salicary duct to look for obstruction

(third line investigation of the salivary glands)

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20
Q

What are the indications for sialography? (3)

A
  • Find out what is causing the symptoms e.g. what is causing obstruction/narrow/stricture
  • To assess gland function
  • plan for intervention procedures e.g. basket retrieval or balloon dilatation
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21
Q

What radiographic imaging is sialography used alongside? (3)

A
  • Panoramic = static view
  • Skull views = static view
  • Fluoroscopic approaches = dynamic (live) view
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22
Q

Describe the risks associated with sialography? (4)

A
  • (even although No LA/Scalpel) Can feel discomfort as the contrast is being pushed in against the flow of saliva
    Px will feel Pushing and pressure
  • Swelling
  • No risk of infection however if there is infection we can’t complete the procedure it as it pushes bacteria back into the gland
    If Pus present = short AB’s and reappoint for 1 weeks time
  • Risk of allergy to contrast (iodone based) low risk as it’s a small amount of contrast through the duct
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23
Q

What are the alternatives to sialography?

A

MRI

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24
Q

What are the advantages of sialogrpahy? (2)

A

No needles/LA

Patient can swallow contrast

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25
Q

Describe how a healthy parotid gland would look using sialography.

A

a tree in winter

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26
Q

Describe how a healthy submandibular gland would look using sialography.

A

a bush in winter

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27
Q

Describe what would be seen in a gland with acinar changes.

In what px’s would this be seen in?

A

Globular appearance of contrast

Seen in: Advanced sjogerens or chronic inflammation

28
Q

When imaging sialography when do we need to take radiographs?

A

Take at least 2 images
1. Contrast phase (canula in place)

  1. emptying phase

(5 mins between each, after saliva cleared contrast)

29
Q

During sialography, if the salivary stone changes position between the 2 radiographic images what does this indicate?

A

that intervention techniques can be used

30
Q

When are intervention techniques used? (2)

A
  • when we Can’t use intraoral methods of removal
  • Px Not yet suitable for extraoral gland removal
31
Q

What is the aim of intervention techniques?

A

dilate the duct strictures

32
Q

List the criteria for stone removal via intervention techniques. (4)

A
  1. stone must be mobile
  2. stone should be located within the lumen in the main duct disatl to the post border of the mylohyoid
  3. stone should be distal to the hilum or at the ant border of the gland (parotid)
  4. duct should be patent and wide to allow passage
33
Q

Is US used to diagnose sjogrens?

A

no - used alongside other tests (blood tests, labial gland biopsy, sialometry, Schirmer test)

34
Q

When US a salivary gland with sjogrens what are we looking for? (4)

A
  • Atrophy
  • Heterogenous parenchymal pattern (leopard print)
  • Hypoechoic (darker)
  • Fatty infiltration
35
Q

What are glands with sjogrens at risk of developing?

A

MALT lymphoma

36
Q

How can we differentiate between chronic sialodenitis and sjogrens?

A

Chronic sialo = only affects one gland
Sjogren = affects more than one gland and usually in pairs

37
Q

What is the first line imaging technique for swelling of the salivary glands?

A

ultrasound

38
Q

What is the ultrasound criteria for a benign mass of the salivary gland? (6)

A
  • Well defined
  • Peripheral vascularity
  • encapsulated
  • No lymphadenopathy
  • Sometimes Globulated
  • Cystic components
    Posterior enhancement – cystic content
39
Q

What is the ultrasound criteria for a malignant mass of the salivary gland? (4)

A
  • Irregular margins
  • Poorly defined
  • Increased/tortuous internal vascularity
  • Lymphadenopathy present
40
Q

Why is it sometimes beneficial to biopsy swellings which appear benign on a US?

A

Low grade malignancy mimics benign

41
Q

What is the first line imaging technique for soft tissue lesions?

A

Ultrasound

42
Q

When is MRI imaging used instead of ultrasound imaging when assessing soft tissue lesions? (2)

A
  • when Lesions too large and too deep to be seen in completeness on US
  • Vascular lesions
43
Q

What imaging techniques do we use for imagine bony structures? (3)

A
  • CBCT
  • medical intervention CT = Soft tissues and muscles
  • MRI – marrow changes (Doesn’t involve radiation)
44
Q

What are advantages of using CBCT? (4)

A
  • Low dose
  • multiplanar imaging
  • Images made up of Isotropic voxels = No distortion of the image (cubes of data have equal measurements)
  • Can View CBCT in 3 different planes
    Axial, Coronally, Sagittal
45
Q

What are the highest and lowest fields of CBCT views?

What can each be used for?

A

17cm high = highest field of view
Used for: orthognathic surgery

5cm = smallest
Used for: isolated teeth, cysts and implant planning

46
Q

Compare CBCT to CT (6)

A

CBCT:
* Cone shaped beam
* Lower dose
* Poor soft tissue contrast
* Radiographic contrast not needed
* Patient upright
* quicker (9 secs)

CT:
* Fan shapoed beam
* Higher dose
* Good soft tissue contrast:
Window scanning:
Can change views to see different densities/structures e.g. only bone and air
* Radiographic IV contrast can be used (to image malignancy)
* Patient horizontal
* Longer = up to 3 mins

47
Q

Compare the dose of a Mid face CBCT (5-10cm) to a CT of facial bones.

A

CBCT = 18-674 uSv
CT = 430-860 uSv

48
Q

Provide examples of pathological boney anatomy which is imaged using CBCT. (3)

A
  • Cysts
  • Odontogenic tumours
  • MRONJ
49
Q

What imaging is used to assess myofacial pain (TMJ dysfunction)?

A

none

50
Q

What imaging is used to assess internal derangement (TMJ dysfunction)?

A
  • Consider MRI if there are significant issue (US as an alternative if MRI contraindicated)
51
Q

What imaging is used to assess degenerative changes (crepitus, osteoarthritis or joint replacement)?

A

CBCT

52
Q

Describe the colour of tissues on a T1W MRI. (3)

A
  • Fat is always white
  • Bone is black
  • fluid is black
53
Q

Describe the colour of tissues on a T2W MRI. (3)

A
  • Fat white
  • Fluid white
  • Bone black
54
Q

What are T1W MRI’s useful for assessing?

A

Anatomy

55
Q

What are T2W MRI’s useful for assessing?

A

pathology

56
Q

What does an MRI of internal derangement tell you about the articular disc? (2)

A
  • Determines if there is reduction or not
  • Determines which direction the disc moves in in relation to the condyle
57
Q

Describe the shape of a healthy articular disc.

A

bowtie shaped

58
Q

What is a SPECT scan?

What is it used to assess?

A

single-photon emission computerized tomography

Use: assess activity of joint

59
Q

Why is a SPECT scan only used for screening of joint disease?

A

High sensitivity but low accuracy = can identify increased activity however could be from; tumour, infection, inflammation or hyperplasia

60
Q

If malignancy is suspected clinically, what imaging do we request? (2)

A
  • CT = SCC
  • MRI
    (Depends on type of tumour suspected)
61
Q

What imaging do we request if the primary tumour site is unknown?

A

PET CT

62
Q

List the contraindications & px’s to be caution with when using MRI. (5)

A
  • pacemaker
  • cochlear implant
  • Claustrophobic – panic button provided

Caution with:
- Tattoos (has metallic particles which can heat up and skin feels like its burning)
- Makeup and mascara metal particles within can heat up

63
Q

What is the only contraindication of using CT?

A

allergy to the contrast

64
Q

What are CT’s better for assessing? (5)

A
  • Perineural spread
  • Metastases
  • Bone invasion
  • subtle marrow changes
  • Better ST characteristics of the lesion
    Tumours light up with contrast (subtle grey changes)
65
Q

Describe how PET CT works. (3)

A

radioactive fluorine labelled glucose injected

  • Liquid goes to metabolically active tissues i.e. tumours as they have metabolic activity and growing tumours need glucose
  • Must be superimposed on to CT/MRI (and PET) as PET alone doesn’t give anatomical detail

My BDS4 (57 decks)

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