Other Imaging Modalities

Question 1

sialolith

Answer 1

salivary stone

Question 2

name 3 things that may cause obstruction of salivary glands

Answer 2

mucous plugs
sialoliths (stones)
neoplasm - either benign or malignant

Question 3

why might salivary glands be imaged if a patient has dry mouth

Answer 3

in an attempt to exclude or confirm sjogrens disease

Question 4

why does the anatomical position of salivary glands make them suitable for ultrasound imaging

Answer 4

they are superficial - external to the skeleton - except deep lobe of parotid which requires MRI imaging

Question 5

sialogogue

Answer 5

substance that increases the flow rate of saliva e.g citric acid

Question 6

briefly describe ultrasounds

Answer 6

they use no ionising radiation
They use sound waves that have a high frequency and short wavelength, a coupling agent e.g ultrasound gel is required to transmit the sound waves into tissues
Image displays skin at the top of image then down the image is deeper into the tissues

Question 7

hyperechoic

Answer 7

white on ultrasound images

Question 8

hypoechoic

Answer 8

dark areas on ultrasound

Question 9

what radiograph is of most use is assessing for sialoliths in floor of mouth

Answer 9

mandibular true occlusal

Question 10

symptoms of obstructive salivary gland ‘disease’

Answer 10

prandial swelling and pain (during/ relating to eating of food)
bad taste - salty
sudden rush of saliva into mouth
dry mouth - with no other sjogrens symptoms
thick mucous saliva

Question 11

what gland is most commonly affected by sialoliths

Answer 11

submandibular

Question 12

what is sialography

Answer 12

radiographic examination of the salivary glands - may involve injection of radiographic contrast into ducts/ glands

Question 13

indications for sialography

Answer 13

looking for stricture (narrowing) or obstruction
planning for interventional procedures

Question 14

risks of sialography (with contrast injection)

Answer 14

discomort (injection of contrast)
swelling
infection
allergy to contrast
normal radiograph risks

Question 15

how many radiographs need to be taken when doing sialography with contrast medium

Answer 15

2
- one in contrast phase with cannula in place
- one in emptying phase - time delay, allows gland to work and produce saliva to excrete contrast (assess gland function)

Question 16

what operator setup fault can result in false positives during sialography with contrast

Answer 16

air bubbles in tubing can mimic filling defects e.g stones

Question 17

name 3 possible interventions for a patient with salivary stones (sialoliths)

Answer 17

• incision in FOM to remove stone
• gland removal
• dilation of strictures (possibly with stent too)

Question 18

what is the characteristic pattern of sjogrens syndrome on an ultrasound

Answer 18

leopard print

Question 19

scintiscan

Answer 19

historical test
injection of radioactive technetium - will be uptake into glands if functioning well

Question 20

if salivary gland swelling of unknown cause what would first line investigation be

Answer 20

ultrasound to rule out obstruction or neoplasia

Question 21

features of a benign salivary gland tumour on images

Answer 21

• well defined margins
• encapsulated
• peripheral vascularity
• no lymphadenopathy

Question 22

features of a malignant salivary gland tumour (on an ultrasound)

Answer 22

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

Question 23

are minor or major salivary glands at increased risk of malignant lesions

Answer 23

minor glands more likely to experience malignancy

Question 24

what are CBCT images composed of

Answer 24

isotropic voxels - cubes of data with equal measurements of data in height width and depth

Question 25

what tissue is CBCT not good for

Answer 25

soft tissues

Question 26

discuss the differences between CBCT and CT
- shape of beam
- dose
- soft tissue contrast
- radiographic contrast
- patient positioning

Answer 26

• CBCT cone shape, CT fan shape
• CBCT lower dose
• CBCT poor soft tissue contrast, CT good
• CT radiographic contrast can be used if indicated
• CBCT patient upright or standing, CT patient horizontal

Question 27

what imaging modality is gold standard for viewing articular disc of TMJ

Answer 27

MRI

Question 28

MRI T1 weighted vs T2 weighted

Answer 28

T1 - good for anatomy, fat appears white, cortical bone appears black
T2 - fat and fluid white, bone black

Question 29

what is internal derangement

Answer 29

disc displacement (With or without reduction)

Question 30

SPECT

Answer 30

imaging modality that can be used for assessment of condyles
(single photon emission CT)
highly sensitive but low specificity therefore only a screening method

Question 31

what imaging modalities are best for assessing cancer in head and neck

Answer 31

MRI or CT

Question 32

CT vs MRI
- radiation dose
- waiting time
- contraindications

Answer 32

MRI has no radiation dose
MRI takes longer to acquire
More contraindications for MRI - claustrophobia, pacemakers, cochlear implants

Question 33

what is PET

Answer 33

positive emission tomography
radioactive fluorine labelled glucose injected which goes to metabolically active tissues
Does not give anatomical detail so is overlaid on a CT or MRI
highly sensitive but low specificity
movement of tongue and vocal chords can cause false positives