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my revision > TMJ- Imaging > Flashcards

TMJ- Imaging Flashcards

1
Q

What are the advantages of using plain films

A
  • Low radiation dose
  • Easily accessible
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2
Q

What are the disadvantages of plain films

A
  1. Cannot assess soft tissues of joint
  2. Diagnostic yield os limited to projection & geometry & superimposition
  3. low sensitivity for bone patholofy
  4. Low- moderate value in assessment of “
    - TMJ osseous components
    - facial skeletal asymmetry
    - internal jaw anatomy/ pathology
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3
Q

What are the plain radiography film techniques used to assess TMJ

A
  • Reverse Townes
  • Panormaic
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4
Q

What are the advantages and disadvantages of panormaic

A

ADV:
-Quick & readily available
- comfortable
- section to just condyles

DISADV:
- difficult to reproduce due to inconsistent magnification & geometric distortion
- sensitive to positioning errors
- superimposition & ghost images
- no soft tisssues
- cannot exclude bony pathology

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5
Q

Indications for OPG for TMJ

A
  • Change in occlusion
  • mndibular shift
  • change in movements range
  • altered sensory/ motor
  • recent trauma
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6
Q

Contrainidications for OPG TMJ

A

Joint noises
myofascial pain

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7
Q

Why are PA mandibles not used for TMJ

A
  • condyles not visible as superimposed

Good for fractures at posture-anterior views

How it is conducted:
forehead & nose against image detector. X-ray beam posterior & perpendicular to film

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8
Q

How are reverse townes taken

A

pt opens mouth & condyles move and translate down articular emincence
- beam angled change (dropped 30 degrees upward angle)

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9
Q

What are the advantages of reverse townes plain film?

A

Beam angle changed→ no longer condyles superimposed by base of skull

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10
Q

What is a trauma dislocation

A

condyle is displaced out of the glenoid fossa but still within the joint

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11
Q

What is the most common type of trauma dislocation

A

Anterior dislocation

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12
Q

What is an anterior dislocation & its presentations

A

Condyle displaces anteriorly to articular eminence
presentations: cannot close mouth

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13
Q

What is a superior dislocation & its presentations

A

Roof of glenoid fossa fractures & condyle displaced superiorly into middle cranial fossa

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14
Q

What is subluxation of joint?

A

condyle doesn;t get stuck infront of articular eminence- condyle has an increased range of movmeemnts

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15
Q

What conditions are associated with recurrent dislocations

A

Ehlers Danloas and Marfans

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16
Q

How does Multi-detector Computed Tomography work?

A
  • fan shaped x-ray beam
  • patient moves horizontally through scnner
  • beam and detectors rotate around gantry
  • images are generated as slices to view bone and soft tissues
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17
Q

How can soft tissue differenation be improved in CT

A

Use of contrast agents to improve soft tissue differentiation
Agent is taken up by tissues that are well vascularised
Increases density & therefore attenuation of x-ray beams where more areas of x-ray accumulation

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18
Q

How do Cone beam CT work

A

xray beam is coned shape
- single rotation around patient
Lower dose of ioning radiation compared with MDCT
Cannot view soft tissues

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19
Q

What are the advantages of CBCT

A
  • see bony structures without superimposition
  • assess osseous and ankylosis
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20
Q

what are the indicaitons for multidetector CT

A
  • when a neoplasm is suspected to extend beyond the osseous structures
  • TMJ replacement
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21
Q

How does MRI work

A

Mangetic field (1.5-3 tesla) and radiofrquency
- no ionising radiaiton
- soft tissues: good differentations

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22
Q

what are the disadvantages of MRI

A
  • long scan tme
  • close to pt
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23
Q

Contraindications for MRI

A
  1. Claustrophobia
  2. pacemaker
  3. Metabollic foreign body
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24
Q

What is the MRI sequence

A

T1: FAT is bright e.g bone marrow & salivary glands

T2: Water- white CFS around brain. and. ucosa surface

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25
Q

Using T2, How is pathology presented on MRI

A

More Water & is less dense

26
Q

How is the disc imaged

A
  • MRI: cross sectional
  • disc positioning & startus
27
Q

what is the disc normal anatomy

A

disc is bioconcave
- convex anteroposteriorly

28
Q

What is the discs normal position

A

posterior band 12
Intermediate zone 10

29
Q

Indications for MRI

A
  1. Assess disc status/ position
  2. Assess synovitis in inflammation
  3. bony changes for diagnosis of arthritisi
  4. Allow to see deep structures
30
Q

What is myofascial pain

A

most common TMJ diagnosis
- joint often normal
- Pain is caused by muscle tension, fatigue ot spasm
- related to parafunctional habits

history & exam used for diagnosis
- pain and tender in MOM on palpation
-

31
Q

What is meant by internal derangement

A

Displacement of disc from normal position

32
Q

What is meant by reduction on opening?
& associated symptoms

A

As disc returns from anterior position to normal position→ clicks into place

clicking, pain, trismus/ locking

33
Q

What is a normal position of the disc

A

disc between condyle head, glenoid fossa & eminence

34
Q

What is the position of the disc (open and closed) in anterior displacement with reduction

A

closed: disc is anterior to condylar head

Open: condylar head translates down articular eminence
- disc moves posteriorly reducing to a normal position (located between condyle head, in glenoid fossa and articular eminence

35
Q

What is Anteriorly disc displacement without reduction

A

disc anterior to condylar head- does not return to normal position between temporal bone & mandibular condyle

36
Q

What is degenerative joint disease

A
  • non-inflammatory processes
  • causes wear and tear to sustained microtrauma over a long period of time
    -Deterioration of articular cartilage, exposing bone and causing flattening of the condylar head & bone defects
37
Q

What are the symptoms of degenerative joint disease

A

painful crepitus & trismus

38
Q

What are the imaging features of degenerative joint disease

A
  • erosions
  • flattening of articulating surface
  • osetophytes
  • subchondral cysts
  • sclerosis
  • decreased joint space
    +/- disc displacement
39
Q

Where and when does osteophyte accumulation occur

A

Occur in degenerative joint disease
- occur at muscle attachments
- usually seen anteriorly on condylar head
- fracture & form loose bodies

40
Q

How does sclerosis present in degernative joint disease

A

Increased density in condylar head- whiter on plain film

41
Q

What is a subchondral cyst

A

Formation of fluid filled cavity beneath the articular surface

42
Q

How does a diseased condylar head present

A

more dense
little distinction between cortical & cancellapus bone
- flattening of articulating surface, anterior osteophycte becomes deformed due to microtrauma

43
Q

what is internal deranagement associated with

A

osteoarthritis- RA
- occurs due to microtraumas in the joint

44
Q

How does rheumatoid arthritis affect the TMJ

A

Synovial inflammation associated with bony erosison
- pannus (granulatomous tissue ) grow in synovium
- replacing normal joint space
- more likley to have derangement

45
Q

How does Juvenile arthritis affect the TMJ

A

onset less than 9- 16 years
- chronic/ intermittent synovial inflammation- swollen and painful joints
- tmj Involved in 20-90

if more than 1 joint affected- more likely to be TMJ
- If younger- TMJ is likely to be affected

46
Q

How does inflammatory arthritic conditions present ion imaging?

A

erosions
joint effusion
marrow oedema
synovial enhancement on MRI

47
Q

How does RA present on MRI

A

Sharpened pencil condylar head
- loss of convexity

48
Q

How does JIA (juevenile idiopathic arthtitis) present on an MRI

A
  • Toadstool
  • wide shallow gelnoid fossa
49
Q

What is joint effusion associated with and how does it present

A

Can be seen in both arthritis conditions & following a trauma
- Collection of fluid in the joint space
-Increase in joint space on plain film/ CT
- High T2W signal in the joint space on MRI
Strong relationship between effusion and joint pain

50
Q

What is meant by ankylosis & its causes

A

Fusion of elements of the joint causing trismus
occurs due to: trauma/ infection/ severe juvenile inflammatory arthritis

51
Q

What are the 2 types of ankylosis

A

fiboroius
bony

52
Q

How does ankylosis present

A

reduced/ no joint space
Bony anklyosis: Bony bridge/
Fibrous: jigsaw puzzle interlocking articular surface (temporal bone to condylar head)

53
Q

What is meant by condylar hyperplasia & how does it present

A

larger condyle with normal morhopology
- associated with ipsilateral hemimandible
- glenoid fossa remodel to accommodate
- facial assymmetry
self limiting in 3rd decade

54
Q

Where do tumours arise in the TMJ

A

Condylar head
- alter shape

55
Q

How does osteochondroma differ to condylar hyperplasia

A

osteochondroma is a tumour & does not enlarge ipsilateral half of mandible
- mixture of bone & cartilage present

56
Q

What might present with an oesteochondroma on a CT

A
  • Remodelling of temporal component to accommodate larger head
    -pushing of bone around
57
Q

What is an osteoma

A

Benign
Extra projection of dense Bone

58
Q

What is chondorosarcoma

A

Malignancy
Mass eroding the bone

59
Q

What are the features of chondoromasarcoma

A

Infiltrative
Less well defined
CT: More soft tissue mix with normal bone filling the area of where condyle should be

60
Q

Indications for imaging

A

Suspected osseous abnormality / infections
Failure of conservative treatments
Worsening symptoms
History of trauma
Significant dysfunction
Alterations in range of motion
Sensory or motor abnormalities
Significant changes in occlusion

my revision (13 decks)

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