RADIOLOGY - TMJ imaging Flashcards
what are the TMJ imaging modalities?
plain film
CBCT
CT
MRI
Nuclear medicine
what are the types of plain films that can be taken to image the TMJ?
panoramic
PA mandible
reverse townes
lateral oblique
when would an OPT be indicated for TMJ assessment?
recent trauma
change in occlusion
mandibular shift
sensory/ motor alterations
change in range of movement
what bones make up the TMJ?
condylar head of the mandible
articular eminence and temporal fossa of the temporal bone
what muscles are associated with the TMJ?
temporalis
masseter
pterygoids
digastric
stylohyoid
mylohyoid
geniohyoid
where does the condylar head lie?
within the joint space
what sits superior to the condylar head?
glenoid fossa
what lies superior to the glenoid fossa?
middle cranial fossa
what is continuous to the glenoid fossa anteriorly?
eminence of temporal bone
what lies posterior to the condylar head?
styloid process and mastoid air cells
what lies laterally to the condylar head?
external auditory meatus
what lies anterior to the condylar head?
2 heads of the lateral pterygoid muscle
what are the 2 heads of the pterygoid muscle?
inferior head
superior head
where does the inferior head of the pterygoid attach?
condylar head
where does the superior head of the pterygoid attach?
articular disc
what part of the articular disc is thicker?
posterior aspect
what separates the joint space into its inferior and superior spaces?
articular disc
where do the nerve endings for TMJ sensory function lie?
the posterior attachment of retrodiscular tissues
what happens when nerve endings of TMJ are stretched?
pain is elicited
what plain films can be used to image the TMJ?
Panoramic
PA mandible
reverse townes
lateral obliques
what is an issue when plain films are used to image the TMJ?
may get an artificial position of TMJ when pt bites on the bite block
what is reverse townes imaging?
an AP view of the mandible with an open bite technique
should you take an OPT for TMJ assessment?
in most cases - no
when is an OPT for TMJ assessment indicated?
recent trauma
change in occlusion
mandibular shift
sensory/ motor alterations
change in range of movement
what signs may you see on a DPT that are indicative of inflammatory arthritis (rheumatoid)?
flat and pointed condylar heads
in what cases would a CBCT be taken for trauma on A+E?
if unable to stand or has a low GCS
what imaging modalities are used for trauma of the mandible/ TMJ?
OPT/ panoramic
PA mandible
reverse townes
what is a guardsman #?
bilateral condylar #
+
mandibular symphysis #
why is the midline hard to see on a PA mandible?
superimposition of the cervical spine
what would CBCT be used for in relation to imaging the TMJ?
bony changes - degenerative bone disease e.g., osteoarthritis
what will be present on a CBCT of a pts TMJ with osteoarthritis?
sclerosis and remodeling - a lot of joint space and irregular margins
what is the disadvantage of using CT over CBCT?
increased radiation dose
when would you use CT rather than CBCT for TMJ imaging?
when want to visualise soft tissue and bone - neoplastic masses
what is the gold standard imaging technique for TMJ?
MRI
advantages of MRI?
no radiation dose
soft tissue and bony pathology
what is MRI good for imaging relating to the TMJ?
Articular disc position
- open and closed
what 2 views are used to check position of the disc when taking an MRI?
coronal and parasagittal along axis of condyle
what colour is cortical bone on an MRI?
black
what colour is cancellous bone on MRI?
white
symptoms of anterior disc displacement with reduction?
click on opening
describe anterior disc displacement with reduction?
disc is sitting anterior when mouth closed
disc clicks back to normal position when mouth opened
symptoms of anterior disc displacement without reduction?
limitation of opening with pain
why is pain elicited with anterior disc displacement without reduction?
the retrodiscular tissues stretch
what may be present on MRI with anterior disc displacement and bony arthritis changes?
loss of joint space and changes to condylar head appearance
what is SPECT?
single photon emission CT
nuclear medicine for TMJ imaging
what is injected for SPECT imaging?
IV Technetium 99-metastable (radio-isotope)
*half life 6.5 hours
what is SPECT used for?
condylar hyperplasia
what will show on SPECT scans when there is condylar hyperplasia?
hot spots in areas of increased metabolic activity
give examples of benign tumours which may affect the condylar head?
osteochondroma
osteoblastoma
isolated region of fibrous dysplasia/condylar hyperplasia
tx for condylar hyperplasia?
resection of hyperplastic tissue and distraction osteogenesis to form a new condylar head
what is an alternative imaging modality if MRI not feasible due to contraindications?
arthrography (very rarely used)
what does arthrography image?
soft tissue - specifically articular disc
what can arthrography be used for?
diagnostic and therapeutic purposes e.g., infection of steroids into a space
how is arthrography performed?
inject contrast (iodinated) into joint space
done under fluoroscopic guidance
how does arthrography diagnose disc perforation?
if contrast leaks from lower joint space to upper joint space
