TMD Imaging Flashcards
What area of the joint is shown in a Transpharyngeal image and what are the indications?
Area of joint
- Lateral view of condylar head and neck and the articular surface
Indications:
- TMJ pain dysfunction syndrome
- Investigate presence of joint disease - osteoarthritis and RA
- Pathological conditions affecting condylar head
- Fractures of head and neck of condyle
What is the technique and positioning for transpharyngeal images?
- Dental x-ray set and extra-oral cassette
- Pt holds cassette against side of face over TMJ of interest
- Mouth open - bite block for stability
- X-ray tube head positioned in front of opposite condyle and beneath zygomatic arch
- Aimed through sigmoid notch, slightly posteriorly, across pharynx at condyle under investigation
- View taken of both condyle to compare
What area of the joint is shown in a DPT image and what are the indications?
Area of joint
- Lateral view of both condylar heads lying within focal trough
- If the patient images in the open position it is less likely to show superimposition
- Most panoramics have a TMJ programme to allow pts to image in both the open and closed position (look at rotation and range of translation)
Indications
- TMJ pain dysfunction syndrome
- Disease within joint
- Pathological conditions affecting condylar heads
- Fractures of condylar heads/necks
- Condylar hypo/hyperplasia
What area of the joint is shown in a Reverse Towne’s image and what are the indications?
Area of joint shown
- Posterior view of both condylar heads and necks
Indications
- Articular surfaces of condyles and disease within joint
- Fractures of condylar heads and necks
- Condylar hypo/hyperplasia
What is the technique and positioning for Reverse Towne’s images?
- Pt facing film, head tipped forwards- forehead-nose position, mouth open
- X-ray tubehead aimed upwards at 30 degrees from behind
Main clinical indications of Cone Beam CT
- Full assessment of the whole of the joint to determine the presence and site of any bone disease or abnormality
- To investigate the condyle and articular fossa when the patents is unable to open their mouth
- Assessment of fractures of the condylar head and articular fossa and intracapsular fractures
What area of the joint is shown and what are the indications of tomography
Area of joint shown
- All aspects of: Glenoid fossa, articular eminence, joint space, condylar head
Indications
- Full assessment of whole joint to determine presence and site of any bone disease or abnormally
- Investigate condyle and articular fossa when pt is unable to open mouth
- Assessment of fractures of fossa and intracapsular fractures
What is the technique and positioning for tomography?
Linear tomography
- Linear blurring of unwanted structures - poor image quality
- Requires minimal, but somewhat arbitrary rotation of head to side of interest for true cross-sectional imaging
Multidirectional hypocycloidal tomography
- Improved image quality
- But positioning for true cross-sectional imagining remains subjective
Multidirectional spiral tomography
- Pt positioning objective
- Tomographic movement is spiral
- Improved image greatly
- Computer-controlled sagittal orientation programme selected, which enables correct angulation
What are the advantages of DPT imaging
- Simple technique, but requires care with pt positioning
- Tomographic overcomes the issue of superimposition of left and right sides
- Dedicated TMJ open and closed views
What are the disadvantages of DPT?
- May not always show the articular surface due to superimposition
- Condyle is seen obliquely and not a true lateral
- Lacks sharp detail so may not be able to see subtle bony changes
- Condyle imaged in protruded position
- Does not show the disk
How does TMJ hypoplasia appear radiographically?
- Condyle diminished size
- Thin condylar neck
- Posterior aspect of neck may be curved backwards
- Acute gonial notching
Clinical features of condylar hyperplasia?
- Enlargement of condylar head and neck - developmental
- Typically unilateral
- Condyle continues to grow after puberty due to persistent growth of the condylar change
- Self limiting condition but causes facial asymmetry
How to image for disk derangement?
- No abnormal bony changes on routine plain imaging in internal derangement
- If confirmation of disk position is required (e.g. when unresponsive to tx), the disk can be shown with MRI
- Most pts don’t need MRI assessment
What are the radiological features of degenerative joint disease?
- Irregular condyle outline and loss of cortication - shape, surface
- Erosion(s) of the articular surface of condyle
- Radiolucency under the condyle head
- Osteophyte formation
- Bony sclerosis
What neoplasias can affect the TMJ?
- Rare
- Benign tumours include: condroma, giant cell granuloma
- Malignant tumours include: condrosarcoma, osteosarcoma, secondary deposit (infiltrating from adjacent structures such as salivary glands)
