2. Introduction to TMJ
Imaging Modalities of TMJ
1. Imaging of osseous structures
2. Imaging of soft tissues
Abnormal Findings in TMJ
References
Contents
3. TMJ is a ginglymo-diarthroidal joint
that is freely mobile with superior and
inferior joint spaces separated by
articular disc.
“Ginglymus” meaning a hinge joint,
allowing motion only backward and
forward in one plane, and
“Arthrodia” meaning a joint of which
permits a gliding motion of the
surfaces
Introduction
4. Components of TMJ
1. Glenoid Fossa & Articular Eminence/Protuberance
2. Mandibular Condyle
3. Articular Disk & Capsule
4. Synovial Fluid
5. Discal Ligaments
6. Posterior Attachment or Retrodiscal Tissue or Bilaminar Zone
7. Ligaments associated with TMJ
8. Muscles of Mastication
9. Arterial Supply, Venous Drainage & Sensory Innervation of TMJ
5.
6.
7. Diagnostic Imaging Of TMJ
The type of imaging technique depends upon the clinical problems
associated, so either imaging of hard tissue (OSSEOUS) or soft
tissue is desired.
Certain protocols are to be taken care before the imaging procedure:
The amount of diagnostic information available from particular
imaging modality.
The cost of examination
The radiation dose
11. Panoramic machines have specific TMJ programs which are of
limited usefulness.
• Thick image layers
• Oblique view/distorted view of the joints
• Low image quality
However this imaging modality gives a gross osseous change of
condyle such as:-
Asymmetries
Extensive erosions
Large osteophytes
Tumors
Fractures
12. However panoramic projections doesn’t provide informations about
condylar positions or function.
Mild osseous changes may be obscured, and only marked changes
in articular eminence morphology can be seen as a result of super
imposition by the skull base and zygomatic arch.
For these reasons, the panoramic view should not be
considered as a sole in imaging modality and be
supplemented.
13. Plain Film Imaging Modalities
The plain film usually consists of combinations of following
projections and allows visualization in various planes:-
Transcranial Projections
Transpharyngeal Projections
Transorbital Projections
Submentovertex Projections
14. Transcranial View
It is a view that aids in visualizing the sagittal view of the lateral
aspects of condyle and temporal component. It is taken in both
open and close mouth positions.
Indication Area of joint seen
TMJ pain dysfunction syndrome Lateral aspect of Glenoid fossa
Internal derangement Articular eminence
Range of movement in joints Joint space
Condylar head
15. Film position:
• flat against patients ear
• Centered over TM joint of interest
• Against facial skin parallel to sagittal plane
Position of patient:
Head adjusted so sagittal plane is vertical & ala tragus line
parallel to floor
16. Central Ray
1. The central ray is direct at an angle of 250 (+ve angulation)
from the opposite side, through the cranium and above the
petrous ridge of the temporal bone.
2. The horizontal angulation can be individually corrected for
the condylar long axis, or an average 200 anterior angle may
be used.
17. Closed view- size of joint space, position of head of
condyle, shape & condition of glenoid fossa & articular
eminence
Open view- range & type of movement
Comparison of both sides
Disadvantages :
Superimposition of ipsi-lateral petrous ridge over the
condylar neck
18. Transcranial projections of the left TMJ. Degree of translatory movement
between the closed view (A) and the open view(B)
(A) (B)
19. Transpharyngeal View
(Parma projection, Macqueen-Dell Technique)
This technique provides a sagittal view of the medial pole of the
condyle. It is taken in open mouth position.
Indication Area of joint seen
TMJ pain dysfunction syndrome Lateral view:
Condylar head & neck
Osteoarthritis & rheumatoid
arthritis
Articular surface
Condylar head- Cyst or tumor
Fracture of neck & condyle
20. Film placement-
Patient holds the cassette flat against patients
ear
Centered over TM joint of interest
Against facial skin parallel to sagittal plane
½ inch anterior to EAM
Central ray-
Directed from opp side cranially at angle(-5 to -10
degrees)
Beneath the zygomatic arch, through sigmoid notch
posteriorly across pharynx at the condyle
Comparison of both condylar heads
21.
22. It is taken in the open or protruded position and depicts the entire
medial lateral aspect of condyle in frontal plane.
Transorbital Projections
23. Film position- Behind patients head at an angle of 45 degree to
sagittal pane
Position of patient-
-Sagittal plane vertical
-Canthomeatal line should be 10 degree to the horizontal with
head tipped downwards
Central ray-
-tube head-front of patients face
-directed to joint of interest at an angle of +20 degrees to strike
cassette at right angles
24. Point of entry -
- Pupil of the same eye-asking patient to look straight ahead
- Medial canthus of the same eye
Disadvantage :
If the patient cannot open wide, areas of the joint articulating
surfaces will be obscured because of superimposition
27. Submentovertex Projections
A submentovertex projections provides a view of skull base and
condyles in a horizontal plane. It is often used to determine the
angulations of the long axis of the condylar head so for corrected
tomography.
Indication
1. Evaluating facial asymmetries
2. Condylar displacement
28. Conventional Tomography
Tomography is a radiographic technique that produces multiple
thin image slices, permitting visualization of an anatomic structure
essentially free of superimpositions of overlapping structures.
Tomographs typically are exposed in the sagittal (lateral) plane
with several image slices in the closed (maximal intercuspation)
position and usually only one image in the maximal open position.
29. In "corrected“ sagittal tomography, the condylar long axis with
respect to the midsagittal plane is determined using an SMV
projection
The patient's head is then rotated to this angle, permitting
alignment of image slices perpendicular to the condylar long
axis. This minimizes geometric distortion of the joint and
allows accurate assessment of condylar position.
30. Computed Tomography (CT)
Indicated when more information is needed about the three-
dimensional shape and internal structure of the osseous
components of the joint or if information regarding the surrounding
soft tissues is required.
Multiple image slices are made in both the axial and coronal
planes, although the coronal images are the more useful. Three
dimensional reformatted images also can be produced.
31. These are useful for assessing osseous deformities of the jaws or
surrounding structures. CT cannot produce accurate images of the
articular disk.
CT may be considered for determining the presence and extent of
ankylosis and neoplasms and the extent of bone involvement
32. Indications:
• Extent of ankylosis
• Neoplasms-bone involvement
• Complex fractures
• Complications -polytetrafluoroethylene or silicon sheet implants
-erosions into the middle cranial fossa
• Heterotopic bone growth
33. • CBCT is the recent technology developed for angiography in
1982 and subsequently applied to maxillofacial imaging.
• CBCT has the advantage of reduced patient overdose
compared to medial CT and is likely to replace Conventional
Tomography.
• In CBCT the patient is scanned in closed position and low
resolution scan done in open or other positions.
CBCT
34.
35. Soft tissue imaging is indicated when the TMJ pain and
dysfunction are present and when clinical findings suggest disk
displacement along with symptoms that are unresponsive to
conservative therapy. Imaging should be prescribed only when
the anticipated results are expected to influence the treatment
plan.
The imaging modalities for soft tissues are:
1. Arthrography
2. Magnetic Resonance Imaging (MRI)
36. Arthrography
Norgaard (1940)
It is a technique in which an indirect image of the disk is obtained
by injecting a radiopaque contrast agent into the joint spaces under
fluoroscopic guidance.
However MRI has replaced Arthrography in todays context and is
now the imaging technique of choice for soft tissues.
37. Indications:
Position and function of disk -pain and dysfunction- long standing
History of locking-persistent
Perforations of the disk and retrodiskal tissue.
Joint dynamics
Disc displacement-ant/anteromedial
Contraindications:
Infections in the preauricular region.
Patients allergic to contrast media.
Patients with bleeding disorders and on anticoagulant therapy
41. • Uses Magnetic field and radiofrequency pulses
• Bilateral dual surface coils- 0.5 to 2 tesla-Improve image resolution
• MRI produces excellent image qualities so is the principle
imaging choice for soft tissue.
Oblique sagittal/oblique coronal scans with t1, t2
Closed mouth, partially open and fully open positions
42. • Images in the sagittal and coronal planes without repositioning
the patient
• T1-weighted images best –osseous & diskal tissues
• T2-weighted images- inflammation and joint effusion.
• Motion MRI studies-during opening and closing the patient
open in a series of stepped distances and using rapid image
acquisition. ("fast scan ")
43. Disk is of low signal intensity (dark grey or black) and can be
distinguished from surrounding tissue that has high signal
intensity.
Posterior disk attachment (PDA) shows higher than the disk
and the junction between the posterior band of the disk and
PDA is distinct.
Medial disk displacements-best seen
44. MRI of a normal TMJ.
A. Closed view showing the condyle and temporal component. The biconcave disk
is located with its posterior band (arrow) over the condyle.
B. Coronal image showing the osseous components and disk (arrows) superior to
the condyle.
A. B.
45. This sagittal MR image shows anterior disk displacement in the
closed mouth position. Disc is deformed
46. Advantages of CT
• Direct delineation of bony
structures-surgical anatomy
• Some soft tissues-lateral
pterygoid muscle
• 3-D images from any angle
• Disadvantages-
-high radiation exposure
-soft tissues cant be
appreciated
Advantages of MRI
• Soft tissues-esp disk and its
association
• Information in short
acquisition time
• Disadvatages-
-expensive
-claustophobia
