TMJ IMAGING

CONTENTS

Introduction Radiographic anatomy Types of imaging modalities References Conclusion

TEMPOROMANDIBULAR JOINTTMJ is a ginglymo-

diarthroidal joint that is freely mobile with superior

and inferior joint spaces separated by articular disc.

Radiographic anatomy

Extreme aspects of condyle – medial & lateral poles

Long axis of condyle is slightly rotated on the condylar neck such that the medial pole is angled posteriorly- angle of 15 to 33 degrees with the sagittal plane.

Two condylar axes typically intersect near the anterior border of the foramen magnum-submentovertex projection

Complete calcification of TMJ-20 yrs No cortical border in children-

radiograph Mandibular fossa & articular

eminence-4 yrs-mature shape Pneumatization-sometimes Radiographic joint space-radiolucent

area between the condyle and temporal component

CONVENTIONAL RADIOGRAPHY

Orthopantomogram:

Conventional OPG machine orients the

x ray beam obliquely through the

condyle.

Limited view of the fossa condyle

relationship.

The patient’s head is displaced forward/ the

alignment of the source is altered so that the

central beam is oriented along the long axis of the

condyle.

Condyles - gross osseous changes, extensive

erosions, growths or fractures

No information about condylar position or function

(Mandible is partly opened and protruded when this

Radiograph is exposed)

Dental panoramic tomographIndications- TMJ dysfunction syndrome Disease within joint Pathology-condylar heads Fracture of condylar head & neck Condylar hypo/hyperplasia

Advanced high condylar panoramic radiography

Sagittal (lateral) plane ->several image slices

Closed (maximal intercuspation) position & in maximal open position

Condylar long axis with respect to the midsagittal plane –submentovertex

patient's head is rotated to an angle, permitting alignment of image slices perpendicular to the condylar long axis.

Corrected lateral (sagittal) tomograms. A represents a lateral image slice, B represents a medial image slice of the same joint. Condyle

appears centered in the lateral image and retruded in the medial image. C, Open view

showing the degree of condyle translation during mandibular opening.

A CB

Minimizes geometric distortion of joint- condylar position.

Corrected tomographic technique-not available

20-degree head rotation toward the side of interest is superior to image slices parallel to the midsagittal plane.

Bite block

Coronal tomographs

Maximal open or protruded position

Condyle to the summit of the

articular eminence

Free of superimposition of the

posterior slope of eminence.

Entire condylar head is visible in the

mediolateral plane

CONVENTIONAL RADIOGRAPHS

TRANSCRANIAL VIEW

INDICATION AREA OF JOINT SEEN

TMJ pain dysfunction syndrome

Lateral aspect of:Glenoid fossa

Articular eminence

Joint space

Condylar head

Internal derangementRange of movement in joints

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

View :3 positions-open, close, rest mouth

Central ray A) Postauricular/ Lindblom Technique-1/2 inch behind and 2 inch above

auditory meatus-central ray should be directed

posteriorly so it passes along long axis of condyle.

B) Grewcock approach-central ray passes through a point 2

inches above ext. auditory meatus. C) Gill’s approach- ½ inch anterior and 2 inch above EAM

Central ray aimed downwards at 25 degree to the horizontal, across the cranium, centering through TMJ of interest

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 sidesDisadvantages : Superimposition of ipsilateral petrous

ridge over the condylar neck

Transcranial projections of the left TMJ. degree of translatory movement

between the closed view (A) and the open view

TRANSPHARYNGEAL VIEW/Infracranial/McQueen

Dell

INDICATION AREA OF JOINT SEEN

Tmj pain dysfunction syndrome

Lateral view:Condylar head & neck

Articular surfaceOsteoarthritis & rheumatoid arthritisPathology-condylar head-cyst & tumorFracture of neck & condyle

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 EAMPosition of patient- occlusal plane

parallel to transverse axis of film-soft parts are in a line with nasopharynx and joint

Patient instructed to inhale slowly through

nose, filling of nasopharynx with air

Open mouth-condyles move away from base of

skull and mandibular notch is enlarged on opp

side.

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

TRANSPHARYNGEAL VIEW

Parma modification

Lead lined open ended cone is removed and tube head is brought closer to skin surface producing magnification of structure reducing superimposition

TRANSORBITAL (ZIMMER PROJECTION)INDICATION AREA OF JOINT

SEENTrauma Fracture cases

Ant view of TMJMedial displacement of fractured condyleFracture of neck of condyle

Film position-behind patients head at an angle of 45 degree to sagittal pane

Position of patient--sagittal pane 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

Point of entry may be taken as-- 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 mutual superimposition

Condyle seen below articular eminence

Reverse towne’s

INDICATION AREAS OF JOINT SEEN

Articular surface of condyles and disease within joint

Posterior view of both condylar head and neck

Fracture of condylar head & neck, intracapsular fractureCondylar hypo/hyperplasia

Film position-cassette placed perpendicular to the floor

Long axis of cassette placed vertically Position of patient--sagittal plane vertical & perpendicular to

film-lips are centered on the film-only forehead should touch the film-mouth wide open-angle of negative 30 degrees to film

Central ray-directed midsagittal plane at the level of mandible and perpendicular to film

Forehead –nose position

Appreciation of condyle on left

side

REVERSE

TOWNE’S (Eric

Whaites)

Towne’s view/anteroposterior view Observe occipital area of skull Neck of condylar process Film position-cassette perpendicular to

floor, long axis-vertically Position of patient- back of patients

head touching film. canthomeatal line perpendicular to film

Central ray-30 degree to canthomeatal line & passes it at a point b/n external auditory canals

TOWNE’S VIEW

ULTRASONOGRAPHY

Ultrasonography was described to be an alternative method in the imaging of the TMJ by Stefanoff et al. (1992).

High resolution ultrasonography was used to show satisfying results in further studies by Emshoff et al. (2002) and Jank et al. (2002).

MARCELLO MELIS et al. Use of ultrasonography for the diagnosis of temporomandibular joint disorders: A review . Am J Dent2007;20:73-78

Noninvasive and inexpensive

Disc displacement and joint effusion

Scarce accessibility of the medial

part of the TMJ structures

Need for trained and calibrated

operators

Advantages

Disadvantages

Positioning of the transducer and consequent visualization of the temporomandibular joint (TMJ). A. Horizontal positioning, transverse image of the TMJ. B. Vertical positioning, coronal/sagittal image of the TMJ (depending on the angulation of the transducer).

TMJ ARTHROGRAPHY Norgaard (1940)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

Therapeutic :To delineate loose bodies in the joint spacesDiagnostic aspiration of joint fluid.Intraarticular injections of steroids

Contraindications:Infections in the preauricular region.Patients allergic to contrast media.Patients with bleeding disorders and on anticoagulant therapy

Techniques

Single contrast – lower compartment arthrography is most commonly done

Double contrast – contrast medium into the lower compartment and injection of air into the upper compartment.

Disk is anteriorly positioned and thickened

STEPS

Contrast media – non ionic agents such as iopamidol-370,iodohexol-350

Fluoroscopy aids in accurate positioning of needle

Primary record-video-allows imaging of joint compartments as they move

Only lateral parts seen

Medial aspect of joint-thin section

multidirectional hypocycloidal

tomography

5-6 slides ,2-3 mm apart, patient

mouth open and closed

If further info-contrast –upper joint

space-repeat investigation

ARTHROSCOPYContraindicationsAbsolute

Bony ankylosis.Advanced resorption of the glenoid fossa.Infection around the joint area.Malignant tumors.

Relative Patients at increased risk of hemorrhage.Patients at increased risk for infection.

Arthroscopes:

TypesClassic thin lensRod lensCoherent bundle Graded refractory index system

Field of vision is increased by rotating the instrument.

EQUIPMENT

Arthroscopic sheath : Fits on the

arthroscope- protects the tip.

Used for irrigation , suction of any loose fragment.

Light source : xenon arc illuminator.

T.V camera and video.

Biopsy forceps

TECHNIQUE

Three primary approaches to

the upper compartmentLateral posteriorLateral anterior End aural

Areas visualized

Loss of well defined boundary b/w

PDA and posterior part of the disk

seen in degenerative changes :

Osteoarthritis

elongation of the PDA

Medial capsule

Arthroscopic biopsy

Two approaches1.Blind technique.2.Direct vision technique.

triangulation methoddouble channel sheath method.

Complications

Vascular injuryExtravasation of irrigation fluid into the surrounding tissue Broken instruments in the joint Intracranial damageInfectionNerve injury

Computed Tomography (CT)

Three-dimensional shape and internal structure of the osseous components

Surrounding soft tissue Both axial & coronal images Reformat images in sagittal plane Not diagnostic for disk

Indications

Extent of ankylosis neoplasms-bone involvement Complex fractures Complications -

polytetrafluoroethylene or silicon sheet implants -erosions into the middle cranial fossa

Heterotopic bone growth

DIRECT SAGITTAL CT

SCANS3 scans/joint-closed, half, open-2mm

slice thickness

Neck bent- 45 to 55 degree so that the

plane of ramus is

parallel to the imaging plane

GUNDUZ, K.; AVSEVER, H. & KARACAYLI, U. Bilateral bifid condylar process. Int. J. Morphol., 28(3):941-944, 2010.

Panoramic radiograph displaying duplication of

both condyles.

Coronal computed tomography

MAGNETIC RESONSNCE IMAGING (MRI)

Magnetic field and radiofrequency pulses

Tissue with greater water content emit a

higher signal

Bilateral dual surface coils- 0.5 to 2 tesla-

Improve image resolution

Oblique sagittal/oblique coronal scans with t1, t2

Closed mouth, partially open and fully open

positions

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 ")

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

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.

This sagittal MR image shows anterior disk

displacement in the closed mouth position. Disc is

deformed

Osteophyte lipping of condyle-

osteoarthritis

Complete anterior disc displacement

Open-mouth MRI

medial section Autopsy

anteriorly displaced and deformed, degenerated disc and irregular cortical outline

Advantages of CT Advantages of MRI

Direct delineation of bony structures-surgical anatomy

Reconstruction in all planes

Some soft tissues-lateral pterygoid muscle

3-D images from any angle

Disadvantages-

-high radiation exposure

-soft tissues cant be appreciated

Soft tissues-esp disk and its association

Information in short acquisition time

Disadvatages-

-expensive

-claustophobia

BONE SCINTIGRAPHY Sensitive technique

Bone and joint pathology

Intravenous injection of tracer dose of

radionuclide- technetium methylene

diphosphonate.

Planar and tomographic images are obtained

in all planes.

Indication-to rule out tumors, condylar

hypoplasia,internal derangement

Advantages of bone scintigraphy :Bone changes are demonstrated before they are depicted by radiographic examn up to 6 to 12 months earlier in neoplastic involvement.Up to 2 weeks earlier in bone infection.

Disadvantage Lack of specificity.

Radionuclide imaging of a patient with condylar hyperplasia of the left TMJ

CONCLUSION

Complex joint Multiple pathologies Superimposition and clear view-

correct positioning Proper diagnosis and treatment plan

References

White & Pharoah Eric whaites Karjodkar R. Gray.Risk management in clinical

practice. Part 8. Temporomandibular disorders. British Dental Journal 209, 433 - 449 (2010)

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