Temporomandibular joints, computed tomography TM joints, inner ear, ossicles, parts of ossicles, parameters, planning, reformation techniques , few cases to discuss, radiation dose post processing techniques. virtual labyrinthscopy.

1. CT Temporomandibular
Joints
PRESENTOR :VANI PUSHPA
M Sc. RIT Final semester
210513027
MENTOR: ARSHAD ALAM KHAN
Assistant Professor
Radio-Imaging Technology

2. AIMS:
• IMPORTANT AND RELEVANT ANATOMY
• INDICATION
• MODALITY IMPORTANCE
• PARAMETERS AND PLANNING
• REFORMATION AND POST-PROCESSING
• IMAGE QUALITY
• RADIATION DOSE
• FEW CASES
• VIDEOS REGADNING PLANING AND FILIMING

3. Anatomy:
• The main functions of TM JOINTS are mastication and speech.
• The temporomandibular joint (TMJ) is a complex synovial
articulation between the mandibular condyle and the temporal
bone's glenoid fossa and articular eminence.
• An intra-articular disc divides the joint into superior and inferior
compartments which is fibro cartilaginous biconcave disc
• The TMJ is normally subject to high biomechanical load from
mastication and is unique in that movement of one joint always
results in movement of the contralateral side as they are connected
by the horseshoe-shaped mandible.

4. Only mobile joint of
skull formed between
head of mandible and
articular fossa of
temporal bone.

5. Temporal bone comprises of four osseous parts namely
Petro mastoid
Squamous
Tympanic
Styloid

6. Auditory apparatus
• External ear
• Ear Pinna
• External auditory canal
• Tympanic membrane
• Middle ear
• Malleus
• Incus
• Stapes
• Inner ear
• Cochlea
• Semicircular canals

10. TMJOINT
Imaging of
osseous
structures
PLAIN
RADIOGRAPHY
PANOMARIC
RADIOGRAPHY
CBCT CT
Imaging of soft
tissues
Arthrography MRI USG

11. Modalities importance :
• Ultrasound could be used to screen for the presence of effusions in patients
with TMD. Ultrasound-guided injection of corticosteroids into the inferior
joint space can be used for the treatment of pain due to TMD
• MRI is an optimal imaging technique for evaluating excellent soft-tissue,
cortical, and bone marrow evaluation.
• MDCT provides excellent bone detail and multiplanar two-dimensional
(2D) and three-dimensional (3D) reconstructions of the TMJ,
• Maxillofacial region,
• Adjacent skull base,
• Ossicles
• Road map for the surgeon
• Dense cortical bone and contrast with air
• But no soft-tissue information

12. Indications for
Bone
Inner ear
• Temporomandibular disorder (TMD)
disorder of the muscles of
mastication
• Dental treatment or trauma
• Fractures
• A palpable mass
• Ankylosis (fusion of bones)
• Otosclerosis
• Imbalance
• Discharge
• Otitis media (infection of the middle
ear)
• Cholesteatoma (noncancerous
growth)
• Inflammatory disease
• Pre and post-operative
• Follow up
• Prior to the cochlear implant
• metastasis

13. Contraindications:
• Pregnancy due to the teratogenic effect of X-rays on the fetus and
children under 14 years of age due to the possible negative effect of X-
rays on the growing body
Relative contraindications
• Obesity (weight more than 180 kg),
• Mental disorders

14. Protocol: HRCT
• Patient position: Supine with head first with arms beside
the trunk
• Topogram: Lateral, 256mm
• Mode of scanning: Helical
• Scan Orientation: Craniocaudal
Starting location : Cranial limit of the petrous bone
End Location : proximal- ramus level
• Gantry tilt: Nil
• FOV- Just fitting the temporal and mandibular joint

15. • Slice thickness: 1mm
• Slice interval: 0.25-0.5mm
• kV/mA: 120/140
• Slice thickness for Reformation: 0.25- 1mm
• Reconstruction Algorithm : Ultra Sharp
• 3D Reformation – MPR, VR, Navigation technique
• Multidetector (64-256 sections) CT acquisitions in the closed- and
open-mouth positions from above the TMJ to the mid-ramus level,
140kV
• Open-mouth scans can also be performed to assess condylar mobility

16. The mandibular condyle is
centered on the glenoid fossa
when the mouth is closed. When
the mouth is open, the condyle
moves anteriorly under the center
of the articular eminence.

19. Image Quality :
• Symmetric position with the orbital plates overlapping with each other.
• Absences of the motion artifacts
• Optimal delineation of the ossicular chain, facial nerve canal and
tympanic cavity.
• 3D reconstructions are prepared for the planning of cochlear implant
surgery
• MPR is prepared in the oblique coronal and sagittal plane using bone
and soft-tissue algorithms

21. Post-processing images :
• Poschl projection images: In a plane perpendicular to the long axis of
the petrous bone show the normal anatomy of the temporal bone from
anteromedial to posterolateral
• Stenvers Projection CT images: In a plane parallel to the long axis of
the petrous bone show the normal anatomy of the temporal bone from
oblique anterior to oblique posterior
• LSCC = lateral semicircular canal
• PSCC = posterior semicircular canal
• SSCC = superior semicircular canal
• Nerves

24. 3D VR IMAGES
• Spatial orientation of various
parts of the temporal bone
• 3D reconstruction is based on
the data from spiral HRCT
using special software using
segmentation, volume
rendering, and surface
rendering algorithm on a CT
workstation.

25. Virtual labyrinthscopy
• Virtual labyrinthscopy of the labyrinth by using
volume rendering and navigation technique. Owing to
the tiny and complex structures of the inner ear and
convenient analysis require high-quality 3d
representation and real-time manipulation of viewing
direction. These features are provided by interactive
direct volume rendering and navigation techniques.

26. MALLEUS AND INCUS FROM
SUPERIOR
TO INFERIOR VIEW
LENTICULAR PROCESS AND LONG PROCESS
OF INCUS.MANUBRIUM, LATERAL
PROCESS, AND NECK OF MALLEUS
RIDGES SEEN IN THE BONY
LABYRINTH USING NAVIGATION
TECHNIQUE.INSIDES THE COCHLEA.

27. Radiation dose
• The effective dose for a typical CT exam of the temporal bone
is 1 mSv

28. Temporomandibular joint fracture. Axial image
showing a severely displaced condylar neck
fracture.

29. Displaced right temporomandibular joint compared
to the intact left TMJ.
A
B

30. zygomaticomaxillary complex (ZMC) fracture

31. Lesion of the EAC

32. REFFERENCE:
• https://doi.org/10.1016/j.crad.2020.06.020
• CT Temporal Bone - Indications, Preparation, Interpretation (medic-
journal.com)
• CT AND MRI PROTOCOL BY SUMEET BHARGAVA, SATISH K BHARGAVA
• CT Temporal Bone Made Easy (Part 1) - Step by Step Approach - Bing
video
• CT Scan of temporal bone technic - Bing video