TMJ Imaging Flashcards
what are the dx with similar symptoms to TMJ
- migraine headache
- tension headache
- temporal arteritis
- ear infection
- sinus infection or tumors
- tooth infection
- facial muscle spasm
- jaw joint sprain
- neuralgia
- oral cancer
- jaw joint tumors
- dental malocclusion
- jaw joint disk displacement
- jaw fracture
imaging technique selection depends on:
- clinical dx
- desire to image hard vs soft tissue
- diagnostic information provided from the imaging technique
- availability
- radiation dose
- $ cost
what are the diagnostic imaging of the TMJ
- 2D imaging - skull radiography
- panoramic
- CBCT
- MRI
- arthrography
- ultrasound
- nuclear medicine
- PET-Ct
what is the preferred CT for dentistry
CBCT
what are the imaging techniques for osseous structures
- 2D skull imaging
- panoramic
- CBCT
- MDCT
what are the imaging techniques for soft tissue structures
-MRI
- arthrography
- ultrasound
what are the imaging techniques for metabolis activity
- nuclear medicine
- PET-CT
what are the advantages of 2D skull radiography
- readily available and accessible health care modality
- broad anatomic region imaged to evaluate the TMJ, mandible, maxilla, paranasal sinuses, and skull base in one radiograph
- relatively low dose of ioninzing radiation
what are the disadvantages of 2D skull radiography
- magnification, superimposition of all dense skull anatomy
- lacks fine anatomical detail
in a PA skull radiogaph the beam is:
90 degrees to sensor and parallel to mid-sagittal skull plane
- mid-sagittal skull plane is 90 degrees to sensor
what are the types of plain film skull imaging
- transcranial
- transorbital
- transpharyngeal
- submental vertex
what are the advantages of panoramic radiography
- simple and quick to perform
- broad anatomic region imaged to evaluate the TMJ, mandible, maxilla, maxillary sinuses, teeth and periodontium in one radiograph
- excellent for identifying fractures, gross degenerative changes in the TMJ, and gross pathological changes of the maxilla and mandible
- relatively low dose of ionizing radiation
- ideal for patient who cannot open his/her mouth
what are the disadvantages of panoramic radiography
- magnification, superimposition and inherent distortion
- lacks fine anatomical detail
- ghost image artifact radiopaque shadows superimposed over normal anatomic structures. this results from projection of x-ray beam through a dense object
what is one day of background radiation
8.5 micro Sv
TMJ module available on:
pano units
pano TMJ projections can be taken in:
open, protruded and closed positions
describe CBCT
- introduced in oral and maxillofacial imaging in 2001
- utilizes relatively low ionization radiation
- multiplane visualization of hard tissues
- no visualization of soft tissues
what are the advantages of CBCT
- controlled magnification
- lack of superimposition
- absence of geometric distortion
- multiplanar and 3D display
- ease in data aacquisition reconstruction and display
- improved structure visualization and diagnostic efficacy
- software capabl of bridging optical scan data with CBCT data
what are the early remodeling changes
- temporal fossa and condylar process demonstrate intact cortices with physiologic thickness
- trabecular patterns are within physiologic limits
- condylar processes are slightly posteriorly displaced in the temporal fossa in the closed mandibular position. the posterior positioning increases the joint spaces
if the condylar process translates to positions just posterior to the crest of the articular eminence this indicates:
slight limitation to the range of condylar translation
what is the effective dose for CBCT large FOV, medium FOV, small FOV
- large: 68-1073 micro Sv
- medium: 45-860 micro SV
- small: 19-652 micro Sv
CEDU to screen a large asymptomatic population for early dx is:
not cost effective due to its high cost
32.4% of patients with CAC diagnosed by PR were victims of:
cerebrovascular accidents
Carotid artery calcification (CAC) visible on pano has _____ probability of reflecting clinically significant stenoses
15%
CACs are linked to increased risk for:
CVA and CV disease
patients with CACs not under a physicians management for CVs should be:
referred to appropriate medical evaluation and management
what does MDCT stand for
mutli detector computed tomography
what are other names for MDCT
- mutlislice CT (MSCT)
- multidetector helical CT
- mutlirow CT
- multirow helical CT
what does the MDCT contain
gantry (CT xray tube and detectors) and couch
what are the different voxel shapes
- nonisotropic MDCT
- Isotropic CBCT
isotropic voxels have higher:
fidelity and better metal artifact profile
what are the types of beams
fan beam
cone beam
what are the planes of imaging
- coronal (frontal)
- axial (transverse)
-sagittal
describe the MDCT
- x ray tube and detector revolve around patient and data is stored in computer
- similar hard tissue pathology in sinuses, TMJ, head and neck as CBCT
why is MDCT not useful in evaluation of disc displacement
poor reliability of imaging the disc and superiority of MRI
describe the dosage in MDCT compared to CBCT
pt receives higher dose of radiation compared to dental CBCT due to larger field of view
what are the advantages of CT
- eliminates superimposition of images of structures superficial/deep to area of interest
- differentiates between tissues easily due to high contrast resolution and windowing ability
- stored images are reconstructed in axial, coronal and sagittal places from a single imaging procedure
- better insurance benefits (maybe)
what are the disadvantages of CT
- high dose of ionizing radiation
- expensive and not as readily available as conventional imaging
- sensitive to artifacts from metallic restorations and patient movement
what is the effective dose for MDCT head, abdomen, chest
- head: 960-1500 micro Sv
- abdomen: 5300 micro Sv
- chest: 5800 micro Sv
what is the most important advantages of MRI
ability to separate tissues with extracellular water from cellular tissues with intracellular water
what are the components of MRI
- magnets
- resonant energy
- imaging
what makes up to MRI system
- image capture
- image processing
what are the experiences for the patient
- confined space
- clanging noise
- mild vibration and movement
what are the tissue density patterns for dense bone for T1, T2, CBCT
- T1: dark
- T2: dark
- CBCT: bright
what are the tissue density patterns for air for T1, T2, CBCT
-T1: dark
- T2: dark
- CBCT: dark
what are the tissue density patterns for fat for T1, T2, CBCT
- T1: bright
- T2: bright
- CBCT: dark
what are the tissue density patterns for water/fluid for T1, T2, CBCT
- T1: dark
- T2: bright
- CBCT: dark
what are the advantages of the MRI
- no ionizing radiation
- best soft tissue imaging: suspected articular disc disorders, particularly disc displacement, edema, perforation, soft tissue adhesions and tumors
- physically painless
what are the disadvantages of MRI
- sensitive to motion artifacts
- expensive financial and temporal demands
- claustrophobia
- physchologically difficult to tolerate
- disc displacement is over diagnosed with 15-35% false positive findings
what is the best modality to study soft tissue disease
MRI
what is the most common imaging sequence to evaluate change in soft tissue structures
T1 and T2
MRI has functional studies of:
fluid dynamics in vascular channels
MRI has ______ in depicting disc perforation
poor reliability
MRI accuracy is no greater than clinical exam for detecting:
disc displacement without reduction
arthrography of TMJ synovial spaces is best imaging for:
meniscal perforation
describe arthrography
- radiographic contrast medium is injected into the inferior/superior joint synovial space and the fill pattern is evaluated radiographically, primarily with tomography
- TMJ uses are disc position, meniscal/disk perforation and fibrosis
- functioning of condyle/disc relationship can be assessed with use of fluoroscopy and videotaping
arthrography has limited use at present due to:
wide availability of MRI and patient discomfort
when do you use arthrography
use on selected patient cases when dynamic imaging results will alter the course of treatment or when indicated prior to joint lavage
what is the most reliable method for identification of perforation in the articular disc
arthrography
what are the disadvantages of arthrography
- invasive
- ionizing radiation
- discomfort due to injection of contrast medium
- possible hypersensitivity due to contrast agent
describe the ultrasound of normal TMJ
- low financial cost
- less invasive
- detects fluid in the joint space
- can be evaluated in open and closed jaw positions
what is nuclear medicine bone scan
imaging technique where bone binds a radioisotope Tc99
- gamma camera takes images of where the radioisotope has collected
- metabolic activity determines degree of radioisotope binding
- binding determines the signal strength
what is injected into a vein in nuclear medicine bone scan
gallium
what are the advantages and disadvantages of nuclear medicine bone scan
- advantages: radioactive isotope concentrates in areas of rapid bone turnover and gives positive response with 10% increase of osteoblastic activity
- disadvantages: expensive and invasive, morphologic changes not imaged, findings not specific to any disease process
what does PET CT stand for
positron emission tomography - computed tomography
combination of PET and CT is referred to as:
hybrid or fusion imaging
PET CT is _____ to plan nuclear medicine alone
superior
PET CT is useful for:
- location of a tumor
- followup of chemotherapy or surgery
-staging dementia, evaluate stroke
what are the advantages and disadvantages of PET scans
- advantages: allows functional study of a metabolic process, provides a visual image that corresponds with patient anatomy
- disadvantages: higher dosimetry, high finances, slow imaging: not capable for time sequences more than 30 seconds
