intro to MSK imaging Flashcards
What 3 things are required for X-ray?
- beam source
- patient
- receptor - x ray film or digital receptor
waht is an x ray (radio graph)?
- radiograph is a recorded image of an antomic part acquired by the passage of xrays through the body. a conventiona lradiograph is one made without contrast enhancement or other equipment modification
What is radiation?
radiation is energy that is transmitted through space or matter
the different forms of energy used in medicine include: mechanical, electircal, thermal, nuclear, electromagnetic
does MRI have radiation?
no
What is the average dose of radiation exposure from
Whole body CT scan?
mammogram?
chest radiograph?
bone densitometry (DEXA)?
x ray security screening?
CT: 10 mSV
mammogram: 0.7 mSv
chest radiograph: 0.1 mSv
DEXA: 0.01mSv
x-ray security: 01 usV
DEXA is really high!!!
What is radiodensity?
What is it determined by?
- refers to amount ofradiation an object absorbs from the x-ray beam
determined by: - composition -effective atomic number and volume density
- thickness
- the greater an objects effective atomic number, volume density and or thickness the greater its radiodensity
What is lucency?
- lucent - clear, allows passage of light
radiolucent: - refers to how much of the beam is allowed to pass through
- appears darker
what is opacity?
not transparent, does not allow passage of light
What is radiolucent?
radiolucent:
- refers to how much of the beam is allowed to pass through
- appears darker
what is radio-opaque?
- refers to how much of the beam is absorbed and does not pass through
-appears lighter
What tissue is the most radiodense natural tissue of the body?
bone
Talk about the radiolucent/radio-opaque scale?
radio graph evaluation (the abcs)
- alignment
- bone density
- cartilage spaces
- soft tissue
4 things with radio graph alignment?
- size of bone
- number of bone
- shape and contour of bone
- bone and joint position
3 things with radio graph bone density?
- general bone density
- focal bone density
- trabecular alteration
radio graph cartilage space. what are you looking for?
- joint space
- width
- symmetry - subchondral bone
- contour
- density
radio graph bone density. What are you looking for?
- gross musculature
- joint capsule
- increase volume
- fat pad sign - periosteum
what is a fat pad sign in the soft tissue of a radio graph indicative of?
fracture
what are the different positions you can ahve for a radiographic projection?
- AP
- PA
- lateral
- AP or PA oblique
- AP or PA axial
- tangential
- transthoracic
- inferosuperior
- superoinferior
- plantdorsal (PD)
- dorsoplantar (DP)
- lateromedial
- mediolateral
- submentovertical
- verticosubmental
- carnicaudal
- orbitoparietal
- parieto-orbital
how many view should you look at in an imaging?
minimum 2
What is the first choice of imaging for an evaluation for frank neurological signs (CNS and PNS)?
MRI
What is the first choice of imaging for evaluation of spinal pathology?
MRI
What is the first choice of imaging for internal joint derangments (ligaments, meniscii, articlar cartilage, labral pathology)?
MRi
What is the first choice of imaging for inflammaotyr arthritis?
none - MRI, CT and NM (bone scan) all rate low
What is the first choice of imaging for evaluation of soft tissue injury (muscle injuries, tendon pathology, calcified bursitis)
MRI
What is the first choice of imaging for osteomyelitis
MRI or NM (bone scan)
What is the first choice of imaging for fluid collections or infections in joints or extraarticular sfot tisseus; unexplained soft tissue mass
MRi
What is the first choice of imaging for osteonecrosis
MRi
What is the first choice of imaging for complicated fractures
CT
What is the first choice of imaging for suspected stress, occult fracture
NM (bone scan)
What is the first choice of imaging for complicated disease processes or finding unexplained by more conservative tests
none - all rate low
What is the first choice of imaging for evaluation of possible neoplasm detected on conventional radiographs
MRi
What is the first choice of imaging for determiningskeletal distribution of neoplasms or other multifocal skeletal disease
NM (nuclear medicine - bone scan)
What does MRI image best?
- excels in display of soft tissue detail
- sensitive for detecting changes and varitions in bone marrow (diagnosing bone tumors, stress fractures, avascular necrosis)
- replaced arthroscopy as in detection of meniscal tears
- best modality for eval of disk hernations and other nerve root impingements
- ability to stage neoplasms in bone and soft tissues
- evaluate the extent of tissue invasion before surgery (more sensitive than bone scan fordetecting bone metastases)
What is a CT scan best for?
- subtle fractures/complex fractures
- detailed evaluation of degenerative changes (spinal arthritic changes)
- first imaging chose in sesriou strauma bc multiple injures to both osseous and soft tissue structures can be determined from one imaging series
- evaluation of spinal stenosis (CT myelography)
- evaluation of loose bodies in a joint
- accurate measurements of osseous alignment in any plane
why is sometimes a CT scan chosen over MRI?
- less time consuming than MRI or ultrasound
- usually less expensive
- less problematic for patients with claustrophobia
would you use an x ray for rib or hip fracture?
NO
