introduction to musculoskeletal imaging

Question 1

limits of imaging

Answer 1

• images are still, dont show stationary movement pattern

- patient may be asymptomatic

Question 2

radiology

Answer 2

radriograph=film that contains image of pt

• plain film has no injection to enhance image
• “normal” xray

Question 3

X-rays (plain film or conventional radiograph)

Answer 3

• is a negative not a print
• making of an x-ray
• -x-ray beam source
• -pt
• -x-ray film

Question 4

positioning for radiographs

Answer 4

• “routine radiographic projections”
• AP
• PA
• lateral (facet joints)
• oblique (IV foramen)

Question 5

reading a radiograph

Answer 5

• need a view box or illuminator

- place radiographs on view box as if patient were facing the person viewing the films

Question 6

osteoblastic activity terminology for looking at a radiograph

Answer 6

• opacity: whiteness
• sclerosis: laying done bone
• hypertrophic bone: nodes
• increased radiodensity
• blastic region: reparative, reactive bone

Question 7

osteoclastic terminology

Answer 7

• radiolucent (beam passes through)
• lucency
• osteopeni(decreased bone mineralization)
• decreased radiodensity(osteoporosis)
• lytic lesion or lysis
• -bone destroying

Question 8

radiodensities

Answer 8

• more dense of tissue less x-rays penetrate the tissue to expose the film
• more dense an object the greater absorption of x-rays and less exposure of film
• radiodensity is also influenced by thickness of material
• distortion
• interface-edge

Question 9

radiodensities of various materials

Answer 9

• air/gas: very dark, black
• soft tissue/fat-relatively dark/gray-black
• water-appears gray
• bone-relatively white (radiopaque
• -bone will vary in presentation depending on thickness, density, calcification
• metals-bright white

Question 10

reading a radiograph-what do you look for

Answer 10

-alignment, density bone, cartilagenous spaces

Question 11

bone: evaluate for on xrays

Answer 11

• density
• fracture
• tumor
• infection
• foreign body
• anomaly

Question 12

joint: look for

Answer 12

• foreign body
• arthritis
• dislocation
• fracture

Question 13

soft tissues: look for

Answer 13

• edema
• hemorrhage
• masses
• calcifications
• foreign bodies

Question 14

contrast enhanced radiographs

Answer 14

• contrast medium is injected into the body prior to taking a radiograph
• contrast may be radiopaque or radiolucent

Question 15

fluoroscopy

Answer 15

-epidural

Question 16

arthrography

Answer 16

-injection of fluid into joint space

Question 17

myelography

Answer 17

-contrast medium can have bad side effects, not usually used

Question 18

computed tomography

Answer 18

• use of a computer and cray to image a cross sectional slice of the body
• CT uses x-ray beams which move through an arc of 360 degrees around a patient
• each image represents an axial cross-sectional slice of the body
• each slice measures .3-2.5 cm in thickness
• shades of gray are assigned specific to each tissues radiation absorption properties
• CT is valuable in evaluation of bone and soft tissue tumors, fractures, intrarticular abnormalities, and bone mineral analysis
• also used in diagnosis of pathology in other body systems

Question 19

magnetic resonance imaging

Answer 19

• does not involve ionizing radiation

- utilizes radiofrequencies of tissues within a magnetic field

Question 20

MRI-technique

Answer 20

• patient positioned in a scanner containing..
• extremely powerful magnetic field coils
• -magnets, strength measured in tesla units
• -1 tesla=10.000 times magnetic strength of the earth
• -radiowave transmitters and radiowave receivers
• -powerful computer
• patient within bore of magnet
• this magnet is superconducting and must be cooled to 4 degrees k
• magnetic field causes certain alignment (magnetization) of atomic nuclei with the field
• radiowaves are turned on which causes a shift in the direction of the body’s magnetic field
• radiowaves are then turned off an the atoms return to their original magnetized state
• the resonant energy which is released is used to create an image
• -this energy is called a signal
• each tissue in the body gives off a slightly different signal based on its location in the bore of the magnet and its chemical composition (bone, fat, blood)

Question 21

MRI-T1 vs T2 weighted images

Answer 21

• T1 weighting: anatomy
• T2 weighting: pathology
• MRI can also be completed with contrast material injected IV

Question 22

T1 weighting

Answer 22

water appears dark, fats are more white in appearance

Question 23

T2 weighting

Answer 23

most pathology has higher water content (edema), water lights up (white) with T2 imaging

Question 24

bone marrow and cortex appearance (CT/xray, T1, T2)

Answer 24

• CT/xray: marrow: gray Cortex: white
• T1: marrow: bright cortex: gray/black
• T2: marrow: gray Cortex: dark gray

Question 25

fat

Answer 25

Ct/xray:black T1: white T2: gray

Question 26

air

Answer 26

- xray:balck - T1: dark - T2: dark

Question 27

water

Answer 27

- ct/xray: gray - T1: dark - T2: bright

Question 28

MRI

Answer 28

- can distinguish bone, muscle, articular cartilage, fibrocartilage, ligaments, tendons, vessels, nerves, fat - excellent for evaluation of the CNE - best study for the diagnosis of soft tissue trauma and tumors

Question 29

MRI contraindications

Answer 29

- ferrous metals or mechanical devices implanted in the patients body-can disrupt magnetic field - orthopedic appliances-NOT a contraindication to MRI, but will distort the image - open vs closed (claustrophobia) vs "open feeling"

Question 30

nuclear scans (nuclear medicine imaging-NM)

Answer 30

- patient is temporarily made radioactive with an isotope - -sensitive to inflammation - -SNOUT to rule out - isotopes are attached to certain physiologic molecules - physiologic function is utilized to obtain image of organ or tissue - ex thyroid - no blackening on bone scan, can rule out inflammation - RA=hot spots all over - bone scan can be used over MRI to show stress fracture - increased uptake implies more disease

Question 31

ultrasound

Answer 31

- high frequency sound waves create an image of living tissue - harmless to pt - creates a real time movie - viewed as sections - used commonly with abdominal imagin, obstetrics, vascular studies (doppler-like police radar) - form of biofeedbakc, see real time movement

Question 32

myelogram

Answer 32

- contrast injected into the subarachnoid space mixes with cerebrospinal fluid to produce a column of radiopaque fluid - typically utilized prior to surgery - no longer used, side effect=violently ill

Question 33

cost and reimbursement

Answer 33

- costs of diagnostic images is expensive, however third party payers have cut back he reimbursement for them - -heirarchy of diagnostic tests - some third party payers require pre-approval of diagnostic imaging tests