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PTRS 746 Musculoskeletal > Imaging > Flashcards

Imaging Flashcards

1
Q

Errors of Observation/Interpretation

A

Errors in detecting and diagnosing pathologies in imaging that are there but are missed, or saying something is there that is not.

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2
Q

True Positive

A

Detects something that really IS there

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3
Q

False Positive

A

Detects something that really it NOT there

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4
Q

True Negative

A

Detects nothing when nothing is there

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5
Q

False Negative

A

Detects nothing when something is there

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6
Q

Specificity

A

Ability for test to detect true negatives. Example - if X-ray detects a fracture, there really is a fracture there. (SPIN)

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7
Q

Sensitivity

A

Ability for test to detect true positives. Example - MRI does not detect soft tissue injury so there is no soft tissue injury. (SNOUT)

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8
Q

X-ray Advantages

A
  • Time/cost effective
  • Non-invasive
  • Low exposure risk
  • Good for initial screening
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9
Q

X-ray Disadvantages

A
  • May miss diagnosis of pathology that really is there.
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10
Q

X-ray Attenuation

A

Reduction of X-ray beam’s density/strength as is it passes through a medium.

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11
Q

X-ray Permeability

A

Ability of the X-ray beam to pass through a medium and reach the film plate.

Example - Air is more permeable than bone.

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12
Q

X-ray Radiodensity

A
  • Ability for X-rays to be absorbed by a structure.
  • Based on structure’s density, composition and thickness
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13
Q

Radiodensity relationship

A
  • Radiodensity of an object is inversely related to the amount of blackening on X-ray film
  • Example - bone is more radiodense (shows up white on film) than air (shows up black on film)
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14
Q

Photographic Qualities

A

Refers to the visibility of an image

-Density, contrast

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15
Q

Geometric Qualities

A

Refers to the clarity of an image

  • Detail, distortion, foreshortening, magnification
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16
Q

Density

A

Amount of blackening on the film.

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17
Q

Contrast

A

Differences in color (density) of nearby structures.

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18
Q

Detail

A

Sharpness or resolution of image. Structures closest to the film plate have more detail.

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19
Q

Distortion

A
  • Structures farther from the film plate or beam source have clarity issues.
  • Occurs due to distance between the beam source, patient and image receptor (film)
  • May also be caused by alignment and patient positioning issues
20
Q

Foreshortening

A

Image appears shorter and wider than it actually is.

21
Q

Magnification

A

Structures farther from the film appear larger than structures closer to the film.

22
Q

X-Ray Views

A
  • Anterior/Posterior (AP)
  • Lateral/Oblique
  • Special
23
Q

Radiology ABCs

A

A - Alignment

B - Bone Density

C - Cartilage

S - Soft tissue

24
Q

A - Alignment

A
  • Gross size of bones
  • # of bones
  • Shape of cortical bone outline
  • Joint position/alignment
25
Q

B - Bone Density

A
  • Cortical bone = dense; Medullary/Cancellous bone = less dense
  • Weight bearing surfaces are more dense
  • “Washed out” bone indicates osteoporosis
  • Sclerosis (hardening/thickening of bone) indicates arthritis or RA
26
Q

C - Cartilage

A
  • Joint space
  • Subchondral bone integrity
  • Joint margins (smooth or rough)
  • Epiphyses and growth plates (esp. children)
27
Q

S - Soft tissue

A
  • Size of musculature/soft tissue
  • Outline of joint capsules
  • Periosteum integrity
28
Q

CT Advantages (2)

A
  • Sensitive and specific for fractures
  • Useful for quick brain/neurological injury assessment
29
Q

CT Disadvantages (3)

A
  • Radiation exposure
  • Issues with diagnosing histological problems
  • Small amounts off tissue show up uniformly gray
30
Q

MRI

A

Magnets cause protons of all cells to align according to electromagnetic field (resonance) that then return to their resting state after EMF is removed.

31
Q

MRI Advantages (4)

A
  • Good sensitivity
  • Great for soft tissue images
  • No radiation exposure
  • Little distortion of images
32
Q

MRI Disadvantages

A
  • Expensive
  • Low specificity
  • Can’t be done on patients with ferrous (iron based) materials in their body (implants, exposure to metal)
33
Q

T1 Images

A
  • How long it takes excited protons to return to resting state
  • Fat, bone, and hemorrhage are BRIGHT
  • Fluid/fluid filled structures are DARK
34
Q

T2 Images

A
  • How long excited protons remain “in phase” or aligned with EMF
  • Fat and bone are DARK
  • Fluid/fluid filled structures are BRIGHT
35
Q

Contrast MRI

A
  • Contrast media injected intravenously or into joint
  • Where contrast travels to depends on blood flow
  • Increased T1 image signals
  • Compares images before and after contrast administration
36
Q

fMRI

A
  • MRI done to determine which area of the brain is being utilized when the patient is asked to perform or think about specific tasks
  • Contrast media is deoxyhemoglobin
  • Dependent on blood flow (increased blood flow to brain area means that area is primarily being used to perform the task)
37
Q

DEXA

A
  • Type of X-ray used to determine bone density and body composition.
  • Considered the Gold Standard for bone density
38
Q

Nuclear Medicine

A
  • Imaging done with radiographic tracers to diagnose patients
  • Includes PET, SPECT, and radionuclide scintigraphy
39
Q

Radionuclide Scintigraphy

A
  • Uses label methylene injections
  • Scan taken 2-3 hours after injection
  • Looks at areas of bone activity/mineral turnover
  • Gold standard for stress fracture diagnosis
40
Q

Radionuclide Scintigraphy Advantages (3)

A
  • Very sensitive for early bone and joint diseases (stress fractures, metastatic bone disease)
  • Fast
  • Reasonable cost
41
Q

Radionuclide Scintigraphy Disadvantages

A
  • Poor specificity
  • Easily tricked by areas of high osteoblast activity and blood flow
42
Q

Ultrasound

A
  • Sound waves used to produce image
  • Most commonly used in OBGYN settings
  • Can be used by PTs but should be used for confirmation of diagnosis only
  • Requires a lot of training, technique mastery, and practice to get accurate results
43
Q

Pittsburgh Knee Trauma Decision Rule

A

X-ray ordered if:

  1. Patient has history of fall or blunt trauma AND…
  2. Age < 12 or >50 AND/OR…
  3. Inability to walk 4 steps in ER
44
Q

Ottawa Knee Rule

A

X-ray ordered if:

  1. Age >55
  2. Tenderness at fibular head
  3. Isolated tenderness to patella
  4. Inability to flex knee to 90 5.
  5. **Inability to walk 4 steps after injury or in ER
45
Q

Ottawa Ankle Clinical Decision Rule

A
  • Patient must have pain in the malleolar area AND
  • Point tenderness of posterior aspect/tip of medial malleolus OR
  • Point tenderness of posterior aspect/tip of lateral malleolus OR
  • Inability to walk 4 WBing steps after injury and in ER
46
Q

Ottawa Foot Clinical Decision Rule

A
  • Patient must have pain in the midfoot area AND
  • tenderness at the base of 5th metatarsal OR
  • tenderness at the navicular bone OR
  • Inability to WB for 4 steps after injury and in ER

PTRS 746 Musculoskeletal (9 decks)

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