Lecture 2B Flashcards
T or F: An image can be the sole reason you make a diagnosis
F
When working with patients that have imaging: request access to images themselves and ____________
radiologists interpretation
What is the advantage of radiography
Allows appreciation of basic bone anatomy
What are 2 limitations of radiography?
Cannot see complex boney anatomy
Limited ability to see soft tissue
Radiography has relatively ____________ doses of radiation
low
The light colored objects on an xray are radio__________ the dark areas on an x-ray are ____________
radiopaque
radiolucent
Metal will appear as _____ on an xray whereas fat/air/gas appears as ________
radiopaque
radiolucent
What are 3 views of an xray
AP view
Lateral View
Oblique View
What are the advantages of a CT scan
Excellent demostration of cortical bone anatomy and complex boney anatomy
What is a CT scan?
Computerized reconstruction of multiple slices of tissue through which xrays have been passed
What are limitations for CT scans
Ability to see soft tissue dependent on CT unit
Expensive
The relative dose of radiation for a CT scan is _______
high
What is contrast in a CT scan?
Dye is injected that makes certain areas easier to see
What type of imaging is especially useful for a C-Spine trauma and useful for surgical planning
CT scan
What are the 3 common views of a CT scan?
(1) Sagittal
(2) Coronal
(3 ) Axial
What kind of imaging is good for detecting metabolic activity of bone and high areas of bone turn over?
Bone scan (scintigraphy)
What are limitations of a bone scan?
Lack of diagnostic and anatomic specificity
increased radioscopic uptake
How is a Bone Scan done?
How much relative radiation does a bone scan use?
- Imaging obtains through intro of radioisotopes into body that concentrate in areas with increased metabolic activity
- moderate radiation
T or F: a bone scan can see soft tissues
F
What kind of imaging is best for detecting disease process, fracture, cancer, or areas of the skeleton with increased MSK stress
bone scan
What kind of imaging would be best for a shoulder dislocation?
MRI (because it can see the muscles and ligaments and tendons aswell)
What are the advantages of an mri
Excellent demonstration of soft tissue and bone marrow
How does an MRI work?
Exposing tissue to magnetic field and radiofrequency waves to detect properties of tissue
What are 3 limitations of an MRI?
- Lack of signal in cortical bone
- low sensitivity to some fractures
- Expensive
How much relative radiation does an MRI expose u to
NONE
T1 vs T2 MRI
Which is most common?
T1: Fat tends to show brighest, (best anatomical definition)
T2: Water tends to show brightest (can show swelling)
T1 is most common.
What kind of imaging is the typical choice for evaluating deeper structures and prefered method for intra-articular tissue and bone stress injuries
MRI
What is a contrast added MRI?
Ink is injected into the joint capsule
very painful
What kind of imaging can PTs do?
Ultrasound
What are the advantages to ultrasound imaging?
Allows real time diagnosic imaging (you can see the joint move)
good demonstration of soft tissues
How does ultrasound work?
How much radiation does ultrasound cause?
Method of transmitting high frequency sound into tissue and looking at how much is absorbed vs reflected
NO radiation
Bone will appear as _______ on ultrasound
Fat will appear as ________ on an ultrasound
Bone: Hyperechoic (this is a white color)
Fat: Hypoechoic (dark color)
note: there’s also anechoic which means it’s completely black
Hyperechoic
Hypoechoic
Anechoic
Isoechoic
Appears white
appears dark
appears black
appears the same color as surrounding structures
What are the advantages to a DEXA scan?
Suited for repeat testing if using same device
Good for diagnosis and monitoring
What are disadvantages of a dexa scan
inconsistent preformance between different devices
not useful unless you’re looking at overall bone density
How does a DEXA scan work?
How much radiation does a DEXA scan use?
Measurement of relative Xray attenuation indicative of tissue density
low amounts of radiation
DEXA scan is most frequently used to measure what?
Bone density
Osteoporisis is defined as less than ________ of standard deviations from the mean bone density
-2.5
Osteopenia is defined as ____________ standard deviations from the mean
between -1 and -2.5 SD from the mean
PIttsburgh guidelines for knee trauma: The mechanism of injury has to be what?
Has to be an acute trauma or else no imaging
PIttsburgh guidelines for knee trauma: If the patient passes the first criterion, and If a patient’s age is ______________ they automatically get imaging
Less than 12 years old or more than 50
If a 45 year old patient has blunt knee trauma, what criteria must they pass in order to get knee imaging? (according to the Pittsburgh Guidelines)
Be unable to walk more than 4 weight bearing steps
The Canadian C spine rule:
What are the 3 high risk factors?
If they have any of these what happens?
- 65+
- Dangerous Mechanism
* Fall from 3 feet
* axial load to head
* bad car crash
* crash of any other vehicle not a car (bicycle or ATV) - Numbness or Tingling in extremities
Straight to getting an image/immobilzation
The Canadian C spine rule:
What are the LOW risk factors that require further examination?
If a patient has these risk factors what is the next test?
- Simple low-speed rear end MVC
- Ambulatory at scene of accident
- No neck pain when asked
- No pain during midline c spine palpation
If any of these are true, the next test is to be able to ACTIVELY TURN THEIR HEAD 45 degrees each direction. If they can’ t they need imaging.
Using the The Canadian C spine rule, a 40 year old has a low speed accident where someone rear ends them, what do you need to do next?
Ask if they’re able to turn their head 45 degrees, if not IMMOBILIZE/IMAGING
Ottawa Knee Rule:
Radiography is indicated when aged _____ or older
tenderness at head of fibula
isolated tenderness at ______________
inability to flex to 90 degrees
inability to __________________________
55
patella
inability to bear weight immediately and after in the emergency room (4 steps)
Ottawa Knee Rule:
Radiography is indicated when aged 55 or older
tenderness at head of ____________
isolated tenderness at patella
inability to ________________
inability to bear weight immediately and after in the emergency room (4 steps)
Fibula
Inability to flex to 90 degrees
T or F: The Mechanism of injury must be trauma for you to receive imaging using the Ottawa Knee Rule
F
Ottawa ankle rules:
If there is pain in the malleolar zone and any of these findings:
____________
___________
inability to bear weight immediately after and in emergency room
tenderness at posterior edge of tip of lateral mal
tenderness at posterior edge/tip of medial mal
Ottawa foot rules:
A foot xray is required if these is any pain in the midfoot zone and any of these findings:
___________
____________
inability to bear weight immediately after and in emergency room
Boney tenderness at navicular and base of 5th metatarsal
New Orleans Critera for receiving a CT of your head:
Headache
_______
Age more than 60
___________
Deficits in short term memory
_____________________
Seizure
Vomiting
Intoxication
Physical evidence of trauma above clavicle
New Orleans Critera for receiving a CT of your head:
_____
Vomiting
________
Intoxication
__________
Physical evidence of trauma above clavicle
_____________
Headache
Age more than 60
Deficits in short term memory
Seizure
Canadian CT head rule:
_______________
suspected open skull fracture
_________________
vomiting more than once
____________________-
Amnesia before impact of greater than 30 minutes
____________________
Failure to reach GCS (glasgow coma score) of 15 within 2 hours of injury
sign of basal skull fracture
age more than 64
dangerous mechanism of injury
1. Pedestrian struck by motor vehicle
2. ejected from motor vehicle
3. fall from more than 3 feet
Canadian CT head rule:
Failure to reach GCS (glasgow coma score) of 15 within 2 hours of injury
____________________
sign of basal skull fracture
_________________
age more than 64
______________________
dangerous mechanism of injury
1. Pedestrian struck by motor vehicle
2. ejected from motor vehicle
3. fall from more than 3 feet
suspected open skull fracture
vomiting more than once
Amnesia before impact of greater than 30 minutes
