Lecture 2B Flashcards by Alexander Lee

T or F: An image can be the sole reason you make a diagnosis

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When working with patients that have imaging: request access to images themselves and ____________

radiologists interpretation

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What is the advantage of radiography

Allows appreciation of basic bone anatomy

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What are 2 limitations of radiography?

Cannot see complex boney anatomy

Limited ability to see soft tissue

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Radiography has relatively ____________ doses of radiation

low

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The light colored objects on an xray are radio__________ the dark areas on an x-ray are ____________

radiopaque

radiolucent

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Metal will appear as _____ on an xray whereas fat/air/gas appears as ________

radiopaque

radiolucent

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What are 3 views of an xray

AP view

Lateral View

Oblique View

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What are the advantages of a CT scan

Excellent demostration of cortical bone anatomy and complex boney anatomy

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What is a CT scan?

Computerized reconstruction of multiple slices of tissue through which xrays have been passed

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What are limitations for CT scans

Ability to see soft tissue dependent on CT unit

Expensive

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The relative dose of radiation for a CT scan is _______

high

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What is contrast in a CT scan?

Dye is injected that makes certain areas easier to see

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What type of imaging is especially useful for a C-Spine trauma and useful for surgical planning

CT scan

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What are the 3 common views of a CT scan?

(1) Sagittal

(2) Coronal

(3 ) Axial

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What kind of imaging is good for detecting metabolic activity of bone and high areas of bone turn over?

Bone scan (scintigraphy)

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What are limitations of a bone scan?

Lack of diagnostic and anatomic specificity

increased radioscopic uptake

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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

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T or F: a bone scan can see soft tissues

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What kind of imaging is best for detecting disease process, fracture, cancer, or areas of the skeleton with increased MSK stress

bone scan

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What kind of imaging would be best for a shoulder dislocation?

MRI (because it can see the muscles and ligaments and tendons aswell)

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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?

1. 65+ 2. Dangerous Mechanism * Fall from 3 feet * axial load to head * bad car crash * crash of any other vehicle not a car (bicycle or ATV) 3. 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?

1. Simple low-speed rear end MVC 2. Ambulatory at scene of accident 3. No neck pain when asked 4. 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

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