Week 4 Flashcards
What is ultrasound imaging based on?
The creation, propagation, and monitoring of sound waves with the frequency of at least 20,000 Hz
What are the two categories ultrasound imaging?
- Therapeutic (1930’s) used for treatment - heating
* Diagnostic (1950’s) used for imaging - reflection
What are the image generation challenges of sonography?
- Principles of sound wave propagation
- Effects of different tissue densities
- Effect of frequency on penetration & resolution
- Lack of clarity compared to other forms of imaging
What are the image recognition challenges of sonography?
- Planes of view
- Knowledge of anatomy
- Constant monitoring of orientation of the sound head
What are the image interpretation challenges of sonography?
It comes with a steep learning curve in order to know how to interpret it
How are sound waves in an ultrasound generated?
They are generated by reverse piezoelectric effect, where they are sent down to a tissue, where the waves are absorbed, reflected and they scatter, and return and are attenuated on the sound head
What is the depth of sound wave penetration based on?
It is based on the frequency of the sound waves.
What do we see with higher frequencies of sound waves?
With higher frequencies, there is poor penetration however there is better formation of image
What do we see with lower frequencies of sound waves?
There is significantly increased tissue penetration, however resolution is poor
What are the characteristics of an anechoic structure on imaging?
- Structures without internal reflectors
- No echoes returned by sound waves
- Seen as black, most commonly fluid like urine and blood vessels
What are the characteristics of an hypoechoic structure on imaging?
- Structures with low-level echoes
* Seen as gray with things like: muscle, synovial tissue and peripheral nerves
What are the characteristics of an hyperechoic structure on imaging?
- Structures with high level echoes
* Seen as bright gray/white and can be used to visualize bone, tendons and fascia
When looking at imaging, what are the things that we are looking at?
Because we have a layered view, it is about looking at changes in the echo or specific differentiation between tissues that will clue you in to what you’re looking at
Under the white reflection that is seen in bone, what can we see?
All we see is black, because of the almost 100% reflection that is seen from the bone
Why is therapeutic US present a greater risk than diagnostic US?
Therapeutic US (0.5 – 3 W/cm2) presents a potentially greater risk than Diagnostic US (0.005- 0.03 W/cm2) due the higher intensities utilized and the higher risk of tissue heating
What are the biological effects of diagnostic US on patients?
There are no biological effects on patients caused by exposure to present diagnostic ultrasound instruments.
What are the benefits of US?
- Inexpensive
- Non-invasive
- Safe
- Real-time
- In office
- Bilateral examination
- Dynamic Examination
What are the drawbacks of US?
- Operator dependent
* Availability
What are the characteristics of the prudent use of diagnostic imaging?
Pregnancy
• ALARA principle (As Low As Reasonably Achievable)
• Informed consent, < 5 min of exposure to fetus.
Gaseous Cavities
• Avoid direct, prolonged exposure of lung tissue
• Do not use in individuals that have recently had a contrast medium injected.
What is the 2-5 MHz curved (sector) array US head used for?
- Abdominal wall
- Multifidus
- Bladder images
- Diaphragm
What is the 5-10 MHz linear array US head used for?
- TrA
- Multifidus
- Diaphragm
What are the advantages of a curvilinear probe of an ultrasound head?
It presents a wider field of view, because the array goes out, so a greater width of tissue is able to be seen. It can also provide more depth than the linear probe.
Transducer elements, sector footprint & wider far-field of view
What are the advantages of a linear probe of an ultrasound head?
It presents image that are more squared, and it has a regular footprint with a better near field of view, but a limited far field of view. Not really used for structures that are deeper
What is probably the most important aspect of utilizing an ultrasound?
Probe orientation
In what direction should the transducer/ultrasound head be facing?
Head to toes
What should be done to an ultrasound when a person is trying to get a better radiographic image?
Lower the frequency or zoom in
What is an artifact?
Anything that is an incorrect representation of the
anatomy
What could an artifact be?
- Structure is not real
- Structure is missing or improperly located
- Structure of improper brightness, shape or size
What causes an artifact?
Produced by improper equipment operation,
imaging technique or violation of previous assumptions
What is an acoustic shadowing artifact?
When there is a deflection of the sound, which prevents the visualization of deeper structures
What is an edge (Refractile) shadowing?
When we have a bypass through anechoic fluid and will allow for a deeper penetration underneath
What is an acoustic enhancement artifact?
AN artifact that allows structures deep to an anechoic structure appear brighter than they should
___ changes the behavior of a sound wave in an x-ray
Anechoic changes the behavior of a sound wave in an x-ray
What are the things that an anechoic structure can do to an image?
- Where it creates blind spots
- What it might do to tissues directly below
What types of tears is a x-ray better at visualizing?
A full thickness tear
What are the specific uses of ultrasound imaging to PT?
• Pelvic Floor Muscles (PFM) • Transversus Abdominis (TrA) • Internal Oblique (IO) • Rectus Abdominis (Diastasis Recti) • Multifidus • Diaphragm • Deep Neck Flexors • Quadriceps Angle
What is rehabilitative ultrasound imaging used for in pelvic floor?
It can be used as an indicator for when a person is able to contract and relax their pelvic floor muscles
True or False
Ultrasound can be used for dry needling to help visualize trigger points
True, Ultrasound can be used for dry needling to help visualize trigger points
What is scintigraphy/bone scans?
An aspect of nuclear medicine where a radioactive isotope
is injected IV and is absorbed by tissue target and scintillation camera detects the distribution of the isotope in order to form an image
What is included in nuclear medicine?
• Bone Scan • Thyroid Scan • Renal Scan • Leukocyte Scan • Cardiac Scan (Stress Test) • Ventilation-perfusion Lung Scan
What is the most commonly used radioactive isotope used for bone scans, and why?
Technetium (Tc-99m) Methylene
Diphosphonate (MDP), because it bond well with areas of higher metabolism for the bone
True or False
Bone scans are non specific, meaning it will not tell you the type of lesion that is being visualized
True, Bone scans are non specific, meaning it will not tell you the type of lesion that is being visualized
Why do bone scans visualize the entire skeletal system?
Because there is constant remodeling of bones
What do darker regions of a bone scan mean?
That there is more uptake of the isotope, which are referred to as hot spots
What is a cold spot in a bone scan?
Spots of decreases in bony metabolism
Why is the urinary bladder and kidney visualized in a bone scan?
Because of the mode of excretion of the isotope
Why is the antecubital fossa of the elbow visualized in a bone scan?
Because it is the injection site of the isotopes
Why is further evaluation of a bone scan generally needed?
Because a bone scan is not specific to a type of lesion, especially in instances of tumors
What are the areas of increased uptake in a bone scan?
- Healing fractures
- Open growth plates
- Primary bone tumors
- Metastatic tumors
- Stress fractures
- Area of inflammation (bone around arthritis)
- Areas of infection (may be hot of cold)
- Increased vascularity
What are the areas of decreased uptake in a bone scan?
• Avascular bone
• Certain metastases
(especially multiple myeloma)
• Areas of infection (may be hot or cold)
What are the indications of bone scans for PT?
• Stress response - (stress fractures, suspicion not showing on other images) • Suspicion of bony metastasis - Insufficiency fractures • Evaluation for polytrauma
