Introduction Flashcards
What mandate discusses the use and ordering of images by PTs?
RC 13 from the house of delegates.
Order the typical pricing for an L-S MRI, radiograph and CT scan. What about order of radiation?
Radiograph < CT < MRI
MRI (0) < radiograph < CT
Radiodensity refers to the amount of radiation that is absorbed by material, metal being the highest, air the lowest. What is the term for increased or decreased opacity?
Decreased = lucency Increased = sclerosis
What types of injuries are plain flims (radiographs) best for?
- Fracture
- Bony alignment
- Arthritis
- Bone infection
ABCS
-Alignment, Bone, Cartilage, Soft tissue
How is the orientation of a plain film named?
By the direction it passes from point-of-entry to point-of-exit. Eg.Ventrodorsal goes in the chest and out the back, w/ pt on back.
What’s important to remember when examining alignment on radiograph?
Always check more than 1 view.
How do fx appear on radiograph?
Lucent line. Often seen best when examining cortical bone for consistency.
T/F: Acute stress fx does not appear on radiograph.
True
What are you looking for to identify normal bone density and cartilage?
BONE DENSITY
-normal tribecular structure, transitions
CARTILAGE
- sub chondral space
- smooth surface
Define heterotrophic ossification and myositis ossificans.
HO: formation of bone growth outside the skeleton
-caused by surgery or trauma to hips and legs
MO: HO of muscle
-trauma or hereditary
What is arthrography?
Air or contrast injected into joint
-assess internal structure
Does a bone scan detect pathology on its own?
No, a radiopharmaceutical needs to be injected; imaging 3-4 hours later.
- meds concentrate in area of increased fxn.
- METABOLIC ACTIVITY
What is a bone scan used to detect?
- cancer
- fx
- infection
- metabolic disease (Paget’s)
What is the benefit of a CT scan?
Shows tissue very well.
- lung
- bone
- organs
Can enhance structures by changing greyscale
How are axial images oriented in CT? What about sagittal images?
AXIAL
As if the pt were supine and you were looking up from the feet.
SAGITTAL
-viewed from left to right
What is a CT scan useful for that xrays are not?
Cancer
CV disease
Internal trauma
MSK
Can scan people with metallic implants (no MRI)
Where does MRI excel over CT?
Small soft tissue injury, such as intervertebral disks, shoulder and knee.
-no displaced fx
only axial
A CT of which body part results in the most radiation?
Pelvis.
A myelogram contains a contrast dye. Where is it injected to assess spinal cord and nerves?
Subarachnoid space (into CSF). Radiograph after.
How does MRI work?
Strong magnetic field changes H+ orientation via radio frequency - relaxtion times.
How many MRI sequences are typically used?
2-6.
What is a T1 MRI good for?
Anatomy
- fluids are dark
- fat and bone bright
What is a T2 MRI good for?
Inflammation
- fluids are bright
- fats are dark
What type of imaging would you use for tendon, meniscus, ligament and cartilage?
Proton density imaging
-T1 and T2 properties
