Medical Imaging & upper limb radiology Flashcards
Plain film Radiography, aka traditional X ray, is similar to a 2D shadow of a 3D object. Radiation is absorbed or……………….. by matter, leaving an image on the otherwise exposed film.
Attenuated
* Attenuation is affected by atomic number and the thickness of the material
Will a more dense or less dense material show up black on an X ray?
less dense! Ex: air shows up black.
Attached is a photo from the slides showing different material in an X ray. What are the 5 radiographic densities?
Air
Fat (oil)
Water (blood, fluid)
Bone
Metal/foreign body
In an X ray, the……… sign refers to the loss of normal borders between thoracic structures. It is usually caused by an intrathoracic radiopaque mass that touches the border of the heart or aorta. It can indicate pneumonia.
silhouette
Why does proper positioning matter when taking X rays?
Things can be magnified or distorted. We almost always need 2 views at 90 degrees!
Often plain film radiography will be enhanced by the addition of contrast media. What are the two most common types?
barium or iodine containing compounds
Which tests do NOT use radiation?
Ultrasounds
MRI
CT combines the use of x-rays and computers to produce “slices” of the body. It greatly enhances greyscale, so it allows better soft tissue imaging. It is excellent for viewing what?
BONE
What are the pros of CT scans?
- Excellent imaging of bone
- Improved soft tissue imaging
- Can produce images in all three planes
- Often the best imaging option available / procedure of choice
Cons of CT scans?
- Exposure to ionizing radiation (much more than traditional x-ray)
- Takes longer than traditional x-ray
- Possible allergic reaction if contrast media is used
Nuclear imaging is when a radioisotope is used (usually technetium) and is taken up in metabolically active tissues. This provides sensitive, early, physiologic information, not just anatomical info! What are some examples?
Bone scan
Lung ventilation/perfusion studies
Thyroid scan
Stress Thallium study (Heart fxn.)
SPECT=Single Positron Emission Computed Tomography
PET=Positron Emission Tomography
Many others including fused images
In a bone scan, what does it mean if there is a “hot spot?”
metabolically active tissues, indicating infection, fracture, or malignancy.
Here is an example photo of a PET scan of a normal brain vs a brain with alzheimers:
Not all MRIs are the same! It is possible to produce images which enhance different tissue. The two most common scans are T1 and T2.
what will show high signal intensity on T1?
What will show high signal intensity on T2?
FAT
FLUID
MRI is typically used for what?
- Neurologic exams (Brain, Spinal cord)
- Musculoskeletal exams (Joints, Muscles, Ligaments, Tendons)
CT is often preffered for what?
Chest
Abdomen
Pelvis
Head trauma
Pros of MRI
- Unparalleled soft tissue imaging
- Like CT, can produce axial, sagittal, and coronal slices
- Can be used w/ or without contrast media
- NO ionizing radiation
Cons: Expensive, noisy, poor imaging of bone!
What are the ABC’s of a radiology report?
Alignment
Bone
Cartilage
Soft tissue
When it comes to bone alignment, ……………. is partial loss of continuity, while……………. is complete loss of continuity.
Subluxation
Dislocation
When examining bone in radiology, we look at the margins (for breaks in the cortex, or even cracks in the periosteum) and at the density. What do the terms sclerotic and lytic mean when it comes to density?
Sclerotic: brighter white (increased density)
Lytic: darker (decreased density)
Just know the concept (regarding periosteum) that a solid or lamellated reaction is less reactive on a test than something causing spiculated borders. Here is a picture:
When looking for cartilage, we are examining the spaces on the radiograph for uniformity in contour and size. What is important to know in kids?
¨In children the epiphyseal plates are cartilaginous and can be mistaken for fracture lines.
Soft tissue does not image well on plain film X-Rays. Tissue lines show faintly and should be examined beginning from what?
the periosteum to the skin lines.
Trauma to bone may produce fragments that penetrate the soft tissue. If a compound fracture has punctured through the skin and then partially reduced, air under the skin may be noted as what?
Black lucency on the radiograph.
Inflammation or swelling in soft tissues may be seen by displacement of the surrounding fat pads. What particular bone is this seen in and what is it typically called?
radial head fractures
sail sign
There are 2 different protocols for viewing the shoulder, one for non-traumatic and one for traumatic. What are the traumatic views, and why?
AP Neutral
Transthoracic lateral
Axial
* These views are used because they dont require the patient to rotate and move the arm alot
Here is a photo of a common shoulder view
Here is an axial view of the shoulder:
What kind of dislocation is this?
an anterior glenohumeral dislocation
What do we need to remember about a radionuclotide bone scan?
It is very sensitive but not very specific. We know if something is going on but we dont know what.
Here is an anterior inferior glenohumeral dislocation vs a posterior
This is an axial CT. What is wrong with the bone?
The tissue in the lesion is LESS DENSE than normal bone.
What are the numbers of this axial MRI?
1= deltoid
2= infraspinatus
3= tendon of subscapularis
4= glenoid of scapula
5= coracoid process
For an MRI with contrast, just know that gadolinium will……….. the signal from pathologic tissues.
increase
What are the numbers of this coronal MRI?
1= deltoid
2= supraspinatus
3= trapezius
4= glenoid
5= subscapularis
What is the 3rd most common malignant bone tumor? (it is about 10% of all primary malignant bone tumors)
chondrosarcoma
chondrosarcoma is a slow growing (usually), large soft tissue mass w/ late development of pain. Where is this most common?
Pelvis (pubic rami), proximal humerus, neck of femur, ribs & sternum.
