Overview of Diagnostic Imaging Flashcards
Name four methods of diagnostic imaging
Radiography and computed tomography
Scintigraphy
MRI
Ultrasonography
What is the physical basis of radiography/CT and what can these images show?
X-rays
Show variations in physical density
What is the physical basis of scintigraphy and what can this show?
Gamma rays
Shows metabolic activity
What is the physical bases for MRI and what can this show?
Radiowaves
Shows magnetization ?!!
What is the physical basis for ultrasonography and what can this show?
High frequency sound
Shows echogenicity
Define radiography
Making images representing a shadow of an object placed in an xray beam
Which structures show as most radiopaque/radiolucent?
Opaque: Bone - Soft tissue and liquid - Fat - Air : Lucent
How does CT differ from a standard radiograph?
Ring of xrays taken and amalgamated to make cross sectional slice - uaully looked at in the tranverse but can also look at sagittal plane and rebuild to make 3D image
What is scintigraphy most often useful for?
Bone metabolism
Where is diffuse uptake often noted in the normal anima;?
Growth plates and joints
Why is scintigraphy useful?
More sensitive than radiographs for bony changes
What is the main use of MRI?
Brain and spinal imaging
How does MRI work?
Apply a pulsed magnetic energy and collecting radiowaves emitted by patient between pulses
Must be contained in a tunnel to allow a uniform magnetic field to form around the patient.
How would a heamotoma appear on MRI?
Heterogenous
How are colour changes on MRI referred to?
“Signal”
- An “Abnormal signal”
Fat has a “bright signal”
