Week 11- mri Flashcards
what does mri stand for
Magnetic Resonance Imaging
how can we change the random movement of a proton
applying a magnet and it can be measured via energy released.
difference in proton density shows image due to contrast.
what is t1
T1 – known as the fat image. Fat – hyperintense (bright) and water(edema, swelling , CSF, IVD’s) hypointense (dark
fat= bright
what is t2
T2 – known as the water image. Tissues containing mobile hydrogenprotons (IVD’s, CSF, edema) are hyperintense (bright).
csf= bright
in the brain how could you differentiate t1 and t2
fat illuminated around brain (benath skin)
t2= ventricles filled with csf in centre of brain
when would we use mri
spinal cord, spine, IVD’s, ligamets, musculatureand vertebral marrow
to investigate or diagnose conditions that affect soft tissue such as tumours or brain disorders.
why would we use mri ovr ultrasound
evaluate damage to cartilage, bone or other structures inside and around a joint, MRI is the better choice. MRI is also preferred for conditions that impact deep or large areas since ultrasound can evaluate only a small area at a time.
function of ultrasound
to study a developing fetus (unborn baby), a person’s abdominal and pelvic organs, muscles and tendons, or their heart and blood vessels.
internal body structures
how does ultrasound work
high-frequency sound waves.
when they bounce off different parts of the body, they create “echoes” that are picked up by the probe and turned into a moving image.
when is ultrasound no useful
Bones.*
Fractures.*
Tissues containing air
.* Cancer.*
Intracapsular assessment
.* Total joint replacements.
* Mostly DUE to bio effects
why would we use an xray over an ultrasound
x-rays is done which have penetrating ability (recommended for hard tissue) while in
ultrasound (recommended for hollow structures and soft tissues) is done.
why would we use xray over mri
to get a better view of your bones, while MRIs are preferred for soft tissue images and don’t use any radiation
why do you have to wait 1 weeks befor baby scan
Heat is the main biological effect and therefore many recommendations suggest minimising featal US, and only conducting imaging where there is clear clinical need.
limitations of ultrasound
Operator dependant modality.*
Poorly repeatable- probe in different are
gives off heat
