MRI Flashcards
What is an MRI?
non-invasive, cross-sectional imaging technology
What is the most technologically advanced imaging modality to date?
MRI
Which imaging modality produces high resolution image without radiation exposure?
MRI
An MRI uses a ___________ _____________ & _______________ ____________ to create an image.
magnetic field & radiofrequency signals
Images made in an MRI are based on measurements of what?
electrons emitted from hydrogen protons
What are the 3 components of an MRI?
magnetic field, radiofrequency, and three gradient coils
What do the three gradient coils provide?
“slices” in any direction
Radiofrequency Coils
transmits a radiofrequency pulse, which alters alignment of protons
How long does an MRI take?
20-90 minutes
Axial
feet are coming toward you
Sagittal
Left to right
Coronal
Front to back
What are the two different views provided w/an MRI?
T1 & T2
How does water appear in a T1 view?
darker
How does fat appear in a T1 view?
bright white
How does water appear in a T2 view?
bright white
How does fat appear in a T2 view?
darker
What is the T1 view best used for?
anatomic detail
What is the T2 view best used for?
pathological conditions & inflammation
Gyri
folds of the brain
Sulci
indentations or grooves of the brain
Where does the CSF fill into?
sulci, fissures & ventricles
What are the ABCDES of examining an MRI?
Alignment
Bone Signal
Canal Space/CNS
Disc Integrity
Edema
Soft Tissues
Fracture lines appear as low-signal or dark on T1, T2, or both?
both
Edema (inflammation)
abnormal fluid
How does edema appear on T1 view?
low intensity (darker)
How does edema appear on T2 view?
high intensity (bright white)
How does muscular atrophy appear on T1 view?
bright white (fat)
How does muscular atrophy appear on T2 view?
bright white (fluid)
How is a Short Tau Inversion Recovery (STIR) adjusted? What adjustments are made to the image?
adjusted T1 image that suppresses fat (dark) & enhances fluid (bright white)
How is Fluid Attenuated Inversion Recovery (FLAIR) adjusted? What adjustments are made?
adjusted T2 image that suppresses normal CSF fluid (makes it darker) to highlight other abnormalities
When is FLAIR commonly used?
brain imaging
Normal Pressure Hydrocephalus
abnormal build up of CSF in the ventricles of the brain
What is the effect of NPH on the brain? How does it appear on an MRI?
increases pressure on the brain
increase in ventricle size
brain being “squished”
What is the gold standard for intraarticular pathologies such as SLAP tears, labrum tears, & RTC tears?
coronal MR anthrography (MRA)
What are hip MRI indications?
labrum
What are knee MRI indications?
meniscus, cruciate ligaments, & collateral ligaments
What are ankle/foot MRI indications?
stress & navicular fx
What are shoulder MRI indications?
rotator cuff
What are elbow MRI indications?
tendons
What are wrist/hand MRI indications?
scaphoid & lunate fx
What are the pros of an MRI?
- increased soft tissue detail & contrast
- imaging in multiple planes w/o patient repositioning
- changes & variations in bone marrow
- NO IONIZING RADITION EXPOSURE
What are the cons of an MRI?
- expensive
- less available than a CT
- increased time
- claustrophobia
- requires safety check
What are safety considerations for an MRI?
- patient to answer safety screening beforehand
- assess for absolute or relative contraindications
What are contraindications to using an MRI?
- morbid obesity
- claustrophobia
- pediatrics
- kidney disease
- pregnancy
