Intro to MRI + Cross-Sectional Anatomy Notes

CH B

What does MRI stand for?

magnetic resonance imaging

What is the unit used to measure the strength of magnetic fields?

Tesla (T)

What type of MRI scanner is “old style” and uses a longboard?

long bore

How long are the longboards in a long bore scanner?

268 cm or 9 ft

What type of MRI scanner has two types of gantry openings and uses a shortboard?

short bore

How long are the shortboards in a short bore scanner?

125-180 cm

What is the diameter for a standard short bore gantry opening?

60 cm

What is the diameter for a wide short bore gantry opening?

70-80 cm

What type of MRI scanner produces images less detailed than long/short bores and has a “hamburger bun” shape?

open scanner

What type of patients are usually scanned by an open scanner?

larger patients

What is the strength of a traditional open scanner?

0.2-0.6 T

What is the strength of a traditional closed MRI scanner?

1.5 T

What is the strength of a high field MRI scanner?

3 T

What component in a MRI machine creates a path for magnets for follow?

gradient coils

What is known as the “antenna of the MRI”?

radio-frequency coils

What do radio-frequency coils do?

broadcast RF signal to subject and/or receive return signal

What molecules does the MRI target in body cells to produce signals?

water molecules

How does the magnet from the MRI machine affect protons?

aligns protons in water molecules (direction-wise)

What does the emitted radio pulse do to the aligned protons?

causes protons to turn away by about 90 degrees

What happens when the protons relax back to their aligned direction?

releases radio signal that is detected by system

What MRI sequence shows CSF as dark, white matter as light gray, and pathologies as dark? (dark - light - dark)

T1-weighted

What MRI sequence shows CSF as light, white matter as dark gray, and pathologies as light? (light - dark - light)

T2-weighted

What MRI sequence shows CSF as dark, white matter as dark gray, and pathologies as light? (dark - dark - light)

flair

What is the most commonly used contrast agent?

gadolinium-based contrast agents

What are 3 indications for a MRI scan?

anomalies of brain brain/spinal cord/nervous systems, tumors, and injuries/abnormalities to joints

What are 3 things that can prevent a MRI scan?

certain pacemakers, cochlear implants, and insulin pumps

How can the magnet in a MRI machine be shut off?

depletion of magnetic field by performing a quench

What is a term that describes the rapid release of cryogenic fluid?

quench

What is the unfortunate consequences of quenching?

expensive payment and takes magnet out of commission for weeks

When an object is completely safe to have during a MRI scan, it is known as what?

MR safe

When an object may or may not be safe to have during a MRI scan, it is known as what?

MR conditional

When an object is under any circumstances unsafe to have during a MRI scan, it is known as what?

MR unsafe

What term describes a primary central nervous system tumor?

gliosarcoma

Where does gliosarcoma begin its growth?

brain or spinal cord

What term describes a cancer of the brain from glial (supportive) brain cells?

glioma

How is gliosarcoma categorized as?

malignant