MRI Hardware, History and Magnetism

Question 1

Gadolinium contrast gets first approval by FDA in what year?

Answer 1

1988!!

Question 2

How does Gad function as a contrast agent?

Answer 2

it SHORTENS the t1 time of tissue

Question 3

The substances that bind to gadolinium ions are defined as

Answer 3

Chelates

Question 4

Gadolinium chelates used in MR imaging are :

diamagnetic or paramagnetic?

Answer 4

paramagnetic

Question 5

Gadolinium has ___ unpaired electrons?

Answer 5

7

Question 6

Gadolinium makes bowel appear T1 and T2 Hypointense

True or False

Answer 6

True

Question 7

an anti-peristalsis agent in MR Enterography procedures.

Answer 7

Glucagon

Question 8

How come when we use contrast, a metastatic lesion will enhance?

Answer 8

has to do with the breakdown in the blood brain barrier

Question 9

What is the standard dose of gadolinium?

Answer 9

0.1 mmol/KG (pay attention, must be in KG)

Question 10

Following the administration of IV gadolinium contrast, it is recommended to:

Answer 10

Follow the injection with a flush of 5 mL saline

Question 11

VoLumen is a contrast agent used for

Answer 11

bowel enhancement

Question 12

The location of the coils installed in the MRI scanner, from the inner point closest
to the patient to the outer most edge are :

shim coils, main magnet, RF coils and gradient coils..what order?

Answer 12

RF radiofrequency coils, gradient coils,

shim coils, main magnet

Question 13

the time it takes for the gradient to reach its full amplitude is called

Answer 13

gradient rise time

think about the time it takes for you to fully stand up/rise up??

Question 14

What rise time measured in?

Answer 14

microseconds “mT/m (millitestla / meter)

Question 15

s the speed rate of ascent or descent of a gradient from

zero to its maximum amplitude, either positive or negative

Answer 15

the gradient slew rate

Question 16

How do we calculate the gradient slew rate

Answer 16

it is the amplitude divided by the rise time in msec.

Question 17

the time the gradients are on during a TR period, the

“gradient working time.”

Answer 17

duty cycle

Question 18

What is the primary cause of the noise in the MRI room?

Answer 18

the rapid successive switching of gradient coils

Question 19

If a sagittal slice plane has been selected, the ___ gradient is enabled to alter the
magnetic field around the patient’s body.

x y or z

Answer 19

x

Question 20

If a coronal slice plane has been selected, the __ gradient is enabled to alter the
magnetic field around the patient’s body.

x y or z

Answer 20

Y

Question 21

If a axial slice plane has been selected, the ___ gradient is enabled to alter the
magnetic field around the patient’s body.

Answer 21

z

Question 22

Applying two gradients simultaneously during slice selection would produce an
____ slice

Answer 22

oblique

Question 23

what is an example of when we do a “oblique” slice?

Answer 23

YX gradient combination in a coronal

oblique of the shoulder, parallel to the supraspinatus tendon

Question 24

In a cross sectional view of MRI system coils, the RF coils are closest to the patient.

True or False?

Answer 24

true

Question 25

Why is a fast spin echo the most concerning in regards to RF heating?

Answer 25

it has multiple echo train lengths leading to potential increase in tissue heating.

Question 26

What is the SAR measured in?

Answer 26

watts / kg

Question 27

Larger patient = increased or decrease SAR??

Answer 27

large patient = increased SAR

Question 28

When going from a linear coil to a quadrature coil, SNR is increased by ___ %? 40 , 60 , 80

Answer 28

40

Question 29

Radiofrequency (RF) shielding can be achieved by lining the scanner room walls with copper. True or False

Answer 29

True

Question 30

doubling the magnetic field strength will double the SNR

Answer 30

True

Question 31

What is the ideal consistent room temp that the MRI scanning room should be?

Answer 31

65-75 with humidity of 50-70%

Question 32

what is a positive to using the body coil?

Answer 32

the large FOV capability, but it lacks the high SNR.

Question 33

The MRI system component that produces the magnetization of proton spins (alignment) is known as the main magnet or the gradient system?

Answer 33

main magnet

Question 34

The MRI system component that provides the ability to perform spatial encoding is the main magnet or gradient system?

Answer 34

gradient system

Question 35

The liquid cryogens are cooled in a superconducting magnet at a temperature of _________

Answer 35

4 Kelvin

Question 36

The purpose of shimming the magnet is to make the B0 field as homogenous as possible True or False?

Answer 36

True

Question 37

The array processor is responsible for reconstructing the collected MR images/data using the Fourier transform, and is located in the MR equipment room.

Answer 37

True

Question 38

Field strength at magnet isocenter is measured in units of: tesla or gauss?

Answer 38

Tesla

Question 39

The unit of measurement of the magnetic field surrounding the periphery of the MR scanner is expressed as: Gauss or Tesla?

Answer 39

gauss

Question 40

The liquid cryogens most often used to maintain field strength in a super conducting MR system are

Answer 40

Helium

Question 41

Doubling the magnetic field strength will ___ the SNR. double or decrease?

Answer 41

double

Question 42

who coined the word electricity?

Answer 42

William Gilbert

Question 43

What is Joseph Fourier famous for?

Answer 43

he developed the mathematical equation to analyze the heat transfer between solid bodies

Question 44

Who first realized that the earth was one big giant?

Answer 44

William Gilbert, same person that coined the world electricity

Question 45

Who discovered that an electric current could produce a magnetic field?

Answer 45

Oersted

Question 46

Who is Michael Faraday?

Answer 46

He discovered electromagnetic induction. When a magnet was moved inside a coil of copper, a tiny electric current flows through the wire (aka Faradays Law)

Question 47

Whos equations describe how electric and magnetic fields are generated and altered by each other and by charges and currents?

Answer 47

Maxwell

Question 48

Who is Nikola Tesla?

Answer 48

He discovered the first rotating magnetic field. aka Tesla :)

Question 49

who developed the equation showing precession of nuclear spins being proportional to magnetic field strength?

Answer 49

Larmor

Question 50

In 1946 _____ proposed a Nobel Prize winning paper stating that the nucleus behaves like a magnet. He realized that a charged particle (proton) spinning on its own axis has a _____ momentum.

Answer 50

Feliz Bloch, and magnetic momentum

Question 51

Who created the fourier transform?

Answer 51

Richard Ernst in 1975

Question 52

Who obtained the first MRI picture?

Answer 52

Lauterbur

Question 53

The type of rock upon which magnetism was discovered is called?

Answer 53

magnetite

Question 54

______ discovered that tumors and normal tissue can be distinguished by NMR because of their relaxation times

Answer 54

Damadian

Question 55

What is the principle nucleus utilized in MR and why is it it used so much in MR?

Answer 55

hydrogen, bc our body has an abundance of it and its a primary element in both water and fat

Question 56

Magnetic field inhomogeneity is expressed in ____ per million

Answer 56

parts per million (ppm)

Question 57

10,000 gauss= __ tesla?

Answer 57

10,000 gauss= 1 tesla

Question 58

The main magnetic field is parallel to the long axis of B___ b0 or b1? .

Answer 58

b0

Question 59

one of the three magnetic states of matter : weak magnetic moment

Answer 59

paramagnetic

Question 60

one of the three magnetic states of matter : relatively strong magnetic field..are iron or iron-like substances

Answer 60

ferromagnetic

Question 61

one of the three magnetic states of matter : no magnetic field

Answer 61

Diamagnetic

Question 62

Gadolinium is considered what type of magnetic state? Ferromagnetic, paramagnetic, or diamagnetic

Answer 62

Paramagnetic because it creates a weak magnetic field