MRI

Question 1

MRI scanners in clinical use have field strengths between 0.2T and 3.0T, with 1.5T being the most common

Answer 1

T

Question 2

Magnetic field homogeneity refers to the uniformity of the magnetic field throughout the magnet.

Answer 2

T

Question 3

Superconducting magnets operate at room temperature

Answer 3

F (They are cooled using liquid helium and surrounded by liquid nitrogen for thermal insulation.)

Question 4

Superconducting magnets consume large amounts of liquid helium in modern scanners

Answer 4

F (Modern scanners are designed to consume little liquid helium, making them more efficient.)

Question 5

The long narrow bore of superconducting magnets improves magnetic homogeneity

Answer 5

T

Question 6

Permanent MRI magnets are used widely in clinical practice

Answer 6

F

Question 7

Resistive MRI magnets require large amounts of electricity to generate a high magnetic field.

Answer 7

F. (Resistive magnets consume large amounts of electricity but produce only low-strength magnetic fields)

Question 8

The RF system transmits RF energy at the Larmor frequency and detects echoes emitted by the patient.

Answer 8

T

Question 9

As the field strength increases, the requirement for RF power decreases.

Answer 9

F. (RF power requirements increase with higher field strengths)

Question 10

Receive coils can be separate from transmit coils in MRI systems

Answer 10

T

Question 11

The amplitude of the echo detected by the RF coil does not require amplification

Answer 11

F. (Echo signals are very small and must be amplified before processing)

Question 12

The gradient system alters the magnetic field to provide spatial information about the patient

Answer 12

T

Question 13

Gradient coils alter the main
𝐵0 magnetic field strength.

Answer 13

T

Question 14

The loud noise in an MRI scanner is caused by the switching on and off of gradient coils.

Answer 14

T

Question 15

In the absence of an external magnetic field, hydrogen protons are randomly oriented

Answer 15

T

Question 16

Hydrogen protons align parallel or antiparallel to 𝐵0, creating equal energy levels.

Answer 16

F. (Protons align in two different energy states)

Question 17

The Larmor frequency is the resonant frequency of the tissue at a given magnetic field strength.

Answer 17

T

Question 18

The Larmor equation determines the frequency at which protons resonate

Answer 18

T

Question 19

T1 relaxation involves the transfer of energy to surrounding tissues (the lattice).

Answer 19

T

Question 20

Water has long T1 relaxation times

Answer 20

T

Question 21

Water has long T1 relaxation times and appears white on T1-weighted images

Answer 21

F. (Water has long T1 times but appears black on T1-weighted images)

Question 22

T2 relaxation involves the loss of phase coherence

Answer 22

T

Question 23

T2 relaxation always involves energy transfer

Answer 23

F. (T2 weighting may or may not involve energy transfer)

Question 24

T1 relaxation always involves energy transfer

Answer 24

T

Question 25

T1 relaxation times are dependent on B0

Answer 25

True

Question 26

T1 relaxation times are independent of B0

Answer 26

F. (T1 relaxation times are dependent on B0)

Question 27

In a Spin Echo sequence, T1 weighting requires a short repetition time (Tr) and echo time (Te)

Answer 27

T

Question 28

Inversion Recovery sequences start with a 90-degree pulse followed by a 180-degree pulse.

Answer 28

F. (They start with a 180-degree pulse, followed by a 90-degree pulse.)

Question 29

STIR is a fat suppression sequence, and FLAIR is a CSF suppression sequence.

Answer 29

T

Question 30

Gradient Echo sequences produce low signal-to-noise ratio (SNR) images.

Answer 30

T

Question 31

GE sequences are faster and have improved SNR compare to SE sequences

Answer 31

F. (GE sequences are faster but have reduced SNR compared to Spin Echo sequences)

Question 32

Image acquisition time is proportional to the number of frequency encoding steps.

Answer 32

F. (It is proportional to the number of phase encoding steps)

Question 33

Wrap-around artefact can be mitigated by increasing the field of view (FOV).

Answer 33

T

Question 34

The projectile effect depends on the rate of change of the magnetic field

Answer 34

T

Question 35

Cryogens used in MRI systems can pose hazards such as frostbite or asphyxiation

Answer 35

T

Question 36

AR measures the RF power absorbed per kilogram of tissue during an MRI scan

Answer 36

T

Question 37

Superconducting magnets are the most commonly used type in clinical MRI.

Answer 37

T

Question 38

Superconducting magnets have poor homogeneity

Answer 38

F. (They have excellent homogeneity)

Question 39

Permanent magnets are very stable and unaffected by external disruptions

Answer 39

F. (Permanent magnets are sensitive to external disturbances and temperature changes, which can destabilize the magnetic field.)

Question 40

Resistive magnets are energy-efficient and produce high field strengths.

Answer 40

F. (Resistive magnets consume large amounts of electricity and produce low field strengths.)

Question 41

Superconducting magnets are always on, regardless of whether a scan is in progress.

Answer 41

T

Question 42

The strength of 𝐵0 is unaffected by gradient coils

Answer 42

F

Question 43

The loud noise during MRI scans is caused by RF coil vibrations

Answer 43

F. (It is caused by the rapid switching of gradient coils.)

Question 44

The spatial resolution of an image depends on the central lines of k-space

Answer 44

F. (Spatial resolution is determined by the peripheral lines of k-space, while contrast is influenced by the central lines)

Question 45

Slice Thickness depends on the RF pulse bandwidth and the amplitude of the slice selection gradient

Answer 45

T

Question 46

A narrower RF bandwidth and lower gradient amplitude produce thicker slices.

Answer 46

F. (A narrower RF bandwidth and lower gradient amplitude produce thinner slices.)

Question 47

Energy transfer in T1 relaxation occurs via dipole-dipole interactions

Answer 47

T

Question 48

In T1-weighted images, fat appears bright and water appears dark.

Answer 48

T

Question 49

T1 is typically shorter than T2 for liquids

Answer 49

F. (T1 and T2 are similar for liquids)

Question 50

Gradient Echo (GE) sequences are faster than Spin Echo sequences but have lower SNR.

Answer 50

T

Question 51

The echo is the signal emitted by rephased spins and contains image information

Answer 51

T

Question 52

FID is used to form images

Answer 52

F. (FID does not contain image information and is ignored)

Question 53

The Fourier Transform is used to extract frequency and spatial information from MR signals.

Answer 53

T

Question 54

Frequency encoding is applied along the Y-axis, while phase encoding is applied along the X-axis.

Answer 54

F. (Frequency encoding is along the X-axis, and phase encoding is along the Y-axis.)

Question 55

The number of phase encoding steps determines the image acquisition time

Answer 55

T

Question 56

The projectile effect depends only on the strength of the magnetic field

Answer 56

F. (It also depends on the rate of change of the field and the properties of ferromagnetic materials)

Question 57

Chemical shift artefacts of the first kind can occur in both Spin Echo and Gradient Echo sequences.

Answer 57

T

Question 58

Superconductive magnets are attractive as they offer little to no resistance

Answer 58

T

Question 59

B0 is altered by gradient coils

Answer 59

T

Question 60

Anti-parallel protons are of lower energy than parallel 'with field' protons

Answer 60

F. (Antiparallel 'against field' protons have higher energy)

Question 61

T2 relaxation time is known as longitudinal relaxation time

Answer 61

F. (T1 Spin-Lattice relaxation time is known as longitudinal relaxation time)

Question 62

Contrast shows up better on a T1 weighted image

Answer 62

T

Question 63

Technetium is the most common contrast agent used in MRI

Answer 63

F. (Gadolinium)

Question 64

The rate limiting factor to produce an image is the number of phase encoding steps

Answer 64

T