MRI

Question 1

Why do patients and physicians favor MRI?

Answer 1

Noninvasive

Non-ionizing

Question 2

T/F: MRI is considered a true multiplanar imaging

Answer 2

True

Question 3

With soft tissue imaging, what is preferred, MRI or CT?

Answer 3

MRI

Question 4

What is the first responder to bone pathology ?

Answer 4

Bone Marrow

Question 5

Bone marrow activity is important for bone pathology, what imaging system is used to see bone marrow?

Answer 5

MRI

Question 6

What percentage of sensitivity to change in the bone can MRI detect?

Answer 6

1% but is only regional

Question 7

What two things interact with MRI processing?

Answer 7

Hydrogen protons (has magnetic charge)

External Magnetic field

Question 8

Atomic nuclei have to have what characteristics to be manipulated by MRI?

Answer 8

Odd number of proton and neutrons

Question 9

In which plane or direction of magnetic fields can hydrogen ions align?

Answer 9

Parallel or Anti-parallel

Question 10

MRI magnets range of strength ?

Answer 10

.2-1.5 to 3 Tesla

Question 11

MAgnetic field of earth

Answer 11

.25G(equator)

.6G(poles)

G=Gauss

Question 12

10,000G= ___Tesla

Answer 12

1 Tesla

Question 13

At what frequency and angle does the radio frequency have to be in order misalign the hydrogen to 90 or 180 degrees on its axis

Answer 13

Lamor-Frequency (42.58 MHz/T)

90 degrees

Question 14

In which tissue do the proton orient the fastest in order?

Answer 14

1. Fat
2. Water
3. Bone barely has H-looks black

Question 15

Pulse Sequence:

Time between each RF pulse varying from 500-4000msec

Answer 15

Time Repitition

Question 16

Pulse sequence:

Time from RF to listening for signal generated by patient varying from <40 to 100msec or >

Answer 16

Time echo

Question 17

Pulse sequence:

Determining factor of type of image created

Answer 17

TR + TE

Question 18

Pulse sequence:

Weighted image w/ short TR and short TE

Answer 18

T1/ fat image

Question 19

Pulse sequence:

Appearance of water and fat with T1

Answer 19

Fat=bright

Water=dark

Question 20

Pulse sequence:

Weighted image w/ long TR and Long TE

Answer 20

T2- waterimage

Question 21

Pulse sequence:

How does fat and water appear on T2

Answer 21

Water=bright

Question 22

Pulse sequence:

Why do the hydrogen’s align quicker in fat?

Answer 22

Hydrogen is less tightly bound to fat than it is to water substances

Question 23

Pulse sequence:

Image type is determined by TR and TE and what else?

Answer 23

Angle flip: Angle of deflection /flip of hydrogen proton

Question 24

Pulse sequence:

Spin echo

Answer 24

90 degree flip angle

Question 25

Pulse sequence: Gradient echo

Answer 25

<90 degrees flip angle

Question 26

MRI Image Type: Fat image-structures containing fat appear brighter/whiter (bone marrow, subcutaneous fat) Water-containing structures (edema, neoplasm, inflammation, CSF, large amounts of Fe) appear dark long TR, short TE

Answer 26

Spin Echo T1 *standard*

Question 27

MRI image Type: Proton density Good anatomical detail, has properties of both T1 and T2

Answer 27

Spin T2 first Echo

Question 28

MRI Image type: Water image Loosely bound water (neoplasms, edema, CSF) appear bright/white Tightly bound or low water content (ligaments, sclerosis, cortical bone) or large amounts of Fe appear dark/black

Answer 28

Spin T2 second echo *Classic/Standard*

Question 29

MRI Image Types: Multiple echoes/TR Faster exam time Very sensitive to edema 90-180 degree flip angle

Answer 29

Fast Spin Echo

Question 30

MRI IMAGE type: Fast MRI using short TR and TE w/ flip angle < 90degrees, Provides a T2 image in less time but does sacrifice some signal

Answer 30

Gradient Echo | GRE, GRASS, FLASH, FISP, MPGR, SPGR

Question 31

MRI image type: Technique that suppresses signal from fat, making small areas of pathology (often appearing bright because of edema) more evident and increasing the overall sensitivity of the exam, usually accomplished (STIR) More sensitive to H20 and edema

Answer 31

Fat Supression (STIR)

Question 32

Image type that displays functional joint movement.

Answer 32

kMRI

Question 33

Image type that is used to image vascular flow?

Answer 33

MRA

Question 34

Image type that reveal distribution of fluid restriction as seen in stroke?

Answer 34

Diffusion MRI

Question 35

Image type that displays concentration of biochemical metabolites?

Answer 35

MR spectroscopy

Question 36

Image type that displays changes in oxygen concentration associated with neural activation and provides high resolution imaging of the brain

Answer 36

Functional MRI

Question 37

Image weight bearing image (kMRI) that can reveal pathologies that may be missed such as canal stenosis, transitional motion and disc lesion

Answer 37

Upright MRI

Question 38

Indication for MRI

Answer 38

Suspicion of Cervical, thoracic, lumbar disc disease Suspicion of central canal/ foramina or lateral recess stenosis Suspicion of spinal cord pathology Congenital disorders Marrow infiltration Bone neoplasm Failed back syndrome Failure to improve w/ tx Active vs. inactive spndylolithesis(STIR preferred) Painful scoliosis

Question 39

Contraindications to MRI

Answer 39

1st trimester Ferromagnetic artifacts e.g., Aneurysm Clips Intraocular foreign bodies (welders)permanent eyeliner Subcutaneous Metal shards & some Shrapnel Cardiac pacemekers/defibrillators/implanted neurotranmitters (TENS units) Cochlear Implants, some prosthetic heart valves Calustrophobia -- ~5% rejection rate Individual patient rejection criteria have been established by each MRI facility should be stringently enforced

Question 40

1971 in MRI history

Answer 40

Damadian discovered Nuclear Magnetic resonance ability to differentiate cancerous from healing tissue

Question 41

1976 in MRI history

Answer 41

Damadian et al. First NMR image of mouse and later human thorax

Question 42

What is MR Imaging looking for?

Answer 42

Water/edema

Question 43

DiscHErniation without surrounding osteophytosis, can be acute, subacute of chronic. Seen on MRI

Answer 43

Soft herniation

Question 44

These symptoms describe: Saddle paresthesia or anesthesia Bowel or bladder disturbances Lower extremity mote weakness and sensory deficits Reduced or absent lower external reflexes LBP Uni/bilateral sciatic

Answer 44

CaudaEquina Syndrome

Question 45

Cyst that can have no symptoms, no way to be seen on plain films (on MRI) and is due to complication of facet DJD

Answer 45

Synovial cyst

Question 46

Modic Endplate: Represents changes that demonstrate disruption and fissuring of the endplate by vascularized fibrous tissues that invade the adjacent marrow Appears dark on T1 and bright on T2 Can convert to a type II

Answer 46

Type one Modic *Represents marrow edema*

Question 47

ModicEnplate Changes: Demonstrate endplate disruption with fatty marrow replacement in the adjacent vertebral body. Bright on T1&2

Answer 47

Modic Type II *fat degeneration of subchondral marrow*

Question 48

ModicEndplate change: Reflects the relative absence of marrow in areas of fibrous or compact bone deposition. Correlate with bone sclerosis on plain film Dark T1&T2

Answer 48

Modic Type III

Question 49

Cyst found on MRI typically in sacrum Perineural- fluid filled meninges dilation of nerve root sheath Asymptomatic, 20% symptomatic May need drainage

Answer 49

Tarlov’s cyst