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Skeletal Radiology A > MRI > Flashcards

MRI Flashcards

1
Q

Why do patients and physicians favor MRI?

A

Noninvasive

Non-ionizing

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2
Q

T/F: MRI is considered a true multiplanar imaging

A

True

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3
Q

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

A

MRI

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4
Q

What is the first responder to bone pathology ?

A

Bone Marrow

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5
Q

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

A

MRI

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6
Q

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

A

1% but is only regional

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7
Q

What two things interact with MRI processing?

A

Hydrogen protons (has magnetic charge)

External Magnetic field

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8
Q

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

A

Odd number of proton and neutrons

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9
Q

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

A

Parallel or Anti-parallel

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10
Q

MRI magnets range of strength ?

A

.2-1.5 to 3 Tesla

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11
Q

MAgnetic field of earth

A

.25G(equator)

.6G(poles)

G=Gauss

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12
Q

10,000G= ___Tesla

A

1 Tesla

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13
Q

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

A

Lamor-Frequency (42.58 MHz/T)

90 degrees

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14
Q

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

A
  1. Fat
  2. Water
  3. Bone barely has H-looks black
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15
Q

Pulse Sequence:

Time between each RF pulse varying from 500-4000msec

A

Time Repitition

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16
Q

Pulse sequence:

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

A

Time echo

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17
Q

Pulse sequence:

Determining factor of type of image created

A

TR + TE

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18
Q

Pulse sequence:

Weighted image w/ short TR and short TE

A

T1/ fat image

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19
Q

Pulse sequence:

Appearance of water and fat with T1

A

Fat=bright

Water=dark

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20
Q

Pulse sequence:

Weighted image w/ long TR and Long TE

A

T2- waterimage

21
Q

Pulse sequence:

How does fat and water appear on T2

A

Water=bright

22
Q

Pulse sequence:

Why do the hydrogen’s align quicker in fat?

A

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

23
Q

Pulse sequence:

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

A

Angle flip: Angle of deflection /flip of hydrogen proton

24
Q

Pulse sequence:

Spin echo

A

90 degree flip angle

25
Q

Pulse sequence:

Gradient echo

A

<90 degrees flip angle

26
Q

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

A

Spin Echo T1

standard

27
Q

MRI image Type:

Proton density

Good anatomical detail, has properties of both T1 and T2

A

Spin T2 first Echo

28
Q

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

A

Spin T2 second echo

Classic/Standard

29
Q

MRI Image Types:

Multiple echoes/TR

Faster exam time

Very sensitive to edema

90-180 degree flip angle

A

Fast Spin Echo

30
Q

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

A

Gradient Echo

GRE, GRASS, FLASH, FISP, MPGR, SPGR

31
Q

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

A

Fat Supression (STIR)

32
Q

Image type that displays functional joint movement.

A

kMRI

33
Q

Image type that is used to image vascular flow?

A

MRA

34
Q

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

A

Diffusion MRI

35
Q

Image type that displays concentration of biochemical metabolites?

A

MR spectroscopy

36
Q

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

A

Functional MRI

37
Q

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

A

Upright MRI

38
Q

Indication for MRI

A

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

39
Q

Contraindications to MRI

A

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

40
Q

1971 in MRI history

A

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

41
Q

1976 in MRI history

A

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

42
Q

What is MR Imaging looking for?

A

Water/edema

43
Q

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

A

Soft herniation

44
Q

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

A

CaudaEquina Syndrome

45
Q

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

A

Synovial cyst

46
Q

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

A

Type one Modic

Represents marrow edema

47
Q

ModicEnplate Changes:

Demonstrate endplate disruption with fatty marrow replacement in the adjacent vertebral body.

Bright on T1&2

A

Modic Type II

fat degeneration of subchondral marrow

48
Q

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

A

Modic Type III

49
Q

Cyst found on MRI typically in sacrum

Perineural- fluid filled meninges dilation of nerve root sheath

Asymptomatic, 20% symptomatic

May need drainage

A

Tarlov’s cyst

Skeletal Radiology A (5 decks)

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