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Advanced Imaging > Midterm Exam Material > Flashcards

Midterm Exam Material Flashcards

1
Q

Ordering MR

A

“I have a clinical suspicion of ________”

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2
Q

MR

A

H ions are excited by energy in the form of radio frequency using a surface coil. A strong magnet makes them spin in alignment. The changing moment causes an electric current in the surface coil.

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3
Q

Field Strength

A

Low vs high: how long does it take for the H ions to stop gyrating

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4
Q

Magnetic strengths measured in Tesla

A

0.3-0.5 Low field strength: Sufficient for spine
0.5-1.0 Intermediate field strength
1.5-3.0 High field strength: Required for extremities
<4.0 creates too much heat and human eyes cannot see any difference

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5
Q

MR contraindications

A 
Brain aneurysm clips
Intra-ocular foreign bodies
Subcutaneous metal
Pacemakers and some heart valves
Neurotransmitting spinal implants
Cochlear implants
High iron tatoos
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6
Q

Water’s view

A

X-ray to check orbit for metal

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7
Q

Echo time (TE)

A

Time from excitation to detection of signal

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8
Q

Repetition time (TR)

A

Time between excitation pulses (longer TR result in T2 images)

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9
Q

Fast spin echo (FSE)

A

Multiple echoes between repetition time (making it faster with good resolution)

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10
Q

Larmor Frequency

A

Frequency of precession of a proton

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11
Q

Radio Frequency (RF)

A

The energy that excites the protons

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12
Q

High/ bright signal

A

White

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13
Q

Intermediate signal

A

Light gray

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14
Q

Low signal

A

Dark gray

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15
Q

Signal void

A

Black

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16
Q

Hypo intense

A

Darker

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17
Q

Hyper intense

A

Brighter

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18
Q

Iso intense

A

Same

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19
Q

T1

A

Fat is bright: good anatomical detail

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20
Q

T2

A

Water is bright: physiologic information especially edema

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21
Q

Fat suppressed (T1)

A

STIR or FS PD FSE: Eliminate fat then image should be dark and anything that shows as bright is ABNORMAL WATER (Ex inflamed bone marrow or new vasculature of neoplasm)

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22
Q 
Proton Density (PD)
not very common
A

Fat is light gray
Water is medium gray
Good for cartilage evaluation

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23
Q

STIR

A

Short T1 Inversion Recovery

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24
Q

FS PD FSE

A

Fat Suppressed Proton Density Fast Spin Echo

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25
Q

STIR information

A

Fat is black (suppressed)
Water is bright
Takes longer than FS PD FSE
Good for bone marrow edema, synovial fluid, tendons, ligaments and cartilage evaluation

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26
Q

Gadolinium Contrast used in spinal MRI when?

A
  1. Looking for a tumor or px with history of tumor
  2. Infection (contrast enhances sepsis)
  3. ddx scar tissue from other tissue in px with previous surgery
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27
Q

Chronic back pain associated with?

A

Atrophied multifidi

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28
Q

MCC leg pain in the world

A

Lateral recess stenosis

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29
Q

Nerve entrapment in lateral recess via

A

Enlarged facet joint

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30
Q

Evaluating IVF in C-spine

A

Plain film and/or CT: NOT MRI

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31
Q

Evaluating dens

A

CT is preferred if pathology is suspected. (Normal for dens to have less signal since very little fatty marrow)

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32
Q

Disc bulge (P)

A

Physiologic: 1-3mm due to compressive forces throughout the day

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33
Q

Disc bulge (D)

A

Degenerative: not a herniation, can contribute to stenosis, due to lack of water binding from decreased GAGs, can’t be undone

34
Q

Degenerative disc bulge/ desiccation

A

Decreased disc signal on MRI

35
Q

Normally innervated part of disc

A

Outer 1/3 of disc

36
Q

Annular tears

A

Typically on periphery of disc
Contributes to DDD
Increased signal on T2 (Torn fibers fill with fluid)
Associated with disc herniation in lumbar spine ONLY

37
Q

High intensity zone (HIZ)

A

Presence of HIZ means tear is recent

38
Q

Significance of annular tears

A

Increased capillaries and decreased nerve conduction velocity (Pain and neurologic findings)

39
Q

Disc displacement

A

Extends past boundary of endplate

Applies to bulges and herniations

40
Q

Herniation

A

Local aka focal 0-25%

41
Q

Bulge

A

Broad based 26-50%

Circumferential >51%

42
Q

Percent of population with asymptomatic disc herniation

A

30%

43
Q

Protrusion

A

Base is wider than posterior extension

Can be herniation or non-contained herniation (sometimes asymptomatic)

44
Q

Extrusion

A

Base is narrower than posterior extension. Always associated with symptoms

45
Q

Sequestration

A

Disc material has lost continuity with parent disc and may migrate

46
Q

Relief from herniation

A

Herniation needs to shrink 20% (?) before symptoms go away

47
Q

Signs of disc herniation (need 3 of 5)

A
  1. Leg pain
  2. Confined to dermatome
  3. Neural stretch tests recreate/exacerbate leg pain
  4. Neurologic findings (2 of 4: weakness, reflex, pinwheel, atrophy)
  5. MR/CT correlating to dermatome
48
Q

Leg pain causes

A

Disc herniation, lateral recess stenosis, degenerative spondylolisthesis

49
Q

Spondylosis deformans

A

Normal aging

50
Q

IVOC

A

Pathologic process

51
Q

IVOC characteristics

A

Loss of disc height, vacuum phenomenon, disc calcification, decreased T2 signal, posterior spur (osteocartilagenous ridge)

52
Q

Spondylosis deformans endplate changes

A

Aka modic changes

53
Q

Modic Type 1

A

Decreased T1 (fat)
Increased T2 (water) INFLAMMATION
Sign of acute degeneration
Associated with PAINFUL discs

54
Q

Modic Type 2

A 
Increased T1 (fat)
Isointense T2 (water)
Change in nutrition of disc causes endplate changes not yet visible on X-ray
55
Q

Modic Type 3

A 
Decreased T1 (fat)
Decreased T2 (water)
Sclerosis visible on X-ray
No active marrow
End stage endplate change
56
Q

Subchondral sclerosis

A

Associated with poorer outcomes

57
Q

Modic Type 1 summary

A

Reversible inflammation of cartilaginous endplate (painful)

58
Q

Modic Type 3 consequences

A

Changes at one level predispose adjacent areas for degeneration

59
Q

Lateral recess stenosis

A

Canal is supposed to look like isosceles triangle, only TPs should be lateral

60
Q

Clinical result of bilateral lateral recess stenosis caused by facet osteoarthrosis…

A

Back pain and non-dermatome leg pain

61
Q

Clinical result of central stenosis

A

Sclerotogenous pain

62
Q

Signs of degenerative spondylolisthesis

A

Intermittent scleratogenous leg pain (not past knee)
Often reduced by leaning forward or sitting down
No neurologic findings
Very common (female, fat, 40, L4)

63
Q

Recent compression fracture on MR

A

Fracture causes bleeding and bone marrow edema which dissipates in 6 weeks (up to 1 year)

64
Q

Pathologic compression fracture ddx

A

Mets (+ bone scan)
MM (+ lab work)
OP (- both)

65
Q

Benign characteristics

A 
Normal marrow
Focal involvement
No pedicle involvement
Posteriorly angulated fragment?
No soft tissue mass
Fluid sign
66
Q

Malignant characteristics

A 
Abnormal fatty marrow
Multifocal involvement (why bone scan is needed)
Pedicle involvement
Posterior convexity? 
Soft tissue mass
No fluid sign
67
Q

Homogenous alteration in signal indicates…

A

Destruction of endplates

68
Q

Arnold-Chiari malformation

A

Type 1: 1-4mm usually asymptomatic
Type 2: >5mm MC symptoms are HA and dizziness, may cause syrinx formation
Associated with upper cervical anomalies

69
Q

Syrynx/ syringomyelia

A

CSF filled cavity within the parenchyma of the spinal cord

Caused by arnold-chiari, cord tumor, cord trauma, idiopathic, left sided thoracic scoliosis

70
Q

Syrinx treatment

A

Drainage or laminectomy

71
Q

MRI and tumors

A

Fat suppressed MRI very sensitive. Provides extent of soft tissue extension when present (*calcium is a signal void)

72
Q

Hemangioma

A 
An A/V malformation
Decreased T1 (fat)
Increased T2 (water)
In 100% of population on MRI
Not clinically significant
73
Q

MRI for spinal mets

A

Very sensitive, limited to FOV, marrow replacement alters signal, assess extent of cortical involvement and soft tissue extension if present

74
Q

Paget’s

A

Thickening of osteoid, enlargement and softening

75
Q

Brain bleeds

A

First 24-48 hours blood is isointense with brain tissue (CT is needed)
>48 hours blood is hyperintense (signal is increased as hemoglobin degrades)

76
Q

Subdural hematoma

A

Small vessel bleeds: worsening headaches, altered mental status

77
Q

Diffusion tensor imaging (DFI)

A

Assesses how water moves, helpful in acute brain bleeds, helpful in brain injuries assessing neural flow

78
Q

Evaluating for stroke (immediately?)

A

Diffusion MRI

79
Q

Evaluating for brain tumors

A

MRI (sensitive and shows surrounding edema)

80
Q

Evaluating MS

A

MRI: sensitive and shows plaque as increased signal (especially on T1)

Advanced Imaging (3 decks)

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