Midterm Exam Material Flashcards
(80 cards)
1
Q
Ordering MR
A
“I have a clinical suspicion of ________”
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.
3
Q
Field Strength
A
Low vs high: how long does it take for the H ions to stop gyrating
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
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
6
Q
Water’s view
A
X-ray to check orbit for metal
7
Q
Echo time (TE)
A
Time from excitation to detection of signal
8
Q
Repetition time (TR)
A
Time between excitation pulses (longer TR result in T2 images)
9
Q
Fast spin echo (FSE)
A
Multiple echoes between repetition time (making it faster with good resolution)
10
Q
Larmor Frequency
A
Frequency of precession of a proton
11
Q
Radio Frequency (RF)
A
The energy that excites the protons
12
Q
High/ bright signal
A
White
13
Q
Intermediate signal
A
Light gray
14
Q
Low signal
A
Dark gray
15
Q
Signal void
A
Black
16
Q
Hypo intense
A
Darker
17
Q
Hyper intense
A
Brighter
18
Q
Iso intense
A
Same
19
Q
T1
A
Fat is bright: good anatomical detail
20
Q
T2
A
Water is bright: physiologic information especially edema
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)
22
Q
Proton Density (PD) not very common
A
Fat is light gray
Water is medium gray
Good for cartilage evaluation
23
Q
STIR
A
Short T1 Inversion Recovery
24
Q
FS PD FSE
A
Fat Suppressed Proton Density Fast Spin Echo
25
STIR information
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
26
Gadolinium Contrast used in spinal MRI when?
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
27
Chronic back pain associated with?
Atrophied multifidi
28
MCC leg pain in the world
Lateral recess stenosis
29
Nerve entrapment in lateral recess via
Enlarged facet joint
30
Evaluating IVF in C-spine
Plain film and/or CT: NOT MRI
31
Evaluating dens
CT is preferred if pathology is suspected. (Normal for dens to have less signal since very little fatty marrow)
32
Disc bulge (P)
Physiologic: 1-3mm due to compressive forces throughout the day
33
Disc bulge (D)
Degenerative: not a herniation, can contribute to stenosis, due to lack of water binding from decreased GAGs, can't be undone
34
Degenerative disc bulge/ desiccation
Decreased disc signal on MRI
35
Normally innervated part of disc
Outer 1/3 of disc
36
Annular tears
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
High intensity zone (HIZ)
Presence of HIZ means tear is recent
38
Significance of annular tears
Increased capillaries and decreased nerve conduction velocity (Pain and neurologic findings)
39
Disc displacement
Extends past boundary of endplate
| Applies to bulges and herniations
40
Herniation
Local aka focal 0-25%
41
Bulge
Broad based 26-50%
| Circumferential >51%
42
Percent of population with asymptomatic disc herniation
30%
43
Protrusion
Base is wider than posterior extension
| Can be herniation or non-contained herniation (sometimes asymptomatic)
44
Extrusion
Base is narrower than posterior extension. Always associated with symptoms
45
Sequestration
Disc material has lost continuity with parent disc and may migrate
46
Relief from herniation
Herniation needs to shrink 20% (?) before symptoms go away
47
Signs of disc herniation (need 3 of 5)
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
Leg pain causes
Disc herniation, lateral recess stenosis, degenerative spondylolisthesis
49
Spondylosis deformans
Normal aging
50
IVOC
Pathologic process
51
IVOC characteristics
Loss of disc height, vacuum phenomenon, disc calcification, decreased T2 signal, posterior spur (osteocartilagenous ridge)
52
Spondylosis deformans endplate changes
Aka modic changes
53
Modic Type 1
Decreased T1 (fat)
Increased T2 (water) INFLAMMATION
Sign of acute degeneration
Associated with PAINFUL discs
54
Modic Type 2
```
Increased T1 (fat)
Isointense T2 (water)
Change in nutrition of disc causes endplate changes not yet visible on X-ray
```
55
Modic Type 3
```
Decreased T1 (fat)
Decreased T2 (water)
Sclerosis visible on X-ray
No active marrow
End stage endplate change
```
56
Subchondral sclerosis
Associated with poorer outcomes
57
Modic Type 1 summary
Reversible inflammation of cartilaginous endplate (painful)
58
Modic Type 3 consequences
Changes at one level predispose adjacent areas for degeneration
59
Lateral recess stenosis
Canal is supposed to look like isosceles triangle, only TPs should be lateral
60
Clinical result of bilateral lateral recess stenosis caused by facet osteoarthrosis...
Back pain and non-dermatome leg pain
61
Clinical result of central stenosis
Sclerotogenous pain
62
Signs of degenerative spondylolisthesis
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
Recent compression fracture on MR
Fracture causes bleeding and bone marrow edema which dissipates in 6 weeks (up to 1 year)
64
Pathologic compression fracture ddx
Mets (+ bone scan)
MM (+ lab work)
OP (- both)
65
Benign characteristics
```
Normal marrow
Focal involvement
No pedicle involvement
Posteriorly angulated fragment?
No soft tissue mass
Fluid sign
```
66
Malignant characteristics
```
Abnormal fatty marrow
Multifocal involvement (why bone scan is needed)
Pedicle involvement
Posterior convexity?
Soft tissue mass
No fluid sign
```
67
Homogenous alteration in signal indicates...
Destruction of endplates
68
Arnold-Chiari malformation
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
Syrynx/ syringomyelia
CSF filled cavity within the parenchyma of the spinal cord
| Caused by arnold-chiari, cord tumor, cord trauma, idiopathic, left sided thoracic scoliosis
70
Syrinx treatment
Drainage or laminectomy
71
MRI and tumors
Fat suppressed MRI very sensitive. Provides extent of soft tissue extension when present (*calcium is a signal void)
72
Hemangioma
```
An A/V malformation
Decreased T1 (fat)
Increased T2 (water)
In 100% of population on MRI
Not clinically significant
```
73
MRI for spinal mets
Very sensitive, limited to FOV, marrow replacement alters signal, assess extent of cortical involvement and soft tissue extension if present
74
Paget's
Thickening of osteoid, enlargement and softening
75
Brain bleeds
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
Subdural hematoma
Small vessel bleeds: worsening headaches, altered mental status
77
Diffusion tensor imaging (DFI)
Assesses how water moves, helpful in acute brain bleeds, helpful in brain injuries assessing neural flow
78
Evaluating for stroke (immediately?)
Diffusion MRI
79
Evaluating for brain tumors
MRI (sensitive and shows surrounding edema)
80
Evaluating MS
MRI: sensitive and shows plaque as increased signal (especially on T1)
