TQ Emphasis Flashcards
Low field strength (in Tesla)
0.3-0.5 Tesla
Intermediate field strength (in Tesla)
0.5-1.0 Tesla
- High field strength (in Tesla)
- How many degrees Fahrenheit does high field strength raise the body temperature?
- 1.5-3.0 Tesla
- 2˚
- What is the highest Tesla field strength that can be seen by the human eye?
- How many degrees Fahrenheit does this field strength raise the body temperature?
- 4 Tesla
- 4-5˚ (we stop at 3 Tesla because this is too high of a temperature for the body to endure)
Small extremities should be obtained on high field strength magnets…what is considered “small”?
Small = elbows to fingers & ankles to toes
Need high field strength, 1.5-3.0 Tesla, to detect these small ligaments
When sending a patient for an MR with a Traditional Bore Magnet, what is a crucial question to ask them first?
Are you claustrophobic?…if yes, they would do better with open magnet
What are the 3 things that determine image quality?
1) Field strength — higher field strength = prettier image
2) Coil — should be dedicated coil for specific body part
3) Post-imaging software — changes ~ every 10 years (upgrades cost ~$100k)
What is one of the most recently added contraindications to MR?
Lycra (found in clothing materials such as yoga pants)
What type of metals are contraindications to MR?
Ferromagnetic
Note: most metals used in surgery are NOT ferromagnetic
Terminology: Time from excitation to detection of signal
TE/Time Echo
Terminology: Time between excitation pulses
TR/Repetition time
- Shorter TE & TR =
- Longer TE & TR =
- T1
- T2
Terminology: Uses MULTIPLE echos between repetition time making it faster with good resolution (like a loop/overlap of echos)
FSE/Fast Spin Echo
Terminology: Frequency of precision of a proton (is what determines radio frequency)
Larmor Frequency
Terminology: The energy that excites the protons
RF/Radio Frequency
Abbreviations:
- TE =
- TR =
- FSE =
- RF =
- Time Echo
- Repetition Time
- Fast Spin Echo
- Radio Frequency
- Hypo-intense =
- Hyper-intense =
- Iso-intense =
- Darker
- Brighter
- Same
MR sequence for best ANATOMICAL detail
T1
MR sequence for best PHYSIOLOGIC info
T2
Best for cartilage evaluation (and used for brain imaging)
PD/Proton Density
What does STIR stand for?
Short T1 Inversion Recovery
What is a faster/quicker study: STIR or FS PD FSE?
STIR takes LONGER to do than FS PD FSE
What does FS PD FSE stand for?
Fat Suppressed Proton Density Fast Spin Echo
When is Gadolinium administered?
At the END of a study with T1 image
Regular water black, enhance accumulation of fluid
Use Gadolinium when you have clinical suspicion of: (3 things)
- Tumor/METs/pt with hx of aggressive tumor
- Infection
- Prior surgery in area of complaint
How do we differentiate between scar tissue and discs on MR?
Gadolinium contrast needed to differentiate scar tissue and discs.
- scar tissue has MORE blood supply than the disc…will accumulate gadolinium on T1
On what view and where would you look for Lateral Recess Stenosis (LRS)?
Transaxial view, just BELOW the disc/endplate (right where the spinal nerve comes out)
Landmarks:
- on an axial image, “25R” indicates what?
You are 25mm to the R of midline
Landmarks:
- What is the best way to find your placement in the lumbar spine?
Go to the lowest lumbar and count up
Transaxial image is viewed as if you are looking through…
The patients feet, towards their head
- Where do you look for a PARS defect?
- Is MR a good modality to look for a PARS defect?
- Location: PARS defect is right where the Pedicle meets the Lamina (near the IVF)
- MR is NOT good for visualizing PARS defects
Sagittal view: what is the oblique line running through the spinal nerve/IVF?
Fascicles
Disc bulge can compress fascicles —> leg pain
Sagittal: What is the tiny dark circle running along the bottom of the IVF?
Vascular tissue (vessels)
- What color are vessels on T2 images?
- What is the modality of choice to view vessels?
- DARK ((because they’re moving fast—can be visualized (bright) IF the blood is flowing slow enough))
- MRA (magnetic resonance ANGIOGRAPHY)
What does fatty infiltrate of the erector spinae (or any muscle) indicate?
Atrophy. Indicated chronic back pain if in spinal muscles.
If the posterior aspect of the disc and vertebral body are not in a straight line, what does this indicate?
Disc bulge
How well does MRI image strains/sprains in the spine?
NOT WELL AT ALL
What does Inverted Bun Sign indicate on Transaxial image?
Facet dislocation
With Lateral Recess Stenosis, what spinal ROM compresses the nerve?
Lateral bending and Rotation
What is the most common cause of leg pain in the world?
Lateral Recess Stenosis
Is MRI a good modality to evaluate IVF narrowing and reveal OA?
NO. MRI is NOT a good modality to evaluate IVF narrowing.
Plain film or CT are best for this
Sagittal: Cerebellum breaks the foramen magnum line. What does this indicate?
Arnold Chiari Malformation
The dens is imaging dark/black on all MR sequences. What does this indicate?
NORMAL.
No fatty marrow inside dens—will be black on all MR sequences.
What is the modality of choice for assessing the dens?
CT
If a transaxial image looks “cut off” or black on one side, what does this indicate?
Improper coil used
What ages do disc bulges occur?
ANY age!
Is a degenerative disc bulge the same as a herniation?
No
What sagittal MR sequence is better for evaluating disc bulge: T1 or T2?
T2 – bulge (degenerated disc) will be dark (due to lack of nutrition/water), CSF will be bright white
What is the difference between a bulge and a herniation?
- Bulge: CIRCUMFERENCE of disc is bigger than circumference of endplate
Is MR necessary to prove disc herniation?
No. MR is NOT necessary to prove disc herniation.
Plain film is NOT diagnostic, either. Rely on clinical findings.
What does a recent (≤6 weeks) annular tear look like on a T2 sagittal image?
Bright signal within posterior aspect of disc bulge or herniation.
What MR view is needed to ddx a disc bulge from a disc herniation?
Transaxial: lateral collection of disc will be extending into the IVF.
*** A recent (≤6 weeks) annular tear looks increased signal within herniation on a T2 sagittal image. What is this area of increased signal called?
High intensity zone (HIZ) — indicates recent annular tear
Can significant annular tears result in reduced nerve conduction velocities?
Yes
What are the 3 locations of disc herniations?
- foraminal/far out
- central
- paracentral
What percentage of the disc is displaced in each type of displacement:
- LOCAL
- BROAD BASED
- CIRCUMFERENTIAL
- Local = 0-25% (This is where and how we see herniations)
- Broad based = 26-50% (Bulge sticking out around half of the disc)
- Circumferential = ≥ 51% (Bulge sticking out around entire circumference of disc)
Define:
- Disc Protrusion
- Disc Extrusion
- Disc Sequstration
- Protrusion: Width of the base is WIDER than the length of posterior extension
- Extrusion: Width of the base is NARROWER than the length of the posterior extension
- Sequstration: DISPLACED disc material lost continuity with parent disc (can migrate…lead to cauda equina syndrome—911!)
- Are disc PROTRUSIONS aways symptomatic?
- How much of the population is walking around with disc protrusions?
- Disc protrusions are NOT always symptomatic (MOST ARE symptomatic, but not all)
- ⅓ of the population is walking around with disc protrusions (and are Asymptomatic)
What % must a central disc protrusion shrink for symptoms to cease?
20% shrinkage
Is MRI necessary to diagnose a disc herniation?
NO. Follow clinical criteria.
List the 5 signs/criteria for diagnosing disc herniation:
Need 3/5 consistent to same nerve level)
- Primarily leg pain
- Leg pain confined to dermatome
- Neural stretch tests recreate pain
- At least 2/4 neuro findings consistent with dermatome
- muscle weakness
- decreased reflex
- abnormal pinwheel
- atrophy
- MR or CT correlating to dermatome (NOT NECESSARY for dx)
When would you order an MR to evaluate disc herniation?
If there is progressive neurological deficit (this is the pt that will need surgical intervention)
Modality (or modalities) to evaluate loss of disc height:
- X-ray
- MR
- CT
Modality (or modalities) to evaluate vacuum phenomenon:
- X-ray
- CT
Modality (or modalities) to evaluate disc calcification:
- X-ray
- CT
Modality (or modalities) to evaluate posterior spur/osteocartilagenous ridge:
- X-ray
- MR
- CT
What type of modic endplate change can be stopped and is reversible?
Modic Type 1 endplate changes can be stopped and is reversible
What type of modic endplate changes can be stopped without progression (NOT reversible)?
Modic Type 2 endplate changes can be stopped but is not reversible.
What type of modic endplate changes cannot be stopped (NOT reversible)?
Modic Type 3 endplate changes cannot be stopped (NOT reversible)
What type of modic endplate changes are associated with painful discs?
Modic Type 1
What type of modic endplate changes are involved with change in nutrition to the disc?
Modic Type 2
What type of modic endplate changes show sclerosis on x-ray?
Modic Type 3
How do the MR sequences image with Type 1 Modic Endplate Changes?
- Decreased T1
- Increased T2
How do the MR sequences image with Type 2 Modic Endplate Changes?
- Increased T1
- Isointense/slightly decreased T2
How do the MR sequences image with Type 3 Modic Endplate Changes?
- Decreased T1
- Decreased T2
What area of the spine does Lateral Recess Stenosis occur?
ONLY the lumbar spine
How does the potential for Lateral Recess Stenosis appear on AP lumbar x-ray?
Facet joints OUTSIDE of the VB disc (joints enlarged & project lateral to disc-body junction)
What type of leg pain does degenerative Spondylolisthesis of the lumbar spine present with? Can the pain be reproduced?
Scleratogenous leg pain—cannot be reproduced with provocative tests.
How to clinically differentiate Degenerative Spondy and disc herniation:
Degenerative spondy does NOT have any neurological findings (disc herniation does have neuro findings)
Modality of choice to view degenerative spondy?
X-ray
MR can be done to ease patient’s concerns…not necessary for dx thought
Is “cancer phobia” a reason to take MR?
YES.
Degenerative Spondylolisthesis:
- What grade is most common?
- Average % of forward slippage?
- Most common spinal level?
- Grade 1
- 10% forward slippage
- Most common at L4
The “4 F’s” are risk factors for _____?
Degenerative Spondy
Goal for degenerative spondy care: (what % of improvement are we looking for?)
50% improvement (objectively and subjectively)
How do we age compression fractures with MR?
Bone marrow edema usually gone within 6 weeks:
- if T1 signal decreased (dark) = recent (water/edema dark)
- if T2 signal increased (bright white) = recent (water/edame bright)
Osteoporosis: results of Bone Scan & Blood/Urine Labs
(-) Bone scan (except at fracture site)
(-) Blood & Urine
METS: results of Bone Scan & Blood/Urine Labs
(+) Bone scan
(-) Blood & Urine
MM: results of Bone Scan & Blood/Urine Labs
(-) Bone Scan
(+) Blood & Urine Labs
5 indicators of normal marrow (osteoporosis) compression fracture:
- focal involvement
- NO pedicle involvement
- posteriorly angulated fragment
- NO soft tissue mass
- FLUID SIGN
5 indicators of abnormal marrow (METS/MM) compression fracture:
- multifocal involvement
- pedicle involvement
- posterior CONVEXITY
- soft tissue mass
- NO fluid sign
How many millimeters is a Type 1 Arnold-Chiari Malformation? Type 2?
- Type 1: 1-4mm
- Type 2: 5mm
If a patient is <50yoa an has balance issues, you should suspect:
Arnold-Chiari Malformation
If BOTH Occipitilization and C2/3 blocked vertebra are present, suspect:
Arnold-Chiari Malformation
Visualized field necessary when taking MR of Syrynx/Syringomyelia:
Must see top & bottom of syrynx to be sure there’s no tumor
Signs & Symptoms of Syrynx/Syringomyelia:
- sensation loss over trapezius
- cuts/bruises/burns on hands (can’t feel their hands)
Modality of choice for tumors
MR with contrast (fat suppressed)
Most common tumor of the spine? How does it present on MR?
Hemangioma:
- Decreased T1
- Increased T2
Modality of choice to evaluate spinal METS (or other aggressive tumors):
T1 with Gadolinium
T2 is good too, but T1 w/contrast is best
Modality of choice to evaluate ACUTE brain bleed?
CT
Modality of choice to evaluate SUBACUTE & CHRONIC brain bleeds:
MRI
Types of brain bleeds:
- Hemorrhagic stroke
- Torn dura (trauma-related)
Modality of choice to evaluate torn EPIDURAL vessels:
CT (acute)
- epidural vessels are large—bleed fast
Modality of choice for SUBDURAL vessels:
MRI
- slow bleed, pt usually asymptomatic for 3-5 days
What modality evaluates how water moves and is helpful in brain injuries to assess neural flow?
DFI (Diffusion Tensor Imaging)
Modality of choice for evaluating brain tumors:
MRI
Modality of choice for evaluating MS:
MRI (high signal plaques, ESPECIALLY on T1
Note: BRAIN MRI, not cervical MRI
What % of Tarlov/Meningial Cysts are located in the sacral canal? If not in the sacral canal, where are else would they be located?
- 99% in sacral canal
- can be located in Lumbar Spine (called Arachnoid cysts here)
Are Tarlov/Meningial Cysts asymptomatic?
Yes, Tarlov cysts are almost ALWAYS asymptomatic
Are Tarlov Cysts a contraindication to chiropractic?
NO. Normal variant.
Modality of choice for evaluating Tarlov/Meningial Cysts:
MRI
NOT visible on plain film x-ray, confusing when appear on CT
Synovial Cysts act like a disc herniation in some instances…what is the prognosis compared to disc herniation? Are synovial cysts a contraindication to chiro?
Synovial Cysts have a MUCH BETTER prognosis than disc herniation. NOT a contraindication to chiro are.
What is the Gold Standard to evaluate vasculature?
Digital Subtraction
- MRA (Magnetic Resonance ANGIOGRAPHY): almost as detailed as digital subtraction, can be done w/o contrast (though faster w/Gadolinium), image can be spun and viewed in many planes.
What does MOTSA stand for?
Multiple Overlapping Thin Slab Acquisitions
Initial modality to assess Vertebral Artery Dissection.
MRA (does NOT always accurately dx VAD)
Where is the only place you’ll see coracoclavicular ligament of shoulder?
1st or 2nd slice of Coronal Oblique View (MR)
Where to look for Rotator Cuff Tears (RCT) on MR:
11:00 or 1:00 positions on coronal oblique view
What can you see attaching to the labrum on the anterior part of 11 or 1:00 on coronal oblique view?
Intercapsular portion of biceps tendon
How does the labrum appear on MR?
Triangle of solid black
What is the only type of RCT visible via arthroscopic surgery?
Under surface tear (bottom, partial thickness tear)
Modality of choice to view RCT? Be specific.
MRI: T2 (synovial fluid and edema will be bright)
What does SLAP stand for? What is the AKA of SLAP lesion?
- Superior Labral Anterior to Posterior Lesion
- AKA Peel-Back Lesion
Best view to evaluate SLAP Lesion:
Coronal Oblique MRI
- What position of the clock can we view SLAP 1 Lesions?
- What position of the clock can we view SLAP 2 Lesions?
- SLAP 1 = 11-1:00 (only shows up on a couple of slices!!!)
- SLAP 2 = 11 through 1:00 (shows up throughout)
What is the modality of choice for evaluating the labrum of the shoulder (& hip)? Be specific.
MR-Arthrogram (saline fluid injected into joint, T2 will show saline in tear/joint space as white)
If fracture is suspected in the shoulder/humeral head (or the hip/femoral head), what should we automatically suspect?
Labral tear
Do SLAP 1 and SLAP 2 have different prognoses?
No. Both respond well to conservative care.
What does GIRD stand for?
Glenohumeral Internal Rotation Deficit
GIRD: Repetitive tensile load during the ___(a)___ phase of throwing is causing thickening of the ___(b)___?
(a) follow-through
b) PIGHL (Posterior Inferior Glenohumeral Ligament
GIRD: Tight, thick PIGHL (Posterior inferior glenohumeral ligament) leads to shift of the _____ contact point.
Glenohumeral
GIRD: In the ___(a)___ phase of throwing, the thick PIGHL is beneath the humeral head and pushes it ___(b)___.
(a) late cocking
(b) Posterior Superior
GIRD: The displaced humeral contact point and/or excess _____ rotation causes twisting of biceps and Peel-Back SLAP tear.
External rotation (increased)
GIRD: …leads to ___(a)___ external rotation of humerus & ___(b)___ internal rotation of humerus
(A) Excessive external rotation
(B) Decreased internal rotation
3 Causes of RCT:
- GIRD
- Overuse
- Bad Mechanics
GIRD present in what % of each of these populations:
- College & Pro baseball players
- High school baseball players
- Little Leaguers
- 100% of College & Pro baseball players
- 75% High school baseball players
- 50-75% Little Leaguers
What % of difference between shoulders (rotation) is positive for GIRD?
≥ 10% difference (some say 25˚ or greater)
Best modality, view & location to evaluate Anterior Labral Tear:
MR-Arthrogram (w/saline contrast)—Transaxial view @ 3 or 9:00 (equator)
Best modality, view & location to evaluate Posterior Labral Tear:
MR-Arthrogram (w/saline contrast)—Transaxial view @ 3 or 9:00 (equator)
Modality of choice, view, and location to evaluate Full Thickness RCT with Retraction:
MRI, coronal oblique (11 & 1:00)
Full thickness RCT with Retraction: A tear greater than how many centimeters worsens the surgical outcome?
A tear >5cm worsens the surgical outcome of Full thickness RCT with retraction
