Test 2: CT of the Spine Flashcards
Indications for CT of the spine
- MRI contraindicated
- before and after spinal surgery (bony anatomy, alignment of hardware)
- visualize fractures, including pars defects
- characterize osseous lesions: neoplasm/metastases, hemangioma, bone cyst, osteoid osteoma
Spine CT: contrast or non contrast?
NON
Best imaging modality to view spinal cord?
MRI
If a patient is contraindicated to get an MRI, but needs imaging of an IV disc, what type of imaging will be used?
CT, soft tissue window
What imaging findings might come with a pars defect? What imaging modality is a pars defect best seen, and why?
anterolisthesis, elongated, flute shaped spinal canal, horizontal lucency at pars interarticularis in sagittal and axial CT views
-CT best: too much overlap on XR
Burst fracture: characteristics on CT
- break in cortical continuity (areas of lucency)
- narrowed spinal canal
- loss of height of vertebral body
- vertebral body misshapen
- may see fragments displaced posteriorly into spinal canal
Vertebral augmentation: define the concept and list 2 procedures
- procedures used for palliation of pain related to vertebral compression fractures
- 2 types: percutaneous vertebroplasty (PV) and balloon-assisted kyphoplasty
management of compression fractures
- initially: conservative management is the gold standard
- medical management with or without methods of immobilization
- medication
complications of medication for treatment of pain in compression fractures:
NSAIDS: gastrointestinal hemorrhage, ulcers
Narcotics: addiction, constipation, nausea, somnolence
osteoporotic fractures: talk about pain, medication, and what happens over time
most patients have a spontaneous resolution of pain within 4-6 weeks of onset, even without medication
extra credit: causes of vertebral compression fractures
- osteoporosis (most common)
- direct trauma
- neoplasm/metastatic disease
indications for vertebral augmentation
- conservative treatment failed
- pain refractory to oral medications for 6-12 weeks
- contraindications to medication
- hospitalization with IV narcotics administered
Define percutaneous vertebroplasty
Injection of low viscosity PMMA cement into vertebral body using a unipedicule or bipedicule needle
Success rate for pain relief? who benefits most?
89-93% success rate; women and people <75 years old benefit most
Percutaneous Vertebroplasty: Clinical History/Physical exam criteria for indication/contraindication of PV procedure:
- focal pain at spinal process level corresponding to level of fracture
- 6-12 weeks after onset of pain: time frame for treatment (first 6-12 conservative)
Patients treated EARLIER if:
-they required hospitalization and IV narcotics for pain
-they have a history of a successful prior PV
DISQUALIFICATION for PV:
-radicular pain involving LEs or LBP radiating to hips (pt may need a different intervention)
PV: complications; acute and delayed
ACUTE: 1-3.9%
-cement leak: symptomatic or asymptomatic
-cement pulmonary embolism: symptomatic or asymptomatic
-bleeding
-infection
-neurological deficit
DELAYED:
-risk for new fractures at other levels: cement decreases compliance
-clustering of fxs as a natural history of OP?
Balloon kyphopasty: explain the procedure
insertion of a unipedicle or bipedicle needle, inflation of intravertebral balloon to create a void in which high-viscosity bone cement is injected
-more recently developed (than PV?)
Between Balloon kyphoplasty and PV:
- which has better outcomes?
- which has fewer complications?
- which has better height restoration?
- which is better for burst fxs?
- which is more expensive?
- no difference in outcomes
- no difference in complications
- “some believe” kyphoplasty offers better height restoration
- kyphoplasty may be better for burst fxs; can offer more controlled angular and fracture correction
- kyphoplasty more costly
is cement bright or dark on CT?
bright
osseous metastasis: appearance on XR, CT
heterogenous, patchy appearance within bone
Indications for CT myelogram:
- pt has a need for visualization of soft tissue within spinal canal:
- pt cannot get an MRI
- pt has hardware that obscures spinal canal on CT or MR
CT myeologram: technique
- injection of contrast by lumbar puncture (into thecal sac) under fluoroscopic XR guidance
- subsequent imaging of spine
CT myelogram: contraindications
-elevated INR or bleeding disorders
MRI indications: 6 main categories
- degenerative disease
- osseous/extraosseous infection
- neoplasm
- demyelinating/inflammatory disease
- trauma
- postop spine imaging
MRI: absolute and relative contraindications
ABSOLUTE: -pacemaker -ferromagnetic aneurysm clip -cochlear implant -IVC filter -orbital metallic foreign body RELATIVE -metal fragments, depending on location -1st trimester pregnancy (risk v. benefits) -transcutaneous nerve stimulators -claustrophobia
Contrast enhanced MRI: indications
- postop spine recurrent back pain evaluation: to view granulation tissue from recurrent or new disc herniation
- metastatic bone disease (bone and spinal cord)
- primary SC lesions (tumor, demyelination)
- spinal infection (discitis, osteomyelitis, epidural abscess)
Noncontrast MRI: indications
- degenerative disease
- low back pain
- preoperative planning
- radiculopathy
Contraindication for MRI contrast
Pt with EGFR <30
- measure of kidney function
- risk of nephrogenic system fibrosis (NSF)
Non Contrast MRI for Cervical Spine: what sequences are used for the cervical spine, and which views for each sequence?
Cervical spine:
- T1 and T2: sagittal and axial views
- STIR: sagittal view
- Gradient Echo: axial view
Non Contrast MRI for Thoracic and Lumbar Spine: sequences used and views
Thoracic/Lumbar Spine:
- T1 & T2: sagittal and axial
- STIR: sagittal
why might an MRI be better than an XR or CT in the case of viewing a fracture?
the age of the fracture can better be determined by the presence or absence of fluid/edema in the bone and surrounding area. newer fracture=edema in bone
MRI Basics: T1 weighted image hyperintense (bright) or hypointense (dark)? -water: -fat: -normal bone: -sclerotic bone:
- water: hypointense
- fat: hyperintense
- normal bone: hypointense
- sclerotic bone: markedly hypointense
MRI Basics: T2 weighted image hypo/hyperintense? -water: -fat: -normal bone: -sclerotic bone:
- water: hyperintense
- fat: hyperintense
- normal bone: hypointense
- sclerotic bone: markedly hyperintense
MRI Basics: STIR hypo/hyperintense? -water: -fat: -normal bone: -sclerotic bone:
- water: hyperintense
- fat: hypointense
- normal bone: hypointense
- sclerotic bone: markedly hyperintense
What are water-rich structures that will show up on MRI?
- CSF
- normal disc space
- bone/soft tissue edema
- fluid collections: cysts, abscesses, postop seroma
How does aging affect normal bone appearance on MRI?
Yellow (fatty) bone marrow increases with normal aging; so a younger bone will appear darker on MRI than an older bone
Calcified ligament or disc: hypointense or hyperintense on MRI?
Hypointense (sclerosis)
C-spine exiting nerve root numbering
Exiting nerve root named for the lower vertebra
Ex) at C5-C6, exiting nerve roots are C6
C7-T1: C8 nerve roots
T-spine exiting nerve root numbering
Exiting nerve roots from the level above
ex) at T1-T2, exiting nerve roots are T1
zygapophyseal joints: anatomy and function
facet joints
-articulation point of 2 vertebrae
-composed of inferior and superior articular processes
-put your hands up like you’re going give somebody a high 10: your hands are oriented like superior facets
-point your hands down, keeping your palms facing your body: your hands are oriented like inferior facets
function:
-carry axial load of body
-limit spine ROM
-form posterior border of intervertebral foramen
intervertebral neural foramina
- foramen through which spinal nerves exit the spinal canal
- within foramen, motor and sensory nerve roots become mixed spinal nerves (“exiting nerve”)
- facet joints make up the back of this foramen
- more or less directly inferior/superior to vertebral pedicles of vertebrae above and below
where does the spinal cord terminate? what happens then?
terminates at L1-L2 (conus medullaris) then becomes cauda equina
contents: cauda equina
pia-wrapped 3-5 lumbar nerves, 5 sacral nerves, 1 coccygeal nerve
-cuada equina is still within the thecal sac
sciatic nerve
Contains fibers from the anterior and posterior branches of the lumbosacral plexus
L4-S3
-sensory: skin of whole leg
-motor: hamstrings, lower leg, ankle/foot
cervical spine XR: list views
- AP
- AP open mouth (odontoid)
- Lateral (must include T1, need to see prevertebral soft tissues)
- bilateral oblique
- flexion
- extension
cervical spine XR AP open mouth view: what are we looking for?
- alignment of odontoid process
- C1/C2 alignment
- lateral masses
cervical XR AP view: what are we looking for?
-alignment: single row, top to bottom. including:
uncovertebral joint alignment
TP, SP alignment
cervical lateral XR view: what to look for
- IV disc spaces
- prevertebral soft tissue
- SPs
- facet joints
cervical XR lateral view: maneuvers to enhance views of lower C-spine
- swimmer’s view: elevate arm nearest cassette
- cervical spine CT
- pull down on arms during cross table lateral (pt supine, shoulders depressed)
cervical XR lateral view: what bony landmarks to use to analyze alignment
- anterior column of vertebrae: vertebral bodies
- posterior column: SPs
- middle column: facets
- Sps: middle of anterior spinous process lines up C1-C3 (WHAT DOES THIS MEAN?)
pseudosubluxation of C2 and C3: cervical XR
normal in children due to joint laxity; may be seen in up to 20% of children under age 8
predental space: cervical XR; define and give norm values
distance from dens to C1 body
- adult: 3mm
- child: 5mm
cervical spine: oblique XR view; what is best viewed?
head turned to best expose neural foramina
- foraminal stenosis
- facet joints
- pedicles
cervical spine flexion and extension XR views: 2 main reasons
- helps detect ligamentous injury (instability) not apparent on neutral view
- assessment of RA at C1-C2 and any associated instability
Cervical spine XR, flexion view-Vertebral body angulation/translation patterns of instability
Criteria for instability at C-spine
- 3.5 mm translation
* **“vertebral body subluxation should be no greater than 1mm as compared to extension view” - 1.7mm or greater disc space widening
- angulation between 2 adjacent vertebra of 11 degree or more
ADI measurements: what is it, norms for adults, children
- atlantodens interval: distance between the anterior aspect of the dens and the posterior aspect of the anterior ring of the atlas.
- adults: ADI <3.5mm
Type I dens fx
<5%
-(usually unstable) fracture through tip of dens at attachment for alar ligament
Type II dens fx
> 60% (most common type)
- fracture through the base of the dens
- no alar involvement-relatively stable (in my notes, but later type II fx is listed as an unstable fx)
Type III dens fx
30%
- subdentate (does not involve dens)
- through the body of C2
- unstable-atlas and occiput can move together as a unit
what type of injury most commonly results in cervical spine fracture?
hyperflexion injury
c-spine flexion injuries: list 7 types
- anterior subluxation: anterolisthesis
- simple wedge fx: stable, fx of vertebral body
- unstable wedge fx: interspinous ligaments involved
- unilateral interfacet dislocation: “jumped facet”
- bilateral interfacet dislocation: “jumped facet”
- flexion teardrop fx
- anterior atlantoaxial dislocation
jumped facet: define
top vertebrae “jumps forward”: inferior facet of top vertebra lies anterior to superior facet of inferior vertebra
- can be unilateral or bilateral
- unilateral: 50% anterolisthesis
jumped facet: imaging characteristics
- anterolisthesis
- widening of interspinous distance
- widening of facet jt
3 types of extension injuries in the c-spine
- hangman’s fx
- extension teardrop fx: avulsion at anterior vertebral body
- hyperextension with pre-existing spondylosis (disc degeneration)
hangman fx: bony areas affected, injury type, what is seen in imaging
- fx involving both par interarticularis of C2
- secondary to hyperextension and distraction
- imaging: shows fractures at bilateral lamina and pedicles and usually anterolisthesis at C2-C3
Jefferson fx: bony areas affected, how it happens, imaging characteristics
- burst fx of C1 (UNSTABLE)
- axial loading (diving into shallow water)
- open mouth anterior view: bilateral, lateral offset of C1 on C2
- lateral view: widening of ADI if transverse ligament affected
list 3 cervical flexion injuries that are UNSTABLE
- bilateral interfacetal dislocation
- flexion teardrop fx
- wedge fx with posterior ligamentous rupture
list 3 cervical extension injuries that are UNSTABLE
- odontoid fx type II
- Hangman’s fx
- extension teardrop fx
what views are taken for lumbar spine X rays?
lateral, oblique
Lateral lumbar XR: what is visualized
- IV disc spaces
- SPs
- pedicles
- alignment
- vertebral body height
what is viewed on the lumbar oblique XR view?
Scotty dog!
- Nose: TP
- Eye: pedicle
- Front leg: inferior articular facet
- Neck of dog: pars interarticularis
common site for pars defects
L4/L5
common site for anterolisthesis-lumbar
L5/S1
spondylolisthesis: lumbosacral spine; 2 major types
Lumbo Sacral Spine L5-S1
- anterolisthesis: forward slippage
- retrolisthesis: backward slippage
spondylolisthesis: 5 major types/causes
- dysplastic: caused by defect in formation of part of vertebra
2* Isthmic: pars defect
3* Degenerative: caused by arthritic changes - Traumatic: usually pedicle, lamina, or facet jt fx
- Pathologic: caused by abnormal bone (e.g. tumor)
*most common!
spondylolisthesis: Grades
Grade I: 0-25% Grade II: 25-50% Grade III: 50-75% Grade IV: 75-100% Grade V: >100% (spondyloptosis)
spondylolysis
- defect of lumbar vertebrae at pars interarticularis
- pars located anterior to lamina and posterior to pedicle
- typically secondary to stress fx from repetitive injury
spondylolisthesis in C-spine: example
hangman’s fx
Thoracic Lumbar spine fxs: flexion fractures
- compression fx: anterior parts of vertebral body breaks, loses height; posterior part intact (usually stable)
- axial burst fx: vertebra loses height both anteriorly and posteriorly
- chance fx: seatbelt injury
thoracic/lumbar spine fxs: rotation fxs
- transvers process fx: uncommon, rotation or extreme lateral bending
- fracture dislocation: involves bone and soft tissue, vertebra may move off an adjacent vertebra; unstable
Wedge fx: thoracic
compression fx secondary to hyperflexion and compression
- buckled anterior cortex with loss of height of anterior vertebral body
- anterosuperior fx of vertebral body
- most common in thoracic spine
- considered serious if: fx involves adjacent vertebrae, anterior wedge >50%, severe hyperkyphosis, bone fragments suspected within spinal canal
chance fracture: describe, most common location?
T12-L2: thoracolumbar junction
- flexion fracture primarily (also extension, but it’s classically thought of as a flexion injury)
- seatbelt injury: compression injury to anterior vertebral body; transverse fx through posterior vertebral body and posterior elements
Schmorl’s node: describe
- vertical disc herniation through cartilaginous vertebral body endplates
- may or may not be symptomatic
- common with increasing age
- strong heritability >70%
Sacrum: views, features
AP view: SI joints, sacral ALA, coccyx
Lateral view: sacral coccygeal angle, cortical integrity, pre-sacral soft tissue (tumor involvement)
