Radiologic Evaluation of the Spine

Why are C-spine images ordered?

• post trauma (canadian c-spine rule)

• pain (neck, UE, headache)

• pre-operativelu

• suspected malignancy

• suspected anomaly or abnormality

• suspected instability

What is the purpose of the Canadian C-Spine Rules?

to determine if cervical spine imaging is needed after trauma

What high-risk factors in the Canadian C-Spine Rule requires cervical spine imaging?

• age > 65 y/o

• dangerous mechanism of injury

• paresthesias in extremities

if any are present = radiography indicated

What are the low-risk factors in the Canadian C-Spine Rule that allow assessment of cervical ROM?

• simple read-end MVC

• delayed onset of neck px

• sitting position in ED

• ambulatory at any time after injury

• absence of midline C-spine tenderness

if none are present = radiography indicated

If a patient has at least one low-risk factor in the Canadian C-Spine Rule, what should you assess next?

assess active cervical rotation (45 degrees to the left and right)

if can rotate bilaterally 45 degrees = no imaging indicated

if can’t rotate bilaterally 45 degrees = cervical spine imaging indicated

Which radiographic views best visualize the intervertebral foramina in the cervical and thoracic spine?

cervical: right and left oblique views

thoracic: lateral view

What structures are visualized on the AP open-mouth (odontoid) cervical spine radiograph?

• dens and body of C2 (axis)

• angle of mandible

• anterior arch of atlas

• posterior arch of atlas

• lateral AA facet joints

• atlas TP

• C2 spinous process

Where is the central ray (CR) directed for the AP open-mouth (odontoid) view?

through the center of the open mouth

What structures are visualized on an AP lower cervical spine radiograph?

• lower 5 cervical vertebrae

• upper thoracic vertebrae & associated ribs

• medial clavicle

• trachea

mandible obscured the upper cervical vertebrae (C1-C2)

What structures are visualized on a lateral cervical spine radiograph?

• all 7 cervical vertebrae (C1-C7)

• intervertebral disc spaces

• articular pillars (stacked facets) & facet joints

• spinous processes

• prevertebral soft tissues

What is visualized on an oblique cervical spine radiograph?

• intervertebral foramina

• uncovertebral joints (b/t vertebral bodies)

• facet joints

• pedicles

obtained at 45 degrees from lateral view

What is a lateral cervical spine view with stress?

non-routine radiograph used to assess joint alignment while soft tissue structures are stressed; may be used to evaluate ligamentous instability or abnormal motion

What view is this?

AP open mouth (odontoid)

What view is this?

oblique (intervertebral foramina)

What view is this?

lateral (facet joints, no IF)

What view is this?

AP lower cervical (SP leading to sternum, clavicle, 1st rib)

What are common indications for a CT image of the spine?

• acute trauma in adults

• degenerative conditions and OA

• post-operative evaluation of bone graft or fusion

• infectious processes of the spine

• image guidance for spinal interevntions (i.e., biopsy or injections)

• neoplastic conditions & complications

• inflammatroy lesions and crystal deposition disease (i.e., gout or arthritis)

• congenital or developmental spine abnormalities (i.e., scoliosis, spondylolysis)

• spinal cord syrinxes & other masses

• MRI contraindicated

What are common indications for a MRI image of the spine?

• degenerative disk disease

• extradural soft tissue and bony neoplasm

• intradural extramedullary masses

• intradural masses or leptomeningeal disease

• intramedullary tumors

• treatment fields for radiation therapy

• intrinsic spinal cord pathology (demyelination & inflammatory)

• spinal vascular malformations or subarachnoid hemorrhage

• syringohydromyelia

• post-operative intraspinal fluid/soft-tissue changes

• meningeal abnormalities

• spinal infections

• pre-operative assessment

What spinal structures are best visualized in the axial/transverse CT plane?

• spinal canal & cord

• nerve roots

• pedicles

• facet joints

• vertebral body cross-sections

What spinal structures are best visualized in the sagittal CT plane?

• vertebral alignment

• vertebral bodies

• spinous processes

• intervertebral disc spaces

• spinal curvatures

• spondylolisthesis

• compression fractures

What spinal stuctures are best visualized in the coronal plane?

• scoliosis

• lateral alignment

• vertebral body symmetry

• transverse processes

What are the ABCDS when interpreting spine imaging?

A: alignment and anatomy

B: bone density

C: canal space

D: disc integrity

S: soft tissue

What MRI planes and sequences are commonly used for spine imaging?

planes: sagittal and axial

T1-weighted: anatomy and structural detail

T2-weighted: detecting fluid abnormalities (edema, inflammation, disc abnormalities, CSF)

What is the signal intensity of the CSF on T1 and T2 MRI?

T1 = low (dark)

T2: high (bright)

What is the signal intensity of the intervertebral discs on T1 and T2 MRI?

T1: intermediate (gray)

T2: high (bright)

What is the signal intensity of cortical bone and ligaments on T1 and T2 MRI?

T1: low (dark)

T2: low (dark)

What is the signal intensity of the spinal cord on T1 and T2 MRI?

T1: intermediate (gray)

T2: intermediate (gray)

What is the signal intensity of muscle on T1 and T2 MRI?

T1: intermediate (gray)

T2: intermediate (gray)

What is the purpose of the Swimmer’s lateral view?

to better visualize the lower cervical spine and upper thoracic spine by elevating one arm overhead to remove shoulder superimposition

When is a thoracic spine oblique view used?

to visualize the facet joints

Waht is a thoracolumbar view used for?

to view the thoracolumbar junction (a commong injury site), using a coned/narrowed exposure field

Why is an RAO oblique view used for sternum imaging?

to project the sternum over the homogenous density of the heart, improving contract and reducing superimposition from thoracic spine

Which view is commonly used to visualize the sternoclavicular (SC) joints?

RAO oblique view

Why is an oblique view needed for sternum radiographs?

to avoid superimposition of the thoracic spine over the sternum

How are rib radiographs obtained?

• anterior, posterior, and axillary

• right or left side

• upper ribs (1-9)

• lower ribs (8-12)

What structures are visualized on an AP thoracic spine radiograph?

• vertebral bodies

• intervertebral disc spaces

• pedicles

• spinous processes

• transverse processes

• articular processes

• costovertebral joints

• posterior ribs

What structures are visualized on a lateral thoracic spine radiograph?

• vertebral bodies

• intervertebral disc spaces

• intervertebral foramina

upper thoracic vertebrae may be partially obscured by the shoulders

What view is this?

anteroposterior (AP)

• vertebral bodies, transverse processes, ribs

What view is this?

lateral

What view is this?

swimmer’s

What structures can be visualized in an AP lumbar spine radiograph?

• all 5 lumbar vertebrae (L1-L5)

• sometimes sacrum and coccyx

• vertebral bodies

• pedicles

• spinous processes

• transverse processes

• IV disc spaces

What structures can be visualized in a lateral lumbar spine radiograph?

• vertebral bodies

• intervertebral disc spaces

• pedicles

• spinous processes

• intervertebral foramina

• lumbosacral articulation

What structures can be visualized in an oblique lumbar spine radiograph?

• facet joints

• superior and inferior articular processes

• pars interarticularis

• pedicles

Why is a lateral L5-S1 spot view obtained?

to better visualize the L5-S1 junction by reducing exposure to surrounding structures and overcoming superimposition from the ilia

What is visualized on an AP axial/sacroiliac radiograph?

bilateral SI joints

What is visualized on an oblique sacroiliac radiograph?

an individual sacroiliac joint

What view of the lumbar spine is this?

lateral

What view is this?

anteroposterior (AP)

What view is this?

oblique

What view of the lumbar spine is this?

lateral L5-S1

What is a stable fracture?

no ligament disruption; no bone or joint displacement

What is an unstable fracture?

displacement of potential for displacement; fracture-dislocation or bilateral facet dislocation

What immobilization devices are commonly used for stable vs unstable cervical fractures?

cervical collar (C-collar): typically used for stable fx

halo immobilizer: used for unstable fx

What is a Clay-Shoveler’s fracture?

avulsion fx of a spinous process (common at C6, C7, T1); stable fx

What is the mechanism of a Clay-Shoveler’s fracture?

hyperflexion of the neck or forceful contraction of the trapezius and rhomboid muscles (often during heaving labor of UE)

What radiographic view is most useful for identifying a Clay-Shoveler’s fracture?

lateral cercial spine view

What is an odontoid fracture?

fracture of the dens of C2, accounting for ~20% of cervical fractures

What are common mechanisms of a dens fracture?

motor vehicle accidents (MVA) or falls that cause extreme force on the dens or alar ligaments

What are the three types of dens fractures?

type I, type II, type III

What is a type I dens fracture?

avulsion fracture of dens tip due to alar ligament stress

What is a type II dens fracture?

fracture at the junction of the dens and C2 body (difficult to heal)

What is a type III dens fracture?

fracture extending below the junction into the C2 vertebral body

What imaging is used to identify a dens fracture?

radiograph (AP open-mouth/odontoid) or a CT

What is the attachment and function of the alar ligament?

attaches the dens to the occipital bone; provides restraint against excessive rotation of the head and upper cervical spine

What is a teardrop fracture?

a triangular fragment of the vertebral body separates; unstable

What is a teardrop fracture often associated with?

• ligament rupture

• disc injury

• spinal cord injury (SCI)

What is the mechanism of a teardrop fracture?

hyperflexion and compression force

What is a wedge fracture?

an anterior compression fracture in which the vertebral body becomes wedge-shaped; usually stable

What is the mechanism of a wedge fracture?

hyperflexion and compression forces

What is a Jefferson fracture?

a burst fracture of the naterior and posterior arches of C1 (atlas)

What is the mechanism of a Jefferson fracture?

axial compression (diving accidents)

What imaging is used to identify a Jefferson fracture?

AP open-mouth (odontoid) view and CT

What is a burst fracture?

an axial compression fracture in which the vertebral body is crushed and fragments may be displaced outward (comminuted)

What is the mechanism of a burst fracture?

axial compression, causing the intervertebral disc to transmit force into the vertebral body resulting in “bursting”

What is a Hangman’s fracture?

a fracture of the bilateral pars interarticularis/pedicles

What is the mechanism of a Hangman’s fracture?

hyperextension of the cervical spine

What is the Denis Three-Column Model and what is it used for?

a model to assess thoracic and lumbar spine fracture stability; anterior, middle, and posterior column

What structures are included in the anterior column of the Denis Three-Column Model?

• anterior longitudinal ligament

• anteriro 2/3 of vertebral bodies

• anterior annulus fibrosus

• anterior intervertebral disc

What structures are included in the middle column of the Denis Three-Column Model?

• posterior longitudinal ligament

• posterior 1/3 of vertebral bodies

• posterior annulus fibrosus

• posterior intervertebral discs

What structures are included in the posterior column of the Denis Three-Column Model?

• everything posterior to posterior longitudinal ligament

• posterior ligamentous structures

• pedicles

• laminae

• facets

• transverse processes

• spinous processes

How does the Denis Three-Column Model determine fracture stability?

stable: injury to one column

potentially unstable: injury to two columns (depends)

unstable: injury to all three columns

What is a flexion-compression fracture of the thoracic/lumbar spine?

an anterior wedge compression fracture caused by compression of the anterior column with varying involvement of the middle and posterior columns

What is the mechanism of a flexion-compression fracture?

flexion combined with axial compression

What are the three patterns of flexion-compression injury?

1. anterior column failure only

2. anterior column failure & posterior column ligamentous failure

3. failure of all three columns

What is the first pattern for a flexion-compression injury?

• only anterior column failure

• middle and posterior columns remain intact

• <50% loss of vertebral body height

• stable fracture

What is the second pattern for a flexion-compression injury?

• both anterior column & posterior ligamentous failure

• >50% loss of vertebral body height

• potentially unstable fracture

What is the third pattern for a flexion-compression injury?

• failure of all 3 columns

• anterior wedging

• posterior vertebral body disruption

• unstable fracture

• risk of SC, nerve root, or vascular injury from displaced fracture fragments

What is an axial compression injury of the thoracic/lumbar spine?

an injury caused by axial compression that produces a burst fracture

What are the five subtypes of axial compression fractures?

• fx of both endplates

• fx of superior endplate

• fx of inferior endplate

• burst rotation fx

• burst lateral flexion fx

What is the most common subtype of axial compression fractures?

fracture of the superior endplate

What is a Chance (seatbelt) fracture?

a flexion-distraction injury where the anterior vertebral body is compressed/crushed while the posterior vertebral body is pulled apart

What is the mechanism of a Chance fracture?

caused by hyperflexion over a fixed restraint (horizontal split of entire vertebrae)

What is a flexion-distraction injury?

mechanism that produces a Chance (seatbelt) fracture; characterized by failure of the posterior column

What are the two types of flexion-distraction injuries?

• classic chance fracture

• flexion-distraction subtype

What is a rotation fracture-dislocation?

involves failure of the posterior and middle columns with varying degrees of anterior column injury; unstable (multiple columns disrupted)

What is the mechanism of a rotation fracture-dislocation?

lateral flexion and rotation, with or without a posterior-to-anterior force

What structures are commonly disrupted in a rotation fracture-dislocation?

• posteriro ligaments

• articular facets

• middle column structures

• often portions of the anterior column

What is the characteristic radiographic finding of a rotation fracture-dislocation?

a “slice” appearance, caused when the upper vertebral body rotates and carreis part of the lower vertebral body with it

Is a rotation fracture-dislocation stable or unstable?

unstable

What type of joint is formed by an intervertebral disc?

a symphysis joint (fibrocartilage)