RAH Med 4 Ortho - Spinal Imaging

Spinal imaging

Topics for today

Overview:– Imaging choices– Anatomy• Mostly cervical spine

– Trauma

Case examples/quiz

Imaging choices

Traditional approach:– Xray at presentation (clinical criteria can

exclude need for imaging)– CT scan if needed– MRI for specific indications (cord, ligaments etc)

Recent changes:– International guidelines support the use of CT

as first line imaging in suspected cervical spine injury, this will become common.

Cervical spine anatomyLateral film:Bones• Vertebral bodies• “Posterior elements”

Soft tissues• Prevertebral• Intervertebral discs

Joints• Intervertebral• Uncovertebral• Facet

Cervical spine anatomy

C2

C3

C4

C5

C6

C7

T1

Lateral film :Bones• Vertebral bodies

Roughly the same height and width (except C2)

C1 has an anterior arch (in green) but no “body”

To exclude fractures, you must see the top of T1.

1

Cervical spine anatomyLateral film :Bones• Vertebral bodies• “Posterior elements”

Spinal canal

Lamina

Pedicle

Body

Spinous process

Transverse process

Facet

2

3

4

5

6

7

PedicleFacet

Spinous process

Cervical spine anatomyLateral film :Soft tissues• Prevertebral (orange)• Intervertebral discs

(green)

Intervertebral discs are quite small in the cervical spine.

The prevertebral tissues should be less than half a vertebral body above C5, and less than one vertebral body below C5.

Cervical spine anatomyLateral film :Joints

• Intervertebral

• Uncovertebral

• Facet1

2

3

3

2

1

Cervical spine anatomyLateral film:Alignment:

• Anterior vertebral line (orange)

• Posterior vertebral line (purple)

• Spinolaminar line (blue)

These lines are usually smooth lordotic curves. In this case, they are nearly straight. Why?

Spinal collar forces a straight/slightly kyphotic position

Cervical spine anatomyFrontal film:Structures that commonly demonstrate pathology and should be routinely assessed

• Vertebral bodies• Pedicles• Spinous processes• Transverse processes

Vertebral body

Pedicles

Spinous processTransverse processes

Cervical spine anatomyFrontal film:Alignment:

• Spinous processes (orange)

• Pedicles (green)• Lateral borders (purple)

The lines are curved because of the tilted head position, but should always be smooth curves. Sudden shifts or steps are concerning.

Thoracolumbar spine anatomyThe anatomy and principles are almost identical:

• Check alignment

• Check the anterior and posterior elements.

• No prevertebral soft tissues in thoracic or lumbar spine.

Assessing spinal trauma

General approach

Alignment:– Spinal lines, abrupt steps can suggest fracture or dislocation

(intervertebral or facet joints).– Joint spaces. Widening can suggest ligament injury.

Bones:– See a fracture (cortical step etc.)– Absent normal anatomy (ie can’t see pedicles)– Vertebral body height loss.

Soft tissues:– Prevertebral soft tissue swelling.

Assessing spinal trauma

Factors that influence management Stability:

– 3 major ligament “bundles” between:• Anterior vertebral bodies• Posterior vertebral bodies• Posterior elements

– Damage to 2 or more is “unstable”Cord injury:

– Vertebral body fragment displaced into the canal (retropulsion)

– Significant displacement between vertebral bodies (anterolisthesis / posterolisthesis)