Imaging the Spine

Question 1

Spinal anatomy that can be seen on imaging?

Answer 1

• Bones
• Ligaments
• Intervertebral discs
• Spinal cords and nerves
• Blood vessels

Question 2

Imaging tests available?

Answer 2

X-rays (only show bone outlines)

CT scans (show bone outlines in more detail and some soft tissue structures, e.g: lumbar discs)

MRI (shows bone outlines in less details but shows bone marrow, discs, ligaments and spinal cords/nerves, i.e: it shows all the soft tissue structures)

Question 3

Normal spinal curvatures?

Answer 3

There is nothing angular about the spine; should be smooth and curved to form:

• Cervical lordosis
• Thoracic kyphosis
• Lumbar lordosis

Question 4

Consistent anatomy of C3-C7, all 12 thoracic vertebrae and the 5 lumbar vertebrae?

Answer 4

Vertebral body

Posterior arch comprising:

• 2 pedicles (neural foramen, for spinal nerves, lies inferior to the pedicle)
• 2 laminae
• 1 spinous process
• 2 transverse processes

Articular processes project superiorly and inferiorly between the pedicles and laminae, forming the facet joints

Question 5

General rule with the appearance of vertebrae on imaging?

Answer 5

Consecutive and adjacent vertebrae should have a similar size and normal anatomy should be observed (on lateral and AP view)

Question 6

Variations in the image appearance of the spine that are bad?

Answer 6

1. Variation from normal alignment
2. Variation from normal anatomy

Question 7

Anatomy of C1 vertebra?

Answer 7

Has no vertebral body but does have anterior and posterior arches, united by 2 large lateral masses, i.e: it forms a ring It articulates with the occipital condyles and C2

Question 8

Anatomy of C2 vertebra?

Answer 8

Odontoid process projects superiorly into C1, forming a joint with the anterior arch of C1

Question 9

Describe the trauma in this image

Answer 9

A vertebra has been squashed, resulting in a fracture and bone fragmentation

Question 10

Describe the trauma in this image

Answer 10

Focal kyphosis and misaligned vertebrae

Question 11

When is a CT scan used to image spinal trauma?

Answer 11

• If an X-ray shows a fracture but more detail is required; also, to check if anymore fractures are present
• X-ray is normal but there is a high clinical suspicion of a fracture
• For pre-operative planning

Question 12

Function of spinal ligaments?

Answer 12

Tether the vertebrae together and are responsible for spinal stability

Question 13

Viewing ligaments on imaging?

Answer 13

Not seen on X-ray or CT scan; however, seeing normal vertebral alignment on these tests implies that the ligaments are intact and the spine is stable

Question 14

Signs of ligament damage on X-ray/CT?

Answer 14

Abnormal vertebral alignment implies ligament damage and an unstable spine

Question 15

How can ligaments be seen with imaging?

Answer 15

Only by MRI:

• Normal ligaments are black (a black line should be seen anterior and posterior to the vertebral column, indicating anterior and posterior longitudinal ligaments of the spine)
• Damaged ligaments are light

Question 16

When is MRI used to image spinal trauma?

Answer 16

• Provide detail of spinal ligaments
• In patients with neurological deficit that has not been explained by X-ray or CT, to show soft tissue abnormality like:
• Acute prolapsed intervertebral disc
• Epidural haematoma
• Spinal cord damage

Question 17

Imaging features of bony tumours in the spine?

Answer 17

X-ray and CT findings:

• Bone destruction
• Vertebral collapse (pathological fractures)
• Bone sclerosis, as tumours can lay down new bone

Unique MRI findings:

• Early - bone marrow infiltration
• Late - extradural mass and spinal cord compression

Question 18

Describe intervertebral disc disease

Answer 18

Normally, they cushion the body from spinal stresses; healthy discs are pliable and contain water but discs can dehydrate as a prelude to disease

Nucleus pulposus can herniate through the annulous fibrosus into the spinal canal; herniated disc can press on spinal nerve and produce sciatica

Question 19

Imaging of intervertebral discs?

Answer 19

Discs cannot be seen on X-rays but it may show disc space narrowing (correlates poorly with symptoms of sciatica)

CT and MRI show discs and prolapse, but MRI is best as it can show the early disc dehydration that precedes herniation

Question 20

Imaging of the spinal cord?

Answer 20

Only adequately shown on MRI