spine radiology word

Spine radiology (lecture 1& 2 )

Imaging technique :
1. plain film ( major role in trauma )
2. MRI : is the gold standard imaging method of the spine as it is able to visualize the spinal cord, nerve roots and IVD , which are invisible on plain films and poorly seen on computed tomography

3. CT will show the bony anatomy in greater detail than radiographs and is

therefore useful in trauma, bone tumours and for operative planning.

4 .myelography : taking radiographs following the injection of contrast into the subarachnoid space by lumbar puncture to opacify the cerebrospinal fluid (CSF) and visualizethe cord and nerve roots, has now been replaced by MRI.

5 . radionuclide bone scans: useful for the detection of bony metastases or recent

fractures

Radiographic signs of spinal abnormality

1.Disc space narrowing
Normally, the disc spaces are the same height at all levels in the cervical and thoracic spine. In the lumbar spine, the disc spaces increase slightly in height going down the spine. A reduction in IVD height usually seen in:
1. degenerative disc disease :and may be associated with endplate sclerosis and osteophytes around the endplate margins
2. disc space infection : usually showing reduction in intervertebral space associated with poor visualization of the endplates .
2. Collapse of vertebral bodies
A collapsed vertebral body is one that has lost height.
If any collapse is present, it is essential to look at the adjacent disc
to see if it is narrowed, to check if part of any pedicle or cortical margin is destroyed and to assess the posterior vertebral wall to ensure that there is no compromise of the central spinal canal containing the cord or cauda equina.


Causes of vertebral collapse include:
• Metastases and myeloma. Bone destruction, or replacement
of normal marrow by a lytic tumour,The pedicles are a good place to look for evidence of bone destruction on plain film examination. The disc spaces are usually normal
• Infection. The adjacent disc space is nearly alwaysnarrow or obliterated. There may be bone destruction next to the affected disc but the pedicles are usually intact .
• Osteoporosis. There is generalized reduction in bone density leading to compression fractures. The disc spaces are normal or even slightly increased in height and the pedicles are intact .

• Trauma. A compression fracture is commonly due to hyper flexion of the spine, causing the vertebral body to become wedge-shaped . The discs are normal but may be impacted into the fractured bone. Associated
fractures may be seen in the pedicles or neural arch, but otherwise the bone and discs are normal.
• Eosinophil granuloma. Complete collapse of one or more vertebral bodies may occur in children or young adults with a solitary site of Langerhans’ cell histiocytosis (eosinophil granuloma). The vertebral body is flattened and sometimes referred to as a ‘vertebra plana’ .

3.Pedicle abnormalities

On plain films, the pedicles are best assessed in the frontal view and are very well demonstrated on CT scans. Destruction or sclerosis of one or more of the pedicles is a sign of spinal metastases.
4.Dense vertebrae
Sclerosis, which is demonstrated on plain films or CT, may affect just one vertebra or may be part of a generalized process involving many bones. Common causes include the following:
• Metastases, particularly from primary tumours of the
prostate or breast .
• Malignant lymphoma.
• Paget’s disease. This may be difficult to distinguish from neoplastic disease, but a useful diagnostic feature is expansion of the overall size of the vertebra with coarsening of the trabecular pattern in Paget’s disease
• Haemangioma, a benign vascular abnormality that gives
rise to characteristic vertical striations in a vertebra that is
normal in size .


Spinal abnormalities

Spinal trauma

Cervical spine injuries are important to identify as significant neurological damage can occur if an unstable injury is unrecognized. Plain films are the commonest initial investigation for trauma to the spine and will usually comprise a lateral, anteroposterior and open mouth or peg view .
The following should be looked for:
• Alignment of the vertebral bodies and facet joints.
• Fractures of the vertebral bodies, pedicles,laminae and spinous processes.
• Indirect signs of fracture such as prevertebral soft tissue swelling.
It is important that the entire cervical spine from the cranio-cervical to the cervico-thoracic junction has been imaged otherwise a low unstable injury may be missed..
it may remain difficult to obtain satisfactory films, so CT scan is indicated:
1. in severely ill patients, so the entire spine segment can be imaged.
2.patients with high risk of spinal injury
3. Un explained soft tissue swelling
4.a fracture is seen on the plain radiograph

MRI is indicated in any patient with

1.potential spinal cord injury is suspected clinically or there are progressive neurological defects such as due to a contusion of the cord.
2.Children may suffer a significant ligamentous injury without evidence of any fractures on radiographs or CT, called SCIWORA (spinal cord injury without radiological abnormality), and are best imaged with MRI

assess the alignment of the vertebral bodies by assessment of following lines integrity :
Drawing lines on the lateral film along the anterior and posterior surface of the vertebral bodies (which equates to the anterior and posterior longitudinal ligaments, respectively).
A line drawn at the junction of the lamina and spinous process indicates the posterior border of the spinal canal and represents the ligamentum flavum.


Any interruption of these lines or significant angulation between endplates indicate there may be serious injury .
3. A line drawn along the tips of the spinous processes may not be smooth due to the presence of bifid spinous processes; it is more useful to ensure the spinous processes are approximately equally spaced, indicating intact interspinous ligaments.
The prevertebral soft tissue is usually outlined by air in the nasopharynx and trachea and parallels the anterior border of the vertebrae. Excessive thickening of the prevertebral tissue may indicate an underlying haematoma secondary to a fracture .
The distance between the odontoid peg and the posterior
border of the anterior arch of the atlas (atlanto-dens interval)
is a marker of the integrity of the transverse ligament
and should be ≤3 mm in adults or 5 mm in children it widened in trauma but is more commonly subluxed in chronic conditions such as rheumatoid arthritis .

mechanism of injury :

1.Hyperflexion is the commonest where the anterior structures are in compression and the posterior elements are distracted , if it mild can result an anterior wedge fracture of the vertebral body only . or in severe trauma produce comminuted fracture through the antero inferior vertebral body with a fragment that is forced posteriorly into the neural canal and tears of the posterior element ligaments,producing an unstable flexion teardrop injury which is highly associated with cord injury.
. 2. Hyperextension injuries may also result in teardrop-shaped fragments of bone arising from the anterior vertebral body due to avulsion bythe anterior longitudinal ligament but is not usually associated with cord injury
A more severe hyperextension injury can result in a fracture involving the pars interarticularis of C2, which is known as a ‘hangman’s fracture
3. axial force : Blows to the top of the head can result infractures of the lateral masses of C1 – a fracture known as Jefferson’s fracture. On the open mouth view, this fracture is suspected if the C1 lateral masses do not line up with the lateral borders of the C2 vertebral body .
Degenerative spinal disease
Degenerative spine disease or spondylosis results primarily from degeneration of the intervertebral disc and occurs maximally in the lower cervical and lower lumbar regions .
radiological signs of spndylosis :
-reduced disc height with loss of hydration
-secondary bone changes of osteoarthritis such as osteophytes
-tear in the annulus fibrosis seen as hyper signal intensity in T2-weighted MRI images
- facet joint arthropathy. ( become inflammed , hypertophied with osteophytes ).


Disc herniation
herniation can be
1-Degenerative , when degenerated annulus fissures may allow herniation of disc material beyond the normal margins of the intervertebral space
2-post trumatic

Disc herniation is best identified on MRI , can be small Focal or wide base according to its size , variable in position ( central , para central , foraminal )
M RI is very informative imaging technique in patients who continue to have symptoms following surgery for back pain. Symptomatic postoperative scarring impinging a nerve root can be distinguished from disc herniation if contrast-enhanced images are obtained. Scarring enhances following contrast administration in contradiction to recurrent disc herniation, which does not enhance .

Infection

The spread of infection to the spine is usually via the haematogenous
route. In children, infection may originate purely within the disc (discitis). Beyond childhood, any infection in the disc is due to local
spread of infection from the bony endplate and is termed discitis osteomyelitis.

1. pyogenic infection

- destruction of the intervertebral disc and adjacent vertebral bodies, there is narrowing of the disc space with erosion of the adjoining vertebral endplate.
- collapse of the vertebral body and sclerosis in Later coarse of the disease
2. Tuberculous infection : Tuberculous infection can be more
insidious
-may allow preservation of the disc space in the early coarse of disease
-may present with complications such as bone collapse resulting in sharp angulation (focal kyphosis) known as a gibbus


Involvement of local soft tissue can be seen in both, such as a paravertebral abscess which, in the lumbar spine,may spread into the adjacent psoas muscles . In severe cases, the infection can spread inside the neural canal and compress the cord or nerve roots, which is a neurosurgical emergency.
MRI signs of infection : is the preferred investigation as it can demonstrate
1.disc space narrowing with fluid (pus) in the disc
2. altered signal in the adjacent vertebral body (infection or oedema
3.adjacent soft tissue swelling and any spinal cord or nerve
root compression .
4.Bony fusion of the vertebral bodies across the obliterated disc spaces occurs with healing and tuberculous paravertebral abscesses may eventually calcify
Needle biopsy/aspiration of the infected disc or adjacent vertebral body under fluoroscopic or CT control is useful to confirm the diagnosis and
identify the responsible organism

Congenital abnormalities

Spina bifida is a result of an in utero incomplete closure of the embryological neural tube, usually in the lumbosacral region, and may be associated with neurological complications, it varies in severity from asymptomatic spina bifida occulta, where there is failure of fusion of a posterior bony neural arch but with intact overlying soft tissues and skin(seen in approximately 25% of the population), to severe cases, where there may be protrusion of the neural elements(meningomyelocele) or just the membranes (meningocele)from the spinal canal which require corrective surgery soon after birth.
vertebral body anomalies such as hemivertebrae , butterfly vertebrae or segmentation anomalies where there is failure of disc formation. These are often associated with varying degrees of focal spine deformities such as kyphosis or scoliosis

Spinal cord and cauda equine compression

The causes of intra spinal compression can be divided according to the site of origin of the responsible spaceo ccupying lesion :
• Extradural lesions: myeloma, lymphoma and metastases
are the commonest malignant spinal tumours that can compress the dural sac and its contents, potentially at multiple sites .
Infection and degenerative disc protusions may also cause extrinsic compression of the cord or cauda equina.
.Intradural extramedullary lesions (i.e. within the dural sac but not within the spinal cord): meningioma and nerve sheath tumours such as neurofibromas or schwannomas
• Intradural intramedullary lesions (i.e. within the spinalcord): primary spinal cord tumour such as ependymoma astrocytoma or metastases


Syringomyelia is a condition where a CSF-contained cavity forms within the middle of the cord due to local damage or mass. In the cervical region, a syringomyelic cavity (syrinx) is often associated with a
Chiari I malformation where the cerebellar tonsils lie below the level of the foramen magnum and it can present with upper limb sensory disturbance and lower limb weakness. Transverse myelitis and multiple sclerosis
Transverse myelitis is an inflammatory condition of the spinal cord can be seen in multiple sclerosis ,Connective tissue diseases, vasulitis and infection
It can only be identified on MRI with T2-hyperintense lesions which typically do not involve the entire cross-section of the cord and do not respect the grey–white junction.
In multiple sclerosis, cord lesions will often
be associated with white matter plaques in the brain.