Neuroradiology of spine

NEURORADIOLOGY OF SPINE

Department of radiology Collage of medicine

INDICATION OF MRI

for precise localization of the level of a lesion which is difficult to be done from clinical examination.

ADVANTAGE OVER CT SCAN:

MRI is a direct multiplanar acquisition i.e. can be easily applied in any plane, including optimal sagittal axis.

SIGNAL INTENSITY:

- The annulus fibrosus, spinal ligaments & dura matter & the cortical bone of the vertebrae give low signals. -Epidural & paraspinal fat give high intensity signal.

SIGNAL INTENSITY:

-The gel of the normal nucleus pulposus of the normal intervertebral discs gives high intensity signal on T2 weighted image sequences. -In the normal adult disc, a shelf of annulus causes a low signal horizontal band resulting in a bilocular appearance , & with normal aging, the intensity of the signal from the nuclei decreases.



MRI OF LUMBER SPIN
T2 weighted image Normal discs Normal ligament Normal thecal sac

NORMAL ANATOMY:

SPINAL CANAL -The spinal canal is bounded anteriorly by vertebral bodies & intervertebral discs , backed by the posterior longitudinal ligament, poster laterally by pedicles & laminae lined by ligamenta flava. -The normal intervertebral foramens are oval or boot shaped & symmetrical in the absence of scoliosis.

NORMAL DISC & INTERVERTEBRAL FORAMEN

Disc content: Center: neuclus pulposus. Annulus fibrosus

Vertebral body

Intervertebral foramen: contain dorsal root ganglion , spinal nerve root & epidural fat.

NORMAL ANATOMY:SPINAL CANAL

-If sagittal diameter in the cervical & lumber regions below 12mm ,&14 mm respectively , indicate potentially significant developmental narrowing.

NORMAL ANATOMY:SPINAL CORD

The spinal cord descends from the medulla oblongata , commencing at about the level of foramen magnum & terminates at the conus medullaris , which lies between the lower border of 12th thoracic & the upper border of the third lumber vertebra.

MR MYELOGRAM

Spondylosis:
Spondylosis: This process involve intervertebral disc prolapse & degeneration & it is caused by wear & tear , it involve intervertebral discs , vertebral bodies & facet joints , it is the commonest cause of entrapment neuropathy & of neurological disability due to spinal cord disease.

Spondylosis:

1-DISC PROLAPSE: Extrusion of the softer material from within an intervertebral disc into or through a posterior or posterolateral radial tear in the annulus fibrosus.

DISC PROLAPSE

NORMAL DISC / DISC PROLAPSE

NORMAL SPINAL CANAL / ACQUIRED SPINAL CANAL STENOSIS

DISC PROLAPSE
Disc prolapse takes the form of focal broad based bulge in the margin of annulus or , a focal mass extending upwards or downwards in the anterior epidural space, Far lateral protrusions or extruded fragments, Involve the intervertebral foramens, not the spinal canal & they are commonest in the lumber spine.


2-DEGENERATIVE CHANGES:
When affect the disc leads to: a-loss of normal bright signal of the nucleus on T2 weighted image. b- loss of the normal height of the disc.

DISC DEGENERATION

When involve articular surface leads to: articular surface irregularities & osteophyte formation.

DISC DEGENERATION

When involve ligaments leads to calcification or ossification which result in diffuse thickening or a focal mass which may compress the neural tissue.

Posterior longitudinal ligament

Disc prolapse at c3-4, c4-5. c5-6, c6-7. Posterior longitudinal ligament thickening , & ligamentum flavum thickening.

SPINAL CORD COMPREESSION:

Spinal cord compression from disc prolapse & degeneration is damaging cord substance & is seen in the form of focal signal changes in the cord substance .

SPINAL CORD COMPREESSION

Posterior disc prolapse at level c4-5 which obliterate anterior subarachnoid space at this level , there is abnormal high signal intensity area within the cord substance ,indicate cord degeneration.

SPINAL CORD COMPREESSION

Axial section, T2weighted image: there is abnormal high signal intensity area within the cord substance ,indicate cord degeneration.

SPINAL CANAL STENOSIS

Significant spinal canal stenosis when?
1-The stenosis is enough to eliminate csf signal intensity on MRMYELOGRAPHY. 2-cauda equina entrapment.