NEURORADIOLOGY OF SPINE
DR. DALIA AL – FALAKIDepartment of radiologyCollage of medicineobjectives
1- demonstrate the normal cross sectional anatomy of the spine. 2-identify the disc prolapse and degenerative changes. 3- diagnose vertebral metastatic diseaseINDICATION 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 sacNORMAL 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 fibrosusVertebral 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 PROLAPSENORMAL 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 vertebral endplates leads to following stages: Stage one: vascular granulation tissue which manifested by low signal intensity on T1w & high signal intensity on T2w image.DISC DEGENERATION
Stage two: fat deposition which manifested by high signal intensity on T1w & high signal intensity on T2w image.DISC DEGENERATION
Stage three: sclerosis which manifested by low signal intensity on T1w & low signal intensity on T2w image.
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, this can involve posterior longitudinal ligament, cruciform ligament at craniocervical junction, ligamentum flava & the capsular ligaments of the facet joints.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 at or minimally below the related intervertebral level & the signal change is deep within the cord unlike plaques of demyelination of multiple sclerosis which usually extend to the pial surface of spinal cord.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