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Intervertebral Disc

The intervertebral disc (IVD) is a fibrocartilaginous structure located between adjacent vertebral bodies, acting as a shock absorber and flexible spacer in the vertebral column. Each disc consists of two primary components: the central nucleus pulposus, a gelatinous, hydrophilic core that resists compressive forces, and the surrounding anulus fibrosus, a dense, multi-lamellar fibrocartilaginous ring that provides tensile strength and structural support.

The IVD allows spinal flexibility, load distribution, and motion, while maintaining vertebral alignment. Disc thickness varies along the spine, being thicker in the lumbar region to accommodate greater load and thinner in the thoracic region. Degenerative changes can affect both the nucleus and annulus, leading to conditions such as disc herniation, annular tears, and disc height loss, which can impact spinal biomechanics and nerve root function.

Function

  • Absorbs and distributes axial loads and compressive forces

  • Provides spinal flexibility for flexion, extension, lateral bending, and rotation

  • Maintains intervertebral spacing for foraminal nerve roots

  • Contributes to spinal stability and alignment

  • Resists torsional, tensile, and shear stresses

Synonyms

  • IVD

  • Intervertebral fibrocartilaginous disc

  • Vertebral disc

  • Spinal disc

MRI Appearance

T1-weighted images:

  • The nucleus pulposus shows intermediate signal intensity, slightly higher than surrounding anulus fibrosus

  • The anulus fibrosus is low signal intensity (hypointense) due to dense fibrocartilage

  • Degenerative changes or fissures may show focal high signal in the anulus

T2-weighted images:

  • Healthy nucleus pulposus appears high signal intensity (hyperintense) due to high water content

  • Anulus fibrosus remains low signal (hypointense), creating a clear distinction

  • Degenerated discs show loss of T2 hyperintensity in the nucleus (desiccation) and possible high signal annular tears

STIR (Short Tau Inversion Recovery):

  • Highlights edema or inflammation within the disc

  • Normal anulus and nucleus remain low and intermediate signal, respectively

  • Pathological conditions such as acute disc injury, inflammatory changes, or infection appear hyperintense

T1 Post-Contrast (Gadolinium-enhanced):

  • Normal discs show minimal to mild enhancement of outer anulus due to sparse vascularity

  • Pathological discs (degenerative, infected, or torn) demonstrate enhancement along the outer annular fibers or fissures, highlighting abnormal vascularized tissue

CT Appearance:

  • Intervertebral discs appear as soft tissue density structures between vertebral bodies

  • Degenerative changes such as disc space narrowing, calcification, or osteophyte formation are well seen

  • CT is excellent for assessing disc height, calcification, and adjacent osseous structures, but the disc soft tissue itself is less well defined compared to MRI

MRI images

intervertebral disc mri sag image -img-00000-00000

MRI images

intervertebral disc axial image

CT images

Intervertebral disc ct axial image -img-00000-00000

CT images

Intervertebral disc ct coronal image -img-00000-00000

CT 3D VRT image

Intervertebral disc ct 3 image