How can you determine from the MRI how bad disc desiccation is at L5-S1 level?

Several MRI findings can indicate disc desiccation at the L5-S1 level. Here's how radiologists typically assess disc desiccation:

Signal Intensity: Desiccated discs often have low signal intensity on T2-weighted MR images. The normal bright signal of a well-hydrated disc decreases as the disc loses water content.

Height of the Disc: A desiccated disc typically has a reduced disc height compared to adjacent discs or compared to expected normal height values for that specific level.

Disc Bulge or Protrusion: In some cases, a desiccated disc may bulge or protrude due to the loss of disc height and structural integrity. The protrusion may impinge on nearby nerve roots or cause spinal canal narrowing.

Tear in the Annulus Fibrosus (Outer Layer of the Disc): Desiccated discs may show evidence of tears or fissures in the annulus fibrosus. These tears can allow the soft inner material of the disc (nucleus pulposus) to herniate or bulge out.

Modic Changes: Modic changes are bone marrow abnormalities seen on MRI in the vertebrae adjacent to a degenerated disc. These changes can indicate chronic inflammation and reaction to the degenerative process in the disc.

Facet Joint Degeneration: Degenerative changes in the facet joints (small joints between vertebrae) can often accompany disc desiccation at L5-S1. These changes can include osteophytes (bone spurs), narrowing of the joint space, and sclerosis (increased bone density).

Radiologists assess these findings collectively when interpreting MRI images to determine the severity and extent of disc desiccation at the L5-S1 level. Quantitative measurements of disc height and signal intensity changes can also be used to objectively assess disc desiccation.