High intensity zone

High intensity zone is defined as a bright white signal on T2W images in the posterior annulus of the disc and represents a fissure/tear in the posterior annulus.

A high intensity zone (HIZ) generally occurs due to:

  • post-traumatic changes 
  • instability of the spine and degenerative changes of the disc

HIZs in the posterior annulus represent the in-growth of the vascularised granulation tissue into the tears in the posterior part of the painful disc induced by inflammation. The posterior annular fibres are structurally weaker as compared to the anterior annular fibres thereby predisposing them to disruption 1

MRI
  • T2: high signal intensity in the posterior annulus on sagittal images 
  • the HIZ can occur at the superior, middle or lower portions (most commonly) of the annulus
  • lumbar area at L4/5 and L5/S1 levels more commonly involved
Spine
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Article information

rID: 34762
Tag: cases
Synonyms or Alternate Spellings:
  • HIZ

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