The lumbar high-intensity zone: 20 years on.

The high intensity zone (HIZ) was first described by Aprill and Bogduk on lumbar spine magnetic resonance imaging (MRI) studies in 1992. Correlation with lumbar computed tomography (CT) discography showed that the HIZ represents a deep radial tear of the annulus fibrosus, which may be a cause of chronic low back pain. Initial studies comparing the finding of a HIZ on MRI with discography suggested that it may be a highly specific marker of a painful lumbar disc, but later investigators demonstrated that it is also present in asymptomatic individuals. The purpose of this article is to review the literature regarding the lumbar HIZ 20 years after its initial description.