What is the significance of a high-intensity zone (HIZ) on T2-weighted MRI in the intervertebral disk, and what does it indicate?

A high-intensity zone (HIZ) on T2-weighted MRI of the intervertebral disk represents a focal area of high signal intensity within the annulus fibrosus, indicative of an annular tear. Key diagnostic features include its location within the posterior annulus and its appearance as a bright spot on T2-weighted images. Clinically, HIZ is often associated with low back pain, although not all HIZs are symptomatic. Common pitfalls include mistaking HIZ for other high-signal lesions such as Schmorl's nodes or Modic changes.