CT Read logoCT Read
Understanding Findings

Herniated Disc on MRI: Reading Tips

Understand a herniated disc on MRI: disc bulge vs protrusion vs extrusion, lumbar MRI levels, nerve root compression, spinal stenosis, and red flags.

CT Read Editorial12 min readPublished 2026-05-05

Reviewed by a board-certified radiologist

Herniated Disc on MRI: Reading Tips medical imaging guide cover
Spine specialist reviewing lumbar MRI images with a herniated disc on a workstation
Synthetic editorial illustration for patient education. Not a real patient study or diagnosis.

Before You Read

Use this article as a plain-language guide, not a diagnosis

This guide explains common imaging terms, patterns, and follow-up questions so you can better understand your radiology report. Always confirm important findings with your radiologist or treating clinician.

Introduction

A herniated disc occurs when the soft inner core of a spinal disc pushes through the outer ring, compressing spinal nerves and causing sciatica. MRI is the best imaging modality to evaluate disc herniations.

Disc Pathology Grading on MRI

  • Bulging: The disc extends symmetrically beyond the vertebral border. Typically mild.
  • Protrusion: A focal projection of disc material, but the base remains wider than the dome.
  • Extrusion: The projected material narrow at its base, compressing nerves severely. Fragments may sequester (separate from the disc).

Frequently asked questions

Related articles