MRI of the ageing and herniating intervertebral disc

The role of diagnostic imaging from the patient's perspective is to provide answers to four basic questions:--what is wrong?, How bad is it?, Is it clinically relevant?, Can it be treated? In the assessment of spinal disorders, multiple modalities have evolved in an attempt to answer the questions poised. Without doubt, the advent of MRI has given this process significant benefits primarily because of the unparalleled way of depicting normal and abnormal tissues in a non-invasive manner. In particular, MRI is admirably suited to study the intervertebral disc and goes a long way in answering the first two questions, aiding in the accurate analysis of disc morphology, defining pathological states, and delineating the extent and effect of disease. This information however, needs to be equated with the clinical signs and symptoms before any decisions concerning treatment options can be made. At this point one needs to exercise some degree of prudence and remember that MRI as yet does not differentiate abnormal asymptomatic from symptomatic painful disc levels. Enhancement with gadolinium compounds may go some way in providing some answers by defining the tissue response at or around the damaged points within the disco-vertebral unit. Modern MRI scanners and techniques demonstrate exquisitely, the structural status of the disc but the functional impact of these structural alterations cannot as yet be fully determined by MRI--there lies the challenge for the future. This article reviews the current MRI knowledge concerning the ageing and herniating intervertebral disc in a clinical context, and critically appraises its present role in a practical fashion.