Study design: Retrospective review of magnetic resonance imaging and discography in patients investigated for low back pain before spinal fusion.
Objective: To determine the sensitivity of magnetic resonance imaging in the detection of painful anular tears manifested by the high-intensity zone.
Summary of background data: Two studies have produced results showing that magnetic resonance imaging has a high specificity for the detection of painful anular tears manifested by a high-intensity zone. However, in a recent study, results showed no significant correlation between the high-intensity zone and pain reproduction. The sensitivity of magnetic resonance imaging in identifying anular tears in a symptomatic population has not been determined.
Methods: Anular tears were identified in magnetic resonance images by the presence of a high-intensity zone in the posterior anulus. The results were compared with the demonstration of painful anular tears on discogram, which has been considered the gold standard.
Results: The study group comprised 58 patients (31 men, 27 women; mean age 42, range 21-63 years). One hundred and fifty-two discs were injected and examined by discography, and 108 were considered degenerate. Of these, 86 had anular tears (54 posterior, 6 anterior, 26 both). Seventy anular tears were associated with concordant pain provocation. Twenty-seven high-intensity zones were identified in magnetic resonance imaging, of which 24 were associated with pain reproduction by discography. The sensitivity, specificity, positive predictive value, and negative predictive value of magnetic resonance imaging in the diagnosis of concordantly painful posterior anular tears are therefore 26.7%, 95.2%, 88.9%, and 47%, respectively.
Conclusion: These results confirm that the high-intensity zone is a marker of a painful posterior anular tear. However, the usefulness of this sign is limited by low sensitivity.