Diagnosis of osteomyelitis in children: utility of fat-suppressed contrast-enhanced MRI.

OBJECTIVE

The purpose of this study was to determine whether the use of fat-suppressed contrast-enhanced MRI, compared with unenhanced MRI alone, increases reader confidence in the diagnosis of osteomyelitis and its complications in children.

MATERIALS AND METHODS

MRI studies of 78 skeletally immature children and adolescents (median age, 3.6 years) with suspected nonspinal osteomyelitis were reviewed in consensus by two readers. Unenhanced images were evaluated first and then contrast-enhanced MR images. Images were scored for the presence or absence of osteomyelitis, abscess, septic arthritis, and physeal involvement on a 5-point scale ranging from definitely absent to definitely present. Forty-two additional studies were evaluated to test interobserver agreement.

RESULTS

Osteomyelitis was clinically diagnosed in 40 cases (51%). There was no significant difference between the sensitivity and specificity of unenhanced MRI (p = 1.0) and those of contrast-enhanced MRI (p = 0.77) for the diagnosis of osteomyelitis. Nonetheless, there was a significant (p < 0.001) increase in confidence in the diagnosis of osteomyelitis and its complications. This increase in confidence was most pronounced for the diagnosis of abscess (46%). The addition of contrast enhancement was least useful in findings deemed definitely absent on unenhanced MR images.

CONCLUSION

Although it does not increase the sensitivity or specificity of the diagnosis, use of contrast-enhanced MRI does increase reader confidence in the diagnosis of osteomyelitis and its complications in cases in which bone or soft-tissue edema is found on unenhanced images. In the clear absence of edema on unenhanced images, however, contrast enhancement is not needed.