Imaging studies show limited diagnostic value in SpA
MedWire News: Imaging studies of the heel are not sufficiently specific to be used for the diagnosis of spondyloarthropathy (SpA), a study by French researchers has found.
Nevertheless the team believes that magnetic resonance imaging (MRI) and power Doppler ultrasound (PDUS) are valuable for the ongoing assessment and evaluation of heel pain in patient with SpA.
Antoine Feydy (CHU Cochin, Paris) and team compared the diagnostic capabilities of the two imaging modalities in 51 patients with definite SpA and 24 patients with degenerative noninflammatory low back pain, who acted as controls.
All patients underwent bilateral heel MRI and PDUS performed by two experienced radiologists who were blinded to the patients' clinical and biologic profiles.
Among the SpA patients, the mean age was 50.8 years and the mean disease duration was 13 years. In all, 25 patients were free of heel pain, 13 had a history of heel pain, and 13 reported current heel pain. Among the latter group, 10% had swelling, 38% had pain at the Achilles tendon, and 67% had pain at the aponeurosis.
Imaging revealed a high prevalence of abnormalities in both SpA patients and controls, Feydy et al report in Annals of Rheumatic Diseases.
On MRI, heel abnormalities were detected in 81% of SpA patients with current heel pain and in 56% of other SpA patients; similarly, PDUS abnormalities were observed in 58% and 17% of these groups, respectively.
However, the frequency of MRI abnormalities was not significantly different between SpA patients without heel pain and controls (53% vs 67%). Indeed, the most specific imaging finding to SpA patients - edema of the calcaneum on MRI (specificity 94%) - was not sufficiently sensitive to be used for diagnosis (22%).
The researchers calculated that the most useful features to assess painful heels in SpA were intra- or peri-aponeurosis signal abnormalities on MRI (sensitivity 70%, specificity 78%) and the presence of any of several early signs on PDUS (sensitivity 58%, specificity 87%).
"Bone edema on MRI was specific to painful heels (specificity 86%) but was not often present (38% of painful heels)," they add. "PDUS was rarely positive, even in painful heels (11%)."
The team concludes that MRI and PDUS are not useful in SpA patients without heel pain, but have a diagnostic role in SpA patients with ensethopathy.
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By Joanna Lyford