What is the best imaging modality to diagnose CPPD?
Plain radiography, ultrasonography (US), and computed tomography (CT) can be used to identify CPPD. Radiographs (knee > wrist > symphysis pubis) typically show CC, but not always. Some studies have demonstrated a higher sensitivity and specificity of US as compared with conventional radiography in detecting CPPD, but it is important to note that the success of this modality is operator-dependent and the specificity of findings is not perfect (the “double contour sign”, classically described in gout, has also been reported in some patients with CPPD). CT scanning accurately distinguishes calcifications and is exceptionally useful in detecting axial CPPD. Magnetic resonance is of little use in this setting (insensitive to tissue calcification). New imaging technologies, such as advanced magnetic resonance imaging techniques, diffraction-enhanced synchrotron imaging, and dual-energy CT, hold promise for the future.
