Radionuclide Methods in the Diagnosis of Sacroiliitis in Patients with Spondyloarthritis: An Update

Sacroiliitis, inflammation of the sacroiliac joint (SIJ), is the hallmark of ankylosing spondylitis and spondyloarthritis (SpA) in general. The arsenal of recommended diagnostic modalities for imaging of the SIJ is scanty and, in practice, includes only conventional X-rays and magnetic resonance imaging (MRI). This review suggests that bone scintigraphy, particularly single-photon emission computed tomography (SPECT) with calculation of indices, or SPECT in combination with low-dose computed tomography (CT) can be a sensitive and specific tool for the diagnosis of sacroiliitis and can be used as part of the individualized approach to the diagnosis of axial SpA. In addition, [(18)F]fluoride positron emission tomography (PET)/CT imaging and immunoscintigraphy, using labeled monoclonal anti-cytokine antibodies, are promising methods of current scientific interest in this field.