Imaging helps refine diagnosis and management in PsA

Imaging complements clinical judgement in psoriatic arthritis (PsA) diagnosis and management, helping guide treatment to achieve remission or minimize disease progression, according to Professor Mikkel Østergaard of the University of Copenhagen, Denmark, who spoke at AIM 2026.

“Establishing a specific diagnosis is not always easy. Detection of inflammation and monitoring of disease activity and structural damage progression are other challenges,” noted Østergaard. “Optimal PsA management requires help from imaging.”

Conventional radiography (CR) is easily accessible and remains useful for assessing structural damage, including bone erosions, joint-space narrowing and new bone formation, in both peripheral and axial disease. However, CR does not show current inflammation (which can be seen on ultrasonography or MRI), limiting its value when the immediate question is whether active inflammatory disease is driving symptoms.

Ultrasonography is the most feasible imaging modality in clinical practice for visualizing inflammation and structural lesions in joints, tendons and entheses, as well as soft tissue oedema in peripheral disease. However, it cannot detect bone oedema and axial disease. It may be particularly useful in psoriasis patients with joint pain but no definite swelling on examination, as it can help confirm inflammatory arthritis or indicate otherwise when pain is not accompanied by objective inflammatory findings. It may also support treatment response assessment through evaluation of residual inflammation.

MRI is the most comprehensive of the three imaging modalities. It can visualize key PsA pathologies detected by CR and ultrasonography combined, making it valuable for early diagnosis and disease monitoring. “MRI also provides prognostic information when axial PsA is suspected, in which case, imaging of both the sacroiliac joints [SiJs] and the spine should be done,” said Østergaard.

“Both ultrasonography and MRI outperform clinical assessment for evaluation of joints and entheses. However, imaging needs not be used routinely,” he said. “It is useful in cases of diagnostic uncertainty, or when imaging information may assist treatment decisions [eg, use of newer agents such as guselkumab for suppressing inflammation before irreversible radiographic damage occurs]. In patients with clear clinical presentation, additional imaging may not be necessary.”

“Emerging imaging techniques that may impact PsA management include low-dose CT and MRI-based synthetic CT, which showed promise for improved structural damage assessment in SiJs and spine, as well as whole-body MRI for monitoring total inflammatory burden in peripheral and axial PsA,” Østergaard continued.

The evolving role of imaging in PsA management is reflected in the 2025 update of the European Alliance of Association for Rheumatology (EULAR) Recommendations for the Use of Imaging in the Diagnosis and Management of Spondyloarthritis in Clinical Practice. A significant change vs the original 2015 version is replacement of CR with MRI of the SiJs – and spine in case of symptoms in that region – as the first imaging modality for diagnosing axial spondyloarthritis. CR or preferably low-dose CT not recommended in 2015 for diagnostic purposes is now suggested as an alternative modality for the SiJs if MRI is contraindicated or not available. Ultrasonography and MRI are also both now recommended for monitoring structural damage in peripheral spondyloarthritis, along with CR. [Ann Rheum Dis 2026;85:s837-s838; Ann Rheum Dis 2015;74:1327–1339].