The diagnosis of chronic inflammatory rheumatism with axial involvement is not always easy, and is fraught with difficulties : radiological sacroiliitis is not an early sign of spondyloarthritis and the delay in detecting radiological signs contributes to the delay in diagnosis.

Nevertheless, spondyloarthritis is now the second most common chronic inflammatory rheumatic disease, affecting 0.43% of the french population.

The aim of this retrospective study is to evaluate the diagnostic performance of whole-body SPECT-CT CzT-based camera (VERITON-CT) in the assessment of chronic inflammatory rheumatism with axial involvement

MRI of the sacroiliac joints and thoracolumbar spine were used as a gold standard.

The present study was conducted by the Department of Rheumatology and Nuclear Medicine of the University Hospital Centre of Nancy (France).

An initial number of 51 hospitalised patients (35 females, 16 males) who underwent SPECT-CT CzT-based camera for polyarthralgia or spinal pain between November 2021 and February 2023 and initial suspicion of chronic inflammatory rheumatism were included in the study.

The investigators retrospectively reviewed the electronic medical records of the consecutive patients using medical softwares (DxCare or VNA Philips). The investigators collected demographic data (age, gender), clinical data (anamnesis, pain level (EVA) and location, standardized clinical activity scores like Ankylosing Spondylitis Disease Activity Score (ASDAS), Widespread Pain Index (WPI), symptom severity scale (SSS)), biological data (protein chain reaction in milligrams per litre), and medical imaging data (X-rays, MRI and CT scans).

The data collected was entered into an Excel spreadsheet protected by a security code.

For medical imaging data, the investigators performed a reading of the sacroiliac and thoracolumbar spine medical imaging under the supervision of an experienced rheumatologist specialising in chronic inflammatory rheumatism.

The investigators assessed the diagnostic performance of VERITON-CT (sensitivity, specificity), using MRI of the sacroiliac joints and thoracolumbar spine as the gold standard.

Inclusion Criteria:

• Hospitalised patients (hospitalisation sector or day hospital)
• Patients who underwent SPECT-CT CzT-based camera for polyarthralgia or spinal pain between November 2021 and February 2023
• Patients who underwent axial MRI
• Initial suspicion of chronic inflammatory rheumatism

Exclusion Criteria:

• Patients who did not give their consent
• Patients with extravasation of contrast agent at the injection site
• Patients with a missing phase on SPECT-CT (Blood-Pool phase or Delayed phase)

78 patients with SPECT-CT

Among them : 51 patients with axial MRI (spine n=42 and/or sacroiliac joints n=47) :

• 1 excluded for extravasation of contrast agent at the injection site
• 1 excluded for "blood- pool phase" SPECT missing

For a total of n = 47 patients (sacroiliac MRI); 25 classified as spondyloarthritis : axial spondyloarthritis, ankylosis spondylitis, psoriatic arthritis, SAPHO syndrome ; And 22 non-spondyloarthritis : Fibromyalgia, osteoarthritis, rheumatoid arthritis, Bertolotti syndrom, scoliosis, familial Mediterranean fever…

For a total of n = 42 patients (thoracolumbar MRI); 22 patients in spondyloarthritis group (15 spondyloarthritis, 4 psoriatic arthritis and 3 SAPHO syndrome) and 20 in non-spondyloarthritis group (1 rheumatoid arthritis, 2 fibromyalgia, 13 osteoarthritis, 1 familial Mediterranean fever, 2 arthralgia in IBD and 1 arthralgia in cystic fibrosis).