Performance of 18F-sodium fluoride positron emission tomography with computed tomography to assess inflammatory and structural sacroiliitis on magnetic resonance imaging and computed tomography, respectively, in axial spondyloarthritis

Abstract

Purpose To assess increased sacroiliac joint (SIJ) uptake on 18 F-NaF PET/CT and to compare with MRI for inflammation and with CT scan for structural damages in a population of 23 patients with spondyloarthritis (SpA). Methods Twenty-three patients with active SpA according to the Assessment of SpondyloArthritis international Society (ASAS) and/or modified NY criteria were included. All patients had a pelvic radiograph, MRI, and CT scan of the SIJ and 18 F-NaF PET/CT examinations within a month, analyzed by three blinded readers. MRIs were assessed according to the ASAS criteria and SPARCC method. On CT scans, erosion and ankylosis were quantified using the same methodology. On the 18 F-NaF PET, abnormal uptake was assessed using a qualitative method inspired by the ASAS criteria and two quantitative approaches (the PET-activity score according to the SPARCC method and Maximum Standardized Uptake Value (SUVmax)). Results Structural sacroiliitis was observed on 7 radiographs and 10 CT scans; 10 MRIs showed inflammatory sacroiliitis, and 20 patients had a positive PET. The inter-reader reliability was good for the PET activity score and good to excellent for the SUVmax. A positive PET was not correlated with a positive MRI or with a structural sacroiliitis on CT scan. The PET-activity score and SUVmax were correlated with the SPARCC inflammation score but not with erosion or ankylosis scores on CT scan. Conclusion Abnormal uptake by the SIJ on 18 F-NaF PET is more frequent than inflammatory and structural sacroiliitis in a population of SpA patients. The PET activity score and SUVmax had good correlations with inflammatory sacroiliitis but not with structural lesions on CT scan.

Multi-Modal Imaging to Assess the Interaction Between Inflammation and Bone Damage Progression in Inflammatory Arthritis

“…Examples of other applications include combining CT with positron emission tomography (PET). PET/CT using 2-deoxy-2[18F]fluoro-d-glucose (FDG) to visualize glucose metabolism has been has recently been used to investigate increased glycolysis due to inflammation in inflammatory arthritis, demonstrating correlations between metabolic markers identified with PET and clinical diseases activity in rheumatoid arthritis ( 44 ), and between PET activity score and inflammation score on MRI in patients with sacroiliitis in spondylarthropathy ( 45 ). Further, PET uptake predicts radiographic progression in RA ( 46 ).…”

Update of imaging in the diagnosis and management of axial spondyloarthritis

“…Another study has shown a moderate correlation between 18 F-fluoride uptake on PET-MRI and BME in the SIJ (kappa= 0.64) and a poor correlation in the spine (kappa=0.25) [121]. Overall, the correlation between osteoblastic activity on PET and BME is still controversial, especially in the spine [119,122]. Concerning structural lesions, no correlation was found between 18 F-fluoride PET and the presence of erosions, ankylosis, and sclerosis visible on the SIJ CT scans [119].…”

“…Positron emission tomography (PET) is a nuclear imaging technique that can be used as hybrid imaging when combined with CT or MRI for anatomical reference. Similarly to MRI, PET may be useful in the early diagnosis of axSpA since it may allow early detection of inflammatory changes even before structural damage occurs [119]. It can visualize and quantify disease activity at different targeted binding sites in the whole body (bone marrow, synovial tissue, ligament, and entheses) through the use of different specific tissue tracers.…”

“…Concerning inflammatory lesions in axSpA patients, a study showed a significant correlation between 18 F-Fluoride PET uptake in the SIJ and inflammation on MRI (ICC[IC95] = 0.61[0.26; 0.82]; p= 0.001), even if it was detected in only half of the patients [119]. Interestingly, 18 F-fluoride PET scans recognized twice as many as having sacroiliitis compared to MRI and CT scans suggesting that 18 F-fluoride PET may be a more sensitive technique to detect early lesions not yet visible on MRI or CT scans [119]. Another study has shown a moderate correlation between 18 F-fluoride uptake on PET-MRI and BME in the SIJ (kappa= 0.64) and a poor correlation in the spine (kappa=0.25) [121].…”

Axial Psoriatic Disease: Clinical and Imaging Assessment of an Underdiagnosed Condition

“…Since the syndesmophyte formation is not clearly identifiable on MRI, new techniques dedicated to bone remodelling, such as PET-CT, may play a role [57]. In recent years, the PET diagnostic potential has been considered in both infectious and inflammatory diseases, such as polymyalgia rheumatica, vasculitis, and rheumatoid arthritis [58].…”