Session Title: Imaging of Rheumatic Diseases - Poster II: XR/CT/PET/MRI
Session Type: ACR Poster Session B
Session Time: 9:00AM-11:00AM
Background/Purpose: We aimed to assess increased SIJ uptakes on 18-FNa (an osteoblastic tracer) PET/CT and to compare with MRI SIJ assessments for inflammation and structural damage in MRI in a population of 23 patients with SpA. (IDRCB : 2012-A00568-35).
Methods: This prospective study included 23 patients with active SpA according to ASAS and/or modified mNY criteria (males 43%, median age 43 y, median symptom duration 7.7 y, HLA-B27 30%, median CRP 8mg/L, median BASDAI 6.1). Pelvic radiograph, MRI of the SIJ and 18-FNa PET/CT were performed during the same month. For MRI, SIJ were assessed for the presence of inflammation (ASAS criteria) and were quantitatively assessed according to SPARCC methods for scoring inflammation and structural damage. On the PET, SIJ were scored blinded to MRI and CT by two nuclear physician according to a slice by slice approach. A positive PET was defined when unilateral uptake was observed on 2 consecutive slices or bilateral uptake on a single slice. As for SPARCC MRI methods, quantitative assessment on 18-FNa PET was performed according to SIJ quadrants for six consecutive slices through the cartilaginous region of the joint (PET-activity score). The Standardized Maximal Uptake Value (SUV-max) was measured for each SIJ, corresponding to the highest uptake value of the SIJ.
Results: 7 patients had radiographic sacroiliitis, 9 had inflammatory sacroiliitis on MRI (mean SPARCC 7.65)., 9 had structural sacroiliitis on MRI The concordance between the two readers for a positive PET was good (73.9%) as well as the inter-reader reliabilities for the PET-activity score (ICC= 0.69 (95%CI: 0.40 to 0.86)). 18 patients had a positive PET with a mean PET-activity score of 15.7 (± 14). The mean SUV-max for a positive PET was 1.91 versus 1.27 for a negative one. According to a binary approach, a positive PET did not correlate to both inflammatory and structural damages on MRI. The PET-activity score (r=0.57, p=0.005) and SUV-max (p<0.05) correlated with the SPARCC inflammation score .Only backfill score amongst MRI structural lesions correlated negatively with the PET-activity score (r=-0.45 p=0.03). The SUV max was associated with SPARCC inflammation and backfill (r= 0.02; p=0.046) and (r= -0.1; p=0.04), respectively.
Conclusion: In axial SpA, the frequency of a positive 18-FNa PET (78.3%) was higher than the frequency of an ASAS positive MRI for inflammatory sacroiliitis (39.1%). Compared to MRI, PET SIJ uptake had a good correlation with inflammatory sacroiliitis while correlation with structural lesions was absent except for backfill.
To cite this abstract in AMA style:remy O, fehd B, marie R, willy NS, olivier M, isabelle CV, walter M, robert L, pierre O, Loeuille D. Performance of Magnetic Resonance Imaging and 18fluoride Sodium Positron Emission Tomography with Computed Tomography to Assess Inflammatory and Structural Abnormalities of the Sacroiliac Joint in Axial Spondyloarthritis [abstract]. Arthritis Rheumatol. 2016; 68 (suppl 10). https://acrabstracts.org/abstract/performance-of-magnetic-resonance-imaging-and-18fluoride-sodium-positron-emission-tomography-with-computed-tomography-to-assess-inflammatory-and-structural-abnormalities-of-the-sacroiliac-joint-in-axi/. Accessed December 3, 2020.
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