Fat Metaplasia on Sacroiliac Joint Magnetic Resonance Imaging at Baseline Is Associated with Spinal Radiographic Progression in Patients with Axial Spondyloarthritis.
OBJECTIVE
To study the relationship between inflammatory and structural lesions in the sacroiliac joints (SIJs) on MRI and spinal progression observed on conventional radiographs in patients with axial spondyloarthritis (axSpA).


METHODS
One hundred and ten patients who fulfilled the ASAS axSpA criteria were enrolled. All underwent SIJ MRI at baseline and lumbar spine radiographs at baseline and after 2 years. Inflammatory and structural lesions on SIJ MRI were scored using the SPondyloArthritis Research Consortium of Canada (SPARCC) method. Spinal radiographs were scored using the Stoke AS Spinal Score (SASSS). Multivariate logistic regression analysis was performed to identify predictors of spinal progression.


RESULTS
Among the 110 patients, 25 (23%) showed significant radiographic progression (change of SASSS≥2) over 2 years. There was no change in the SASSS over 2 years according to the type of inflammatory lesion. Patients with fat metaplasia or ankyloses on baseline MRI showed a significantly higher SASSS at 2 years than those without (p<0.001). According to univariate logistic regression analysis, age at diagnosis, HLA-B27 positivity, the presence of fat metaplasia, erosion, and ankyloses on SIJ MRI, increased baseline CRP levels, and the presence of syndesmophytes at baseline were associated with spinal progression over 2 years. Multivariate analysis identified syndesmophytes and severe fat metaplasia on baseline SIJ MRI as predictive of spinal radiographic progression (OR, 14.74 and 5.66, respectively).


CONCLUSIONS
Inflammatory lesions in the SIJs on baseline MRI were not associated with spinal radiographic progression. However, fat metaplasia at baseline was significantly associated with spinal progression after 2 years.
Division of Rheumatology, Department of Internal Medicine, Medical College, The Catholic University of Korea, Seoul, South Korea; Division of Rheumatology, Department of Internal Medicine, Incheon St. Mary's Hospital, The Catholic University of Korea, Incheon, South Korea.
Kwi Young
KY
Kang
Division of Rheumatology, Department of Internal Medicine, College of Medicine, Ewha Womans University, Seoul, South Korea.
In Je
IJ
Kim
Department of Radiology, Korea University Guro Hospital, College of Medicine, Korea University, Seoul, South Korea.
Min A
MA
Yoon
Division of Rheumatology, Department of Internal Medicine, Medical College, The Catholic University of Korea, Seoul, South Korea; Division of Rheumatology, Department of Internal Medicine, Incheon St. Mary's Hospital, The Catholic University of Korea, Incheon, South Korea.
Yeon Sik
YS
Hong
Division of Rheumatology, Department of Internal Medicine, Medical College, The Catholic University of Korea, Seoul, South Korea.
Sung-Hwan
SH
Park
Division of Rheumatology, Department of Internal Medicine, Medical College, The Catholic University of Korea, Seoul, South Korea.
Ji Hyeon
JH
Ju
D000273:Adipose Tissue / Q000378:metabolism / Q000473:pathology*; D000328:Adult; D018450:Disease Progression; D005260:Female; D015796:HLA-B27 Antigen / Q000378:metabolism; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008679:Metaplasia / Q000175:diagnosis / Q000378:metabolism; D008875:Middle Aged; D011859:Radiography; D012446:Sacroiliac Joint / Q000378:metabolism / Q000473:pathology*; D012720:Severity of Illness Index; D013131:Spine / Q000000981:diagnostic imaging* / Q000473:pathology; D025241:Spondylarthritis / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D055815:Young Adult
D015796:HLA-B27 Antigen