Can magnetic resonance imaging differentiate undifferentiated arthritis based on knee imaging?
OBJECTIVE
To compare findings as observed on enhanced magnetic resonance imaging (MRI) of the knee joints, in oligoarticular-undifferentiated arthritis (UA) in those with established rheumatoid arthritis (RA) and spondyloarthropathy (SpA).


METHODS
A total of 55 patients with knee arthritis were consecutively recruited for the study, including 25 with undifferentiated oligoarthritis of the knee joint(s), 15 fulfilling the American College of Rheumatology criteria for RA and 15 with SpA. Laboratory investigations included erythrocyte sedimentation rate, C-reactive protein, complete blood count, aspartate aminotransferase, alanine aminotransferase, serum creatinine, and urine analysis. In all patients in the UA and in the RA group, rheumatoid factor and anti-CCP2 antibody (ELISA) were tested. All patients underwent enhanced MRI of the more symptomatic knee. All groups were compared in terms of demographics, laboratory investigations, and MRI findings.


RESULTS
Synovial thickness differed significantly in the RA group compared to UA and SpA groups (p < 0.001). The RA group showed a higher rate of bony and cartilaginous erosions and bone marrow edema compared to UA and SpA groups (p < 0.001). Enthesitis was found in all patients in the SpA group (100%) and differed from RA and UA groups (p < 0.001).


CONCLUSIONS
Patients with RA showed more destructive changes in terms of synovial thickening, bone marrow edema, cartilaginous and bone erosions compared to UA and SpA groups. Enthesitis is a common feature on MRI in SpA, while absent in the RA and UA groups. This latter finding may have important clinical implications for classification purposes, and can help to determine the evolving pattern of patients with UA of the knee joint.
Emad
Yasser
Y
Department of Rheumatology and Rehabilitation, Faculty of Medicine, Cairo University, Cairo, Egypt. yasseremad68@yahoo.com
Ragab
Yasser
Y
Shaarawy
Ahmed
A
Abou-Zeid
Alaa
A
Saad
Ahmed
A
Fawzy
Magdy
M
Jokhdar
Hani
H
Rasker
Johannes J
JJ
D000328:Adult; D001168:Arthritis / Q000097:blood / Q000175:diagnosis* / Q000473:pathology; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000175:diagnosis* / Q000473:pathology; D001219:Aspartate Aminotransferases / Q000097:blood; D001772:Blood Cell Count; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000378:metabolism; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D025242:Spondylarthropathies / Q000097:blood / Q000175:diagnosis* / Q000473:pathology; D013583:Synovial Membrane / Q000473:pathology*
D002097:C-Reactive Protein; D001219:Aspartate Aminotransferases