Spondyloarthritis-related and degenerative MRI changes in the axial skeleton - an inter- and intra-observer agreement study

Abstract

BackgroundThe Back Pain Cohort of Southern Denmark (BaPa Cohort) was initiated with the aim of evaluating the clinical relevance of magnetic resonance imaging (MRI) in the diagnosis of early spondyloarthritis (SpA). In order to facilitate the collection of MRI data for this study, an electronic evaluation form was developed including both SpA-related and degenerative axial changes. The objective of the current study was to assess the intra- and inter-observer agreement of the MRI changes assessed.MethodsThree radiologists evaluated 48 MRI scans of the whole spine and the sacroiliac joints from a subsample of the BaPa Cohort, consisting of patients with non-specific low back pain and patients with different stages of SpA features. The spine was evaluated for SpA-related and degenerative MRI changes and the SIJ for SpA-related changes. Inter- and intra-observer agreements were calculated with kappa statistics. In the interpretation of the kappa coefficient, the standards for strength of agreement reported by Landis and Koch were followed.ResultsA total of 48 patients, 40% men and mean age of 31 years (range 18 – 40 years), were evaluated once by all three readers and re-evaluated by two of the readers after 4-12 weeks. For MRI changes in the spine, substantial to almost perfect observer agreement was found for the location and the size of vertebral signal changes and for disc degeneration and disc contour. For the sacroiliac joints, substantial or almost perfect observer agreement was found for the grading of bone marrow oedema and fatty marrow deposition, the depth of bone marrow oedema and for subchondral sclerosis. Global assessment of the SpA diagnosis had substantial to almost perfect observer agreements.ConclusionThe acceptable agreement for key MRI changes in the spine and sacroiliac joints makes it possible to use these MRI changes in the BaPa Cohort study and other studies investigating MRI changes in patients with non-specific low back pain and suspected SpA.

Classification of axial SpA based on positive imaging (radiographs and/or MRI of the sacroiliac joints) by local rheumatologists or radiologists versus central trained readers in the DESIR cohort

“…In the DESIR cohort, agreement between two trained central readers as well as between central-reading and local-reading on pos-MRI was substantial, thereby comparable to levels of agreement reported in a study designed to test inter-reader and intrareader agreement between experienced radiologists on a pos-MRI (κ=0.79–0.85) 19. Though, it should be noted that at the start of the DESIR cohort, the ASAS definition of a positive MRI-SI was not published yet.…”

Associations Between Spondyloarthritis Features and Magnetic Resonance Imaging Findings: A Cross‐Sectional Analysis of 1,020 Patients With Persistent Low Back Pain

“…Agreement of the MRI evaluations of the spine and SI joints using the current methodology has been tested in a previous study with kappa analysis using weighted kappa for the ordinal variables (17). However, 4 variables (fatty marrow deposition at the apophyseal joints, soft tissue edema around the apophyseal joints, bone marrow edema at the costovertebral joints, and erosion in the vertebral corner) were not tested for agreement because of a low number of positive ratings (17). All other MRI findings in that study had kappa values of Sclerosis in at least 1 region * The presence of a given finding was defined by a minimum of 2 lesions seen on a single sacroiliac (SI) joint slice or 1 lesion seen on at least 2 consecutive slices.…”

“…ARNBAK ET AL .0.6 for interobserver and intraobserver agreement, except for erosions at the SI joints and spinal corner lesions, which had kappa values for interobserver agreement of 0.53 and 0.57, respectively (17). Statistical analysis.…”

Prevalence of degenerative and spondyloarthritis-related magnetic resonance imaging findings in the spine and sacroiliac joints in patients with persistent low back pain

“…In general, the MRI findings included in the current study had kappa values of more than 0.6, with the exception of vertebral corner lesion and erosions at the SIJs, which had kappa values for interobserver agreement of 0.53 and 0.57, respectively [12]. Furthermore, four variables (erosions at the vertebral corner, bone marrow oedema at the costovertebral joints, fatty marrow deposition at the apophyseal joints, and soft tissue oedema around the apophyseal joint) were too rare to be included in the kappa analysis [12]. These six variables were, however, included because they are widely regarded as key MRI findings in the assessment of SpA [9,11].…”

“…The MRI evaluation protocol has previously been tested for inter-and intra-observer agreement [12]. In general, the MRI findings included in the current study had kappa values of more than 0.6, with the exception of vertebral corner lesion and erosions at the SIJs, which had kappa values for interobserver agreement of 0.53 and 0.57, respectively [12].…”