Anatomic Distribution of Sacroiliac Joint Lesions on Magnetic Resonance Imaging in Patients With Axial Spondyloarthritis and Control Subjects: A Prospective Cross‐Sectional Study, Including Postpartum Women, Patients With Disc Herniation, Cleaning Staff, Runners, and Healthy Individuals

Abstract

Objective To investigate the anatomic location and distribution of lesions on magnetic resonance imaging (MRI) in the sacroiliac (SI) joints in patients with axial spondyloarthritis (SpA), women with and without postpartum pain (childbirth within 4–16 months), patients with disc herniation, cleaning staff, runners, and healthy persons. Methods In a prospective cross‐sectional study of 204 participants, MRI of the entire cartilaginous compartment of the SI joint was scored blindly by 2 independent, experienced readers, according to Spondyloarthritis Research Consortium of Canada definitions of SI joint inflammation and structural lesions in each SI joint quadrant or half and in each of 9 slices. The locations of the lesions (unilateral/bilateral, upper/lower, sacral/iliac, and anterior/central/posterior slices) were analyzed based on concordant reads. Results Bone marrow edema (BME) occurred in all quadrants in nearly all participant groups, but rarely bilaterally, except in patients with axial SpA and women with postpartum pain. Fat lesions were mainly found in axial SpA and occurred in all quadrants, but mostly bilaterally in sacral quadrants. Erosion was rare, except in axial SpA, where it was mainly iliac and often bilateral. Sclerosis was exclusively iliac and most frequent in women with postpartum pain. Conclusion The location and distribution of common SI joint lesions in axial SpA and non–axial SpA were reported, and group‐specific patterns were revealed. BME distributed bilaterally or unilaterally, both locally and more widespread in the SI joint, is common in both postpartum women with pain and axial SpA patients, which limits the use of BME to differentiate these groups. This study indicates that the presence of fat lesions, especially when widespread, and/or erosion, particularly when located centrally or posteriorly, are diagnostically important and should be investigated further.

Spine abnormalities associated with bone edema on sacroiliac joints MRI in patients with non-inflammatory chronic back pain

“…Topographic distribution of SIJ BME has been poorly studied in patients with ax-SpA and no preferential localization has been identified. Recently, two studies have provided new information: BME was found throughout the joint, without predominance for the iliac or sacral bone, the upper or lower part and the anterior or posterior part [9,33]. BME associated with ax-SpA is usually bilateral unlike BME unrelated to ax-SpA which is almost exclusively unilateral [33,34].…”

“…Recently, two studies have provided new information: BME was found throughout the joint, without predominance for the iliac or sacral bone, the upper or lower part and the anterior or posterior part [9,33]. BME associated with ax-SpA is usually bilateral unlike BME unrelated to ax-SpA which is almost exclusively unilateral [33,34]. BME at the lower and posterior part of SIJ is often considered specific to inflammatory diseases and particularly ax-SpA whereas BME can also be observed at these locations in non-inflammatory conditions [16].…”

MRI in axial spondyloarthritis: understanding an ‘ASAS-positive MRI’ and the ASAS classification criteria

“…A common example would be a marathon runner with enthesitis of the Achilles tendon who also happens to have some stress-related bone marrow edema at the SIJ in MRI [33,34]. This patient would fulfil the ASAS classification criteria, whereas the probability for an axSpA diagnosis might be quite small.…”

Frequency and anatomic distribution of magnetic resonance imaging lesions in the sacroiliac joints of spondyloarthritis and non-spondyloarthritis patients

“…The anatomic distribution of inflammatory and structural lesions in a large cohort of patients with and without SpA has previously been investigated in a single study. 13 Division of the SI joint to enable easy analysis seems indispensable in current practice, as it has been suggested that some segments are preferentially associated with the inflammatory or mechanical origin of the lesions. 13 In this retrospective study, we aimed to analyse and compare the anatomic distribution of structural and inflammatory lesions present on the MRI of SI joint in patients with and without SpA, including, as in current practice, patients with non-specific low back pain, women with obstetric history, and athletes, with no age restrictions.…”