Diagnostic features of osteitis condensans ilii by MRI-a systematic literature review.

OBJECTIVE: To describe and evaluate the current knowledge of MRI characteristics of osteitis condensans ilii (OCI) in the diagnostics and differentiation of OCI from other conditions. MATERIALS AND METHODS: The databases PubMed, EMBASE, Scopus, and Web of Science were searched from their inception to March 2024 using the search terms "Magnetic Resonance Imaging" (MESH term in PubMed) and "osteitis condensans ilii" and limited to English language. Two reviewers independently screened titles, abstracts, and full-text eligibility and assessed the risk of bias according to Quality Assessment of Diagnostic Accuracy Studies, QUADAS-2. RESULTS: The search identified 53 records. Case reports, letters/notes, and conference abstracts were excluded, resulting in 24 reports assessed by full-text, 9 research articles, 14 reviews, and a book chapter. Five retrospective research studies were found eligible for the review. Detailed MRI features of OCI were only described in two studies of patients with pain where they encompassed manifest subchondral iliac sclerosis often accompanied by bone marrow edema (BME) located peripheral to the sclerosis and displaying a continuous distribution and frequently accompanied by sacral BME. Erosions were rare and ankylosis did not occur. Fat deposition in the bone marrow was frequent and similar to BME often located to anterior strain-related joint areas. The QUADAS-2 assessments revealed risks of bias in all studies analyzed, especially regarding general applicability of the MRI features. CONCLUSION: There is a lack of valid data describing characteristic MRI features in general groups of OCI patients with and without pain.

Magnetic Resonance Imaging Topography of Bone Marrow Edema in the Sacroiliac Joint of Postpartum Women.

OBJECTIVE: A traditional monoplanar semicoronal and a biplanar magnetic resonance imaging (MRI) assessment method were used to compare the topographical distribution of postpartum strain-related bone marrow edema (BME) at the sacroiliac joint (SIJ). METHODS: The presence and topographical location of SIJ BME were assessed independently by three readers in 71 women 12 months postpartum. A traditional monoplanar semicoronal and a biplanar BME evaluation by 8 (upper and lower) and 12 joint (upper, middle, and lower) regions, respectively, was performed with >4 weeks between the two assessments. Descriptive results were reported as mean ± SD and ranges, and interreader agreement by intraclass correlation coefficient (ICC). RESULTS: By semicoronal assessment, 38 (53.5%) women had BME with a mean ± SD SPARCC score of 2.3 ± 4.0 (range 0-22; ICC 0.93, 95% confidence interval [CI] 0.92-0.94). Forty-one (57.8%) had BME by biplanar assessment with a mean ± SD sum score of 2.9 ± 5.8 (range 0-32.7; ICC 0.89, 95% CI 0.88-0.91). By semicoronal assessment, the highest frequency and mean SPARCC scores were in the anterior upper regions of ilium (24%, mean 0.6) and sacrum (21%, mean 0.3) followed by the posterior upper sacral (20%, mean 0.4) and posterior lower iliac (20%, mean 0.3) regions. By biplanar assessment, the anterior middle joint regions had highest BME frequency and sum scores, sacral side (32%, mean 1.9) and iliac side (27%, mean 2.0), respectively; frequencies and sum scores were generally higher in the anterior compared to the posterior joint regions. CONCLUSION: The 12-region biplanar assessment revealed a predominantly anterior middle location of postpartum SIJ BME whereas the 8-region monoplanar approach did not demarcate distinct strain-prone SIJ regions. Complementing traditional monoplanar semicoronal SIJ MRI evaluation by a semiaxial assessment may facilitate discrimination of strain-related conditions from early axial spondyloarthritis.

Evolution of Magnetic Resonance Imaging Lesions at the Sacroiliac Joints During and After Pregnancy by Serial Magnetic Resonance Imaging From Gestational Week Twenty to Twelve Months Postpartum.

OBJECTIVE: Sacroiliac (SI) joint magnetic resonance imaging (MRI) findings simulating sacroiliitis related to axial spondyloarthritis (SpA) may occur in women before and after birth. This study was undertaken to explore the prevalence, evolution, and topography of SI joint MRI lesions in pregnant and postpartum women. METHODS: A prospective cohort study included 103 first-time mothers who underwent up to 5 serial SI joint MRI between gestational week 20 and 12 months postpartum. After calibration, 3 assessors independently evaluated bone marrow edema (BME), including sacroiliitis according to the Assessment of SpondyloArthritis international Society (ASAS), as well as structural lesions, using the Spondyloarthritis Research Consortium of Canada (SPARCC) and a novel 2-plane assessment method. RESULTS: BME was frequent both during pregnancy and the postpartum period, peaking at 3 months postpartum with a prevalence of 69% (SPARCC) and 80% (2-plane method), but still present in 54% (SPARCC) and 58% (2-plane method) of subjects at 12 months postpartum. At 12 months postpartum, sacroiliitis according to the current ASAS definition was met in 41%, while 21% and 14% of women fulfilled the newly proposed ASAS MRI thresholds for active and structural SI joint lesions, respectively. BME clustered in the anterior middle joint portions at all time points, and ligamentous BME was rare. At 12 months postpartum, SPARCC erosion scores ≥3 (ASAS threshold) were observed in only 2.8% of women. CONCLUSION: At 12 months postpartum, 41% of women met the current ASAS sacroiliitis definition, which may result in false-positive assignments of axial SpA diagnosis in postpartum women with back pain. The topographical BME distribution and virtually absent erosions (ASAS threshold) at 12 months postpartum may help discriminate postpartum strain-related conditions from axial SpA-related sacroiliitis.

Differences in topographical location of sacroiliac joint MRI lesions in patients with early axial spondyloarthritis and mechanical back pain.

BACKGROUND: Early diagnostics of axial spondyloarthritis (axSpA) remains a challenge. Traditional imaging one-plane sacroiliac joint (SIJ) MRI assessment is used. By introducing a two-plane assessment system, the objective was to analyse the differences in SIJ MRI changes in early axSpA compared with changes in patients with mechanical back pain (MBP) by exploring the differences in volume and location. METHODS: MRIs in the early diagnostic state of 25 axSpA patients (mean age 31.3 years) and 59 MBP patients (mean age 32.3 years) were included. The MRIs were assessed by two readers regarding the distribution of bone marrow edema (BME) in 14 joint portions and structural changes in six joint portions in addition to SIJ anatomical variations and lumbar spine disc degeneration. RESULTS: AxSpA patients had a significantly higher overall BME sumscore (volume) of 25.1 compared to MBP patients 6.8, p < 0.005. The MBP group had the highest prevalence (66%) and sumscore (5.7) in the middle anterior sacrum. The axSpA group had significantly higher prevalence and sumscores in all joint portions except the three cartilaginous anterior sacral joint portions, including the ligamentous compartments (prevalence 40-60% compared to 8-15%, p both < 0.005). The axSpA group had also a significantly higher prevalence of erosions and fatty marrow disposition, but there were no differences in the prevalence of anatomical variations except the bipartite iliac bony plate. CONCLUSIONS: AxSpA patients demonstrated a widespread distribution of both inflammatory and structural changes, including high BME occurrence in the ligamentous joint portions whereas patients with MBP had the highest occurrence of BME in the middle anterior sacrum. These findings may help differentiate axSpA patients from other back pain conditions in the early diagnostic phase.

Pregnancy-related sacroiliac joint findings in females with low back pain: a four-year magnetic resonance imaging follow-up study.

BACKGROUND: Pregnancy-related pain may be associated with sacroiliac joint (SIJ) changes, detectable by magnetic resonance imaging (MRI). PURPOSE: To analyze the prevalence and course of SIJ MRI and clinical findings in women referred with low back pain and relate these to pregnancy. MATERIAL AND METHODS: A retrospective follow-up study from a longitudinally collected cohort comprising 328 women. RESULTS: Women reporting debut of pain in relation to a pregnancy (PP group) tended to have a higher baseline prevalence of all investigated MRI findings, cumulated positive SIJ tests, and a potential fulfilment of the spondyloarthritis diagnosis compared to remainders. The prevalence of subchondral bone marrow edema (BME), any SIJ MRI finding, and potential fulfilment of the spondyloarthritis diagnosis were significantly higher in the PP group compared to women who had not been pregnant. In the total study group, the prevalence of ≥1 MRI finding increased over the four-year study period from 34% to 47% (P<0.001), driven by increasing prevalence of BME (25% to 32%; P=0.008) and fatty marrow deposition (FMD) (20% to 25%; P=0.020). In addition, the BME volume score increased. Over time, the PP group had persisting high prevalence of buttock pain and total MRI findings and their FMD volume score increased, but there were no between-group differences in MRI variables at follow-up. CONCLUSION: Overall, the prevalence of MRI findings increased over time. Although the PP group had different clinical and SIJ MRI characteristics cross-sectional at baseline compared to remainders, longitudinal analyses revealed that these diminished over time.

Anatomical variation at the sacroiliac joints in young adults: estimated prevalence by CT and concomitant diagnostics by MRI.

OBJECTIVE: To estimate the prevalence of atypical anatomical morphologies at the sacroiliac joints (SIJ) in young adults by CT and analyze the diagnostic ability of MRI to detect the variations in addition to concomitant MRI findings that could be misdiagnosed as inflammatory changes. MATERIALS AND METHODS: The study sample constituted CT examinations of 155 individuals aged 18-40 years and prospectively collected comparative SIJ MRI examinations of 49, who also filled out a questionnaire on back and buttock pain. The CT and MRIs were analyzed by two musculoskeletal radiologists regarding seven SIJ variations and additional subchondral bone marrow edema (BME) by MRI. RESULTS: CT and MRI interobserver agreements were good or very good for most variations. Mean age of the 155 individuals was 28 years, 99 (64%) were males; 88 (57%) had at least one SIJ variation, and most frequent were dysmorphic cartilaginous joint facets (n = 33, 21%), bipartite iliac bony plate (n = 27, 17%), accessory SIJ (n = 24, 16%), and iliosacral complex (n = 18, 12%), with a female predominance of all variations. The ability of MRI to detect the frequent variations was satisfying. Dysmorphic cartilaginous joint facets, accessory SIJ, and iliosacral complex were frequently observed in individuals reporting symptoms and were accompanied by BME, often located anteriorly in sacrum/inferiorly in ilium. CONCLUSION: Atypical SIJ morphology is frequent in young adults, especially females, demanding further research into the anatomical natural variation. Most of the variations were detectable by MRI and three variations warrant further exploration as they often were accompanied by symptoms and/or BME.