The value of a repeat MRI examination of the sacroiliac joints following an inconclusive initial examination.

OBJECTIVE: Assess the diagnostic utility of repeat sacroiliac joint (SIJ) magnetic resonance imaging (MRI) examinations following an inconclusive initial examination performed for suspected sacroiliitis. METHOD: Subjects with > 1 SIJ MRI examinations, an inconclusive first scan and at least 6 months interval between scans, were included. All scans were evaluated for the presence of structural/active SIJ lesions as well as any other pathology. Clinical data was extracted from the patients' clinical files, and any missing data was obtained by a telephone interview. Diagnosis and active/structural scores were compared between first and follow-up examinations (t test). RESULTS: Seventy-one subjects were included in the study, 77.4% females, mean age 41.0 ± 15 years, mean time interval between exams 30.4 ± 25.24 months. Twelve subjects performed > 2 scans. In only two subjects (2.81%), both females, MRI diagnosis changed from inconclusive to definite sacroiliitis. None of the subjects with > 2 scans had evidence of sacroiliitis in any of the following MRI examinations. Significant differences were observed between the scores of active SIJ lesion of the first and follow-up MRI (1.51/1.62, p = 0.02) but not for scores of structural lesions (1.22/1.68, p = 0.2). CONCLUSIONS: Repeat SIJ MRI when the first MRI is inconclusive for sacroiliitis is more valuable in ruling out than in securing diagnosis of sacroiliitis. We suggest that when MRI findings are inconclusive, decision-making should be based on clinical data.

The influence of age on the prevalence of inflammatory and structural MRI lesions in the sacroiliac joints of patients with and without axial spondyloarthritis.

OBJECTIVES: To compare the influence of age on inflammatory (bone marrow oedema [BME]) and structural (fat lesions [FL], erosions and ankylosis) MRI lesions in the sacroiliac joints (SIJ) of patients with and without axial spondyloarthritis (axSpA). METHODS: In a retrospective study, SIJ MRI (STIR/T1 sequences) of consecutive patients with chronic back pain diagnosed with axSpA or non-SpA were evaluated based on SIJ quadrants (SIJ-Q). Two blinded readers evaluated BME and structural lesions. Reader agreement was evaluated for prevalence of MRI lesions related to age. RESULTS: MRIs of 309 (175 axSpA, 134 non-SpA) patients were evaluated. Their mean age was 38.5 (11.4) and 43.4 (13.8) years, 67% and 36% were male, CRP was 1.6 (2.4) and 1.1 (2.1) mg/dl and median symptom duration was 48 and 60 months for axSpA and non-SpA, respectively. SIJ-Q with BME and erosions were significantly more frequent in axSpA vs non-SpA patients independent of age, while this difference was seen for FL only in patients ≥50 years. The proportion of patients with ≥1 or ≥3 BME or chronic lesions except for FL increased with age in both groups, and was constantly higher in axSpA vs non-SpA. In univariate analyses, only female sex was significantly associated with more FL. CONCLUSIONS: The proportion of patients with MRI lesions was high in both axSpA and non-SpA patients. However, the prevalence of BME and erosions was significantly more frequent in patients with axSpA, was independent of age and also allowed for discrimination. FL occurred more frequently only in older age groups and were less reliable for discrimination vs non-SpA patients.

MRI-guided sacroiliac joint injections in children and adults: current practice and future developments.

Common etiologies of low back pain include degenerative arthrosis and inflammatory arthropathy of the sacroiliac joints. The diagnostic workup revolves around identifying and confirming the sacroiliac joints as a pain generator. Diagnostic sacroiliac joint injections often serve as functional additions to the diagnostic workup through eliciting a pain response that tests the hypothesis that the sacroiliac joints do or do not contribute to the patient's pain syndrome. Therapeutic sacroiliac joint injections aim to provide medium- to long-term relief of symptoms and reduce inflammatory activity and, ultimately, irreversible structural damage. Ultrasonography, fluoroscopy, computed tomography, and magnetic resonance imaging (MRI) may be used to guide sacroiliac joint injections. The populations that may benefit most from MRI-guided sacroiliac joint procedures include children, adolescents, adults of childbearing age, and patients receiving serial injections due to the ability of interventional MRI to avoid radiation exposure. Most clinical wide-bore MRI systems can be used for MRI-guided sacroiliac joint injections. Turbo spin echo pulse sequences optimized for interventional needle display visualize the needle tip with an error margin of < 1 mm or less. Published success rates of intra-articular sacroiliac joint drug delivery with MRI guidance range between 87 and 100%. The time required for MR-guided sacroiliac joint injections in adults range between 23-35 min and 40 min in children. In this article, we describe techniques for MRI-guided sacroiliac joint injections, share our practice of incorporating interventional MRI in the care of patients with sacroiliac joint mediated pain, discuss the rationales, benefits, and limitations of interventional MRI, and conclude with future developments.

Added value of 3D THRIVE (T1-weighted high-resolution isotropic volume examination) MRI pulse sequence in the detection of bony erosions of sacroiliac joints in patients of spondyloarthritis.

Purpose: Early depiction of bony erosions in sacroiliac (SI) joints increases the diagnostic accuracy of spondyloarthritis. The new 3D magnetic resonance imaging (MRI) sequence THRIVE (T1-weighted high-resolution isotropic volume examination) can depict cartilage erosions in sacroiliac joints. The aim of the study was to compare the diagnostic capacity of the new MRI sequence 3D THRIVE (T1-weighted high-resolution isotropic volume examination) with the routinely used T1 TSE pulse sequence in the depiction of structural erosions in sacroiliac joints by using MRI sequence zero echo time (zero ET) as a reference standard. Material and methods: Seventy five adult patients were included in this study. They underwent MRI sacroiliac joints examination using routine T1 TSE and STIR pulse sequences with the addition of the new 3D THRIVE and zero echo time (zero ET) sequences. Images of T1 TSE, 3D THRIVE, and zero ET sequences were evaluated by 2 radiolo-gists separately for the detection of sacroiliac joints erosions, then a comparison between T1 TSE and 3D THRIVE sequences was done using a CT-like image MRI sequence zero ET as a reference standard. Sensitivity, specificity, and accuracy for each sequence were calculated by the 2 readers. Results: Sensitivity, specificity, and accuracy of 3D THRIVE were higher than those of T1 TSE for reader 1 (sensitivity: 94.5% vs. 86.2%; specificity: 93.4% vs. 85.1%; and accuracy 95.2% vs. 88.5%) and for reader 2 (sensitivity: 93.3% vs. 79.9%; specificity: 94.7% vs. 86.2%; and accuracy 95.8% vs. 82.1%). Conclusions: Using CT-like image MRI sequence zero ET as the reference standard, 3D THRIVE pulse sequencing of the sacroiliac joints has much better diagnostic value in the depiction of bony erosions in patients suspected having spondyloarthritis as compared to the routinely used T1 TSE sequence.

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.

The utility of magnetic resonance imaging lesion combinations in the sacroiliac joints for diagnosing patients with axial spondyloarthritis. A prospective study of 204 participants including post-partum women, patients with disc herniation, cleaning staff, runners and healthy persons.

OBJECTIVES: To investigate the diagnostic utility of different combinations of SI joint MRI lesions for differentiating patients with axial SpA (axSpA) from other conditions with and without buttock/pelvic pain. METHODS: A prospective cross-sectional study included patients with axSpA (n = 41), patients with lumbar disc herniation (n = 25), women with (n = 46) and without (n = 14) post-partum (birth within 4-16 months) buttock/pelvic pain and cleaning assistants (n = 26), long-distance runners (n = 23) and healthy men (n = 29) without pain. Two independent readers assessed SI joint MRI lesions according to the Spondyloarthritis Research Consortium of Canada MRI definitions and pre-defined MRI lesion combinations with bone marrow oedema (BME) and fat lesions (FAT), respectively. Statistical analyses included the proportion of participants with scores above certain thresholds, sensitivity, specificity, positive and negative predictive values and likelihood ratios. RESULTS: BME adjacent to the joint space (BME@joint space) was most frequent in axSpA (63.4%), followed by women with post-partum pain (43.5%), but was present in nearly all groups. BME adjacent to fat lesions (BME@FAT) and BME adjacent to erosions (BME@erosion) were only present in axSpA patients and in women with post-partum pain, but scores ≥3 and ≥4, respectively, were only seen in axSpA patients. FAT@erosion was exclusively recorded in axSpA patients. FAT@joint space and FAT@sclerosis were present in most groups, but with higher scores in the axSpA group. CONCLUSION: BME@joint space and FAT@joint space were frequent in axSpA but also in other conditions, reducing the diagnostic utility. FAT@erosion, and BME@FAT, BME@erosion and FAT@sclerosis above certain thresholds, were exclusively seen in axSpA patients and may thus have diagnostic utility in the differentiation of axSpA from other conditions.

MRI of the sacroiliac joints in athletes: recognition of non-specific bone marrow oedema by semi-axial added to standard semi-coronal scans.

OBJECTIVE: Assessment of combined semi-axial and semi-coronal SI joint MRI in two cohorts of young athletes to explore frequency and topography of non-specific bone marrow oedema (BMO), its association with four constitutional SI joint features, and potential restriction of false-positive assignments of Assessment of SpondyloArthritis International Society-defined sacroiliitis on standard semi-coronal scans alone. METHODS: Combined semi-axial and semi-coronal SI joint MRI scans of 20 recreational runners before/after running and 22 elite ice-hockey players were evaluated by three blinded readers for BMO and its association with four constitutional SI joint features: vascular partial volume effect, deep iliac ligament insertion, fluid-filled bone cyst and lumbosacral transitional anomaly. Scans of TNF-treated spondyloarthritis patients served to mask readers. We analysed distribution and topography of BMO and SI joint features across eight anatomical SI joint regions (upper/lower ilium/sacrum, subdivided in anterior/posterior slices) descriptively, as concordantly recorded by ⩾2/3 readers on both MRI planes. BMO confirmed on both scans was compared with previous evaluation of semi-coronal MRI alone, which met the Assessment of SpondyloArthritis International Society definition for active sacroiliitis. RESULTS: Perpendicular semi-axial and semi-coronal MRI scans confirmed BMO in the SI joint of every fourth young athlete, preferentially in the anterior upper sacrum. BMO associated with four constitutional SI joint features was observed in 20-36% of athletes, clustering in the posterior lower ilium. The proportion of Assessment of SpondyloArthritis International Society-positive sacroiliitis recorded on the semi-coronal plane alone decreased by 33-56% upon amending semi-axial scans. CONCLUSION: Semi-axial combined with standard semi-coronal scans in MRI protocols for sacroiliitis facilitated recognition of non-specific BMO, which clustered in posterior lower ilium/anterior upper sacrum.

CT-guided transarticular biopsy of the sacroiliac joint: Technique and histomorphological results. A preliminary study.

OBJECTIVE: To introduce and evaluate computed tomography (CT)-guided transarticular needle biopsy of the cartilaginous sacroiliac joint (SIJ) and to assess the biopsy results microscopically. MATERIALS AND METHODS: The new CT-guided transarticular biopsy of the SIJ was performed in a young corpse and ten patients, two males and eight females aged 18-81 years. All patients had abnormal findings by magnetic resonance imaging (MRI) of the SIJs, including bone marrow edema, related to different types of joint disorders. The biopsies were focused on areas with bone marrow edema. The quality of the specimens obtained, using two different types of biopsy needles, was assessed microscopically. RESULTS: Biopsies containing cartilage, subchondral plate, and bone marrow from the iliac and sacral sides were obtained from the corpse and three patients and from the iliac bone only in two patients. In three patients, the biopsy needles could not penetrate the bone marrow to the joint facet due to pronounced subchondral sclerosis, but adequate marrow biopsies were obtained. Two biopsies were inadequate, one due to technical problems and one was crushed during preparation. Histological assessment of eight adequate specimens revealed inflammatory bone marrow changes, except in two specimens from females with pronounced sclerosis conforming to osteitis condensans ilii. CONCLUSIONS: Transarticular SIJ biopsies are obtainable and can be directed towards areas with MRI abnormalities. They can be used to confirm inflammatory changes histologically. With the biopsy needles used, severe bone marrow sclerosis may hinder penetration to the cartilage, but bone marrow specimens can be obtained.

Multicentric Reticulohistiocytosis Exhibiting Positive HLA-B*07 and HLA-B*08: A Case Report.

Multicentric reticulohistiocytosis (MRH) is a rare cause of destructive inflammatory arthritis involving both small, as well as larger joints. We report the case of a 40-year-old Caucasian female with a family history of neoplasia who was referred to our service witha two-month history of inflammatory joint pain. On examination, the patient had inflammatory arthritis, mainly involving the peripheral joints, sacroiliac joint pain, and numerous papulonodular mucocutaneous lesions, including periungual "coral beads". Imaging tests revealed erosive arthritis with synovitis and tenosynovitis, sacroiliac joint changes, as well as papulonodular mucosal lesions in the nasal vestibule, the oropharyngeal mucosa, and supraglottic larynx. She tested positive for HLA-B*07 (Human Leukocyte Antigen B*07) and HLA-B*08, ANA (antinuclear antibodies), RF (rheumatoid factor), anti-Ro52, anti-SSA/Ro, and anti-SSB/La antibodies. The skin biopsy was suggestive of MRH, showing a histiocyte infiltrate and frequent giant multinucleated cells. The patient exhibited favorable outcomes under Methotrexate, then Leflunomide. However, she displayed worsening clinical symptoms while under Azathioprine. To our knowledge, this is the first case of MRH to exhibit positive HLA-B*07 together with HLA-B*08. The rarity of MRH, its unknown etiology and polymorphic clinical presentation, as well as its potential neoplastic/paraneoplastic, and autoimmune nature demand extensive investigation.

Sacroiliac joints: anatomical variations on MR images.

OBJECTIVE: To describe the appearance of the anatomical variations of the sacroiliac joints (SIJ) on MR images and to highlight the potential MR features that might be misleading. METHODS: Consecutive MRI examinations of SIJs performed at our department from January 2015 to December 2016 were retrospectively analyzed. As one of our goals was to describe potential misleading edematous or structural changes associated with SIJ anatomical variations, patients fulfilling the ASAS criteria were excluded from this study to ensure that signal intensity changes would not be related to sacroiliitis. Five anatomical variations and a dysmorphic appearance of the SIJ were detected. RESULTS: The final group consisted of 157 patients. Unilateral or bilateral anatomical variations of the SIJ were found in 50 patients (accessory SIJ, iliosacral complex and sacral defect in 17, 18 and 21 patients, respectively, and synostosis in one patient). A dysmorphic appearance of the SIJ was found in 26 patients. No case of an unfused ossification centers was depicted. Structural and/or edematous changes of the facing bones were quite frequently observed in accessory and dysmorphic SIJ. Iliosacral complex and sacral defects could be associated with prominent vessels running along their bony surfaces. CONCLUSION: Several anatomical variations of the SIJs are relatively commonly seen on MR images, particularly in females. These variations may be associated with signal intensity changes, which may be mechanical and not necessarily inflammatory in nature. KEY POINTS: • Anatomical variations of SIJ may involve the cartilaginous or ligamentous part of the joint • Anatomical variations of SIJ are sometimes associated with edematous and/or structural changes of the adjacent bone • Anatomical variations of the SIJ can be misleading on MR imaging.

Postpartum Bone Marrow Edema at the Sacroiliac Joints May Mimic Sacroiliitis of Axial Spondyloarthritis on MRI.

OBJECTIVE: The objective of our study was to compare MRI findings in the sacroiliac joints of postpartum women (as a model of mechanical changes) and women with known axial spondyloarthritis (as an inflammatory model). SUBJECTS AND METHODS: For this prospective multicenter age-matched, case-control study, sacroiliac joint MRI examinations of 30 healthy women (mean age, 34.0 years) in the early postpartum period (mechanical group) and 30 age-matched women (mean age, 33.8 years) with known axial spondyloarthritis (retrospective inflammatory group) were compared. Blinded to clinical information, readers assessed MR images using the following scoring systems: Spondyloarthritis Research Consortium of Canada (SPARCC) MRI index, Berlin method, Assessment of Spondyloarthritis International Society (ASAS) criteria, and SPARCC MRI structural score. Descriptive statistics as percentages of the different findings (i.e., bone marrow edema [BME], erosion, fatty bone marrow replacement, backfill, ankylosis) and scores between groups and between delivery modes were compared. RESULTS: In the postpartum group, 63.3% (19/30) of women showed BME around the sacroiliac joints compared with 86.7% (26/30) of women in the spondyloarthritis group (based on ASAS criteria). Erosions were uncommon in the postpartum group (10.0% [3/30] postpartum vs 56.7% [17/30] spondyloarthritis). Fatty bone marrow replacement, backfill, and ankylosis were not seen in the postpartum group. In subjects with positive MRI findings for sacroiliitis based on ASAS criteria, the SPARCC MRI index (mean ± SD, 13.6 ± 14.5 vs 13.0 ± 10.7; p = 0.818) and Berlin method (4.5 ± 3.0 and 5.5 ± 3.5, p = 0.378) were not different between the postpartum and spondyloarthritis groups. Scores were not different between birth modalities. CONCLUSION: Pregnancy-induced BME at the sacroiliac joints, as a result of prolonged mechanical stress, was present in 63.3% of women who underwent MRI during the early postpartum period and may mimic sacroiliitis of axial spondyloarthritis.

Radiologic approach to axial spondyloarthritis: where are we now and where are we heading?

Current emphasis on diagnosing axial spondyloarthritis (axSpA) in early stage enforced the search for sensitive and specific diagnostic algorithms with the use of imaging methods. The aim of this review was to summarise current recommendations concerning the use of imaging techniques in diagnostics and monitoring of axSpA as well as to outline possible future directions of the development in this field. MEDLINE database was searched between March and April 2018. In the first phase, such keywords were applied: 'ASAS', 'EULAR', 'ASAS-EULAR', 'ASAS/OMERACT', 'axial spondyloarthritis', while in the second step: 'axial spondyloarthritis', 'ankylosing spondylitis', 'magnetic resonance imaging', 'computed tomography', and 'radiography', 'imaging'. An up-to-date summary of European League Against Rheumatism (EULAR) recommendations enriched with recent updates of Assessment of Spondyloarthritis International Society (ASAS) diagnostic criteria regarding imaging in axSpA course was created. Moreover, we outlined the role of new in this field, promising imaging techniques, such as diffusion-weighted imaging and dynamic contrast-enhanced sequences in magnetic resonance imaging (MRI) or low-dose computed tomography (CT). As precise monitoring of axSpA activity is vital, we reviewed the most precise methods: semiquantitative scores (e.g., Spondyloarthritis Research Consortium of Canada scores or CT Syndesmophyte Score) and quantitative analysis of MRI-based apparent diffusion coefficient or perfusion maps and enhancement curves. According to EULAR and ASAS recommendations, radiography and MRI still remain basic methods of axSpA diagnostics and monitoring. However, the knowledge of state-of-the-art international guidelines combined with the awareness of emerging imaging methods is the key to effective management of axSpA.

CT Abnormalities in the Sacroiliac Joints of Patients With Diffuse Idiopathic Skeletal Hyperostosis.

OBJECTIVE: The purpose of this study is to characterize sacroiliac joints (SIJs) findings at CT of patients with diffuse idiopathic skeletal hyperostosis (DISH), a condition characterized (using the Resnick classification criteria) by ossification of at least four contiguous vertebrae in the thoracic spine and preserved disk space, but without radiographic evidence of intraarticular SIJ abnormalities. MATERIALS AND METHODS: Pelvic CT examinations of 104 patients with DISH (fulfilling the Resnick criteria on spinal CT) and 106 age- and sex-matched control subjects whose entire spine lacked CT evidence of DISH (total, 149 men and 61 women; mean [± SD] age, 72.3 ± 8.7 years) were retrospectively evaluated for the presence of intra- and extraarticular bridging osteophytes, spurs, subchondral cystlike changes, erosions, and sclerosis of SIJs. Excluded were patients with known ankylosing spondylitis or inflammatory-related diseases. Data were analyzed using multivariate ANOVA to examine the degree of difference between patients with DISH and control subjects. Logistic regression analysis was used to generate odds ratios to examine their discriminatory ability. ROC analysis was then applied to examine the sensitivity and specificity of the results. RESULTS: The frequency of anterior bridging, posterior bridging, entheseal bridging, and joint ankylosis was significantly higher among patients with DISH compared with control subjects (48% vs 9%, 20% vs 1%, 34% vs 4%, and 23% vs 0%, respectively; p < 0.001 for all comparisons). CONCLUSION: Intraarticular ankylosis seen at CT, an entity not included in the Resnick classification criteria, is common among patients with DISH, which implies that the radiologic classification criteria for DISH need to be revised.

Prevalence and awareness of sacroiliac joint alterations on lumbar spine CT in low back pain patients younger than 40 years.

Background Computed tomography (CT) examinations of the lumbar spine are commonly performed in patients aged ≤40 years due to low back pain (LBP). Purpose To investigate the prevalence and awareness of radiologists for the presence of structural post-inflammatory/other sacroiliac joint (SIJ) alterations on lumbar spine CTs of young patients with LBP. Material and Methods A total of 484 lumbar spine CT examinations (272 men, 212 women; average age, 31 years; age range, 18-40 years) of patients with LBP in which the entire SIJs were visualized were retrospectively reviewed. SIJs were scored (consensus) by two senior radiologists (study reading) for the presence of post-inflammatory structural SIJ findings or other SIJs alterations. The original reports were compared to the study reading. Fifty CT examinations were re-evaluated for reliability assessment (intra-class correlation coefficient [ICC]). Results A total of 150 (31%) abnormal SIJ examinations were registered (ICC: r = 0.7-0.8; P < 0.0001): suspected sacroiliitis = 50 (10.2%); definite sacroiliitis = 16 (3.3%); osteitis-condensans-ilii = 38 (7.8%); diffuse idiopathic skeletal hyperostosis = 24 (5%); degenerative changes = 22 (4.5%); accessory SIJ = 22 (4.5%); and tumor = 1. The SIJs were referenced 39 times (8.0%) in the original readings: pathological findings (n = 15); and normal SIJ (n = 24). Total diagnostic accuracy for these reports only and for the entire readings were 49% and 69%, respectively, and 13% and 1.3%, respectively, for the pathological findings. Conclusion Sacroiliitis and other SIJ alterations are prevalent in young individuals with LBP, albeit, the majority of these alterations are not recognized nor reported by senior radiologists thus may delay efficacious treatment.

Morphologic characteristics of sacra associated with assimilation of the last lumbar vertebra.

BACKGROUND: The impact of lumbosacral transitional states on biomechanics of load transmission between the spine and the legs has been sporadically reported. The aims of the study were to identify morphostructural alterations of sacra associated with assimilation of the last lumbar vertebra and to analyse them in the light of their biomechanical impact. MATERIALS AND METHODS: Linear dimensions of sacrum, its body and base and articular surfaces were measured in 31 normal and 41 transitory sacra. Nineteen sacra presented articular and 22 osseous fusion of the last lumbar vertebra. Measured parameters were compared between normal sacra and the two variations of transitory sacra. RESULTS: Sacra with articular fusion of the last lumbar vertebra showed more pronounced concavity of the sacral curvature and wider than long sacral bodies. The first sacral segment was modified, broaden, ventrally wider and elevated. Almost the whole segment bore at its sides auricular surfaces. Very small portion of the segment was non-articular with less pronounced wedging. Sacra with osseous fusion of the last lumbar vertebra showed similar concavity of the sacral curvature as normal sacra, but longer than wide sacral bodies. The ventral sloping half of the newly formed first segment bore auricular surfaces. The non-articular part was enlarged with pronounced wedging. CONCLUSIONS: The term "sacralisation" includes both types of transitory sacra with mutually different morphostructural characteristics in contrast to the normal sacra. Analysis of these morphologic variations may help in understanding the different biomechanical properties and patterns of load transmission.

Local infliximab injection of sacroiliac joints in non-radiographic axial spondyloarthritis: Impact on clinical and magnetic resonance imaging parameters of disease activity.

OBJECTIVES: To evaluate the effectiveness of infliximab (IFX) injection into sacroiliac joints (SIJs) of non-radiographic axial spondyloarthritis (nr-axial SpA) and its impact on clinical and MRI parameters of disease activity. METHODS: Thirty-seven patients fulfilling the Association of Spondyloarthritis International Society (ASAS) criteria for axial SpA were initially studied, with disease duration not exceeding 1 year and failed to respond to non-steroidal anti-inflammatory drugs (NSAIDs). Only SpA having active sacroiliitis on MRI without spondylitis (number = 7) were selected to receive bilateral SIJ injection of 20 mg IFX. Follow-up MRI was done at 24 weeks post-injection. Patients were clinically evaluated before, and 12 and 24 weeks after SIJ injection. Evaluation included back pain and stiffness scores, and Bath Ankylosing Spondylitis (BAS) Disease indices and C-reactive protein (CRP) levels. ASAS response criteria were also assessed. RESULTS: Twelve and twenty-four weeks after injection, there was significant decrease in back pain, stiffness, and BAS Disease Activity and Global indices. BAS Functional index, CRP, and mean bone marrow edema score of SIJs were decreased without reaching statistical significance. All patients achieved ASAS20 and five (71.4%) achieved ASAS40. CONCLUSION: SIJ injection of IFX could be a therapeutic option in early nr-axial SpA who failed to respond to NSAIDs.

How to inject sacroiliac joints with ultrasound guidance: a pictorial essay.

Active sacroiliitis and sacroiliac joint dysfunction represent a common cause of low back pain in the population and are cause of patients' quality of life reduction and disability worldwide. The use of musculoskeletal ultrasound allows to easily identify the sacroiliac joints and to study every pathological condition affecting its most dorsal part; moreover, musculoskeletal ultrasound allows to guide highly effective injective procedures aimed at improving patients' symptoms and enhance their well-being. This paper aims to briefly explain for the musculoskeletal sonographer the anatomy and biomechanics of the sacroiliac joints, the correct ultrasound scanning method for their visualization and the most appropriate ultrasound guided injection technique to help dealing with the diagnostic and management of sacroiliac joint pain in the everyday scenario.

Coexistence of ankylosing spondylitis and Behçet's disease: Successful treatment with upadacitinib.

BACKGROUND: Ankylosing spondylitis (AS) and Behçet's disease (BD) are distinct inflammatory disorders, but their coexistence is a rare clinical entity. This case sheds light on managing this complex scenario with Janus kinase (JAK) inhibitors. CASE PRESENTATION: A 42-year-old woman presented with a decade-long history of lower back pain, nocturnal spinal discomfort, recurrent eye issues, oral and genital ulcers, hearing loss, pus formation in the left eye, and abdominal pain. Multidisciplinary consultations and diagnostic tests confirmed AS (HLA-B27 positivity and sacroiliitis) and BD (HLA-B51). Elevated acute-phase markers were observed. CONCLUSION: This case fulfills diagnostic criteria for both AS and BD, emphasizing their coexistence. Notably, treatment with upadacitinib exhibited promising efficacy, underscoring its potential as a therapeutic option in patients with contraindications for conventional treatments. Our findings illuminate the intricate management of patients presenting with these two diverse systemic conditions and advocate for further exploration of JAK inhibitors in similar cases.

MRI-based synthetic CT for assessment of the bony elements of the sacroiliac joints in children.

OBJECTIVES: The purpose of this study is to assess the equivalency of MRI-based synthetic CT (sCT) to conventional CT for sacroiliac joint bony morphology assessment in children. METHODS: A prospective study was performed. Children who had (PET-)CT-scan underwent additional MRI. sCT-CT image quality was analyzed by two readers subjectively overall, semi-quantitatively in terms of cortical delineation, joint facet defects, growth plate fusion, ossified nuclei, lumbosacral transitional anomaly, and bony bridges, and quantitatively for disc space height, spinal canal width, and sacral vertebrae width and height. Cohen's kappa and equivalence analyses with Bland-Altman plots were calculated for categorical and continuous measures respectively. RESULTS: Ten patients were included (6 boys; aged 9-16 years; mean age 14 years). Overall sCT image quality was rated good. Semi-quantitative assessment of cortical delineation of sacroiliac joints, bony bridges, and joint facet defects on the right iliac and sacral sides showed perfect agreement. Correlation was good to excellent (kappa 0.615-1) for the presence of lumbosacral transitional anomaly, fusion of sacral growth plates, joint facet defect, and presence of ossified nuclei. sCT-CT measurements were statistically equivalent and within the equivalence margins (-1-1 mm) for intervertebral disc space height and spinal canal width. Intra- and inter-reader reliability was excellent for quantitative assessment (0.806 < ICC < 0.998). For categorical scoring, kappa ranged from substantial to excellent (0.615-1). CONCLUSION: sCT appears to be visually equivalent to CT for the assessment of pediatric sacroiliac joints. sCT may aid in visualizing sacroiliac joints compared to conventional MRI, with the benefit that no ionizing radiation is used, especially important in children. CRITICAL RELEVANCE STATEMENT: MRI-based synthetic CT, a new technique that generates CT-like images without ionizing radiation, appears to be visually equivalent to CT for assessment of normal pediatric sacroiliac joints and can potentially assess structural damage as it clearly depicts bony cortex. KEY POINTS: • MRI-based sCT is a new image technique that can generate CT-like images. • We found that sCT performs similarly to CT in displaying bony structures of pediatric sacroiliac joints. • sCT has already been clinically validated in the sacroiliac joints in adults. • sCT can potentially assess structural damage from erosions or ankylosis as it clearly depicts bony cortex.

The sacroiliac joint across ages - what is normal?

The anatomy of the sacroiliac joint (SIJ) is complex with wide variations inter-individually as well as intra-individually (right versus left) and a frequent occurrence of anatomical variants. Besides, the joints are subject to strain, which may elicit non-inflammatory subchondral changes such as bone marrow edema (BME), sclerosis, and fat deposition simulating inflammatory SIJ changes. Furthermore, normal physiological changes during skeletal maturation can make interpretation of SIJ magnetic resonance imaging in children challenging. Knowledge about the wide range of normal findings is therefore important to avoid misinterpretation of findings as pathological. This review describes the current knowledge about normal SIJ findings across all ages.