Interobserver Agreement and Performance of Concurrent AI Assistance for Radiographic Evaluation of Knee Osteoarthritis.

Background Due to conflicting findings in the literature, there are concerns about a lack of objectivity in grading knee osteoarthritis (KOA) on radiographs. Purpose To examine how artificial intelligence (AI) assistance affects the performance and interobserver agreement of radiologists and orthopedists of various experience levels when evaluating KOA on radiographs according to the established Kellgren-Lawrence (KL) grading system. Materials and Methods In this retrospective observer performance study, consecutive standing knee radiographs from patients with suspected KOA were collected from three participating European centers between April 2019 and May 2022. Each center recruited four readers across radiology and orthopedic surgery at in-training and board-certified experience levels. KL grading (KL-0 = no KOA, KL-4 = severe KOA) on the frontal view was assessed by readers with and without assistance from a commercial AI tool. The majority vote of three musculoskeletal radiology consultants established the reference standard. The ordinal receiver operating characteristic method was used to estimate grading performance. Light kappa was used to estimate interrater agreement, and bootstrapped t statistics were used to compare groups. Results Seventy-five studies were included from each center, totaling 225 studies (mean patient age, 55 years ± 15 [SD]; 113 female patients). The KL grades were KL-0, 24.0% (n = 54); KL-1, 28.0% (n = 63); KL-2, 21.8% (n = 49); KL-3, 18.7% (n = 42); and KL-4, 7.6% (n = 17). Eleven readers completed their readings. Three of the six junior readers showed higher KL grading performance with versus without AI assistance (area under the receiver operating characteristic curve, 0.81 ± 0.017 [SEM] vs 0.88 ± 0.011 [P < .001]; 0.76 ± 0.018 vs 0.86 ± 0.013 [P < .001]; and 0.89 ± 0.011 vs 0.91 ± 0.009 [P = .008]). Interobserver agreement for KL grading among all readers was higher with versus without AI assistance (κ = 0.77 ± 0.018 [SEM] vs 0.85 ± 0.013; P < .001). Board-certified radiologists achieved almost perfect agreement for KL grading when assisted by AI (κ = 0.90 ± 0.01), which was higher than that achieved by the reference readers independently (κ = 0.84 ± 0.017; P = .01). Conclusion AI assistance increased junior readers' radiographic KOA grading performance and increased interobserver agreement for osteoarthritis grading across all readers and experience levels. Published under a CC BY 4.0 license. Supplemental material is available for this article.

Effect of Secukinumab Versus Adalimumab Biosimilar on Radiographic Progression in Patients With Radiographic Axial Spondyloarthritis: Results From a Head-to-Head Randomized Phase IIIb Study.

OBJECTIVE: Spinal radiographic progression is an important outcome in radiographic axial spondyloarthritis (SpA). The objective of the phase IIIb SURPASS study was to compare spinal radiographic progression in patients with radiographic axial SpA treated with secukinumab (interleukin-17A inhibitor) versus adalimumab biosimilar (Sandoz adalimumab [SDZ-ADL]; tumor necrosis factor inhibitor). METHODS: Biologic-naive patients with active radiographic axial SpA, at high risk of radiographic progression (high-sensitivity C-reactive protein [hsCRP] ≥5 mg/L and/or ≥1 syndesmophyte[s] on spinal radiographs), were randomized (1:1:1) to secukinumab (150/300 mg) or SDZ-ADL (40 mg). The proportion of patients with no radiographic progression (change from baseline [CFB] in modified Stoke Ankylosing Spondylitis Spinal Score [mSASSS] ≤0.5) on secukinumab versus SDZ-ADL at week 104 (primary endpoint), mean CFB-mSASSS, proportion of patients with ≥1 syndesmophyte(s) at baseline with no new syndesmophyte(s), and safety were evaluated. RESULTS: Overall, 859 patients (78.5% male, mSASSS 16.6, Bath Ankylosing Spondylitis Disease Activity Index 7.1, hsCRP 20.4 mg/L, and 73.0% with ≥1 syndesmophyte[s]) received secukinumab 150 mg (n = 287), secukinumab 300 mg (n = 286), or SDZ-ADL (n = 286). At week 104, the proportion of patients with no radiographic progression was 66.1%, 66.9%, and 65.6% (P = not significant, both secukinumab doses) and mean CFB-mSASSS was 0.54, 0.55, and 0.72 in secukinumab 150 mg, secukinumab 300 mg, and SDZ-ADL arms, respectively. Overall, 56.9%, 53.8%, and 53.3% of patients on secukinumab 150 mg, secukinumab 300 mg, and SDZ-ADL, respectively, with ≥1 syndesmophyte(s) at baseline did not develop new syndesmophyte(s) by week 104. There were no unexpected safety findings. CONCLUSION: Spinal radiographic progression over two years was low with no significant difference between secukinumab and SDZ-ADL arms. The safety of both treatments was consistent with previous reports.

Characterization of bone marrow lesions in axial spondyloarthritis using quantitative T1 mapping MRI.

OBJECTIVE: Conventional magnetic resonance imaging (MRI) uses T1-weighted and short-tau inversion recovery (STIR) sequences to characterize bone marrow in axial spondyloarthritis. However, quantification is restricted to estimating the extent of lesions because signal intensities are highly variable both within individuals and across patients and MRI scanners. This study evaluates the performance of quantitative T1 mapping for distinguishing different types of bone marrow lesions of the sacroiliac joints. MATERIALS AND METHODS: In this prospective study, 62 patients underwent computed tomography (CT) and MRI of the sacroiliac joints including T1, STIR, and T1 mapping. Bone marrow lesions were characterized by three readers and assigned to one of four groups: sclerosis, osteitis, fat lesions, and mixed marrow lesions. Relaxation times on T1 maps were compared using generalized estimating equations and receiver operating characteristics (ROC) analysis. RESULTS: A total of 119 lesions were selected (sclerosis: 38, osteitis: 27, fat lesions: 40; mixed lesions: 14). T1 maps showed highly significant differences between the lesions with the lowest values for sclerosis (1516±220 ms), followed by osteitis (1909±75 ms), and fat lesions (2391±200 ms); p<0.001. T1 mapping differentiated lesions with areas under the ROC curve of 99% (sclerosis vs. osteitis) and 100% (other comparisons). CONCLUSION: T1 mapping allows accurate characterization of sclerosis, osteitis, and fat lesions at the sacroiliac joint but only for homogeneous, non-mixed lesions. Thus, further sequence development is needed before implementation in clinical routine.

[Computed tomography versus magnetic resonance imaging : Pros and cons in axial spondyloarthritis]. / Computertomographie versus Magnetresonanztomographie : Pro und Kontra in der axialen Spondyloarthritis.

The diagnosis of axial spondyloarthritis depends on direct visualization of the sacroiliitis in addition to clinical assessment and determination of the histocompatibility antigen HLA-B27. While the value of conventional radiographic images has meanwhile been described in many studies as insufficient to diagnose the disease at an early stage, magnetic resonance imaging and also computed tomography now offer the possibility to visualize findings, such as bone marrow edema, erosion, fat metaplasia, backfill and ankylosis. Thus, it is necessary to decide which procedure should be used and when. Furthermore, both cross-sectional imaging techniques are currently undergoing major changes, and technical advancements are making great strides every year. This article provides an overview of which future technologies will be included in the rheumatological diagnostics of the sacroiliac joints. This overview also illustrates which standard methods are established in the diagnostics of axial spondyloarthritis and how they are used.

Sex-specific diagnostic efficacy of MRI in axial spondyloarthritis: challenging the 'One Size Fits All' notion.

OBJECTIVES: Sex-specific differences in the presentation of axial spondyloarthritis (axSpA) may contribute to a diagnostic delay in women. The aim of this study was to investigate the diagnostic performance of MRI findings comparing men and women. METHODS: Patients with back pain from six different prospective cohorts (n=1194) were screened for inclusion in this post hoc analysis. Two blinded readers scored the MRI data sets independently for the presence of ankylosis, erosion, sclerosis, fat metaplasia and bone marrow oedema. Χ2 tests were performed to compare lesion frequencies. Contingency tables were used to calculate markers for diagnostic performance, with clinical diagnosis as the standard of reference. The positive and negative likelihood ratios (LR+/LR-) were used to calculate the diagnostic OR (DOR) to assess the diagnostic performance. RESULTS: After application of exclusion criteria, 526 patients (379 axSpA (136 women and 243 men) and 147 controls with chronic low back pain) were included. No major sex-specific differences in the diagnostic performance were shown for bone marrow oedema (DOR m: 3.0; f: 3.9). Fat metaplasia showed a better diagnostic performance in men (DOR 37.9) than in women (DOR 5.0). Lower specificity was seen in women for erosions (77% vs 87%), sclerosis (44% vs 66%), fat metaplasia (87% vs 96%). CONCLUSION: The diagnostic performance of structural MRI markers is substantially lower in female patients with axSpA; active inflammatory lesions show comparable performance in both sexes, while still overall inferior to structural markers. This leads to a comparably higher risk of false positive findings in women.

New bone formation at the sacroiliac joint in axial spondyloarthritis: characterization of backfill in MRI and CT.

OBJECTIVE: MRI findings of the SI joint space in axial SpA (axSpA) include inflammation and fat metaplasia inside an erosion; the latter is also termed 'backfill'. We compared such lesions with CT to better characterize whether they represent new bone formation. METHODS: We identified patients with axSpA who underwent both CT and MRI of the SI joints in two prospective studies. MRI datasets were jointly screened by three readers for joint space-related findings and grouped into three categories: type A-high short tau inversion recovery (STIR) and low T1 signal; type B-high signal in both sequences; type C-low STIR and high T1 signal. Image fusion was used to identify MRI lesions in CT before we measured Hounsfield units (HU) in each lesion and surrounding cartilage and bone. RESULTS: Ninety-seven patients with axSpA were identified and we included 48 type A, 88 type B, and 84 type C lesions (maximum 1 lesion per type and joint). The HU values were 73.6 (s.d. 15.0) for cartilage, 188.0 (s.d. 69.9) for spongious bone, 1086.0 (s.d. 100.3) for cortical bone, 341.2 (s.d. 96.7) for type A, 359.3 (s.d. 153.5) for type B and 446.8 (s.d. 123.0) for type C lesions. Lesion HU values were significantly higher than those for cartilage and spongious bone, but lower than those for cortical bone (P < 0.001). Type A and B lesions showed similar HU values (P = 0.93), whereas type C lesions were denser (P < 0.001). CONCLUSION: All joint space lesions show increased density and might contain calcified matrix, suggesting new bone formation, with a gradual increase in the proportion of calcified matrix towards type C lesions (backfill).

Anatomical variation of the sacroiliac joint carries an increased risk for erosion and bone marrow oedema in axial spondyloarthritis.

OBJECTIVES: To assess the impact of joint shape variations on inflammatory lesions on SI joint MRIs in patients with axial spondyloarthritis (axSpA). METHODS: A total of 1194 patients from four different prospective cohorts were evaluated, with 684 (57.3%) having sufficient imaging data for inclusion (379 axSpA, 305 controls). All images were evaluated for joint form, erosion, sclerosis, fat metaplasia and bone marrow oedema (BMO) by two independent readers. Logistic regression analyses were used to assess the association of joint form and lesions on imaging for axSpA patients and controls. RESULTS: Atypical joint forms were common in both axSpA (43.5% [154/354]) and control patients (44.2% [134/303]); both intra-articular variants and a crescent joint shape were significantly more common in axSpA patients (18.4% vs 11.6% and 11.0% vs 5.3.%, respectively; P < 0.001). The axSpA patients with intra-articular joint form variants had 2-fold higher odds of exhibiting erosions [odds ratio (OR) 2.09 (95% CI 1.18, 3.69)] and BMO [OR 1.79 (95% CI 1.13, 2.82)]; this association was not observed in controls. Accessory joints increased the odds for sclerosis in axSpA patients [OR 2.54 (95% CI 1.10, 5.84)] and for sclerosis [OR 17.91 (95% CI 6.92, 46.37)] and BMO [OR 2.05 (95% CI 1.03, 4.07)] in controls. CONCLUSIONS: Joint form variations are associated with the presence of inflammatory lesions on SI joint MRIs of axSpA patients. This should be taken into consideration in future research on the interplay of mechanical strain and inflammation in axSpA.

A noninvasive method to quantify the impairment of spinal motion ability in Parkinson's disease.

PURPOSE: There is a high demand on spinal surgery in patients with Parkinson's disease (PD) but the results are sobering. Although detailed clinical and radiological diagnostics were carried out with great effort and expense, the biodynamic properties of the spine of PD patients have never been considered. We propose a noninvasive method to quantify the impairment of motion abilities in patients with PD. METHODS: We present an analytical cross-sectional study of 21 patients with severe PD. All patients underwent a biodynamic assessment during a standardized movement-choreography. Thus, individual spinal motion profiles of each patient were objectively assessed and compared with a large comparative cohort of individuals without PD. Moreover, clinical scores to quantify motor function and lumbar back pain were collected and X-ray scans of the spine in standing position were taken and analysed. RESULTS: Biodynamic measurement showed that 36.9% of the assessed motions of all PD patients were severely impaired. Men were generally more functionally impaired than women, in 52% of all motion parameters. The neurological and radiological diagnostics recorded pathological values, of which UPDRS-III ON correlated with findings of the biodynamics assessment (R = 0.52, p = 0.02). CONCLUSIONS: The decision to operate on a PD patient's spine is far-reaching and requires careful consideration. Neurological and radiological scores did not correlate with the biodynamics of the spine. The resulting motion profile could be used as individual predictive factor to estimate whether patients are eligible for spinal surgery or alternative therapies.

Clinical utility of postprocessed low-dose radiographs in skeletal imaging.

OBJECTIVES: Radiography remains the mainstay of diagnostic and follow-up imaging. In view of the risks and the increasing use of ionizing radiation, dose reduction is a key issue for research and development. The introduction of digital radiography and the associated access to image postprocessing have opened up new opportunities to minimize the radiation dosage. These advances are contingent upon quality controls to ensure adequate image detail and maintenance of diagnostic confidence. The purpose of this study was to investigate the clinical applicability of postprocessed low-dose images in skeletal radiography. METHODS: In our study setting, the median radiation dose for full dose X-rays was 9.61 dGy*cm2 for pelvis, 1.20 dGy*cm2 for shoulder and 18.64 dGy*cm2 for lumbar spine exams. Based on these values, we obtained 200 radiographs for each anatomic region in four consecutive steps, gradually reducing the dose to 84%, 71%, 60% and 50% of the baseline using an automatic exposure control (AEC). 549 patients were enrolled for a total of 600 images. All X-rays were postprocessed with a spatial noise reduction algorithm. Two radiologists assessed the diagnostic value of the radiographs by rating the visualization of anatomical landmarks and image elements on a five-point Likert scale. A mean-sum score was calculated by averaging the two reader's total scores. Given the non-parametric distribution, we used the Mann-Whitney U test to evaluate the scores. RESULTS: Median dosage at full dose accounted for 38.4%, 48 and 53.2% of the German reference dose area product for shoulder, pelvis and lumbar spine, respectively. The applied radiation was incrementally reduced to 21.5%, 18.4% and 18.7% of the respective reference value for shoulder, pelvis and lumbar spine. Throughout the study, we observed an estimable tendency of superior quality at higher dosage in overall image quality. Statistically significant differences in image quality were restricted to the 50% dose groups in shoulder and lumbar spine images. Regardless of the applied dosage, 598 out of 600 images were of sufficient diagnostic value. CONCLUSION: In digital radiography image postprocessing allows for extensive reduction of radiation dosage. Despite a trend of superior image detail at higher dose levels, overall quality and, more importantly, diagnostic utility of low-dose images was not significantly affected. Therefore, our results not only confirm the clinical utility of postprocessed low-dose radiographs, but also suggest a widespread deployment of this advanced technology to ensure further dose limitations in clinical practice. ADVANCES IN KNOWLEDGE: The diagnostic image quality of postprocessed skeletal radiographs is not significantly impaired even after extensive dose reduction by up to 20% of the reference value.

Anatomical Joint Form Variation in Sacroiliac Joint Disease: Current Concepts and New Perspectives.

PURPOSE OF REVIEW: The aim of this article is to further the understanding of anatomical variation of the sacroiliac joint (SIJ) within the rheumatological community and point out promising fields of research in the interplay of SIJ anatomy and joint disease. RECENT FINDINGS: Mechanical strain has long been implicated in onset and progression of axial spondyloarthritis (axSpA). Recent investigations found changes in the pattern of degenerative lesions of the SIJ in the normal population in patients with atypical joint forms. Furthermore, atypical SIJ forms are more prevalent in patients with axial spondyloarthritis and mechanical SIJ disease. Mechanical stress from anatomical joint form variation may have an impact on development and progression of axSpA. Furthermore, mechanically induced bone marrow edema may act as an axSpA mimic on MRI and needs to be more accurately classified.

Axial Involvement in Psoriatic Arthritis cohort (AXIS): the protocol of a joint project of the Assessment of SpondyloArthritis international Society (ASAS) and the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA).

BACKGROUND: Involvement of the axial skeleton (sacroiliac joints and spine) is a relatively frequent manifestation associated with psoriatic skin disease, mostly along with involvement of peripheral musculoskeletal structures (peripheral arthritis, enthesitis, dactylitis), which are referred to as psoriatic arthritis (PsA). Data suggest that up to 30% of patients with psoriasis have PsA. Depending on the definition used, the prevalence of axial involvement varies from 25% to 70% of patients with PsA. However, there are currently no widely accepted criteria for axial involvement in PsA.Objective: The overarching aim of the Axial Involvement in Psoriatic Arthritis (AXIS) study is to systematically evaluate clinical and imaging manifestations indicative of axial involvement in patients with PsA and to develop classification criteria and a unified nomenclature for axial involvement in PsA that would allow defining a homogeneous subgroup of patients for research. DESIGN: Prospective, multicenter, multinational, cross-sectional study. METHODS AND ANALYSES: In this multicenter, multinational, cross-sectional study, eligible patients [adult patients diagnosed with PsA and fulfilling Classification Criteria for Psoriatic Arthritis (CASPAR) with musculoskeletal symptom duration of ⩽10 years not treated with biological or targeted synthetic disease-modifying anti-rheumatic drugs] will be recruited prospectively. They will undergo study-related clinical and imaging examinations. Imaging will include radiography and magnetic resonance imaging examinations of sacroiliac joints and spine. Local investigators will evaluate for the presence of axial involvement based on clinical and imaging information which will represent the primary outcome of the study. In addition, imaging will undergo evaluation by central review. Finally, the central clinical committee will determine the presence of axial involvement based on all available information. ETHICS: The study will be performed according to the ethical principles of the Declaration of Helsinki and International Council for Harmonisation Good Clinical Practice guidelines. The study protocol will be approved by the individual Independent Ethics Committee / Institutional Review Board of participating centers. Written informed consent will be obtained from all included patients.Registration: ClinicalTrials.gov ID: NCT04434885.

Computed Tomography Thermography for Ablation Zone Prediction in Microwave Ablation and Cryoablation: Advantages and Challenges in an Ex Vivo Porcine Liver Model.

PURPOSE: The aim of this study was to investigate the diagnostic accuracy of computed tomography (CT) for the prediction of ablation zones from microwave ablation (MWA) and cryoablation (CA) in an ex vivo porcine liver model. METHODS: Sequential (30 seconds) CT scans were acquired during and after MWA and CA in an ex vivo porcine liver model. We generated 120-kVp equivalent reconstructions of generic dual-energy CT data sets, and comprehensive region-of-interest measurements were statistically correlated with invasive temperature monitoring using Pearson correlation coefficient. Binary logistic regression was performed for prediction of successful ablation. RESULTS: With the use of pooled data from 6 lesions in 2 separate experiments, correlation analysis of attenuation in Hounsfield units (HU) and temperature yielded r = -0.79 [confidence interval (CI), -0.85 to -0.71] for MWA and r = 0.62 (CI, 0.55 to 0.67) for CA.For MWA, there was a linear association between attenuation and temperature up to 75°C; thus, linear regression yielded a slope of -2.00 HU/°C (95% CI, -1.58 to -2.41). For CA, a linear association between attenuation and temperature was observed in the cooling phase with a slope of 2.11 HU/°C (95% CI, 1.79 to 2.58). In MWA treatment, binary logistic regression separated less than 70°C and greater than 70°C with 89.2% accuracy. Within the ice ball, temperatures above and below -20°C were distinguished with 65.3% accuracy. CONCLUSIONS: Our experiments reveal several difficulties in predicting ablation zone temperature from CT attenuation. Microwave ablation leads to gas production in the tissue, which degrades the accuracy of noninvasive temperature measurement, especially at higher temperatures. In CA, CT thermometry is limited by ice ball formation, which leads to homogeneous attenuation, nearly independent of temperature. Further research is needed to define the role of CT thermography in ablation zone monitoring in liver malignancies.

Spinal mobility in the cervical and lumbar spine correlates with magnetic resonance imaging findings for inflammatory and structural changes in patients with active ankylosing spondylitis.

OBJECTIVES: We aimed to assess relationships between single Bath Ankylosing Spondylitis Metrology Index (BASMI) components and corresponding spinal segment magnetic resonance images (MRI) in anti-tumour-necrosis-factor-treated AS patients. METHODS: Using available MRI and BASMI data from the GO-RAISE trial (n=91 patients), MRI scores for active inflammatory (ASspiMRI-a) and chronic structural (ASspiMRI-c) changes in cervical and lumbar spine segments were compared with BASMI cervical (cervical-rotation [CR] angle, tragus-to-wall [TTW] distance) and lumbar (lumbar flexion [LF], lateral-lumbar-flexion [LLF]) spine component scores (linear definition). Generalised linear models were employed to assess relationships between BASMI components and ASspiMRI-a/ASspiMRI-c measurements at baseline and for week-14 (golimumab/placebo groups) and week-104 (all golimumab-treated) change scores. RESULTS: Baseline lumbar ASspiMRI-a scores correlated with LF and LLF (ß=0.231 and 0.238, respectively; both p<0.01), while this was less prominent for ASspiMRI-c scores and LLF (ß=0.142, p=0.04). A significant but weak correlation was found between changes from baseline to week 104 in cervical spine ASspiMRI-c score and TTW distance among all treated patients (ß=0.161, p=0.003). CONCLUSIONS: Detailed assessments indicated baseline spinal mobility impairment in patients with active AS correlated weakly with MRI-detected lumbar spinal inflammation; correlations with chronic, structural damage/changes were very weak. Improved, less variable MRI and spinal metrology assessments are needed for future clinical research.

MRI lesions in the sacroiliac joints of patients with spondyloarthritis: an update of definitions and validation by the ASAS MRI working group.

OBJECTIVES: The Assessment of SpondyloArthritis international Society (ASAS) MRI working group (WG) was convened to generate a consensus update on standardised definitions for MRI lesions in the sacroiliac joint (SIJ) of patients with spondyloarthritis (SpA), and to conduct preliminary validation. METHODS: The literature pertaining to these MRI lesion definitions was discussed at three meetings of the group. 25 investigators (20 rheumatologists, 5 radiologists) determined which definitions should be retained or required revision, and which required a new definition. Lesion definitions were assessed in a multi-reader validation exercise using 278 MRI scans from the ASAS classification cohort by global assessment (lesion present/absent) and detailed scoring (inflammation and structural). Reliability of detection of lesions was analysed using kappa statistics and the intraclass correlation coefficient (ICC). RESULTS: No revisions were made to the current ASAS definition of a positive SIJ MRI or definitions for subchondral inflammation and sclerosis. The following definitions were revised: capsulitis, enthesitis, fat lesion and erosion. New definitions were developed for joint space enhancement, joint space fluid, fat metaplasia in an erosion cavity, ankylosis and bone bud. The most frequently detected structural lesion, erosion, was detected almost as reliably as subchondral inflammation (κappa/ICC:0.61/0.54 and 0.60/0.83) . Fat metaplasia in an erosion cavity and ankylosis were also reliably detected despite their low frequency (κappa/ICC:0.50/0.37 and 0.58/0.97). CONCLUSION: The ASAS-MRI WG concluded that several definitions required revision and some new definitions were necessary. Multi-reader validation demonstrated substantial reliability for the most frequently detected lesions and comparable reliability between active and structural lesions.

Magnetic resonance imaging features of craniofacial fibrous dysplasia.

PURPOSE: To assess the value of magnetic resonance imaging (MRI) in detecting craniofacial fibrous dysplasia (CFD) and diagnosing and differentiating it from intraosseous meningioma. Additionally, the MRI appearance of the typical computed tomography (CT) imaging feature, the ground glass phenomenon, was evaluated. MATERIAL AND METHODS: MRI datasets of 32 patients with CFD were analysed retrospectively. Detectability in MRI was assessed by analysis of 10 randomly selected patients with CFD and 10 normal controls by two blinded readers. Changes of affected bone, internal lesion structure, T1 and T2 signal intensity, and contrast enhancement of the lesion in general and ground glass areas in particular were assessed. Ten patients with intraosseous meningioma (one in each) served as differential diagnosis for CFD. RESULTS: All 10 CFD lesions were reliably detected in MRI. In 32 patients 36 CFD lesions were evaluated. In 66.7% CFD were iso- to hypointense in T1 and hyperintense in T2; this proportion was similar for ground glass areas (65.7%). Ground glass areas were more homogeneously structured than the whole CFD lesion in both T1 (100% vs. 56%, respectively) and T2 (91% vs. 61%, respectively). Contrast enhancement was found in 97% of complete CFD lesions and 93% of ground glass areas. The accuracy for CFD vs. intraosseous meningioma was 100% for 'no soft-tissue component' and 98% for 'bone broadening' in MRI. CONCLUSIONS: Distinct morphological changes of CFD are reliably detected in MRI and allow differentiation from intraosseous meningioma. Areas with ground glass phenomenon in CT show a predominantly homogenous internal structure in MRI with contrast enhancement.

Low-dose computed tomography as diagnostic tool in calcium pyrophosphate deposition disease arthropathy: focus on ligamentous calcifications of the wrist.

OBJECTIVES: To identify specific morphologic features of calcium pyrophosphate deposition disease (pseudogout, CPPD) manifestations of the wrist as detected using low-dose CT-scans. METHODS: In this retrospective study 46 patients with arthritis of the wrist were included. All patients underwent a low dose CT scan of both wrists on a 320-row detector in volume scan mode. Individual radiation exposure was recorded for all patients. Two blinded raters independently evaluated osteoarthritis, cysts, erosions, calcifications (cartilage and ligaments separately) and carpal misalignment in 33 specified locations. An expert rheumatologist classified the patients as CPPD positive or negative. Fisher's exact test was applied to identify differences between both groups. Receiver operating characteristics (ROC) analyses with calculations of area under the curve (AUC) were carried out for both in the literature established and newly identified imaging findings for each rater individually. RESULTS: Twenty-seven patients were classified as CPPD, 19 patients as other diagnoses. Ligamentous calcifications were significantly more prevalent in the CPPD group (p<0.05). All non-ligamentous findings revealed no difference in frequency. AUC analysis for established findings (0.675; 0.619 - rater 1; 2) vs. ligamentous calcifications (0.786 both raters) showed a markedly higher diagnostic accuracy for the latter. Effective radiation exposure was determined to be 0.019-0.095 mSv per patient. CONCLUSIONS: Calcifications of carpal ligaments are highly specific morphologic features of CPPD arthropathy. Low-dose CT is a useful tool to detect these calcifications at a radiation exposure similar to a standard radiograph.

Added value of biomarkers compared with clinical parameters for the prediction of radiographic spinal progression in axial spondyloarthritis.

OBJECTIVES: The objective of this study was to examine whether adding biomarkers to routine clinical parameters improves prediction of radiographic spinal progression in axial spondyloarthritis. METHODS: One hundred and seventeen patients with ankylosing spondylitis who completed the Effects of NSAIDs on RAdiographic Damage in Ankylosing Spondylitis (ENRADAS) trial were included. Radiographic spinal progression was defined as worsening of the modified Stoke Ankylosing Spondylitis Spine Score by ⩾2 points after 2 years. A clinical prediction model was constructed out of baseline syndesmophytes, elevated CRP, cigarette smoking and male sex. The following serum biomarkers were measured at baseline by ELISA: MMP3, VEGF, calprotectin, leptin, high molecular weight adiponectin, osteoprotegerin, sclerostin, N-terminal telopeptide, procollagen type II N-terminal propeptide and serum amyloid A. RESULTS: Repeated cross-validation analyses revealed one biomarker combination with potential added predictive value in addition to the clinical model: leptin + high molecular weight adiponectin + VEGF. This biomarker combination showed an area under the curve (AUC)Biomarkers = 0.731 (95% CI: 0.614, 0.848), which was numerically superior to the clinical model [AUCClinical = 0.665 (95% CI: 0.553, 0.776)]. A combination of clinical parameters + biomarkers showed an improved predictive value compared with the clinical model reflected by AUCClinical+Biomarkers = 0.768 (95% CI: 0.666, 0.871), though not statistically significant (P = 0.051). However, by considering the part of the receiver operating characteristic curve with a specificity ⩾75% resulting in partial AUC (pAUC), the improvement becomes significant (pAUCClinical+Biomarkers = 0.119; pAUCClinical = 0.053; P = 0.01). CONCLUSION: Biomarkers show potential to improve the prediction of radiographic spinal progression in axial spondyloarthritis when used in addition to the clinical parameters, though the added value seems to be rather small.

Progression of Structural Damage in the Sacroiliac Joints in Patients With Early Axial Spondyloarthritis During Long-Term Anti-Tumor Necrosis Factor Treatment: Six-Year Results of Continuous Treatment With Etanercept.

OBJECTIVE: To evaluate radiographic progression in the sacroiliac (SI) joints and to identify its predictors during long-term treatment (up to 6 years) with the tumor necrosis factor (TNF) inhibitor etanercept in patients with early axial spondyloarthritis (SpA). METHODS: Patients with early axial SpA who were treated with etanercept for up to 6 years in the Etanercept versus Sulfasalazine in Early Axial Spondyloarthritis (ESTHER) trial were selected based on the availability of radiographs of the SI joints. Two readers who were blinded with regard to clinical data scored the radiographs according to the modified New York criteria (range 0-4 per SI joint). A sacroiliitis sum score (total range 0-8) was calculated as the mean of the scores of the 2 readers. Active and chronic inflammatory changes in the SI joints on magnetic resonance imaging (MRI) performed at baseline, year 2, and year 4 were assessed according to the Berlin MRI scoring system. RESULTS: Of the 76 patients originally included in the study, 42 had radiographs of the SI joints available at baseline and at least 1 follow-up time point (year 2, 4, or 6). The mean ± SD change in the sacroiliitis sum score was 0.13 ± 0.73, -0.27 ± 0.76, and -0.09 ± 0.68, in the time intervals baseline to year 2, year 2 to year 4, and year 4 to year 6, respectively. In the longitudinal mixed model analysis, elevated C-reactive protein level (ß = 0.58 [95% confidence interval 0.24, 0.91]) and MRI SI joint osteitis score (ß = 0.06 [95% confidence interval 0.03, 0.10]) were independently associated with progression of the sacroiliitis sum score. CONCLUSION: Our findings indicate that long-term anti-TNF therapy decelerates the progression of structural damage in the SI joints. Elevated CRP level and presence of osteitis on MRI were independently associated with radiographic sacroiliitis progression.

Single-source dual-energy computed tomography for the assessment of bone marrow oedema in vertebral compression fractures: a prospective diagnostic accuracy study.

OBJECTIVES: To evaluate the diagnostic accuracy of single-source dual-energy computed tomography (DECT) for the detection of bone marrow oedema (BME) in patients with vertebral compression fractures. METHODS: Patients over 50 years of age with radiographically suspected vertebral compression fracture of the thoracic or lumbar spine were prospectively enrolled. All patients underwent DECT with sequential acquisition of 80 and 135 kVp datasets on a 320-row detector CT scanner and 1.5-Tesla magnetic resonance imaging (MRI) including T1-weighted and short-tau inversion recovery (STIR) sequences. Virtual non-calcium (VNCa) images were reconstructed using a three-material decomposition algorithm. Vertebrae with height loss in CT were scored for the presence of BME in both MRI and DECT and used to determine signal- and contrast-to-noise ratios (SNR and CNR). Contingency analysis using MRI as standard of reference and Fleiss's kappa were calculated. IRB approval was obtained. RESULTS: In total 192 vertebral compression fractures in 70 patients (23 men, 47 women; mean age 70.7 years (SD 9.8)) were included in our analysis. DECT showed a reader-dependent sensitivity of 72% and specificity of 70% for BME. Fleiss's kappa was .40 for DECT and .58 for MRI. T1-weighted images had significantly better SNR and CNR compared to STIR, CT, and VNCa (p < .0001); however, there was no difference between STIR and VNCa. CONCLUSIONS: VNCa images depict BME with adequate sensitivity and specificity and can be acquired on a single-source system. Image quality is adequate but trained readers are needed for image interpretation. KEY POINTS: • Dual-energy CT in a single-source technique can help to detect bone marrow oedema in patients with vertebral compression fractures. • However, given the inferior inter-rater reliability and limited specificity compared to MRI, experienced readers are needed for image interpretation. • Dual-energy CT of the spine has limited sensitivity for the detection of bone marrow oedema in vertebra with previous surgical intervention.

Imaging to Differentiate the Various Forms of Seronegative Arthritis.

Spondyloarthritis (SpA) is a group of diseases characterized by back pain, spinal inflammation, human leukocyte antigen-B27 positivity, and peripheral findings such as dactylitis, enthesitis, and uveitis. It includes ankylosing spondylitis, psoriatic arthritis, reactive arthritis, arthritis associated with inflammatory bowel disease, and undifferentiated SpA. The role of imaging in the diagnosis, management, and follow-up of patients with SpA has become dramatically more important with the introduction of new therapies such as tumor necrosis factor-α inhibitors. Although in many instances differentiating between the SpA entities is straightforward based on the clinical presentation, often such differentiation remains challenging, and categorization of an individual patient into a subset of SpA can be difficult. Imaging, mainly radiography and magnetic resonance imaging, serves as an important diagnostic tool. Diseases in the spondyloarthritis complex share common presentation but at the same time may have distinct radiographic phenotypes. We present these common and distinct imaging manifestations that may potentially help distinguish between the entities in the diagnostic work-up.