[Rheumatoid arthritis-mimics : When appearances are deceptive]. / Rheumatoide Arthritis ­ Mimics : Wenn der Schein trügt.

Rheumatology represents a discipline full of differential diagnoses. Even for classical diseases, such as rheumatoid arthritis as the most frequent chronic inflammatory joint disease and described so clearly in many textbooks, it is not uncommon that it can be a diagnostic challenge in daily practice. This applies to arthritic joint involvement and also to frequently associated extra-articular manifestations. The patient history and results of the clinical examination are essential; however, laboratory and imaging findings often make a significant contribution to confirming the diagnosis, especially in early phases of the disease. This article, which makes no claims to completeness, focuses on diseases that in the opinion of the authors can imitate rheumatoid arthritis due to similar joint and other organ manifestations. These include metabolic, inflammatory infective and non-infective as well as tumorous diseases. A misinterpretation as rheumatoid arthritis as a rule leads to long-term and severe consequences for affected patients. Thus, the diagnosis of rheumatoid arthritis should be questioned and re-evaluated in cases of unusual accompanying symptoms, atypical course of disease and a lack of response to standard treatment approaches.

[Magnetic resonance imaging findings after shoulder surgery: What the radiologist needs to know]. / Besonderheiten der Magnetresonanztomographie nach operativer Schulterintervention.

Even primary diagnostic evaluation of the shoulder is a challenge for radiologists. Many imaging findings that definitely indicate abnormal findings in the untreated shoulder should be evaluated carefully in postoperative patients. Artifacts caused by implants or metal abrasion pose considerable problems in postoperative magnetic resonance imaging (MRI). Classic approaches to minimizing artifacts caused by foreign bodies include using turbo spin echo sequences, increasing bandwidth, and reducing voxel size. In recent years, several vendors have developed dedicated pulse sequences for reducing metal artifacts. Different postoperative imaging findings will be encountered, depending on the kind of surgery done. This review article describes typical postoperative MRI findings, focusing on subacromial decompression, reconstruction of the rotator cuff, labrum procedures, and biceps tenodesis.

[No exchange of information without technology : modern infrastructure in radiology]. / Kein Informationsaustausch ohne Technik : Moderne Infrastruktur einer Radiologie.

Modern radiology cannot accomplish the daily numbers of examinations without supportive technology. Even though technology seems to be becoming increasingly more indispensable, business continuity should be ensured at any time and if necessary even with a limited technical infrastructure by business continuity management. An efficient information security management system forms the basis. The early radiology information systems were islands of information processing. A modern radiology department must be able to be modularly integrated into an informational network of a bigger organization. The secondary use of stored data for clinical decision-making support poses new challenges for the integrity of the data or systems because medical knowledge is displayed and provided in a context of treatment. In terms of imaging the creation and distribution radiology services work in a fully digital manner which is often different for radiology reports. Legally secure electronic diagnostic reports require a complex technical infrastructure; therefore, diagnostic findings still need to be filed as a paper document. The internal exchange and an improved dose management can be simplified by systems which continuously and automatically record the doses and thus provide the possibility of permanent analysis and reporting. Communication between patient and radiologist will gain ongoing importance. Intelligent use of technology will convey this to the radiologist and it will facilitate the understanding of the information by the patient.

Magnetic resonance imaging of sacroiliitis in patients with spondyloarthritis: correlation with anatomy and histology.

Magnetic resonance imaging (MRI) of the sacroiliac joints (SIJs) has become established as a valuable modality for the early diagnosis of sacroiliitis in patients with inconclusive radiographic findings. Positive MRI findings have the same significance as a positive test for HLA-B27. Sacroiliitis is one of the key features of axial spondyloarthritis (SpA) in the classification proposed by the Assessments in Ankylosing Spondylitis (ASAS) group. Early signs of sacroiliitis include enthesitis of articular fibrocartilage, capsulitis, and osteitis. In more advanced disease, structural (chronic) lesions will be visible, including periarticular fatty deposition, erosions, subchondral sclerosis, and transarticular bone buds and bridges. In this article we describe magnetic resonance (MR) findings and provide histologic biopsy specimens of the respective disease stages. The predominant histologic feature of early and active sacroiliitis is the destruction of cartilage and bone by proliferations consisting of fibroblasts and fibrocytes, T-cells, and macrophages. Advanced sacroiliitis is characterized by new bone formation with enclosed cartilaginous islands and residual cellular infiltrations, which may ultimately lead to complete ankylosis. Knowledge of the morphologic appearance of the sacroiliac joints and their abnormal microscopic and gross anatomy is helpful in correctly interpreting MR findings.

[Imaging modalities in psoriatic arthritis]. / Bildgebende Verfahren bei Psoriasisarthritis.

This review presents an overview of the range of imaging modalities used in the diagnostic evaluation of patients with psoriatic arthritis (PsA). Conventional radiography is used to detect structural changes of the joints and tendon attachments. These changes occur late in the course of PsA hence conventional radiography contributes little to the early detection of PsA; however, the detection of periosteal proliferations on radiographs allows a relatively specific diagnosis of PsA. Skeletal scintigraphy and computed tomography are rarely used in PsA. Arthrosonography (ultrasound of the joints) is gaining increasing importance in the early identification of inflammatory soft tissue signs of PsA in the peripheral joints. Sonography enables early detection of synovitis and tenosynovitis as well as superficial erosions and also inflammatory processes of the tendon attachments. Magnetic resonance imaging (MRI) is indispensable for identifying possible involvement of the axial skeleton. Moreover, it allows good visualization of periostitis and arthritis. High resolution microcomputed tomography is an interesting novel diagnostic tool which allows highly sensitive evaluation of the bone structure and can detect very tiny bone lesions where typical signs of PsA are omega-shaped erosions and small corona-like spikes. Another interesting new diagnostic technique is fluorescence optical imaging (FOI) with the Xiralite system which is highly sensitive for detecting inflammatory processes of the hands.

[Imaging in rheumatic diseases. Rheumatoid arthritis and differential diagnostics]. / Bildgebung rheumatischer Erkrankungen. Rheumatoide Arthritis und Differenzialdiagnosen.

Differential diagnostics of arthritides is challenging even for experienced radiologists. Nevertheless, there are simple signs that can give important clues to make a diagnosis. Close cooperation with the attending clinicians is essential to get the most from imaging studies and to provide relevant information for patient management and therapy.

Quantification of periarticular demineralization and synovialitis of the hand in rheumatoid arthritis patients.

UNLABELLED: The bone mineral density (BMD) measurement of the hand in rheumatoid arthritis (RA) patients is no standard measurement method as yet. The aim was to contribute to the standardization of the hand BMD measurement, especially of periarticular regions. As results, we found best precision values for the wrist and a significant correlation between hand and spine/femur BMD depending on disease activity and disease duration. INTRODUCTION: This study was conducted to investigate (i) the precision of periarticular hand BMD measuring, (ii) the periarticular demineralization of the hand, (iii) the correlation between periarticular hand BMD and spine/femur BMD, and (iv) the correlation of hand BMD to hand synovitis. METHODS: A number of 52 RA patients were examined by BMD measurement of the femoral neck, spine, whole hand, metacarpophalangeal (MCP) joints II-V, personal identity profile (PIP) joints II-V, and wrist using dual-energy X-ray absorptiometry (DXA). Synovitis of the hand was examined by ultrasonography and magnetic resonance imaging (MRI). Three subgroups were further analyzed: early RA, established RA with moderate and with high disease activity. Early RA and established RA patients with high disease activity were Followed up after 12 months. RESULTS: We found (1) best precision of BMD measurement for the wrist, (2) BMD in RA significantly reduced if compared to normal controls, (3) a highly significant positive correlation between hand and spine/femur BMD and the power of correlation to depend on disease activity and disease duration (high correlation in RA with moderate disease activity and early RA, very high correlation in RA with high disease activity), (4) a negative correlation between hand BMD and hand synovitis in RA with high disease activity, and (5) a significant reduction of synovitis but no change in hand BMD after 12 months, respectively. CONCLUSIONS: This study shows a highly significant correlation between hand BMD and spine/femur BMD in RA patients depending on disease activity and disease duration. We conclude to measure BMD at different sites including hands in order to quantify bone loss in RA patients most properly.

Contrast-enhanced ultrasonography is more sensitive than grayscale and power Doppler ultrasonography compared to MRI in therapy monitoring of rheumatoid arthritis patients.

PURPOSE: To evaluate wrist and finger joints in patients with rheumatoid arthritis (RA) by grayscale, power Doppler (PD) and contrast-enhanced musculoskeletal ultrasonography (US) and to compare these findings with MRI, clinical (DAS28) and laboratory (ESR; CRP) data. MATERIALS AND METHODS: US was performed at baseline (t0) and after three, six and twelve (t12) months before and after a change of medical treatment. MRI was carried out at t0 and t12 and used as the reference method. Contrast-enhanced US was used to assess one clinically most affected joint region. Different semiquantitative synovitis scores were calculated by grayscale and PD US. RESULTS: Contrast-enhanced US results evaluated by enhancement, slope and semi-quantitative assessment significantly correlated to each other, to grayscale US, CRP, as well as to MRI with the highest correlation coefficients for the used contrast-enhanced US modes (r = 0.56, r = 0.55, r = 0.57; each p < 0.05). Sum scores evaluated by grayscale US showed that synovial inflammation in finger joints was detected significantly more frequently in the palmar aspect than on the dorsal side (p = 0.001). Using power Doppler US, the wrists were significantly more inflamed from dorsal than on the palmar side (p = 0.0004). Significant longitudinal correlations between grayscale and power Doppler US scores were detected. CONCLUSION: Grayscale, power Doppler and contrast-enhanced US are accurate tools for the detection and follow-up of synovitis in RA wrist and finger joints, with contrast-enhanced US being most sensitive compared to MRI. All imaging methods reflected a good response to TNFα blocking therapy.

Defining active sacroiliitis on magnetic resonance imaging (MRI) for classification of axial spondyloarthritis: a consensual approach by the ASAS/OMERACT MRI group.

BACKGROUND: Magnetic resonance imaging (MRI) of sacroiliac joints has evolved as the most relevant imaging modality for diagnosis and classification of early axial spondyloarthritis (SpA) including early ankylosing spondylitis. OBJECTIVES: To identify and describe MRI findings in sacroiliitis and to reach consensus on which MRI findings are essential for the definition of sacroiliitis. METHODS: Ten doctors (two radiologists and eight rheumatologists) from the ASAS/OMERACT MRI working group reviewed and discussed in three workshops MR images depicting sacroiliitis associated with SpA and other conditions which may mimic SpA. Descriptions of the pathological findings and technical requirements for the appropriate acquisition were formulated. In a consensual approach MRI findings considered to be essential for sacroiliitis were defined. RESULTS: Active inflammatory lesions such as bone marrow oedema (BMO)/osteitis, synovitis, enthesitis and capsulitis associated with SpA can be detected by MRI. Among these, the clear presence of BMO/osteitis was considered essential for defining active sacroiliitis. Structural damage lesions such as sclerosis, erosions, fat deposition and ankylosis can also be detected by MRI. At present, however, the exact place of structural damage lesions for diagnosis and classification is less clear, particularly if these findings are minor. The ASAS group formally approved these proposals by voting at the annual assembly. CONCLUSIONS: For the first time, MRI findings relevant for sacroiliitis have been defined by consensus by a group of rheumatologists and radiologists. These definitions should help in applying correctly the imaging feature "active sacroiliitis by MRI" in the new ASAS classification criteria for axial SpA.

[Vasculopathy in Sjögren's syndrome]. / Vaskulopathien bei Sjögren-Syndrom.

Sjögren's syndrome is a systemic autoimmune disease with a predominant involvement of exocrine glands leading to sicca symptoms. Extraglandular involvement occurs in about 40% of patients with skin, musculoskeletal, neurological and organ manifestations. Systemic vasculitic manifestations of Sjögren's syndrome can be assumed in approximately 5%-10% of patients. Leukocytoclastic or cryoglobulinemic vasculitis represent classic vasculitic manifestations of Sjögren's syndrome. In the pathogenesis of vasculitis, B-cell-driven autoimmune processes play a major role by producing autoantibodies against the Ro/SS-A and La/SS-B antigens and cryoglobulins. In patients with Sjögren's syndrome, manifestation of vasculitis, non-Hodgkin's lymphoma and glomerulonephritis, as well as positive cryoglobulins and decreased levels of complement factors, are considered negative prognostic markers. Various immunosuppressive strategies, usually in co-medication with glucocorticoids, are used for the treatment of vasculitis in Sjögren's syndrome. For refractory and severe manifestations, a B-cell-targeted therapy with Rituximab should be also considered.

[Peripartum changes of the pelvic ring: usefulness of magnetic resonance imaging]. / Peripartale Veränderungen des Beckenringes: Wie sinnvoll ist die Magnetresonanztomografie?

PURPOSE: Postpartum pelvic pain beyond the normal level poses a problem to obstetricians. Beyond normal physiologic loosening of the pubic symphysis and sacroiliac joints (SIJs) during pregnancy, symphyseal separation and rupture must be excluded. The aim of this prospective study was to determine whether magnetic resonance imaging (MRI) allows for reliable differentiation of normal postpartum findings and pathologic lesions. MATERIAL AND METHODS: The study included a total of 77 women (mean age 30), among them 21 healthy subjects (group A), 21 asymptomatic postpartum women (group B), and 35 patients with postpartum pelvic pain (group C). The analyzed parameters comprised symphyseal and iliosacral tenderness, subjective pain assessed on a visual analog scale, and data pertaining to obstetric history. All 77 women underwent 1.5T MRI of the pelvic ring using oblique angulated coronal T 1-weighted and STIR sequences for imaging of the symphysis and SIJs in one slice package. Analysis of the MR images comprised signal intensities of pelvic bone marrow, width of the symphyseal cleft, and the symphyseal capsule. RESULTS: Subjects in group A in general had a normal bone marrow signal. The STIR sequence showed increased signal intensity of the pubic bone near the symphysis in 16 women (76 %) of group B and 31 patients of group C (86 %) (not significant). An increased periarticular bone marrow signal of the SIJs on the STIR images was seen in 13 women (62 %) of group B and 23 patients (63 %) of group C. The mean width of the symphyseal cleft differed significantly among the three groups (3.4 mm vs. 5.4 mm vs. 6.7 mm). A width >10 mm was observed in only 4 cases (11 %). Moreover, associated findings such as interpubic hematoma (n=23) or tears of the symphyseal capsule (n=7) were detected in patients of group C. CONCLUSION: The wide overlap of findings between symptomatic and asymptomatic postpartum patients does not allow reliable differentiation by MRI of normal and abnormal findings. MRI contributes to the differentiation of symphyseal contusion and rupture and provides information on severe associated changes.

Low-field MRI for assessing synovitis in patients with rheumatoid arthritis. Impact of Gd-DTPA dose on synovitis scoring.

OBJECTIVE: To investigate the impact of a double dose compared to a single dose of contrast material in low-field magnetic resonance imaging (MRI) on semi-quantitative scoring of synovitis in patients with rheumatoid arthritis (RA). METHODS: This prospective study included 38 RA patients (23 women and 15 men, mean age 51 years). All patients underwent low-field MRI of the hand before administration of contrast medium, after intravenous injection of 0.1 mmol/kg gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA), and after another dose of 0.1 mmol/kg Gd-DTPA. Two readers (A and B) blinded to dosage independently scored the single dose and double dose image sets for synovitis according to outcome measures in rheumatology (OMERACT) recommendations. Contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) were also calculated for each set. RESULTS: 149 metacarpophalangeal (MCP) joints were evaluated. There was good inter-reader agreement for each of the two sets (intra-class correlation coefficient of 0.75 for the single dose set and 0.83 for the double dose). Median CNR and SNR values were 5.4 and 15.9, respectively, for the single dose set and 8.5 and 16.6, respectively, for the double dose set (p<0.0001). Single dose set mean synovitis scores were 1.7 and 1.6 for readers A and B, respectively. Double dose set scores were 1.9 and 2.0, respectively. Thus, higher synovitis scores were recorded for the double dose sets than the single dose sets (p<0.005). CONCLUSION: In low-field MRI, when evaluating RA, the dose of the contrast material influences synovitis scoring. Therefore, dosage of contrast material should be taken into consideration when using extremity dedicated low-field MRI.

[Imaging of enthesitis: a new field for the radiologist?]. / Bildgebung der Enthesitis: Ein neues Feld für den Radiologen?

Entheses are sites where tendons, ligaments, joint capsules, or fasciae attach to bone. Their function is to provide a mechanism for reducing stress at the bony interface by dissipating the biomechanical load acting on the bone. Enthesitis may occur in traumatic, endocrinologic, metabolic, degenerative, or inflammatory conditions and is a major symptom in patients with seronegative spondyloarthritis (SpA). The increasing interest in inflammation of the entheses associated with rheumatoid diseases has fundamentally changed our understanding of the clinical presentation, pathogenesis, and therapy of enthesitis. Conventional radiographs and computed tomography (CT) allow good evaluation of chronic changes of the entheses, such as soft-tissue calcification, erosions, and new bone formation. The method of first choice to evaluate acute enthesitis is magnetic resonance imaging (MRI), which depicts both soft-tissue changes and intraosseous abnormalities. The purpose of this overview is to discuss the MRI appearance of enthesitis in patients with SpA and to provide a morphologic survey of the predominantly affected entheses.

[Magnetic resonance imaging of the hand in rheumatoid arthritis. New scientific insights and practical application]. / Magnetresonanztomographie der Hand bei rheumatoider Arthritis. Wissenschaftliche Ergebnisse und praktische Anwendung.

Magnetic resonance imaging (MRI) is a sensitive diagnostic modality for the detection of inflammatory changes in peripheral joints. Nevertheless, the widespread clinical use of MRI in assessing patients with early rheumatoid arthritis is still hampered by the technical complexity and higher cost of MRI compared with conventional radiography. This overview summarizes the results of recent research and gives practical tips on how to perform MRI of the hands. The authors present an MR protocol for hand imaging, discuss the pros and cons of low-field MR scanners, and outline pitfalls and artifacts. The MRI changes associated with rheumatoid arthritis such as synovitis, tenosynovitis, erosions, and bone marrow edema are described including their prognostic significance. The proven facts on the validation and grading of MR changes in rheumatoid arthritis are summarized. Finally, the role of MRI in the differential diagnosis of arthritis is critically discussed.

Prospective 7 year follow up imaging study comparing radiography, ultrasonography, and magnetic resonance imaging in rheumatoid arthritis finger joints.

OBJECTIVE: To perform a prospective long term follow up study comparing conventional radiography (CR), ultrasonography (US), and magnetic resonance imaging (MRI) in the detection of bone erosions and synovitis in rheumatoid arthritis (RA) finger joints. METHODS: The metacarpophalangeal and proximal interphalangeal joints II-V (128 joints) of the clinically dominant hand of 16 patients with RA were included. Follow up joint by joint comparisons for erosions and synovitis were made. RESULTS: At baseline, CR detected erosions in 5/128 (4%) of all joints, US in 12/128 (9%), and MRI in 34/128 (27%). Seven years later, an increase of joints with erosions was found with CR (26%), US (49%) (p<0.001 each), and MRI (32%, NS). In contrast, joint swelling and tenderness assessed by clinical examination were decreased at follow up (p = 0.2, p<0.001). A significant reduction in synovitis with US and MRI (p<0.001 each) was seen. In CR, 12 patients did not have any erosions at baseline, while in 10/12 patients erosions were detected in 25/96 (26%) joints after 7 years. US initially detected erosions in 9 joints, of which two of these joints with erosions were seen by CR at follow up. MRI initially found 34 erosions, of which 14 (41%) were then detected by CR. CONCLUSION: After 7 years, an increase of bone erosions was detected by all imaging modalities. In contrast, clinical improvement and regression of synovitis were seen only with US and MRI. More than one third of erosions previously detected by MRI were seen by CR 7 years later.

Very early spondyloarthritis: where the inflammation in the sacroiliac joints starts.

Involvement of the sacroiliac joints (SIJ) is a major and characteristic feature of the spondyloarthritides (SpA). In early ankylosing spondylitis and undifferentiated SpA (uSpA) sacroiliitis is the most common early clinical finding and the presumed first manifestation of the disease. Magnetic resonance imaging has proved useful for visualising inflammation in the SIJ in adults and children. Recently, initial localisation of the inflammation in the SIJ has been described in some detail, but it has not been completely defined to date--either in imaging or in histopathological studies. This is mainly owing to the lack of data in very early disease and the lack of follow up studies. Here we present a patient with early disease, which may augment our understanding of this stage of SpA.

Assessment of acute spinal inflammation in patients with ankylosing spondylitis by magnetic resonance imaging: a comparison between contrast enhanced T1 and short tau inversion recovery (STIR) sequences.

OBJECTIVES: To compare the performance of two different MRI sequences-T(1) weighted, fat saturated, spin echo after application of contrast medium, and short tau inversion recovery (STIR) sequences-to detect spinal inflammation in patients with ankylosing spondylitis (AS). METHODS: Both MRI sequences were performed in 38 patients with active AS and compared using the MRI activity scoring system, ASspiMRI-a. One vertebral unit (VU) was defined as the region between two virtual lines drawn through the middle of each vertebral body. RESULTS: Intraclass correlation coefficients were excellent-0.91 and 0.86 for the Gd-DTPA and STIR sequences, respectively. The overall correlation of the single MRI scores for both sequences was also good (r = 0.84, p = 0.01). The intrarater variance was 6.71 and 9.41 and the interrater variance was 13.16 and 19.04 for the Gd-DTPA and STIR sequences, respectively. The smallest detectable distance was 4.7 and 5.6 for the Gd-DTPA and STIR sequences, respectively. The concordance rate for both sequences was 83.5% (range 80.5-87.7% in the three spinal segments). Inflammatory spinal lesions were found in 10.1% of the VUs in the STIR sequence but not in the T(1)/Gd-DTPA sequence, while the T(1)/Gd-DTPA sequence showed inflammatory lesions in 6.4% of the VUs that were found normal by STIR. CONCLUSIONS: Both MRI techniques can evaluate active spinal lesions in patients with AS. More spinal lesions are detected by the STIR sequence, but the reliability between readings and readers is better for the Gd-DTPA sequence. The ASspiMRI-a is a reliable instrument for evaluating acute spinal changes in AS.

Interobserver reliability of rheumatologists performing musculoskeletal ultrasonography: results from a EULAR "Train the trainers" course.

OBJECTIVE: To evaluate the interobserver reliability among 14 experts in musculoskeletal ultrasonography (US) and to determine the overall agreement about the US results compared with magnetic resonance imaging (MRI), which served as the imaging "gold standard". METHODS: The clinically dominant joint regions (shoulder, knee, ankle/toe, wrist/finger) of four patients with inflammatory rheumatic diseases were ultrasonographically examined by 14 experts. US results were compared with MRI. Overall agreements, sensitivities, specificities, and interobserver reliabilities were assessed. RESULTS: Taking an agreement in US examination of 10 out of 14 experts into account, the overall kappa for all examined joints was 0.76. Calculations for each joint region showed high kappa values for the knee (1), moderate values for the shoulder (0.76) and hand/finger (0.59), and low agreement for ankle/toe joints (0.28). kappa Values for bone lesions, bursitis, and tendon tears were high (kappa = 1). Relatively good agreement for most US findings, compared with MRI, was found for the shoulder (overall agreement 81%, sensitivity 76%, specificity 89%) and knee joint (overall agreement 88%, sensitivity 91%, specificity 88%). Sensitivities were lower for wrist/finger (overall agreement 73%, sensitivity 66%, specificity 88%) and ankle/toe joints (overall agreement 82%, sensitivity 61%, specificity 92%). CONCLUSION: Interobserver reliabilities, sensitivities, and specificities in comparison with MRI were moderate to good. Further standardisation of US scanning techniques and definitions of different pathological US lesions are necessary to increase the interobserver agreement in musculoskeletal US.

First clinical evaluation of sagittal laser optical tomography for detection of synovitis in arthritic finger joints.

OBJECTIVE: To identify classifiers in images obtained with sagittal laser optical tomography (SLOT) that can be used to distinguish between joints affected and not affected by synovitis. METHODS: 78 SLOT images of proximal interphalangeal joints II-IV from 13 patients with rheumatoid arthritis were compared with ultrasound (US) images and clinical examination (CE). SLOT images showing the spatial distribution of scattering and absorption coefficients within the joint cavity were generated. The means and standard errors for seven different classifiers (operator score and six quantitative measurements) were determined from SLOT images using CE and US as diagnostic references. For classifiers showing significant differences between affected and non-affected joints, sensitivities and specificities for various cut off parameters were obtained by receiver operating characteristic (ROC) analysis. RESULTS: For five classifiers used to characterise SLOT images the mean between affected and unaffected joints was statistically significant using US as diagnostic reference, but statistically significant for only one classifier with CE as reference. In general, high absorption and scattering coefficients in and around the joint cavity are indicative of synovitis. ROC analysis showed that the minimal absorption classifier yields the largest area under the curve (0.777; sensitivity and specificity 0.705 each) with US as diagnostic reference. CONCLUSION: Classifiers in SLOT images have been identified that show statistically significant differences between joints with and without synovitis. It is possible to classify a joint as inflamed with SLOT, without the need for a reference measurement. Furthermore, SLOT based diagnosis of synovitis agrees better with US diagnosis than CE.