Established rheumatoid arthritis – new imaging modalities

Causal relationship between rheumatoid arthritis and carpal tunnel syndrome: a bidirectional two-sample Mendelian randomization study

BACKGROUND

Although there is considerable evidence of a robust correlation between rheumatoid arthritis (RA) and carpal tunnel syndrome (CTS) in previous research, the causal link between the two remains a topic of controversy.

METHODS

We conducted a two-sample Mendelian randomization (MR) study to explore the causal impact of RA on CTS. We obtained aggregate data from genome-wide association studies (GWAS) of CTS (ebi database and GEO database) and RA (FinnGen database). This study employed five MR analysis methods, with a focus on the inverse variance-weighted (IVW) method. Sensitivity analyses were conducted to ensure the robustness of the results of this study. Additionally, we performed reverse MR analysis.

RESULTS

We selected 84 and 78 single nucleotide polymorphisms (SNPs) significantly associated with RA from two databases as instrumental variables (IVs), respectively. Our results showed that RA patients have a higher risk of getting CTS regardless of whether the ebi database (IVW, OR = 1.045, 95% CI: 1.016-1.075, P = 0.002) or the GEO database (IVW, OR = 1.001, 95% CI: 1.001-1.002, P = 0.001) is selected for CTS data. However, the MR analysis showed no causal link between CTS and the increased risk of RA (ebi: IVW, OR = 1.084, 95% CI: 0.918-1.279, P = 0.341; GEO: IVW, OR = 1.968, 95% CI: 0.011-360.791, P = 0.799).

CONCLUSION

The analysis revealed that RA can increase the risk of CTS, but did not support the causal relationship that CTS can increase the risk of RA.

Comparison of High-Resolution Ultrasonography With Magnetic Resonance Imaging in Rheumatoid Arthritis

Objective:

The aim of this study was to examine whether high-resolution ultrasonography (HRUS) can provide information, on signs of inflammation and destruction, due to rheumatoid arthritis (RA). The focus was on the wrist joint, during early and late disease and compared the findings to those with magnetic resonance imaging (MRI).

Materials and Methods:

The study was based on 31 RA patients, with joint involvements, who were selected from those attending the outpatient rheumatology clinic. The patients completed both HRUS and MRI examinations, and their results were compared.

Results:

The HRUS and MRI images had near-perfect agreement, for detecting joint anomalies, in those RA patients. While comparing the overall performance of the HRUS and MRI studies, it was observed that HRUS was equal or nearly equal, demonstrating 90.83%, 100.0% and 94.93%, diagnostic sensitivity, specificity, and accuracy, respectively, for diagnosing RA pathologies.

Conclusion:

The early diagnosis of RA with HRUS and MRI examinations is very important, in the early treatment of RA. The HRUS examinations demonstrated a sensitive and reliable diagnostic method for assessing inflammatory activity and destructive changes in the joints of these RA patients, with HRUS findings comparable to those of MRI.

Diagnostic Value of Ultrasound for Detecting Carpal Tunnel Syndrome in Patients With Rheumatoid Arthritis: A Three-Arm Cross-Sectional Study

Objective:

This study was conducted to assess the diagnostic value of sonography in detecting carpal tunnel syndrome (CTS) in patients with rheumatoid arthritis (RA) and to compare the results with a normal control group.

Materials and Methods:

In this three-arm cross-sectional study, the sonographically measured median nerve cross-sectional area (MNCSA) was compared in three groups: RA patients with CTS, RA patients without CTS, and normal subjects (no RA, no CTS). A nerve conduction study (NCS) was performed for all enrolled participants, across the three study arms.

Results:

In this study, 38 RA patients (17 in CTS group and 21 in no CTS group) and 19 healthy subjects were recruited. The MNCSAs were 11.86 (±1.87) mm2 in RA patients with CTS, 10.16 (±1.71) mm2 in RA patients without CTS, and 9.42 (±1.46) mm² in healthy control patients. The accuracy of sonography in detecting CTS was 0.79 (95% confidence interval, 0.67–0.91), with a sensitivity and specificity of 88% and 57%, respectively. The MNCSA in CTS group was significantly higher than the control group ( P = .02).

Conclusion:

In this cohort, the sonographic measurement of MNCSA was an accurate and sensitive method for the diagnosis of CTS, especially in its early stages. In addition, in this cohort, RA without CTS did not increase the MNCSA.

Cy3-tilmanocept labeling of macrophages in joints of mice with antibody-induced arthritis and synovium of human patients with rheumatoid arthritis

γ-Tilmanocept (^99m Tc-tilmanocept) is a receptor-directed, radiolabeled tracer that is FDA-approved for guiding sentinel lymph node biopsy. Tilmanocept binds the C-type lectin mannose receptor (MR, CD206) on macrophages. In this study, nonradioactive, fluorescently-labeled Cy3-tilmanocept was used to detect CD206⁺ mononuclear cells in the cartilage of mice with antibody-induced arthritis and in the synovial fluid and tissue of human subjects with rheumatoid arthritis (RA) for comparison with osteoarthritis (OA), and healthy volunteer (HV) controls. Murine arthritis was induced by injection of monoclonal anti-cartilage antibody followed by injection of Escherichia coli lipopolysaccharide. Post-arthritis development (7-11 days), the mice were injected intravenously with Cy3-tilmanocept followed by in vivo and ex vivo epifluorescence imaging. Two-photon imaging, immunofluorescence, and immunohistochemistry were used to identify articular and synovial macrophages (CD206, F4/80, and Cy3-tilmanocept binding) in murine tissues. Cy3-tilmanocept epifluorescence was present in arthritic knees and elbows of murine tissues; no radiographic changes were noted in the skeletons. However, inflammatory arthritic changes were apparent by histopathology and immunohistochemistry (F4/80), immunofluorescence (CD206) and Cy3-tilmanocept binding. In human RA synovial fluid, Cy3-tilmanocept staining correlated with CD206⁺ /CD16⁺ cells; negligible labeling was observed in OA samples. Cy3-tilmanocept colocalized with CD206 and staining was significantly higher in RA synovial tissue compared to OA or HV. Our results demonstrate that imaging with Cy3-tilmanocept can detect in vivo inflammatory, CD206⁺ macrophages in an early arthritis animal model and in human RA patients. These data establish a novel tool for preclinical research of early arthritis and have implications for early RA detection and monitoring of therapeutic efficacy in humans.

Changes in clinical disease activity are weakly linked to changes in MRI inflammation on treat-to-target escalation of therapy in rheumatoid arthritis

Background

Rheumatoid arthritis (RA) treat-to-target (T2T) regimens often use the disease activity score (28 joints) incorporating C-reactive protein (DAS28_CRP) as an outcome measure. We compared changes in the DAS28_CRP with changes in magnetic resonance imaging (MRI) inflammation on treatment escalation.

Methods

Eighty seropositive RA patients with active disease were enrolled. Group A (N = 57) escalated to another conventional disease-modifying therapy (cDMARD) combination, and Group B (N = 23) to anti-TNF therapy/cDMARDs. Contrast-enhanced 3T-MRI wrist scans were obtained before and 4 months after regimen change. Scan pairs were scored for inflammation (MRI(i)) and damage. Disease activity was assessed using the DAS28_CRP.

Results

Eighty patients were enrolled and 66 MRI scan pairs were available for analysis. Intra-reader reliability was high: intraclass correlation coefficient (average) 0.89 (0.56–0.97). ΔDAS28_CRP did not differ between groups: Group A, −0.94 (−3.30, 1.61); Group B, −1.53 (−3.59, 0.56) (p = 0.45). ΔMRI(i) also did not differ: Group A, 0 (−25, 10); Group B, −1 (−15, 28) (p = 0.12). Combining groups, ΔMRI(i) correlated weakly with ΔDAS28_CRP (Spearman’s 0.36, p = 0.003). Using multiple linear regression analysis adjusting for confounders, ΔDAS28_CRP was associated with ΔMRI(i) (p = 0.056). Of the individual MRI measures, only Δtenosynovitis correlated with ΔDAS28_CRP (Spearman’s 0.33, p = 0.007). ΔMRI(i) was negatively associated with the MRI erosion score at entry (p = 0.0052).

Conclusions

We report the first study investigating the link between changes in clinical and imaging inflammation in a real-world RA cohort escalating to conventional and biologic DMARDs. The association was significant but relatively weak, suggesting that MRI targets cannot yet be advocated as outcomes for T2T escalation.

Trial registration

ANZCTR 12614000895684. Registered 22 August 2014.

Potential of PET-MRI for imaging of non-oncologic musculoskeletal disease

Early detection of musculoskeletal disease leads to improved therapies and patient outcomes, and would benefit greatly from imaging at the cellular and molecular level. As it becomes clear that assessment of multiple tissues and functional processes are often necessary to study the complex pathogenesis of musculoskeletal disorders, the role of multi-modality molecular imaging becomes increasingly important. New positron emission tomography-magnetic resonance imaging (PET-MRI) systems offer to combine high-resolution MRI with simultaneous molecular information from PET to study the multifaceted processes involved in numerous musculoskeletal disorders. In this article, we aim to outline the potential clinical utility of hybrid PET-MRI to these non-oncologic musculoskeletal diseases. We summarize current applications of PET molecular imaging in osteoarthritis (OA), rheumatoid arthritis (RA), metabolic bone diseases and neuropathic peripheral pain. Advanced MRI approaches that reveal biochemical and functional information offer complementary assessment in soft tissues. Additionally, we discuss technical considerations for hybrid PET-MR imaging including MR attenuation correction, workflow, radiation dose, and quantification.

Pilot study on 18 F-FDG PET/CT for detection of inflammatory changes in blood-induced knee arthropathy in a rabbit model

RATIONALE

¹⁸ F-FDG-PET/CT has a potential role in the early detection of haemophilic arthritis, at a time when treatment may still avoid further joint degeneration. The purposes of this pilot study were to determine the ability of ¹⁸ F-FDG-PET/CT to detect inflammatory changes associated with blood-induced arthropathy in knees of a rabbit model.

METHODS

Ten juvenile rabbits were imaged at baseline and weeks 5 and 17 post intraarticular autologous blood injections (ABI). Five rabbits in group 1 (G1) had ABI into the same knee joint every 2 weeks (total, eight injections). Five rabbits in group 2 (G2) had only two injections into the same knee, at weeks 5 and 17. Images were assessed visually and semi-quantitatively by measuring maximal standardized uptake values (SUVmax) and standardized uptake ratio (SUR = SUVmax in affected knee/SUVmax in non-affected knee).

RESULTS

More rabbits in G1 than G2 presented with positive chronic inflammatory synovial scores at week 17. Mean iron staining scores in injected knees were greater for G1 than for G2 (P = 0.049). No increased uptake was identified in the injected knees in any of the rabbits at baseline or at week 5. At week 17, all G1 rabbits demonstrated increased uptake in their affected knees with higher mean SUVmax (1.5) than normal knees (1.0) (P < 0.02). None of the G2 rabbits showed asymmetric increased uptake. The SUR of G1 was higher at week 17 compared to baseline (P < 0.01) and week 5 (P < 0.01). The SUR at week 17 was higher for G1 than for G2 (1.13) rabbits (P < 0.01).

CONCLUSION

¹⁸ F-FDG-PET is able to detect the inflammatory changes associated with haemophilic arthropathy in this experimental model.

(18)F-FDG and (18)F-NaF PET/CT demonstrate coupling of inflammation and accelerated bone turnover in rheumatoid arthritis

OBJECTIVE

To compare the findings in rheumatoid arthritis (RA)-affected joints between (18)F-fluorodeoxyglucose (FDG) and (18)F-fluoride (NaF) positron emission tomography (PET)/computed tomography (CT).

METHODS

We enrolled twelve RA patients who started a new biologic agent (naïve 9 and switch 3). At entry, both hands were examined by (18)F-FDG PET/CT, (18)F-NaF PET/CT, and X-ray. Intensity of PET signals was determined by standardized uptake value max (SUVmax) in metacarpophalangeal (MCP), proximal interphalangeal (PIP), and ulnar, medial, and radial regions of the wrists. Hand X-rays were evaluated according to the Genant-modified Sharp score at baseline and 6 months.

RESULTS

Both (18)F-FDG and (18)F-NaF accumulated in RA-affected joints. The SUVmax of (18)F-FDG correlated with that of (18)F-NaF in individual joints (r = 0.65), though detail distribution was different between two tracers. (18)F-NaF and (18)F-FDG signals were mainly located in the bone and the surrounding soft tissues, respectively. The sum of SUVmax of (18)F-NaF correlated with disease activity score in 28 joint (DAS28), modified health assessment questionnaire (MHAQ), and radiographic progression. (18)F-FDG and (18)F-NaF signals were associated with the presence of erosions, particularly progressive ones.

CONCLUSION

Our data show that both (18)F-FDG and (18)F-NaF PET signals were associated with RA-affected joints, especially those with ongoing erosive changes.

Evaluation of tocilizumab therapy in patients with rheumatoid arthritis based on FDG-PET/CT

Background

Positron emission tomography (PET) with 2-[18F]-fluoro-2-deoxy-D-glucose (¹⁸F-FDG) can detect the presence of synovitis in rheumatoid arthritis (RA) patients. The aim of this study was to investigate whether the findings of FDG-PET matched the conventional assessments of the disease activity score (DAS) 28, DAS28-CRP, simplified disease activity index (SDAI) and clinical disease activity index (CDAI) in RA patients receiving tocilizumab (TCZ) therapy.

Methods

Seventeen RA patients treated with TCZ were assessed. FDG-PET was performed at baseline and three and six months after the initiation of TCZ therapy. The maximum SUV (SUVmax) of the bilateral shoulder, elbow, wrist, hip, knee and ankle joints were added together (total SUV) and were used to assess the degree of FDG uptake as a representative parameter. The correlations between the ΔSUV and the difference in the clinical parameters at baseline and at each observation period, and the differences in each clinical parameters, were assessed.

Results

The ΔSUV, the differences in the total SUV at baseline and at three/six months after starting treatment positively correlated with the ΔDAS28 (r = 0.615 p = 0.009/ r = 0.775 p < 0.001), ΔDAS28-CRP (r = 0.696, p = 0.002/ r = 0.828, p < 0.001), ΔSDAI (r = 0.652, p = 0.005/ r = 0.686, p = 0.002) and ΔCDAI (r = 0.662, p = 0.004/ r = 0.711, p = 0.001) for each period. The total SUV was significantly decreased at three and six months after the initiation of TCZ (p < 0.05).

Conclusions

A reduction in the FDG uptake was observed at three and six months after the initiation of TCZ therapy. The disease activity estimated on FDG-PET/CT matched the conventional parameters following the TCZ therapy in RA patients.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2474-15-393) contains supplementary material, which is available to authorized users.

Correlation of PUV and SUV in the extremities while using PEM as a high-resolution positron emission scanner

OBJECTIVE

Owing to its unique configuration of two adjustable plate detectors positron emission mammography, or PEM, could theoretically also function as a high-resolution positron emission scanner for the extremities or neck. PEM quantitates its activity via a "PEM uptake value," or PUV, and although its relationship to the standardized uptake value, or SUV, has been demonstrated in the breasts, to our knowledge there are no studies validating PUV in other sites such as the extremities.

MATERIALS AND METHODS

This was a retrospective chart review of two separate protocols of a total of 15 patients. The patients all had hypermetabolic lesions in the extremities or neck on imaging with PET/CT and were sent after their PET/CT to PEM for further imaging. Owing to the sequential nature of these examinations no additional radiotracer was administered.

RESULTS

Spearman's rank order correlation was calculated between the PUVmax obtained from PEM images, and the SUVmax for all. Spearman's rank order correlation for all sites was 0.42, which is not significantly different from 0 (p = 0.13). When neck lesions were excluded from the group, there was a strong and statistically significant correlation between PUVmax and SUVmax, with Spearman's rank correlation of 0.73, and significantly different from 0 (p = 0.0068).

DISCUSSION

The correlation of PUV and SUV in the extremities indicates the potential use of PEM as a semiquantitative, high-resolution positron emission scanner and warrants further investigation, especially in the realms of disease processes that often present in the extremities, such as melanoma, osteomyelitis, and arthritis, as well as playing a role in the imaging of patients with metallic hardware post-limb salvage surgery.

The role of bone scintigraphy in the diagnosis of rheumatoid arthritis according to the 2010 ACR/EULAR classification criteria

We aimed to investigate the role of bone scintigraphy (BS) in the diagnosis of rheumatoid arthritis (RA) as a supplement to the 2010 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) criteria. A total of 156 patients who underwent BS with screening laboratory to confirm RA were enrolled. We divided them into two groups according to the presence of arthritis upon the first physical examination, and evaluated the diagnostic validity of BS as an independent (BS only) or assistant diagnostic tool using the 2010 criteria (BS-assisted). Seventy-five patients had active arthritis (Group I), while the remaining 81 patients did not (Group II). Among them, 56 patients in group I and 5 patients in group II were finally classified as RA. In the group I patients who were eligible for application of the 2010 criteria, the sensitivity of the BS only and BS-assisted diagnosis was not superior to that of the 2010 criteria. However, BS-assisted diagnosis showed high positive prediction values in group I patients with 2010 criteria score < 6 and group II patients. Therefore, BS is still helpful to detect RA even after the introduction of the 2010 criteria, especially among patients who do not satisfy the 2010 criteria as well as those who are ineligible for the 2010 criteria due to dubitable arthritis at clinical presentation.

Imaging of rheumatoid arthritis

Increased awareness of the need for early diagnosis of rheumatoid arthritis and advances in the ability to effectively treat rheumatoid arthritis have made disease remission and maintenance of function a reality for many patients. However, identification of patients who are at risk for erosive disease remains a challenge. As more is learnt about risk factors for disease severity and the role of imaging techniques such as ultrasound and magnetic resonance imaging, the ability to prevent disease progression in the form of joint damage and its attendant deformity and functional limitation will further improve.

Bilateral Evaluation of the Hand and Wrist in Untreated Early Inflammatory Arthritis: A Comparative Study of Ultrasonography and Magnetic Resonance Imaging

Objective.

To compare Doppler ultrasound (US) and 3.0-Tesla magnetic resonance imaging (3.0-T MRI) findings of synovial inflammation in the tendons and joints in an early polyarthritis cohort (patients who presented < 1 year after arthritis onset) using a bilateral hand and wrist evaluation. Also, to evaluate the diagnostic performance of US and MRI findings for rheumatoid arthritis (RA), their ability to predict RA as a diagnostic outcome, and their capacity to improve the accuracy of the 2010 American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) RA classification criteria in early arthritis.

Methods.

Forty-five patients (40 women, 5 men; mean age 45.6 yrs) with untreated recent-onset polyarthritis participated in this prospective study and were examined using an US and MRI approach including both wrists and hands. After a followup of 12 months, patients were classified as having RA if they fulfilled the criteria for RA. The proportion of synovitis identified by US and MRI for each joint and tendon region was compared by chi-square test. The diagnostic performance of US and MRI for RA identification was evaluated using receiver-operating curve (ROC) analysis. Possible associations between synovitis for each joint and tendon region as identified by US or MRI and RA diagnosis at 12 months were tested by logistic regression analysis. The diagnostic performance of the ACR/EULAR RA classification criteria corrected by US and MRI joint and tendon counts was evaluated using ROC analysis.

Results.

Thirty patients fulfilled the ACR/EULAR criteria [early RA (ERA) patients] and the remaining 15 failed to meet these criteria (non-RA). Carpal joint synovitis and tenosynovitis of the flexor tendons was found in 86.7% and 86.7% of patients with ERA on MRI compared with 63.3% and 50% on US, respectively (p < 0.05). The global MRI and US counts revealed a good diagnostic performance for RA diagnosis of both techniques, although MRI was statistically significantly better [area under the curve (AUC) = 0.959 and AUC = 0.853, respectively; z statistic = 2.210, p < 0.05]. MRI identification of carpal joint synovitis (OR 3.64, 95% CI 1.119–11.841), tenosynovitis of the flexor tendons (OR 5.09, 95% CI 1.620–16.051), and global joint and tendon count (OR 2.77, 95% CI 1.249–6.139) were in the multivariate logistic regression model the most powerful predictors of progression toward RA. In the group of ERA patients with US joint and tendon counts ≤ 10, a statistically significant difference was found between the diagnostic performance for RA of the ACR/EULAR criteria as previously described and the diagnostic performance of the MRI-corrected ACR/EULAR criteria (AUC = 0.898 and AUC = 0.986, respectively; z statistic = 2.181, p < 0.05).

Conclusion.

3.0-T MRI identified a higher prevalence of synovitis in comparison to US in an early polyarthritis cohort. Both techniques have good diagnostic performance for RA although MRI reveals a significantly higher diagnostic capability. Synovitis of carpal joints and of flexor tendons as identified by MRI were the most powerful predictors of progression toward RA. In patients with US joint and tendon counts ≤ 10, MRI can significantly improve the diagnostic performance of the 2010 ACR/EULAR classification criteria.

Molecular characterization of rheumatoid arthritis with magnetic resonance imaging

Several recent advances in the field of magnetic resonance imaging (MRI) may transform the detection and monitoring of rheumatoid arthritis (RA). These advances depict both anatomic and molecular alterations from RA. Previous techniques could detect specific end products of metabolism in vitro or were limited to providing anatomic information. This review focuses on the novel molecular imaging techniques of hyperpolarized carbon-13 MRI, MRI with iron-labeled probes, and fusion of MRI with positron emission tomography. These new imaging approaches go beyond the anatomic description of RA and lend new information into the status of this disease by giving molecular information.

Visualizing arthritic inflammation and therapeutic response by fluorine-19 magnetic resonance imaging (19F MRI)

Background

Non-invasive imaging of inflammation to measure the progression of autoimmune diseases, such as rheumatoid arthritis (RA), and to monitor responses to therapy is critically needed. V-Sense, a perfluorocarbon (PFC) contrast agent that preferentially labels inflammatory cells, which are then recruited out of systemic circulation to sites of inflammation, enables detection by ¹⁹F MRI. With no ¹⁹F background in the host, detection is highly-specific and can act as a proxy biomarker of the degree of inflammation present.

Methods

Collagen-induced arthritis in rats, a model with many similarities to human RA, was used to study the ability of the PFC contrast agent to reveal the accumulation of inflammation over time using ¹⁹F MRI. Disease progression in the rat hind limbs was monitored by caliper measurements and ¹⁹F MRI on days 15, 22 and 29, including the height of clinically symptomatic disease. Naïve rats served as controls. The capacity of the PFC contrast agent and ¹⁹F MRI to assess the effectiveness of therapy was studied in a cohort of rats administered oral prednisolone on days 14 to 28.

Results

Quantification of ¹⁹F signal measured by MRI in affected limbs was linearly correlated with disease severity. In animals with progressive disease, increases in ¹⁹F signal reflected the ongoing recruitment of inflammatory cells to the site, while no increase in ¹⁹F signal was observed in animals receiving treatment which resulted in clinical resolution of disease.

Conclusion

These results indicate that ¹⁹F MRI may be used to quantitatively and qualitatively evaluate longitudinal responses to a therapeutic regimen, while additionally revealing the recruitment of monocytic cells involved in the inflammatory process to the anatomical site. This study may support the use of ¹⁹F MRI to clinically quantify and monitor the severity of inflammation, and to assess the effectiveness of treatments in RA and other diseases with an inflammatory component.

Characteristics of synovial inflammation in early arthritis analysed by pixel-by-pixel time-intensity curve shape analysis

OBJECTIVE

Dynamic contrast-enhanced (DCE-MRI) time-intensity curve (TIC) shape analysis has previously been used in oncology, where fast initial enhancement and early washout are associated with malignancy. As RA synovium has some tumour-like features, we investigated DCE-MRI TIC shape expression in early arthritis in relationship to diagnosis.

METHODS

Twenty-eight DMARD-naïve, early arthritis patients (<1 year) with inflammation of at least one knee joint were included. At baseline DCE-MRI of the inflamed knee joint was performed, and the TIC shape type expression, maximal enhancement, maximum slope of increase and total volume of enhancing pixels were calculated. In addition, disease activity parameters were determined. At 2 years of follow-up, patients were classified as RA or non-RA according to established classification criteria.

RESULTS

Type 4 TIC shape, characterized by fast initial enhancement followed by a quick washout phase, was significantly higher in patients fulfilling classification criteria for RA after 2 years of follow-up compared with non-RA patients (15.6 and 7.9%, respectively, P = 0.02). All other DCE-MRI parameters showed no differences between the groups, highlighting the specificity of this observation.

CONCLUSION

A high expression of aggressive DCE-MRI TIC shape Type 4 is associated with RA. Our results are consistent with the view that increased vascularity plays a key role in the pathogenesis of RA. This study underlines the rationale for further studies investigating the prospect of DCE-MRI TIC shape analysis as a diagnostic tool in early arthritis and the relationship with development of destructive disease.

Identification and evaluation of novel synovial tissue biomarkers in rheumatoid arthritis by laser scanning cytometry

Introduction

Suitable biomarkers are essential for therapeutic strategies in personalized medicine in terms of diagnosis as well as of prognosis. With highly specific biomarkers, it is possible, for example, to identify patients with poor prognosis, which enables early intervention and intensive treatment. The aim of this study was to identify and validate biomarkers and possible combinations for a prospective use in immunoscintigraphy, which may improve diagnosis of rheumatoid arthritis (RA) patients with consideration of inflammatory activity in the affected joints. Therefore, we tested several monoclonal antibodies (mAbs) directed against cellular-surface molecules on cells likely to be involved in the pathogenesis of RA.

Methods

Synovial tissue from patients with long-standing RA (accompanied by synovitis with varying states of current activity) and patients with acute non-RA arthritis were stained for surface molecules on different cell types by using fluorochrome-labeled antibodies. Tissue analysis was done by laser scanning cytometry (LSC), and statistical evaluation, by discriminant analysis and ROC analysis.

Results

CD11b, HLA-DR, CD90, and CD64 revealed significant differences between tissues from patients with RA and acute non-RA arthritis. Especially with the expression of CD64, both patient cohorts could be discriminated with high sensitivity and specificity. RA classification was improved by simultaneously investigating the expression of two or three different surface proteins, such as HLA-DR, CD90, and CD29 in the tissue. The simultaneous analysis of CD64 together with CD304 or the combination of CD11b and CD38 was suitable for the identification of RA patients with high current activity in synovitis.

Conclusions

In this study, we showed that LSC is a novel reliable method in biomarker prevalidation in RA. Hence, identified mAbs in situ may allow their potential use in in vivo approaches. Moreover, we proved that biomarker-combination analysis resulted in better discrimination than did single-marker analysis. Combinations of these markers make a novel and reliable panel for the discrimination between RA and acute non-RA arthritis. In addition, further expedient combinations may be novel promising biomarker panels to identify current activity in synovitis in RA.

Sonographic assessment of carpal tunnel syndrome in rheumatoid arthritis: prevalence and correlation with disease activity

Carpal tunnel syndrome (CTS) is one of the most frequent extra-articular manifestations of rheumatoid arthritis (RA). High frequency ultrasonography (US) is a sensitive and specific method in diagnosis of CTS. This study is aimed to: firstly assess diameter frequency of CTS in RA with US and compare with a control group; secondly, investigate relationship of CTS with disease activity. One hundred consecutive RA patients (women/men: 78/22) fulfilling ACR 1987 RA criteria and 45 healthy controls (women/control: 34/11) were enrolled into study. Disease activity parameters, RA and CTS patient global assessment and health assessment questionnaire (HAQ-DI) were recorded. Both patient and control group were questioned about secondary causes of CTS, and Katz hand diagram, Boston CTS questionnaire and Phalen ve Tinel tests were applied once for each hand. Wrist joint and carpal tunnel were assessed with US grey scale and power Doppler US, then cross-sectional area of median nerve (CSA) was calculated. Patients with median nerve CSA between 10.0 and 13.0 mm(2) were evaluated with electromyography (EMG). CTS was diagnosed if CSA of median nerve >13.0 mm(2) or CTS was shown with NCS. Although there was no difference between RA patients and controls in age, sex, history of DM (+) and goitre, CTS was more frequent in RA group (respectively, 17.0% vs. 4.4%, P = 0.038). In RA group with CTS, age, history of DM, disease duration, HAQ-DI score, CTS patient global score, Boston symptom severity and functional status scores were elevated compared to without CTS [respectively, 57 (36-73) vs. 50 (24-76), P = 0.041; 35.3% vs. 6.0%, P < 0.001; 108 (12-396) months vs. 72 (6-360) months, P = 0.036; 1.93 (0.75-2.87) vs. 1.125 (0-2.75), P = 0.013; 52 (1-97) vs. 25 (0-91), P = 0.001; 2.81 (1.18-4.17) vs. 2.0 (1.0-4.01), P = 0.01; 3.37 (1.37-5.0) vs. 2.25 (1.0-5.0), P = 0.008]. No difference was found between CTS (+) and (-) RA patients in acute phase reactants, disease activity and US findings (P > 0.05). Sensitivity of Katz hand diagram was higher than Tinel and Phalen tests (respectively, 100, 60.0, 66.7%). Boston symptom and functional scores of RA patients with CTS diagnosed by EMG were increased than patients CTS (-) by EMG [respectively, 3.05 (1.90-4.27) vs. 1.55 (1.0-2.90), P = 0.002; 3.25 (1.73-3.82) vs. 1.12 (1.0-2.10), P = 0.008]. CTS frequency in RA was found higher than normal population, especially in patients with additional risk factors of CTS. There was no relationship between CTS and disease activity. CTS group had long disease duration and worse functional status. CTS could be a result of the chronic course in RA. In patient with CSA between 10 and 13 mm(2), Boston CTS questionnaire might give additional idea about CTS.

Detection of inflammatory arthritis by using hyperpolarized 13C-pyruvate with MR imaging and spectroscopy

PURPOSE

To examine the feasibility of using magnetic resonance (MR) spectroscopy with hyperpolarized carbon 13 ((13)C)-labeled pyruvate to detect inflammation.

MATERIALS AND METHODS

The animal care and use committee approved all work with animals. Arthritis was induced in the right hind paw of six rats; the left hind paw served as an internal control. The lactate dehydrogenase-catalyzed conversion of pyruvate to lactate was measured in inflamed and control paws by using (13)C MR spectroscopy. Clinical and histologic data were obtained to confirm the presence and severity of arthritis. Hyperpolarized (13)C-pyruvate was intravenously injected into the rats before simultaneous imaging of both paws with (13)C MR spectroscopy. The Wilcoxon signed rank test was used to test for differences in metabolites between the control and arthritic paws.

RESULTS

All animals showed findings of inflammation in the affected paws and no signs of arthritis in the control paws at both visible inspection (clinical index of 3 for arthritic paws and 0 for control paws) and histologic examination (histologic score of 3-5 for arthritic paws and 0 for control paws). Analysis of the spectroscopic profiles of (13)C-pyruvate and converted (13)C-lactate showed an increase in the amount of (13)C-lactate in inflamed paws (median lactate-to-pyruvate ratio, 0.50; mean lactate-to-pyruvate ratio ± standard deviation, 0.52 ± 0.16) versus control paws (median lactate-to-pyruvate ratio, 0.27; mean lactate-to-pyruvate ratio, 0.32 ± 0.11) (P < .03). The ratio of (13)C-lactate to total (13)C was also significantly increased in inflamed paws compared with control paws (P < .03).

CONCLUSION

These results suggest that alterations in the conversion of pyruvate to lactate as detected with (13)C-MR spectroscopy may be indicative of the presence of inflammatory arthritis.

A window on disease pathogenesis and potential therapeutic strategies: molecular imaging for arthritis

Novel molecular imaging techniques are at the forefront of both preclinical and clinical imaging strategies. They have significant potential to offer visualisation and quantification of molecular and cellular changes in health and disease. This will help to shed light on pathobiology and underlying disease processes and provide further information about the mechanisms of action of novel therapeutic strategies. This review explores currently available molecular imaging techniques that are available for preclinical studies with a focus on optical imaging techniques and discusses how current and future advances will enable translation into the clinic for patients with arthritis.

Imaging of inflammation by PET, conventional scintigraphy, and other imaging techniques

Nuclear medicine imaging procedures play an important role in the assessment of inflammatory diseases. With the advent of 3-dimensional anatomic imaging, there has been a tendency to replace traditional planar scintigraphy by CT or MRI. Furthermore, scintigraphic techniques may have to be combined with other imaging modalities to achieve high sensitivity and specificity, and some may require time-consuming labeling procedures. On the other hand, new developments such as combined SPECT/CT increase the diagnostic power of scintigraphy. Also, the advent of PET had a considerable impact on the use of nuclear medicine imaging techniques. In this review, we aim to provide nuclear medicine specialists and clinicians with the relevant information on rational and efficient use of nuclear medicine imaging techniques in the assessment of patients with osteomyelitis, infected vascular prostheses, metastatic infectious disease, rheumatoid arthritis, vasculitis, inflammatory bowel disease, sarcoidosis, and fever of unknown origin.

Optical imaging: new tools for arthritis

Conventional radiography, ultrasound, CT, MRI, and nuclear imaging are the current imaging modalities used for clinical evaluation of arthritis which is highly prevalent and a leading cause of disability. Some of these types of imaging are also used for monitoring disease progression and treatment response of arthritis. However, their disadvantages limit their utilities, such as ionizing radiation for radiography, CT, and nuclear imaging; suboptimal tissue contrast resolution for radiography, CT, ultrasound, and nuclear imaging; high cost for CT and MRI and nuclear imaging; and long data-acquisition time with ensuing patient discomfort for MRI. Recently, there have been considerable advances in nonionizing noninvasive optical imaging which has demonstrated promise for early diagnosis, monitoring therapeutic interventions and disease progression of arthritis. Optical based molecular imaging modalities such as fluorescence imaging have shown high sensitivity in detection of optical contrast agents and can aid early diagnosis and ongoing evaluation of chronic inflammatory arthritis. Optical transillumination imaging or diffuse optical tomography may differentiate normal joint clear synovial fluid from turbid and pink medium early in the inflammatory process. Fourier transform infrared spectroscopy has been used to evaluate fluid composition from joints affected by arthritis. Hemodynamic changes such as angiogenesis, hypervascularization, and hypoxia in arthritic articular tissue can potentially be observed by diffuse optical tomography and photoacoustic tomography. Optical measurements could also facilitate quantification of hemodynamic properties such as blood volume and oxygenation levels at early stages of inflammatory arthritis. Optical imaging provides methodologies which should contribute to detection of early changes and monitoring of progression in pathological characteristics of arthritis, with relatively simple instrumentation.

The value of ultrasonography in predicting arthritis in auto-antibody positive arthralgia patients: a prospective cohort study

Introduction

Ultrasonography (US) has better sensitivity than clinical evaluation for the detection of synovitis in early rheumatoid arthritis (RA). Patients presenting with arthralgia and a positive anti-citrullinated protein antibodies (ACPA) and/or Rheumatoid Factor (IgM-RF) status are at risk for developing RA. In the present study, US utility and predictive properties in arthralgia patients at risk for the development of arthritis were studied.

Methods

192 arthralgia patients with ACPA and/or IgM-RF were included. Absence of clinical arthritis was confirmed by two physicians. US was performed by one of two trained radiologists of any painful joint, and of adjacent and contralateral joints. Joint effusion, synovitis and power Doppler (PD) signal in the synovial membrane of the joints and tenosynovitis adjacent to the joint were evaluated and classified on a 4-grade semi-quantitative scale. Grade 2-3 joint effusion, synovitis, tenosynovitis and grade 1-3 Power Doppler signal were classified as abnormal.

Results

Forty-five patients (23%) developed arthritis after a mean of 11 months. Inter-observer reliability for synovitis and PD was moderate (kappa 0.46, and 0.56, respectively) and for joint effusion low (kappa 0.23). The prevalence of tenosynovitis was too low to calculate representative kappa values. At joint level, a significant association was found between US abnormalities and arthritis development in that joint for joint effusion, synovitis and PD. At patient level, a trend was seen towards more arthritis development in patients who had US abnormalities for joint effusion, synovitis, PD and tenosynovitis.

Conclusions

US abnormalities were associated with arthritis development at joint level, although this association did not reach statistical significance at patient level. US could potentially be used as a diagnostic tool for subclinical arthritis in seropositive arthralgia patients. However, further research is necessary to improve test characteristics.

Musculoskeletal molecular imaging: a comprehensive overview

Molecular imaging permits non-invasive visualization and measurement of molecular and cell biology in living subjects, thereby complementing conventional anatomical imaging. Herein, we review the emerging application of molecular imaging for the study of musculoskeletal biology. Utilizing mainly bioluminescence and fluorescence techniques, molecular imaging has enabled in-vivo studies of (i) the activity of osteoblasts, osteoclasts, and hormones, (ii) the mechanisms of pathological cartilage and bone destruction, (iii) skeletal gene and cell therapy with and without biomaterial support, and (iv) the cellular processes in osteolysis and osteomyelitis. In these applications, musculoskeletal molecular imaging demonstrated feasibility for research in a myriad of musculoskeletal conditions ranging from bone fracture and arthritis to skeletal cancer. Importantly, these advances herald great potential for innovative clinical imaging in orthopedics, rheumatology, and oncology.

Early detection of bony alterations in rheumatoid and erosive arthritis of finger joints with high-resolution single photon emission computed tomography, and differentiation between them

OBJECTIVE

To evaluate high-resolution multi-pinhole single photon emission computed tomography (MPH-SPECT) for the detection of bony alterations in early rheumatoid arthritis (ERA), early osteoarthritis (EOA) of the fingers and healthy controls.

METHODS

The clinically dominant hands of 27 patients (13 ERA, nine EOA, five healthy controls) were examined by MPH-SPECT and bone scintigraphy. Additionally, magnetic resonance imaging (MRI) was performed in the ERA patients. Number of affected joints, localisation, pattern of tracer distribution and joint involvement were scored. Quantitative analysis was achieved by measurement of the region of interest (ROI) in all patients. The MPH-SPECT and MR images were fused in the ERA group.

RESULTS

Bone scintigraphy detected fewer joints (26 joints,13/22 patients) with increased tracer uptake than did MPH-SPECT (80 joints, 21/22 patients). Bone scintigraphy did not show recognisable uptake patterns in any group of patients. With MPH-SPECT central tracer distribution was typical in ERA (10/13 patients, EOA 2/9). In contrast, an eccentric pattern was found predominantly in EOA (7/9, ERA 2/13). Normalised counts were 4.5 in unaffected joints and up to 222.7 in affected joints. The mean uptake values in affected joints were moderately higher in the EOA patients (78.75, and 62.16 in ERA). The mean tracer uptake in affected joints was approximately three-times higher than in unaffected joints in both groups (ERA 3.64-times higher, EOA 3.58). Correlation with MR images revealed that bone marrow oedema and erosions matched pathological tracer accumulation of MPH-SPECT in 11/13. MPH-SPECT demonstrated increased activity in 2/13 patients with normal bone marrow signal intensity and synovitis seen on MR images.

CONCLUSION

MPH-SPECT is sensitive to early changes in ERA and EOA and permits them to be distinguished by their patterns of uptake.

Monocyte scintigraphy in rheumatoid arthritis: the dynamics of monocyte migration in immune-mediated inflammatory disease

BACKGROUND

Macrophages are principal drivers of synovial inflammation in rheumatoid arthritis (RA), a prototype immune-mediated inflammatory disease. Conceivably, synovial macrophages are continuously replaced by circulating monocytes in RA. Animal studies from the 1960s suggested that macrophage replacement by monocytes is a slow process in chronic inflammatory lesions. Translation of these data into the human condition has been hampered by the lack of available techniques to analyze monocyte migration in man.

METHODS/PRINCIPAL FINDINGS

We developed a technique that enabled us to analyze the migration of labelled autologous monocytes in RA patients using single photon emission computer tomography (SPECT). We isolated CD14+ monocytes by CliniMACS in 8 patients and labeled these with technetium-99m (99mTc-HMPAO). Monocytes were re-infused into the same patient. Using SPECT we calculated that a very small but specific fraction of 3.4 x 10(-3) (0.95-5.1 x 10(-3)) % of re-infused monocytes migrated to the inflamed joints, being detectable within one hour after re-infusion.

CONCLUSIONS/SIGNIFICANCE

The results indicate monocytes migrate continuously into the inflamed synovial tissue of RA patients, but at a slow macrophage-replacement rate. This suggests that the rapid decrease in synovial macrophages that occurs after antirheumatic treatment might rather be explained by an alteration in macrophage retention than in monocyte influx and that RA might be particularly sensitive to treatments targeting inflammatory cell retention.

Inflammatory arthritis: an overview for primary care physicians

Continuing advances in the treatment of inflammatory arthritides such as rheumatoid arthritis (RA), ankylosing spondylitis (AS), and psoriatic arthritis (PsA) have made remission a realistic goal for patients. Despite these advances, early diagnosis of inflammatory arthritis by primary care physicians (PCPs) and subsequent referral to a rheumatologist remain a challenge. Delayed diagnosis and referral, which may extend to several years in some cases, may lead to irreversible joint destruction and compromised function. The aim of this review is to aid PCPs in preventing the potential delay in disease recognition and patient referral by highlighting the currently accepted criteria for disease activity, clinical response, and remission of RA, AS, and PsA. In addition, a discussion of the benefits and risks of the currently approved traditional disease-modifying antirheumatic drugs and biologic treatments, and the importance of comanagement of these conditions across specialties, will be addressed. Because PCPs are often the first point of contact for disease recognition, they can play a critical role in the management of these patients.

The role of conventional radiography and scintigraphy in the third millennium

Imaging represents a cornerstone for diagnosing and monitoring rheumatic diseases. In the last few years, with the availability of highly effective therapies, demand for the technical performance of imaging has increased exponentially, leading to rapid development of new technologies such as magnetic resonance imaging (MRI) and ultrasound (US). In both clinical practice and clinical trials, there is a need for tools that are sensitive to change and to therapy response, which are able to depict inflammatory changes early, before irreversible joint damage has occurred. Despite these advances, conventional radiography (CR) and bone scintigraphy (BS), the two oldest imaging tests, continue to provide enormous diagnostic and prognostic help for the study of many musculoskeletal disorders. Furthermore, CR is an inexpensive, widely available and reproducible tool for evaluating and monitoring structural damage. This chapter focuses on the roles of CR and BS in rheumatological clinical practice, taking into account their performance in comparison with the newer imaging techniques.

Biodistribution and radiation dosimetry of 99mTc-HMPAO-labeled monocytes in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) involves the accumulation of monocyte-derived macrophages in the affected synovial tissue. This process of cell migration could be portrayed scintigraphically to monitor noninvasively the effects of therapy on the progress of the disease. For this purpose, labeling of purified autologous monocytes with 99mTc-hexamethylpropyleneamine oxime (99mTc-HMPAO) at very high specific radioactivity has recently been developed. The aim of this study was to assess the biodistribution and radiation dosimetry of 99mTc-HMPAO-labeled monocytes in adult patients with RA.

METHODS

In 8 patients with RA, monocytes were isolated from 100 mL of blood and labeled with 99mTc-HMPAO to a yield of 10 Bq/cell. Multiple whole-body scans were performed up to 20 h after reinjection of an average of 200 MBq of 99mTc-HMPAO-labeled monocytes. Urine and blood samples were collected. The fraction of administered activity in 7 source organs was quantified from the attenuation-corrected geometric mean counts in conjugate views. Radiation-absorbed doses were estimated with OLINDA/EXM software.

RESULTS

Autologous monocytes labeled with 99mTc-HMPAO at high intracellular yields showed in vivo kinetics comparable with labeled leukocytes, with initial trapping in the lungs followed by distribution into the liver, spleen, and bone marrow. The radiation-absorbed estimates for 99mTc-HMPAO-labeled monocytes were comparable with those for 99mTc-HMPAO-labeled mixed white blood cells, with an effective dose of 0.011 mSv/MBq.

CONCLUSION

99mTc-HMPAO-labeled monocytes have biodistribution and radiation dosimetry similar to those of 99mTc-HMPAO-labeled mixed white blood cells and might therefore be used for in vivo monitoring of immunomodulating therapy in patients with RA.