Optimised, low cost, low field dedicated extremity MRI is highly specific and sensitive for synovitis and bone erosions in rheumatoid arthritis wrist and finger joints: comparison with conventional high field MRI and radiography

New clinical opportunities of low-field MRI: heart, lung, body, and musculoskeletal

Contemporary whole-body low-field MRI scanners (< 1 T) present new and exciting opportunities for improved body imaging. The fundamental reason is that the reduced off-resonance and reduced SAR provide substantially increased flexibility in the design of MRI pulse sequences. Promising body applications include lung parenchyma imaging, imaging adjacent to metallic implants, cardiac imaging, and dynamic imaging in general. The lower cost of such systems may make MRI favorable for screening high-risk populations and population health research, and the more open configurations allowed may prove favorable for obese subjects and for pregnant women. This article summarizes promising body applications for contemporary whole-body low-field MRI systems, with a focus on new platforms developed within the past 5 years. This is an active area of research, and one can expect many improvements as MRI physicists fully explore the landscape of pulse sequences that are feasible, and as clinicians apply these to patient populations.

Using a Dedicated Extremity MRI Scanner for Depicting Anatomic Structures of Common Wrist Pathologies: A Pilot Comparison with a 3-Tesla MRI Scanner

Background  This pilot study explored the value of a dedicated extremity magnetic resonance imaging (MRI) scanner by focusing on the qualitative depiction of important wrist structures in common wrist pathologies, the overall image quality, artifacts, and participant experience in undergoing the examinations. Methods  Images of the right wrist of 10 healthy adult volunteers were acquired with a 0.31-Tesla (T) dedicated extremity MRI and a 3-T MRI system, using a dedicated wrist coil. Images were separately evaluated by three radiologists. Paired images were randomized and graded for the visibility of anatomical details, including the triangular fibrocartilage complex (TFCC; central disc, meniscus homolog, and ulnar attachment), carpal ligaments (scapholunate [SL] and lunotriquetral [LT] ligaments), intercarpal cartilage, and median and ulnar nerves. Mean values and standard deviations of evaluation results were calculated for each sequence. Participants' experience in undergoing the examination in both MRI scanners was explored using a questionnaire. Results  The mean values of anatomic structures and overall image quality were significantly in favor of the 3-T MRI scanner, compared with the dedicated extremity MRI scanner. With respect to patient satisfaction in undergoing the examination, the overall trend suggested that patients were more in favor of the dedicated extremity MRI scanner. Conclusion  For defining the real clinical value of the dedicated MRI scanner in the treatment of hand and wrist pathology, studies focused on pathologies are needed, which is certainly warranted, considering the important benefits of these devices including lower costs and higher accessibility for both patients and health care providers.

Diagnostic Image Quality of a Low-Field (0.55T) Knee MRI Protocol Using Deep Learning Image Reconstruction Compared with a Standard (1.5T) Knee MRI Protocol

OBJECTIVES

Low-field MRI at 0.55 Tesla (T) with deep learning image reconstruction has recently become commercially available. The objective of this study was to evaluate the image quality and diagnostic reliability of knee MRI performed at 0.55T compared with 1.5T.

METHODS

A total of 20 volunteers (9 female, 11 male; mean age = 42 years) underwent knee MRI on a 0.55T system (MAGNETOM Free.Max, Siemens Healthcare, Erlangen, Germany; 12-channel Contour M Coil) and a 1.5T scanner (MAGNETOM Sola, Siemens Healthcare, Erlangen, Germany; 18-channel transmit/receive knee coil). Standard two-dimensional (2D) turbo spin echo (TSE), fat-suppressed (fs) proton density-weighted (PDw), T1w TSE, and T2w TSE sequences were acquired in approximately 15 min. In total, 2 radiologists blinded to the field strength subjectively assessed all MRI sequences (overall image quality, image noise, and diagnostic quality) using a 5-point Likert scale (1-5; 5 = best). Additionally, both radiologists evaluated the possible pathologies of menisci, ligaments, and cartilage. Contrast ratios (CRs) of different tissues (bone, cartilage, and menisci) were determined on coronal PDw fs TSE images. The statistical analysis included Cohen's kappa and the Wilcoxon rank sum test.

RESULTS

The overall image quality of the 0.55T T2w, T1w, and PDw fs TSE sequences was diagnostic and rated similar for T1w (p > 0.05), but lower for PDw fs TSE and T2w TSE compared with 1.5T (p < 0.05). The diagnostic accordance of meniscal and cartilage pathologies at 0.55T was similar to 1.5T. The CRs of the tissues were not significantly different between 1.5T and 0.55T (p > 0.05). The inter-observer agreement of the subjective image quality was generally fair between both readers and almost perfect for the pathologies.

CONCLUSIONS

Deep learning-reconstructed TSE imaging at 0.55T yielded diagnostic image quality for knee MRI compared with standard 1.5T MRI. The diagnostic performance of meniscal and cartilage pathologies was equal for 0.55T and 1.5T without a significant loss of diagnostic information.

Magnetic resonance imaging as a structural refinement to the American College of Rheumathology clinical classification criteria for knee osteoarthritis

OBJECTIVE

To evaluate if fulfilment of the definition of osteoarthritis (OA) based on the American College of Rheumatology (ACR) clinical criteria corresponds to pathological knee findings evaluated by magnetic resonance imaging (MRI). To evaluate if any such criteria is associated with a specific MRI pattern.

METHODS

Forty-six consecutive patients aged 50 years or more referred by their general practitioners (GPs) to a radiology department because of non-traumatic knee pain underwent MRI using a dedicated low field (0.2 T) machine.

RESULTS

MRI results were compared against the ACR criteria for knee OA. Patients with knee pain fulfilling the ACR criteria showed more severe synovial fluid effusion (OR 6.2, 95% CI 2.02 to 19.1), cartilage lesions in the medial area (OR 2.4, 95% CI 1.2 to 5) and higher mean number of osteophytes (OR 2.3, 95% CI 1.1 to 4.5). The association between single criteria and MRI features was more difficult to establish. Nonetheless, crepitus at joint movement was associated with synovial fluid effusion (p=0.02); bone enlargement was more frequent in patients with lesions of the posterior cruciate ligament (p=0.0001); no palpable warmth was associated with cartilage lesions (p=0.02), and morning stiffness shorter than 30 minutes was associated with the surface of bone edema (p=0.02).

CONCLUSIONS

The ACR clinical criteria identify patients showing the most important features of OA. The association between individual clinical ACR criteria and OA pathology depicted by MRI may be difficult to explain on the basis of anatomical changes and needs further evaluation.

Susceptibility-weighted imaging at high-performance 0.5T magnetic resonance imaging system: Protocol considerations and experimental results

The high-performance low-field magnetic resonance imaging (MRI) system, equipped with modern hardware and contemporary imaging capabilities, has garnered interest within the MRI community in recent years. It has also been proven to have unique advantages over high-field MRI in both physical and cost aspects. However, for susceptibility weighted imaging (SWI), the low signal-to-noise ratio and the long echo time inherent at low field hinder the SWI from being applied to clinical applications. This work optimized the imaging protocol to select suitable parameters such as the values of time of echo (TE), repetition time (TR), and the flip angle (FA) of the RF pulse according to the signal simulations for low-field SWI. To improve the signal-to-noise ratio (SNR) performance, averaging multi-echo magnitude images and BM4D phase denoising were proposed. A comparison of the SWI in 0.5T and 1.5T was carried out, demonstrating the capability to identify magnetic susceptibility differences between variable tissues, especially, the blood veins. This would open the possibility to extend SWI applications in the high-performance low field MRI.

Low-Frequency Magnetic Resonance Imaging Identifies Hand Joint Subclinical Inflammation in Systemic Sclerosis

Objectives: The aim of this work was to determine hand joint inflammation in systemic sclerosis (SSc); patients with rheumatoid arthritis (RA) with hand joint involvement were used as controls. Our investigation also aimed at examining the relationship between these subclinical inflammatory changes in the hands, verified by low-frequency MRI, and clinical (especially cardiopulmonary) manifestations, disease activity, and functional capacity in patients with diffuse cutaneous (dcSSc) and limited cutaneous SSc (lcSSc). Methods: Out of 250 SSc patients, the selection included 82 patients with signs and symptoms of joint involvement, and 35 consecutive RA patients. These patients underwent clinical and laboratory investigations, and hand X-ray and MRI of the dominant hand. Synovitis/tenosynovitis, bone edema, and erosions were investigated, and the bone changes were quantified and scored using the RAMRIS method. HAQ index, modified Rodnan skin score, examination of internal organ involvement, and serological markers for SSc, as well as rheumatoid factor (RF) and cyclic citrullinated peptides antibodies (ACPA), were performed on all experimental group subjects. Results: MRI of the dominant hand showed a significantly higher number of cases with synovitis (78%) than the number of patients with clinically swollen joints (17.1%; p < 0.001); bone edema was found in 62 (75.6%) SSc patients. MRI also showed a higher number of erosions (52; 63.4%) compared to those (22; 27.5%) detected with X-ray (p < 0.001). The average values of the total MRI score of synovitis/edema and erosions in the wrist (p < 0.001) and MCP joints (p < 0.001) were statistically higher in RA than in SSc patients (p < 0.001). The probability of the MRI-detected inflammatory changes was considerably higher in SSc patients who had vascular complications (digital ulceration, OR = 4.68; 95% IP: 1.002−22.25; p < 0.05), in patients with more severe functional impairment (OR = 8.22; 95% IP: 1.74−38.89; p < 0.01), and in patients with active disease (OR = 3.132; 95% IP: 1.027−9.551; p < 0.05). In our investigation, patients with a limited form of the disease and with inflammatory changes on MR more often had higher functional impairment compared to the other group without MRI inflammation. Conclusions: Our data show that in SSc MRI can detect a significant subclinical joint inflammation. RAMRIS confirmed the high degree of joint inflammation in RA, but also revealed a great deal of joint inflammation in SSc. That inflammation is associated with systemic inflammation (disease activity), vascular complications, and more severe forms of the disease, as synovitis cannot be precisely diagnosed by the clinical examination of joints. These results suggest that a careful joint investigation is necessary in SSc, and that in symptomatic patients, MRI may identify joint inflammation. In clinical practice, this evidence might drive to an early targeted therapy, thus preventing joint erosions.

[New clinical applications for low-field magnetic resonance imaging : Technical and physical aspects]

Hintergrund

Die Niederfeld-Magnetresonanztomographie (MRT) erlebt aufgrund technischer Neuerungen eine Renaissance. Die Geräte der neuen Generation bieten neue Anwendungsspektren in der Bildgebung und eine mögliche Antwort auf den steigenden Kostendruck im Gesundheitssystem.

Fragestellung

Einfluss der Feldstärke auf die Technik, Physik, Bildakquisition und die diagnostische Qualität der Untersuchungen.

Material und Methode

Rekapitulation der wichtigen grundlegenden physikalischen Parameter für Bildgewinnung und Qualität. Erste klinische Erfahrungen mit einem neuen 0,55-T-Niederfeldscanner.

Ergebnisse

Niedrigere Feldstärken als die klinisch aktuell verbreiteten 1,5 T und 3 T sind in der Bildgewinnung durch ein zu erwartendes geringeres Signal-zu-Rausch Verhältnis gekennzeichnet. Ob dies eine diagnostische Limitation ist, muss in Studien evaluiert werden, da es verschiedene Optionen gibt, dieses vermeintliche Defizit zu kompensieren. Dies kann durch eine Verlängerung der Akquisitionszeit oder durch Einsatz von Nachverarbeitungsverfahren mit Hilfe der künstlichen Intelligenz (KI) geschehen. Zudem ist zu validieren, in welchen Körperregionen und bei welchen Krankheitsbildern die Bildqualität diagnostisch ausreichend ist. Erste Untersuchungen in unserer Klinik sind vielversprechend und zeigen beispielsweise diagnostische Qualität ohne relevanten Zeitverlust für Untersuchungen der Lendenwirbelsäule. Potenzielle Stärken aufgrund geringerer Suszeptibilitätsartefakte ergeben sich in der Lungenbildgebung oder bei Implantaten.

Schlussfolgerung

Niederfeldscanner bieten eine Vielzahl von neuen Anwendungsfeldern mit feldstärkebedingten Vorteilen. Bei den meisten anderen klinischen Untersuchungsfeldern kann mindestens eine diagnostische Qualität erwartet werden.

Low-Field Magnetic Resonance Imaging: Its History and Renaissance

ABSTRACT

Low-field magnetic resonance imaging (MRI) systems have seen a renaissance recently due to improvements in technology (both hardware and software). Originally, the performance of low-field MRI systems was rated lower than their actual clinical usefulness, and they were viewed as low-cost but poorly performing systems. However, various applications similar to high-field MRI systems (1.5 T and 3 T) have gradually become possible, culminating with high-performance low-field MRI systems and their adaptations now being proposed that have unique advantages over high-field MRI systems in various aspects. This review article describes the physical characteristics of low-field MRI systems and presents both their advantages and disadvantages for clinical use (past to present), along with their cutting-edge clinical applications.

Comparison between 1.5T and 3.0T MRI: both field strengths sensitively detect subclinical inflammation of hand and forefoot in patients with arthralgia

Objective: Magnetic resonance imaging (MRI) of small joints sensitively detects inflammation. This inflammation, and tenosynovitis in particular, has been shown to predict rheumatoid arthritis (RA) development in arthralgia patients. These data have predominantly been acquired on 1.0-1.5 T MRI. However, 3.0 T is now commonly used in practice. Evidence on the comparability of these field strengths is scarce and has never included subtle inflammation in arthralgia patients or tenosynovitis. Therefore, we assessed the comparability of 1.5 T and 3.0 T in detecting subclinical inflammation in arthralgia patients.Method: A total of 2968 locations (joints, bones, tendon sheaths) in the hands and forefeet of 28 patients with small-joint arthralgia, at risk for RA, were imaged on both 1.5 and 3.0 T MRI. Two blinded readers independently scored erosions, osteitis, synovitis, and tenosynovitis, in line with the Rheumatoid Arthritis Magnetic Resonance Imaging Score (RAMRIS). Features were summed into inflammation (osteitis, synovitis, tenosynovitis) and RAMRIS (inflammation and erosions). Agreement was assessed with intraclass correlation coefficients (ICCs) for continuous scores and after dichotomization into presence or absence of inflammation, on patient and location levels.Results: Interreader ICCs were excellent (> 0.90). Comparing 1.5 and 3.0 T revealed an ICC of 0.90 for inflammation and RAMRIS. ICCs for individual inflammation features were: tenosynovitis 0.87 (95% confidence interval 0.74-0.94), synovitis 0.65 (0.24-0.84), and osteitis 0.96 (0.91-0.98). Agreement was 83% for inflammation and 89% for RAMRIS. Analyses on the location level showed similar results.Conclusion: Agreement on subclinical inflammation between 1.5 T and 3.0 T was excellent. Although synovitis scores were slightly different, synovitis often occurs simultaneously with other inflammatory signs, suggesting that scientific results on the predictive value of MRI-detected inflammation for RA, obtained on 1.5 T MRI, can be generalized to 3.0 T MRI.

Methotrexate treatment in hand osteoarthritis refractory to usual treatments: A randomised, double-blind, placebo-controlled trial

OBJECTIVE

To examine the effect of methotrexate (MTX) on pain and structural progression in symptomatic erosive hand osteoarthritis (HOA).

METHODS

This 1-year prospective, single-centre, randomised, double-blind, placebo-controlled study (www.ClinicalTrial.gov, NCT01068405) followed up patients with symptomatic erosive HOA. Patients were randomised into two groups based on the drug that was administered: 10 mg methotrexate (MTX) per week or a placebo. The primary endpoint was the change in pain (determined using a visual analogue scale [VAS]) from baseline to 3 months. The secondary endpoints were pain VAS score at 12 months, clinical features (pain VAS score and function), radiographic features (the anatomical radiographic Verbruggen-Veys [VV] score and Gent University Score System), and magnetic resonance imaging (MRI) at 12 months.

RESULTS

Sixty-four patients with HOA were randomised into either the placebo or MTX group. At 3 months, there was no significant difference in the mean decrease in the pain VAS score (mm) (MTX: 21.1 [standard deviation, 27.4], placebo: 11.7 [24.3]; p = 0.2). At 12 months, according to the VV score, erosive joints progressed significantly more to a remodelling phase in the MTX group than in the placebo group (27% vs 15%; p = 0.03). Joints with space loss appeared to be eroding less in the MTX group compared to the placebo group (8% vs 29%; p = 0.2). Synovitis on MRI at baseline could be associated with the erosive structural evolution of non-erosive joints (p = 0.02).

CONCLUSIONS

Weekly doses of 10-mg MTX showed no superiority over the placebo in terms of pain relief at 3 or 12 months.

CLINICAL TRIAL REGISTRATION NUMBER

This study was registered at www.ClinicalTrial.gov (NCT01068405).

Dynamic Contrast-Enhanced MRI Confirms Rapid And Sustained Improvement Of Rheumatoid Arthritis Induced By Tocilizumab Treatment: An Italian Multicentre Study

Objective

This open-label study evaluated the effects of combined tocilizumab (TCZ) and disease-modifying antirheumatic drugs (DMARDs) on magnetic resonance imaging (MRI) changes in synovial membrane enhancement, bone marrow edema (BME), and erosions in the wrist and hand joints of rheumatoid arthritis (RA) patients inadequately responding to DMARDs alone.

Methods

The efficacy of intravenous TCZ 8 mg/kg administered every four weeks for 48 weeks was evaluated on six occasions. The primary endpoints were the changes in the extent and degree of wrist synovitis as measured using the RA MRI Score (RAMRIS) and dynamic, gadolinium-enhanced 0.2T MRI (DCE-MRI). A number of different parameters of DCE-MRI were evaluated.

Results

Fifty-eight patients were treated, eight of whom (13.8%) discontinued the study prematurely. The mean RAMRIS significantly decreased after two weeks and the decrease was maintained for up to 48 weeks. By week 4, the mean RAMRIS synovitis score had significantly decreased from baseline (−0.804±1.575; p=0.018), but not the mean early enhancement (REE) or relative enhancement (RE). However, there were significant decreases in RE at week 24, in REE and N_total (total number of enhancing voxels)*IRE (initial rate of enhancement) at weeks 12, 24 and 48, and in N_total*ME (maximal enhancement) at weeks 24 and 48. Mean BME decreased from baseline to week 48, and bone erosions did not progress. The patients’ clinical parameters significantly improved from baseline until week 48.

Conclusion

TCZ in combination with DMARDs improved wrist synovitis, BME and clinical parameters, without any progression in bone erosions. The RAMRIS for synovitis rapidly improved from as early as two weeks after the first TCZ infusion. (Funded by F. Hoffmann–La Roche; ACTRACE EudraCT No. 2009 012185-32).

Diagnostic test accuracy of magnetic resonance imaging and ultrasound for detecting bone erosion in patients with rheumatoid arthritis

OBJECTIVE

To evaluate and compare the diagnostic test accuracy of magnetic resonance imaging (MRI) and ultrasound (US) for bone erosion in rheumatoid arthritis (RA) patients for a specific and efficient diagnostic recommendation.

METHOD

To evaluate the diagnostic accuracy, the sensitivity, specificity, area under the summary receiver operating characteristic curve, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio of MRI and US for detecting bone erosion were calculated. Subgroup analyses were conducted to evaluate the performance of these values with different standard references when compared with types of machines and scanning positions.

RESULTS

Data from 26 articles were extracted for calculation. The comprehensive values of sensitivity and specificity were 0.77 (95% CI 0.63, 0.87)/0.89 (95% CI 0.80, 0.95) and 0.61 (95% CI 0.43, 0.77)/0.95 (95% CI 0.88, 0.98) for MRI and US, respectively. The 1.5-T Signa MRI system, General Electric© (sensitivity 0.66; specificity 0.90), and different models of LOGIQ US units and General Electric© (sensitivity 0.66; specificity 0.91) had better diagnostic capability to detect bone erosion, while the 2nd metacarpophalangeal joint (sensitivity 0.70; specificity 0.98) showed the best diagnostic performance among the hand joints with US.

CONCLUSIONS

Neither MRI nor US showed satisfactory diagnostic test accuracy in detecting bone erosion. However, the 1.5-T Signa MRI system, General Electric©, and different models of LOGIQ US units and General Electric© showed similarly good performance in detecting bone erosion in RA patients, while the 2nd metacarpophalangeal joint is the best recommended scanning position during US.

KEY POINTS

• In this study, we evaluated the diagnostic accuracy of US and MRI for bone erosion in RA patients, neither MRI nor US showed perfect diagnostic test accuracy.• 1.5-T Signa system and the LOGIQ units both from General Electric© are the machine types of MRI and US with the greatest performance, respectively.• The 2nd MCP joint is the scanning position recommended during US test.• Different reference standards will greatly influence the judgment of the results.

Potential clinical utility of a novel optical tomographic imaging for the quantitative assessment of hand rheumatoid arthritis

Optical tomographic imaging (OTI) was reported to be a novel technique for the early diagnosis and disease activity assessment of rheumatoid arthritis (RA). This study aimed to evaluate the clinical utility of OTI for the detection of hand synovitis of RA patients. Manu-scan was used to perform imaging targeting the proximal interphalangeal (PIP) and metacarpophalangeal (MCP) joints in 12 RA patients and three controls. The enrolled RA patients also underwent magnetic resonance imaging (MRI) and bone scintigraphy (BS) to provide reference images. Of the 181 joints feasible for OTI analysis, 140 joints (111 in RA patients and 29 in controls, 77.3%) in which the difference of the OTI indices in the two measurements was within 20% were evaluated. The OTI indices in RA joints were significantly lower than those in control joints (p < 0.001). Overall, the OTI indices in RA joints decreased as the synovitis grades on MRI or BS increased. Moreover, OTI was able to discriminate between RA and control joints (AUC = 0.815, 95% CI 0.739-0.891), even if RA joints were normal on physical examination (AUC = 0.714, 95% CI 0.594-0.834). OTI was in good agreement (kappa = 0.60) with MRI for evaluating synovitis in RA patients and showed positive results in 11.4% of clinically asymptomatic joints. OTI in this study showed the potential to be a supplementary imaging modality for the quantification of synovial inflammation in PIP and MCP joints of RA patients. Further large-scale trials are needed to confirm these findings.

MR and ultrasound of the hands and wrists in rheumatoid arthritis. Part II. Added clinical value

Advanced imaging has become just as vital for diagnosing, staging, and monitoring disease in rheumatoid arthritis (RA) patients as it is for cancer patients. Part 1 of this review discussed synovitis, tenosynovitis, erosions, and osteitis-key imaging findings that occur in patients with RA. Part 2 will now show how these features, in combination with clinical and serologic data, can assist clinical decision-making at various stages of a patient's disease course. Specifically, assessing current disease activity and prognosticating future aggressiveness inform treatment decisions at initial presentation, during medical treatment, and at clinical remission. In addition to summarizing the current literature on advanced imaging in RA, clinical examples from different stages throughout the disease course will illustrate practical approaches for applying these research results. Last, this review will describe potential future roles of imaging in RA patients.

MRI and ultrasound of the hands and wrists in rheumatoid arthritis. I. Imaging findings

The management of patients with rheumatoid arthritis (RA) has rapidly evolved with the development of newer disease-modifying drugs and the recognition that long-term damage can be mitigated by an earlier and more-informed use of these medications. Historically, radiographs were the mainstay of imaging in RA patients, but radiographic joint narrowing and erosions are late and insensitive findings in the disease. MRI (with intravenous contrast agent) and ultrasound (with power Doppler interrogation) of the hands and wrists are able to demonstrate erosions earlier and with greater sensitivity than radiographs. More importantly, these imaging studies also depict synovitis and active soft-tissue inflammation, which represents a precursor to structural damage. Additionally, MRI can show inflammation within the bones (osteitis), which is proving to be the most important prognosticator of an aggressive disease course. Part I of this review discusses the imaging techniques, pitfalls, definitions, and comparative studies of MRI and ultrasound for identifying and quantifying erosions, synovitis, and osteitis. Part II will demonstrate how these imaging findings influence the clinical management of RA patients throughout their disease course, from presentation through clinical remission.

The value of the simplified RAMRIS-5 in early RA patients under methotrexate therapy using high-field MRI

BACKGROUND

The aim of the study was to evaluate a simplified version of the Rheumatoid Arthritis Magnetic Resonance Imaging Score (RAMRIS) for five joints of the hand (RAMRIS-5) in patients with early rheumatoid arthritis (RA) before and after the initiation of methotrexate (MTX) therapy using high-resolution, 3-T magnetic resonance imaging (MRI).

METHODS

Twenty-eight patients with a seropositive, early RA (disease duration of less than 6 months (range 2-23 weeks)) according to 2010 American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) criteria (mean age 56.8 years, range 39-74) were prospectively assessed with a baseline investigation including clinical assessment (disease activity score of 28 joints (DAS-28) and C-reactive protein (CRP)) and 3-T MRI of the clinically dominant hand. Follow-up visits were performed 3 and 6 months after initiation of a MTX therapy at baseline. MRI scans were analyzed in accordance with RAMRIS and the simplified RAMRIS-5.

RESULTS

DAS-28 and CRP decreased significantly after initiation of MTX therapy. Even though erosion scores increased over time, RAMRIS and RAMRIS-5 also decreased significantly after the start of therapy. There was a strong correlation between the total RAMRIS-5 and RAMRIS at baseline (r = 0.838; P <0.001) and follow-up (3 months: r = 0.876; P <0.001; 6 months: r = 0.897; P <0.001). In the short term (3-month follow-up), RAMRIS and RAMRIS-5 demonstrated similar ability to detect changes for all subgroups (bone edema, erosion, and synovitis). In the long-term comparison (6-month follow-up), RAMRIS-5 also showed similar effectiveness when detecting changes in bone edema and erosion compared with RAMRIS. Deviations occurred regarding only synovitis, where change was slightly higher in RAMRIS-5: SRM (RAMRIS) = 0.07 ± 0.14; SRM (RAMRIS-5) = 0.34 ± 0.06.

CONCLUSIONS

Three-Tesla MRI-based RAMRIS-5 is a simplified and resource-saving RAMRIS score which compares favorably with the RAMRIS when detecting changes in early RA. Even though there is a slight abbreviation between RAMRIS-5 and the original score regarding the change of synovitis, it may be used for diagnosis and therapy monitoring in follow-up evaluations.

MRI of synovitis and joint fluid

Synovitis and joint effusion are common manifestations of rheumatic disease and play an important role in the disease pathophysiology. Earlier detection and accurate assessment of synovial pathology, therefore, can facilitate appropriate clinical management and hence improve prognosis. Magnetic resonance imaging (MRI) allows unparalleled assessment of all joint structures and associated pathology. It has emerged as a powerful tool, which enables not only detection of synovitis and effusion, but also allows quantification, detailed characterization, and noninvasive monitoring of synovial processes. The purpose of this article is to summarize the pathophysiology of synovitis and to review the role of qualitative, semiquantitative, and quantitative MRI in the assessment of synovitis and joint fluid. We also discuss the utility of MRI as an outcome measure to assess treatment response, particularly with respect to osteoarthritis and rheumatoid arthritis. Emerging applications such as hybrid positron emission tomography / MRI and molecular imaging are also briefly discussed. Level of Evidence: 5 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019.

The application value of MRI in the diagnosis of subclinical inflammation in patients with rheumatoid arthritis in remission

Background

To explore the value of MRI in the diagnosis of subclinical inflammation in patients with early rheumatoid arthritis (RA) in remission and to predict the radiographic progression.

Methods

A total of 76 of 156 patients with early RA in remission at 1 year and with available magnetic resonance imaging (MRI) data at baseline and at 12 months were included. Complete clinical and laboratory evaluations were conducted for the patients. MRI images were assessed according to the Rheumatoid Arthritis Magnetic Resonance Imaging Scoring (RAMRIS) system. Progression of bone erosions was defined as an increase of 1 or more units in annual RAMRIS score for erosions compared to baseline.

Results

At 1 year, the majority of patients with RA in sustained remission showed some inflammatory activity on MRI (43.4% synovitis, 39.5% bone marrow edema (BME), and 9.2% tenosynovitis), and 25 of the 76 patients (32.9%) showed MRI progression of bone erosions. A significant difference was observed in MRI BME and bone erosion at 1 year, with higher mean score in patients with progression compared to non-progression of erosions (BME, 4.8 ± 3.6 vs 3.1 ± 2.1, P = 0.01; bone erosion, 13.5 ± 9.6 vs 4.4 ± 3.6, P < 0.001).

Conclusion

Persistent subclinical inflammations were shown in patients with sustained remission; BME in MRI may be a strong predictor of future radiographic progression of bone erosions in patients with persistent clinical remission.

Magnetic Resonance Imaging of Bilateral Hands Is More Optimal Than MRI of Unilateral Hands for Rheumatoid Arthritis

OBJECTIVE

To explore the advantages of magnetic resonance imaging (MRI) of bilateral hands in rheumatoid arthritis (RA).

METHODS

Consecutive patients with active RA were recruited for clinical assessments, radiographs, and MRI of bilateral hands. Bilateral hands were scanned simultaneously on 3.0 T whole-body MRI system and were scored on synovitis, osteitis, and bone erosion according to the RA MRI scoring (RAMRIS) system.

RESULTS

Among 120 patients included, wrist bones and metacarpophalangeal joint (MCPJ) 2 proximal showed bone erosion in early RA. The second to fifth metacarpal bases and the second to fourth MCPJ distal showed more bone erosion in mid-stage or late-stage RA. When MRI of dominant unilateral hand was analyzed, MRI synovitis and osteitis in 5% of wrists and 3 MRI features in 5-14% of MCPJ were misdiagnosed (McNemar test, all p < 0.05). There were 46% wrist synovitis, 29-52% MCPJ2-5 synovitis, 45% wrist osteitis, and 20%-34% MCPJ2-5 osteitis not detected by joint tenderness and/or swelling. When the clinically more severe hand was selected for MRI of unilateral hand according to physical examination, MRI synovitis in 5% of wrists and 3 MRI features in 7-15% of MCPJ were misdiagnosed (all p < 0.05). Scatter plots and linear regression analyses were used to illustrate RAMRIS between dominant or selected hand (Y values) and nondominant or nonselected hand (X values). All linear models were markedly different from a Y = X linear model, indicating the dominant or clinically more severe hand could not represent the contralateral hand to evaluate RAMRIS.

CONCLUSION

MRI of bilateral hands is more optimal than MRI of the unilateral hand in RA.

Silent progression in patients with rheumatoid arthritis: is DAS28 remission an insufficient goal in RA? Results from the German Remission-plus cohort

BACKGROUND

Remission is arguably the ultimate therapeutic goal in rheumatoid arthritis (RA). Applying modern strategies, clinical remission can be achieved in a substantial number of patients with early RA (ERA). Even in those patients, the number and scope of erosions can increase. We, therefore, investigated the value of MRI for the detection of radiological progression in patients with DAS28 improvement and/or clinical remission of the German Remission-plus cohort.

METHODS

Data-sets of 80 RA patients (according to 2010 ACR/EULAR criteria) from the Remission-plus study cohort, who fulfilled the following criteria, were retrospectively analysed: availability of two consecutive MRI scans (low-field MRI, follow-up interval 1 year) of the clinically dominant hand and wrist, and the presence of DAS28 (CRP) scores at both time points, which was used to assess disease activity.

RESULTS

Seventy-one of the 80 investigated patients presented a numerical improvement of the DAS28 (CRP) after 12 months (DAS28(CRP) T0 average (Ø) 4.96, SD 1.2; DAS28 T4 (12 month) Ø 2.6, SD 1.0), 73% of them also improved in the RAMRIS-Score, while 24% demonstrated an increase despite DAS28 improvement and 3% showed equal values. 48% of patients who improved in the DAS28 reached EULAR remission. 41% of these patients had an increase in the RAMRIS Erosion-subscore after 12 months. When considering EULAR response criteria (non-response (n = 7), moderate response (n = 19), good response (n = 45)), an increase of erosions was found in 71.4% of non-responders, 52.6% of moderate responders, and 31.1% of good responders after 12 months, all compared to baseline.

CONCLUSION

Up to 40% of patients in this study demonstrated a progressive erosive disease detected by MRI despite DAS28 improvement or EULAR remission. Future studies are needed to determine the prognostic clinical impact of disease progression in MRI despite clinical remission, and to investigate if DAS28 remission may be an insufficient therapeutic goal and should be accompanied by MRI remission criteria.

Selected issues in diagnostic imaging of spondyloarthritides: psoriatic arthritis and juvenile spondyloarthritis

Spondyloarthritides (also known as spondyloarthropathies) are a group of rheumatic diseases that consists of diversified entities, i.e. ankylosing spondylitis, reactive arthritis, psoriatic arthritis, arthritis in the course of Crohn's disease and ulcerative colitis, and juvenile spondyloarthropathies. In the diagnostics of spondyloarthritides, plain radiography has played a crucial role for years due to its undisputed ability to show distinctive bony changes. Yet as those diseases often manifest themselves by soft tissue pathology and bone marrow inflammation, ultrasonography and magnetic resonance imaging are currently a subject of numerous studies in the quest for setting up diagnostic criteria, especially at early stages of inflammatory processes. In our review, we present an up-to-date insight into classifications, etiopathogenesis and imaging of psoriatic arthritis and juvenile spondyloarthritis.

Recommendations for the use of ultrasound and magnetic resonance in patients with rheumatoid arthritis

OBJECTIVE

To develop evidence-based recommendations on the use of ultrasound (US) and magnetic resonance imaging (MRI) in patients with rheumatoid arthritis (RA).

METHODS

Recommendations were generated following a nominal group technique. A panel of experts, consisting of 15 rheumatologists and 3 radiologists, was established in the first panel meeting to define the scope and purpose of the consensus document, as well as chapters, potential recommendations and systematic literature reviews (we used and updated those from previous EULAR documents). A first draft of recommendations and text was generated. Then, an electronic Delphi process (2 rounds) was carried out. Recommendations were voted from 1 (total disagreement) to 10 (total agreement). We defined agreement if at least 70% of experts voted ≥7. The level of evidence and grade or recommendation was assessed using the Oxford Centre for Evidence-based Medicine Levels of Evidence. The full text was circulated and reviewed by the panel. The consensus was coordinated by an expert methodologist.

RESULTS

A total of 20 recommendations were proposed. They include the validity of US and MRI regarding inflammation and damage detection, diagnosis, prediction (structural damage progression, flare, treatment response, etc.), monitoring and the use of US guided injections/biopsies.

CONCLUSIONS

These recommendations will help clinicians use US and MRI in RA patients.

Diagnostic imaging of psoriatic arthritis. Part II: magnetic resonance imaging and ultrasonography

Plain radiography reveals specific, yet late changes of advanced psoriatic arthritis. Early inflammatory changes are seen both on magnetic resonance imaging and ultrasound within peripheral joints (arthritis, synovitis), tendons sheaths (tenosynovitis, tendovaginitis) and entheses (enthesitis, enthesopathy). In addition, magnetic resonance imaging enables the assessment of inflammatory features in the sacroiliac joints (sacroiliitis), and the spine (spondylitis). In this article, we review current opinions on the diagnostics of some selective, and distinctive features of psoriatic arthritis concerning magnetic resonance imaging and ultrasound and present some hypotheses on psoriatic arthritis etiopathogenesis, which have been studied with the use of magnetic resonance imaging. The following elements of the psoriatic arthritis are discussed: enthesitis, extracapsular inflammation, dactylitis, distal interphalangeal joint and nail disease, and the ability of magnetic resonance imaging to differentiate undifferentiated arthritis, the value of whole-body magnetic resonance imaging and dynamic contrast-enhanced magnetic resonance imaging.

Noninvasively measuring oxygen saturation of human finger-joint vessels by multi-transducer functional photoacoustic tomography

Imaging small blood vessels and measuring their functional information in finger joint are still challenges for clinical imaging modalities. In this study, we developed a multi-transducer functional photoacoustic tomography (PAT) system and successfully imaged human finger-joint vessels from ∼1  mm to <0.2  mm in diameter. In addition, the oxygen saturation (SO2) values of these vessels were also measured. Our results demonstrate that PAT can provide both anatomical and functional information of individual finger-joint vessels with different sizes, which might help the study of finger-joint diseases, such as rheumatoid arthritis.

Minimum Field Strength Simulator for Proton Density Weighted MRI

OBJECTIVE

To develop and evaluate a framework for simulating low-field proton-density weighted MRI acquisitions based on high-field acquisitions, which could be used to predict the minimum B0 field strength requirements for MRI techniques. This framework would be particularly useful in the evaluation of de-noising and constrained reconstruction techniques.

MATERIALS AND METHODS

Given MRI raw data, lower field MRI acquisitions can be simulated based on the signal and noise scaling with field strength. Certain assumptions are imposed for the simulation and their validity is discussed. A validation experiment was performed using a standard resolution phantom imaged at 0.35 T, 1.5 T, 3 T, and 7 T. This framework was then applied to two sample proton-density weighted MRI applications that demonstrated estimation of minimum field strength requirements: real-time upper airway imaging and liver proton-density fat fraction measurement.

RESULTS

The phantom experiment showed good agreement between simulated and measured images. The SNR difference between simulated and measured was ≤ 8% for the 1.5T, 3T, and 7T cases which utilized scanners with the same geometry and from the same vendor. The measured SNR at 0.35T was 1.8- to 2.5-fold less than predicted likely due to unaccounted differences in the RF receive chain. The predicted minimum field strength requirements for the two sample applications were 0.2 T and 0.3 T, respectively.

CONCLUSIONS

Under certain assumptions, low-field MRI acquisitions can be simulated from high-field MRI data. This enables prediction of the minimum field strength requirements for a broad range of MRI techniques.

Dynamic contrast-enhanced imaging of the wrist in rheumatoid arthritis: dedicated low-field (0.25-T) versus high-field (3.0-T) MRI

OBJECTIVE

To compare the assessment of wrist synovitis severity, synovial volume and synovial perfusion parameters on a dedicated low-field (0.25-T) to that of a high-field (3-T) whole-body MR system in patients with rheumatoid arthritis (RA).

METHODS

Twenty-one patients (mean age 50.0 ± 9.8 years) with active RA were recruited prospectively. Dynamic contrast-enhanced MRI examination of the most severely affected wrist was performed at both 0.25 T and 3 T. Three MRI-derived parameters, synovitis severity (RAMRIS grade), synovial volume (ml(3)) and synovial perfusion indices (maximum enhancement and enhancement slope), were compared.

RESULTS

Comparing 0.25- and 3-T MRI, there was excellent agreement for semiquantitative assessment (r: 0.80, p < 0.00001) of synovitis (RAMRIS) as well as quantitative assessment (r: 0.94, p < 0.00001) of synovial volume. Good agreement for synovial Emax (r: 0.6, p = 0.002) and fair agreement (r: 0.5, p = 0.02) for synovial Eslope was found.

CONCLUSIONS

Imaging of the RA wrist at 0.25 T yields excellent correlation with 3 T with regard to the synovitis activity score (RAMRIS) and synovial volume measurement. Fair to good correlation between low- (0.25-T) and high-field (3-T) MR systems was found for perfusion parameters, being better for Emax than for Eslope.

Near-infrared Fluorescence Optical Imaging in Early Rheumatoid Arthritis: A Comparison to Magnetic Resonance Imaging and Ultrasonography

OBJECTIVE

Near-infrared fluorescence optical imaging (FOI) is a novel imaging technology in the detection and evaluation of different arthritides. FOI was validated in comparison to magnetic resonance imaging (MRI), greyscale ultrasonography (GSUS), and power Doppler ultrasonography (PDUS) in patients with early rheumatoid arthritis (RA).

METHODS

Hands of 31 patients with early RA were examined by FOI, MRI, and US. In each modality, synovitis of the wrist, metacarpophalangeal joints (MCP) 2-5, and proximal interphalangeal joints (PIP) 2-5 were scored on a 4-point scale (0-3). Sensitivity and specificity of FOI were analyzed in comparison to MRI and US as reference methods, differentiating between 3 phases of FOI enhancement (P1-3). Intraclass correlation coefficients (ICC) were calculated to evaluate the agreement of FOI with MRI and US.

RESULTS

A total of 279 joints (31 wrists, 124 MCP and 124 PIP joints) were evaluated. With MRI as the reference method, overall sensitivity/specificity of FOI was 0.81/0.00, 0.49/0.84, and 0.86/0.38 for wrist, MCP, and PIP joints, respectively. Under application of PDUS as reference, sensitivity was even higher, while specificity turned out to be low, except for MCP joints (0.88/0.15, 0.81/0.76, and 1.00/0.27, respectively). P2 appears to be the most sensitive FOI phase, while P1 showed the highest specificity. The best agreement of FOI was shown for PDUS, especially with regard to MCP and PIP joints (ICC of 0.57 and 0.53, respectively), while correlation with MRI was slightly lower.

CONCLUSION

FOI remains an interesting diagnostic tool for patients with early RA, although this study revealed limitations concerning the detection of synovitis. Further research is needed to evaluate its full diagnostic potential in rheumatic diseases.

Low-field magnetic resonance imaging or combined ultrasonography and anti-cyclic citrullinated peptide antibody improve correct classification of individuals as established rheumatoid arthritis: results of a population-based, cross-sectional study

BACKGROUND

The aim of the present study was to evaluate the accuracy of two approaches using magnetic resonance imaging (MRI) or combined ultrasonography (US) and anti-cyclic citrullinated peptide antibody (ACPA) for diagnosis and classification of individuals with established rheumatoid arthritis (RA).

METHODS

In 53 individuals from a population-based, cross-sectional study, historic fulfilment of the American College of Rheumatology (ACR) 1987 criteria ("classification") or RA diagnosed by a rheumatologist ("diagnosis") were used as standard references. The sensitivity, specificity and Area under Curve for Receiver Operating Characteristics curves (ROC-area: (sensitivity + specificity)/2) were calculated for "current fulfilment of the ACR 1987 criteria" (list format), "adapted ACR 1987 criteria" (list format, substituting IgM rheumatoid factor with ACPA and clinical joint swelling and erosions on radiography with synovitis and erosions detected by US on a semi-quantitative scale), and RA MRI scoring System (RAMRIS) scores on low-field MRI in the unilateral hand.

RESULTS

For the ACR 1987 criteria the ROC-area was 75% (sensitivity/specificity = 50%/100%) (with "classification" as standard reference) and 69% (44%/94%) (with "diagnosis" as standard reference), while for the adapted ACR 1987 criteria it was 86% (75%/97%) (classification) and 82% (72%/91%) (diagnosis). For RAMRIS synovitis score in metacarpophalangeal (MCP) joints only (cut-off ≥5), the ROC-area (sensitivity/specificity) was 78% (62%/94%) (classification) and 85% (69%/100%) (diagnosis), while for the total synovitis score of MCP joints plus wrist (cut-off ≥10) it was 78% (62%/94%) (both classification and diagnosis).

CONCLUSIONS

Compared with the ACR 1987 criteria, low-field MRI alone or adapted criteria incorporating US and ACPA increased the correct classification and diagnosis of RA.

Insights into rheumatoid arthritis from use of MRI

Magnetic resonance imaging (MRI) is ideal for imaging the joints of rheumatoid arthritis (RA) patients. It produces anatomically detailed images of bone, cartilage, tendons and synovial membrane. It can reveal structural damage, in the form of bone erosion, cartilage thinning and/or tendon rupture, and regions of inflammation, using sequences that reveal water content and vascularity. MRI synovitis, tenosynovitis and bone oedema/osteitis all have prognostic significance, and MRI studies of RA have helped elucidate the mechanisms whereby bone and synovial inflammation lead to joint damage. Bone oedema/osteitis has become an important imaging biomarker, and can be used to help predict progression from undifferentiated arthritis to definite RA. Recent MRI studies have confirmed that subclinical inflammation is often present in patients in clinical remission, and these data may affect disease management. Finally, recent clinical trials are reviewed, in which MRI outcome measures are being established as sensitive response markers.

MRI in rheumatoid arthritis: a useful tool for the clinician?

Over the last two decades, MRI has emerged as an important clinical tool to assist in the diagnosis and management of rheumatic disease. In rheumatoid arthritis (RA), MRI has improved our understanding of the pathological basis of disease and has provided new information about imaging features that reflect joint inflammation and damage. Using MRI, we can now directly observe inflammation involving the synovial membrane and tenosynovium, plus joint damage including bone erosion and cartilage thinning. Inflammation of bone beneath the joint (osteitis) appears as bone oedema which is a feature unique to MRI and yields important diagnostic and prognostic information in patients with inflammatory arthritis. With the introduction of biologics to rheumatology clinical practice, sensitive tools are required to monitor disease activity and progression, so that the disease suppressing effect of these new agents can be measured. MRI fits the bill for this role as it can inform the clinician about the development of bone erosions well before plain radiography, and its ability to reveal cartilage damage is emerging. The use of MRI as a marker of outcome in clinical trials is being paralleled by its increasing role in the clinic. Both extremity and high field MRI have clinical applications in RA and need to be considered along with other advanced imaging techniques as useful tools to add to the clinician's armamentarium. This review will summarise recent advances in this field and will apply current knowledge to specific clinical scenarios relevant to modern rheumatology practice.

Bone marrow oedema assessment by magnetic resonance imaging in rheumatoid arthritis wrist and metacarpophalangeal joints: the importance of field strength, coil type and image resolution

OBJECTIVE

The aim of this study was to examine the influence of different MRI unit field strengths, coil types and image resolutions on the OMERACT RA MRI scoring system (RAMRIS) of bone marrow oedema (BME) and image quality.

METHODS

Forty-one patients and 12 healthy controls participated in this cross-sectional study. Coronal short tau inversion recovery (STIR) and T1-weighted sequences were obtained at 0.23, 0.6, 1.5 and 3T using flex coils (Flex). Additional STIR sequences were obtained with phased array extremity coils (Extr) (at 0.6 and 1.5T) and higher resolution (at 1.5T). In otal, 338 STIR image sets were anonymized and scored according to RAMRIS and parameters of image quality were measured.

RESULTS

The BME sum scores were similar overall when comparing the different MRI units, coil types and voxel sizes, yet significantly higher at the higher resolution of 1.5T Extr compared with 0.23T Flex (P = 0.004), 0.6T Flex (P = 0.03), 1.5T Flex (P = 0.05) and 3T Flex (P = 0.001). Mean differences were relatively minor (0-3.5). Intrareader reliability of BME scores was high [intraclass correlation coefficient ≥ 0.90 for all except 0.23T (0.81) and percentage exact agreement 81-88%]. The smallest detectable difference was better at 0.6, 1.5 and 3T (9-29% of maximum value) than at 0.23T (40%). Image quality was lowest at 0.23T.

CONCLUSION

No major, consistent differences were found between BME scores using STIR sequences obtained at different field strengths, coil types and image resolutions, suggesting that these are equally suited for assessment of BME in RA. However, parameters of image quality and intrareader reliability (favouring 0.6, 1.5 and 3T) should be considered when selecting the MRI acquisition strategy.

Characteristics of geometric distortion correction with increasing field-of-view in open-configuration MRI

Open-configuration magnetic resonance imaging (MRI) systems are becoming increasingly desirable for musculoskeletal imaging and image-guided radiotherapy because of their non-claustrophobic configuration. However, geometric image distortion in large fields-of-view (FOV) due to field inhomogeneity and gradient nonlinearity hinders the practical applications of open-type MRI. We demonstrated the use of geometric distortion correction for increasing FOV in open MRI. Geometric distortion was modeled and corrected as a global polynomial function. The appropriate polynomial order was identified as the minimum difference between the coordinates of control points in the distorted MR image space and those predicted by polynomial modeling. The sixth order polynomial function was found to give the optimal value for geometric distortion correction. The area of maximum distortion was<1 pixel with an FOV of 285mm. The correction performance error was increased at most 1.2% and 2.9% for FOVs of 340mm and~400mm compared with the FOV of 285mm. In particular, unresolved distortion was generated by local deformation near the gradient coil center.

Feasibility and reproducibility of the PsAMRIS-H score for psoriatic arthritis in low-field-strength dedicated extremity magnetic resonance imaging

OBJECTIVES

The psoriatic arthritis magnetic resonance imaging scoring system (PsAMRIS-H) for the evaluation of inflammatory and destructive changes in PsA hands was validated on 0.6-T scanners. The applicability of the PsAMRIS-H on a low-field MRI system as a well-accepted, low-cost imaging modality was evaluated.

METHOD

In 65 consecutive patients (31 males, median age 52 years), 73 scans on a 0.2-T dedicated extremity MRI system were obtained for evaluation of PsA. Images were scored for synovitis, tenosynovitis, periarticular enhancement, bone erosion, bone oedema, and proliferation, and the PsAMRIS-H score was calculated. The intraclass correlation coefficient (ICC) was calculated and the paired t-test conducted.

RESULTS

Intra-reader reliability for the total PsAMRIS-H score was good, with an ICC of 0.81 and 0.77 for readers 1 and 2, respectively, and inter-reader agreement was moderate (0.57 for each reader). However, the PsAMRIS-H score differed significantly between the two readers (22 vs. 31; p < 0.05). When individual components of the PsAMRIS were evaluated, intra- and inter-reader agreement was poor to moderate, especially for tenosynovitis and periarticular inflammation.

CONCLUSIONS

Low-field 0.2-T MRI is capable of quantifying the PsAMRIS-H with good intra-reader reproducibility. However, low signal-to-noise ratio (SNR), low spatial resolution, and system artefacts limit the application of the PsAMRIS-H, leading to low inter- and intra-reader agreement for individual features.

MRI and ultrasonography for diagnosis and monitoring of psoriatic arthritis

Imaging techniques such as magnetic resonance imaging (MRI) and ultrasound (US) have been increasingly used in psoriatic arthritis (PsA) providing additional clues to the pathogenesis of this peripheral, axial and dermatologic disease. This has improved our understanding of the disease and can be used to aid diagnosis and then to follow outcomes of treatment. Both imaging modalities have highlighted the differing involvement of PsA when compared with rheumatoid arthritis (RA) with a significant burden of entheseal disease, flexor tenosynovitis (occurring alone or as part of dactylitis) and other extra-capsular inflammatory changes. MRI scanning has also highlighted the link between the nail and the distal interphalangeal (DIP) joint confirming previous clinical observations. Imaging studies in psoriasis patients have discovered a high level of subclinical inflammatory change but the clinical importance of such findings has not yet been defined. The potential use of MRI and US to monitor treatment outcomes has encouraged research in this field. In MRI, the PsA MRI Score (PsAMRIS) has been developed with promising initial validation. In US, work is ongoing with the OMERACT group to define key pathologies and to develop scoring systems. A few scoring systems are available for enthesitis scoring using US which are further being developed and refined. Further improvements in technologies in both of these fields offer exciting possibilities for future research. New MRI techniques offer the chance to image previously 'dark' structures such as tendons which is key in spondyloarthritides (SpA). Sonoelastography may also improve our understanding of tendon involvement in SpA. Whole-body multi-joint MRI allows a 'snapshot' of inflammation in PsA including joints, entheses and spinal involvement. Three-dimensional US should improve reliability and comparability of US scoring reducing inter-operator variability. The latest machines offer real-time fusion imaging employing US machines with an in-built virtual navigator system linked to previous MRI acquisitions. All of these new techniques should aid our understanding of PsA and our ability to objectively measure response to therapy.

Low-field magnetic resonance imaging study on carpal arthritis in systemic sclerosis--low-grade erosive arthritis of carpal bones is an unexpected and frequent disease manifestation

Introduction

The aim of the present study was to assess the prevalence and characteristics of subclinical arthritis of carpal and metacarpophalangeal joints in patients with systemic sclerosis (SSc).

Methods

Low-field (0.2 T) magnetic resonance imaging (MRI) was performed in consecutive patients with SSc attending our center between January 2010 and March 2011. Results were assessed in a standardized manner using the Rheumatoid Arthritis Magnetic Resonance Imaging Score (RAMRIS) and standardized assessments of all hand joints. Patients with arthritis due to overlap syndromes were excluded.

Results

Of 38 inpatients and eight outpatients who were screened for inclusion, 30 patients participated in the study and 26 patients could be evaluated. Erosions, bone marrow edema, synovitis, and joint effusions were found in 87%, 37%, 68%, and 58%, respectively, and 24% of patients had additional tenovaginitis. Arthritis affected only a low number of joints per analyzed hand. All bones and joints could be affected, but synovitis and bone marrow edema occurred predominantly in the proximal row of carpal bones, most frequently affecting the lunate bone. The extent of inflammatory changes measured with the RAMRIS correlated significantly with the functional status assessed with the validated German functional score questionnaire Funktionsfragebogen Hannover.

Conclusion

Low-grade arthritic changes on low-field MRI are frequent in patients with pure SSc. The features of arthritis in SSc differ from rheumatoid arthritis. The distribution, the MRI pattern and the predilection for the lunate bone raise the hypothesis that arthritis in SSc may be caused not only by immunological inflammation but also by ischemic mechanisms.

Diagnosis of osteoarthritis and prognosis of tibial cartilage loss by quantification of tibia trabecular bone from MRI

A longitudinal study was used to investigate the quantification of osteoarthritis and prediction of tibial cartilage loss by analysis of the tibia trabecular bone from magnetic resonance images of knees. The Kellgren Lawrence (KL) grades were determined by radiologists and the levels of cartilage loss were assessed by a segmentation process. Aiming to quantify and potentially capture the structure of the trabecular bone anatomy, a machine learning approach used a set of texture features for training a classifier to recognize the trabecular bone of a knee with radiographic osteoarthritis. Using cross-validation, the bone structure marker was used to estimate for each knee both the probability of having radiographic osteoarthritis (KL >1) and the probability of rapid cartilage volume loss. The diagnostic ability reached a median area under the receiver-operator-characteristics curve of 0.92 (P < 0.0001), and the prognosis had odds ratio of 3.9 (95% confidence interval: 2.4-6.5). The medians of cartilage loss of the subjects classified as slow and rapid progressors were 1.1% and 4.9% per year, respectively. A preliminary radiological reading of the high and low risk knees put forward an hypothesis of which pathologies the bone marker could be capturing to define the prognosis of cartilage loss.

Current imaging strategies in rheumatoid arthritis

As remission has now become a realistic therapeutic goal in the clinical management of RA due to the introduction and widespread adoption of biologic agents, there is a greater need for earlier diagnoses and objective methods for evaluating disease activity and response to treatment. In this capacity, advanced imaging strategies are assuming an expansive clinical role, particularly as they take advantage of newer imaging technologies and the shift toward imaging at the molecular level. Molecular imaging utilizes target-specific probes to non-invasively visualize molecular, cellular, and physiological perturbations in response to the underlying pathology. Probes for nuclear and MR imaging have been and are being developed that react with discrete aspects of inflammatory and destructive pathways specific to RA. These probes in addition to new MR sequences and contrast agents have the potential to provide an earlier and more reliable assessment of clinical outcome, disease activity, severity, and location, and therapeutic response. Furthermore, these imaging strategies may enable a more fundamental understanding of critical pathophysiological processes and the advent of new molecular therapies. This review will discuss these advances in both nuclear medicine and MRI strategies for imaging RA with a particular emphasis on molecular imaging.

Bone edema on magnetic resonance imaging is an independent predictor of rheumatoid arthritis development in patients with early undifferentiated arthritis

OBJECTIVE

To study magnetic resonance imaging (MRI) as a tool for early diagnosis of rheumatoid arthritis (RA) in patients with early undifferentiated arthritis (UA).

METHODS

Patients (n = 116) without a specific rheumatologic diagnosis, but with ≥2 tender joints and/or ≥2 swollen joints among the metacarpophalangeal, proximal interphalangeal, wrist, or metatarsophalangeal (MTP) joints for >6 weeks but <24 months, underwent clinical, biochemical, conventional radiographic, and MRI examinations and were followed up for >12 months for the final diagnosis of RA or non-RA. Based on univariate analyses, clinical, biochemical, and imaging parameters were selected for inclusion as explanatory variables in multiple logistic regression analysis, with development of RA as the dependent variable. A prediction model was developed, and its performance was tested and compared with that of a previous model developed by van der Helm-van Mil et al (the vdHvM model).

RESULTS

Of the 116 patients with early UA, 27 (23.3%) developed RA. When the prediction model was applied, which included as explanatory variables presence of hand arthritis, positivity for rheumatoid factor (RF), morning stiffness lasting >1 hour, and the Outcome Measures in Rheumatology Clinical Trials MRI summary score for bone edema in the MTP and wrist joints, the outcome of RA or non-RA was correctly identified in 82% of the patients (sensitivity 81%, specificity 82%). Another cutoff value for the prediction index in the model would allow a higher specificity (98%) and higher accuracy (83%), but lower sensitivity (36%). With the vdHvM model, RA/non-RA was predicted in 60.2% of the population.

CONCLUSION

MRI evidence of bone edema in the MTP and wrist joints is an independent predictor of future RA in patients with early UA. A prediction model that includes the variables clinical hand arthritis, morning stiffness, positivity for RF, and bone edema on MRI in the MTP and wrist joints correctly identified the development or lack of development of RA in 82% of patients.