Quantitative assessment of the rheumatoid synovial microvascular bed by gadolinium-DTPA enhanced magnetic resonance imaging

Spectrum of Hand Arthritis

Early diagnosis of arthritis is of paramount importance to slow the progression of disease and joint destruction. Because of temporal dissemination of the clinical and laboratory manifestations of the inflammatory arthritis and overlap of the findings, diagnosis can be challenging in early stages of the disease. This article highlights the utility of advanced cross-sectional imaging, including color-Doppler ultrasound, diffusion-weighted MR imaging, and perfusion MR imaging in the domain of arthropathy so that the reader can apply these principles and techniques in their practices for timely and accurate diagnosis and improved multidisciplinary communications for better management of such conditions.

MR Imaging of Rheumatic Diseases Affecting the Pediatric Population

This article reviews the application of magnetic resonance imaging (MRI) to pediatric rheumatic diseases. MRI can detect early manifestations of arthritis, evaluate the extent of disease, and monitor disease activity and response to treatment.Juvenile idiopathic arthritis (JIA) is the most common pediatric rheumatic disorder, representing a diverse group of related diseases that share a definition of joint inflammation of unknown origin with onset before 16 years of age and lasting > 6 weeks. JIA may lead to significant functional impairment and is increasingly imaged with MRI to assess for active inflammation as a target for therapy. This is particularly true for juvenile spondyloarthritis that includes multiple subgroups of JIA and primarily involves the spine and sacroiliac joints.Other less common pediatric rheumatic diseases considered here are chronic recurrent multifocal osteomyelitis and collagen vascular diseases including polymyositis, dermatomyositis, scleroderma, and juvenile systemic lupus erythematosus.

[Rheumatoid arthritis of the hand : Part 2: Imaging]

BACKGROUND

Rheumatoid arthritis can cause joint destruction, especially joints of the hands. Diagnosed at an early stage, which often includes imaging methods, can minimize structural joint damage and resulting disabilities as well as avoid systemic manifestations such as cardiovascular damage through rapid and continuous so-called targeted treatment approaches.

OBJECTIVE

The aim of this work is the systematic description and report of imaging findings in rheumatoid arthritis as the most common autoimmunologic rheumatologic disease, which is characterized by a typical pattern of synovitis of the hands.

MATERIALS AND METHODS

Narrative review based on the current literature on the subject from the radiological and rheumatological point of view.

RESULTS

Inflammation of the hands represents the most frequently affected area of the body in rheumatoid arthritis. Taking into consideration the topology and typical synovitis patterns of the hands, differences between early and late stages are described. Knowledge regarding image-based morphological changes associated with this complex disease, especially in the hands, is important in the differential diagnosis, especially in early stages of the disease.

CONCLUSIONS

For the diagnosis of rheumatoid arthritis of the hands, the radiologist must be familiar with basic knowledge of arthritis in the hands to confidently analyze the typical patterns present in the diagnostic imaging at initial diagnosis and during the course of the disease, which serve as a guide for therapy decisions.

Value of contrast-enhanced ultrasound for detection of synovial vascularity in experimental rheumatoid arthritis: an exploratory study

Objective

This study aimed to examine the associations between contrast-enhanced ultrasound (CEUS) imaging and synovial hypervascularity and synovitis score in a rabbit model of antigen-induced arthritis (AIA), compared with power Doppler ultrasound (PDUS).

Methods

We investigated 50 knee joints in 25 AIA rabbits (AIA group), and 10 knee joints in five sham-injected rabbits (control group). PDUS and CEUS images were evaluated at the 8th week. Ultrasound-guided synovial biopsies were targeted in the area with hypervascularity, and synovial microvessel density (MVD) was evaluated by immunohistochemical staining of CD31.

Results

The PDUS score was significantly higher in the AIA group (2.61 ± 0.78) compared with the control group (0.50 ± 0.53). CEUS in the AIA group revealed a fast-in/slow-out pattern of contrast enhancement. MVD revealed by CD31+ vessel count and the synovitis score were significantly higher in the AIA group compared with the control group. In the AIA group, CEUS findings showed a better correlation with MVD revealed by CD31+ and synovitis score than PDUS findings.

Conclusion

CEUS is superior to PDUS for estimating synovial hypervascularity and hyperplasia in experimental rheumatoid arthritis.

Responsiveness of different dynamic contrast-enhanced magnetic resonance imaging approaches: a post-hoc analysis of a randomized controlled trial of certolizumab pegol in rheumatoid arthritis

Objective: The aim was to explore dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) as an early marker of therapeutic response in patients with rheumatoid arthritis (RA) starting treatment with certolizumab pegol (CZP).Method: In 40 RA patients initiating CZP (27 patients) or 2 weeks of placebo (PCB) followed by CZP (13 patients), DCE-MRI of the metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints was performed at weeks 0, 1, 2, 4, 8, and 16. Using semi-automated software, three methods for drawing volume regions of interest (ROIs) in MCP2-5 and PIP2-5 were applied: 'Standard' (slices: all; joints: MCP2-5 together and PIP2-5 together), 'Detailed' (slices: slices with high-quality visualization; joints: as Standard), and 'Single-joint' (slices: as Detailed; joints: each joint separately). The number of enhancing voxels (Nvoxel), initial rate of enhancement (IRE), and maximum enhancement (ME) were extracted and analysed for each method.Results: Nvoxel in MCP2-5, and IRE and ME in PIP2-5 decreased statistically significantly (Wilcoxon rank-sum test, p < 0.02-0.03) after 16 weeks of treatment for the Standard method. Nvoxel and ME decreased significantly more in the CZP group than in the PCB group after 1 week of treatment, but not at later time-points. There were no significant changes for DCE-MRI parameters for the Detailed and Single-joint methods.Conclusions: Certain DCE-MRI parameters detected decreased inflammation during CZP treatment in RA patients. Using specific criteria for ROIs, as in the Detailed and Single-joint methods, decreased the statistical power and could not show any changes over time.

ERAMRS: a new MR scoring system for early rheumatoid arthritis of the wrist

PURPOSE

To (i) devise a new semi-quantitative scoring system known as Early Rheumatoid Arthritis Magnetic Resonance Score (ERAMRS) to assess inflammation of the wrist on magnetic resonance imaging in early rheumatoid arthritis and to (ii) test ERAMRS and other MR scoring systems against everyday used clinical scorings.

MATERIALS AND METHODS

One hundred six treatment-naïve patients (81 females, 25 males, mean age 53 ± 12 years) with early rheumatoid arthritis (ERA) underwent clinical/serological testing as well as 3-T MRI examination of the most symptomatic wrist. Clinical assessment included Disease Activity Score-28 and Health Assessment Questionnaire; erythrocyte sedimentation rate and C-reactive protein were measured. MR imaging data was scored in all patients using three devised MR semi-quantitative scoring systems, namely, the (a) ERAMRS system, (b) Rheumatoid Arthritis Magnetic Resonance Imaging Score (RAMRIS) system, and the (c) McQueen Score system.

RESULTS

Synovitis was present in 106 (100%), tenosynovitis in 98 (92%), and bone marrow edema in 84 (79%) of 106 ERA wrists. ERAMRS had the highest correlation with clinical disease activity scores (r = 0.476, p < 0.001) and serological parameters (r = 0.562, p < 0.001). RAMRIS system had the lowest correlation (r = 0.369, p < 0.001 for clinical disease activity; r = 0.436, p < 0.001 for serological parameters). RAMRIS synovitis subscore had a lower correlation than ERAMRS for clinical disease activity (r = 0.410, p < 0.001) and for serological parameters (r = 0.456, p < 0.001).

CONCLUSION

The ERAMRS system, designed to grade inflammation on wrist MRI in ERA, provided the best correlation with all clinical scoring systems and serological parameters, indicating its improved clinical relevance over other MR scoring systems.

KEY POINTS

• We devised a clinically relevant, easy-to-use semi-quantitative scoring system for scoring inflammation on MRI of the wrist in patients with early rheumatoid arthritis. • ERAMRS system showed better correlation with all clinical and serological assessment of inflammation in patients with early rheumatoid arthritis indicating its improved clinical relevance over other MR scoring systems.

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.

Magnetic resonance imaging of the hand and wrist in a randomized, double-blind, multicenter, placebo-controlled trial of infliximab for rheumatoid arthritis: Comparison of dynamic contrast enhanced assessments with semi-quantitative scoring

The objective of this study was to compare the scope and the discriminative power of Dynamic Contrast Enhanced Magnetic Resonance Imaging (DCE-MRI) to those of semi-quantitative MRI scoring for evaluating treatments for rheumatoid arthritis (RA) in multicenter randomized clinical trials (RCTs). Sixty-one patients with active RA participated in a double-blind, parallel group, randomized, multicenter methodology study receiving infliximab or placebo through 14 weeks. The most symptomatic wrist and metacarpophalangeal joints (MCPs) were imaged using MRI. In addition to clinical assessments with DAS28(CRP), the severity of inflammation was measured as synovial leak of gadolinium based contrast agent (GBCA) using DCE-MRI (K_trans, primary endpoint) at weeks 0, 2, 4, and 14. Two radiologists independently scored synovitis, osteitis and erosion using RA MRI Score (RAMRIS) and cartilage loss using a 9-point MRI scale (CARLOS). Infliximab showed greater decrease from baseline in DAS28(CRP), DCE-MRI K_trans of wrist and MCP synovium, and RAMRIS synovitis and osteitis at all visits compared with placebo (p<0.001). Treatment effect sizes of infliximab therapy were similar for DAS28(CRP) (1.08; 90% CI (0.63–1.53)) and MRI inflammation endpoints: wrist K_trans (1.00 (0.55–1.45)), RAMRIS synovitis (0.85 (0.38–1.28)) and RAMRIS osteitis (0.99 (0.52–1.43)). Damage measures of bone erosion (RAMRIS) and cartilage loss (CARLOS) were reduced with infliximab compared to with placebo at 14 weeks (p≤0.025). DCE-MRI and RAMRIS were equally sensitive and responsive to the anti-inflammatory effects of infliximab. RAMRIS and CARLOS showed suppression of erosion and cartilage loss, respectively, at 14 weeks. (ClinicalTrials.gov registration: NCT01313520)

Magnetic resonance imaging in individuals at risk of rheumatoid arthritis

Individuals with rheumatoid arthritis (RA) benefit from early diagnosis and initiation of therapy. There can be delays in both due to diagnostic uncertainties. Imaging modalities, including magnetic resonance imaging (MRI), can detect inflammation earlier than clinical examination alone in early RA patients. Furthermore, the predictive role of MRI for the future development of RA has recently been explored in 'at-risk' individuals. This review details the use of MRI in early and undifferentiated arthritis and summarises the studies to date in individuals at risk of RA.

The Relationship Between Synovial Pathobiology and Magnetic Resonance Imaging Abnormalities in Rheumatoid Arthritis: A Systematic Review

Objective.

Magnetic resonance imaging (MRI) has been increasingly recognized as a critical tool for the assessment of patients with rheumatoid arthritis (RA) and is able to reliably identify synovitis, bone marrow edema, bone erosion, and joint space narrowing (JSN)/cartilage loss. Understanding the exact relationship between each MRI feature and local synovial pathobiology is critical to dissect disease pathogenesis as well as develop future predictive models.

Methods.

A systematic review was performed of the current published literature examining the relationship between MRI abnormalities and synovial pathobiology in patients with RA.

Results.

Eighteen studies were identified; most focused on validation of MRI as a tool to detect and quantify synovitis, with a significant relationship demonstrated. Additionally, from the limited data available, a critical role seems likely for synovial pathways, at least in driving joint damage. However, there was a lack of data examining the relationship between synovial pathobiology and bone marrow abnormalities and JSN.

Conclusion.

Although understanding the interrelationship of these disease biomarkers offers the potential to enhance the predictive validity of modern imaging with concomitant synovial pathobiological analysis, further studies integrating MRI with synovial tissue analysis in well-controlled cohorts at distinct disease stages before and after therapeutic intervention are required to achieve this.

The usefulness of diagnostic imaging for the assessment of pain symptoms in temporomandibular disorders

The causes of pain symptoms in the temporomandibular joint (TMJ) and masticatory muscle (MM) regions may not be determined by clinical examination alone. In this review, we document that pain symptoms of the TMJ and MM regions in patients with temporomandibular disorders (TMDs) are associated with computed tomography and magnetic resonance (MR) findings of internal derangement, joint effusion, osteoarthritis, and bone marrow edema. However, it is emphasized that these imaging findings must not be regarded as the unique and dominant factors in defining TMJ pain. High signal intensity and prominent enhancement of the posterior disk attachment on fat saturation T2-weighted imaging and dynamic MR imaging with contrast material are closely correlated with the severity of TMJ pain. Magnetic transfer contrast, MR spectroscopy, diffusion tensor imaging, and ultrasonography findings have helped identify intramuscular edema and contracture as one of the causes of MM pain and fatigue. Recently, changes in brain as detected by functional MR neuroimaging have been associated with changes in the TMJ and MM regions. The thalamus, the primary somatosensory cortex, the insula, and the anterior and mid-cinglate cortices are most frequently associated with TMD pain.

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.

Lymphatic imaging to assess rheumatoid flare: mechanistic insights and biomarker potential

Proliferation of draining lymphatic vessels coupled with dynamic changes in lymph node volume and flow are characteristic features in rheumatoid arthritis (RA). Furthermore, impaired lymph egress from inflamed synovium is associated with joint flare in murine models of inflammatory-erosive arthritis. Unfortunately, advances towards a greater understanding of lymphatic changes in RA pathogenesis have been slow due to the absence of outcome measures to quantify lymphatic function in vivo. While lymphoscintigraphy is the current standard to assess lymphedema and sentinel lymph nodes in cancer patients, its sensitivity and specificity are inadequate to study lymphatics in RA. The emergence of high-resolution MRI, power Doppler ultrasound, and near-infrared imaging that permits real-time quantification of lymphatic function in animal models has been a major advance, and these techniques have produced a new paradigm of altered lymphatic function that underlies both acute arthritic flare and chronic inflammation. In acute flare, lymphatic drainage increases several fold, whereas no lymphatic contractions are detected in lymph vessels draining chronic arthritic joints. Moreover, these outcomes are now being adapted to study lymphatics in RA towards the development of novel biomarkers of arthritic flare and the discovery of new therapeutic targets. In particular, interventions that directly increase lymphatic egress from diseased joints by opening collateral lymphatic vessels, and that restore lymphatic vessel contractions, provide novel therapeutic approaches with potential for minimal toxicity and immunosuppression. To summarize the origins of this field, recent advances, and future directions, we herein review: current knowledge of lymphatics in RA based on classic literature; new in-vivo imaging modalities that have elucidated how lymphatics modulate acute versus chronic joint inflammation in murine models; and how these preclinical outcome measures are being translated to study lymphatic function in RA inflammation and how effective RA therapies alter lymphatic flow and lymph nodes draining flaring joints.

Trial registration: ClinicalTrials.gov NCT02680067. Registered 7 December 2015; ClinicalTrials.gov NCT01098201. Registered 30 March 2010; and ClinicalTrials.gov NCT01083563. Registered 8 March 2010.

Synovial volume vs synovial measurements from dynamic contrast enhanced MRI as measures of response in osteoarthritis

OBJECTIVE

Synovium is increasingly a target of osteoarthritis (OA) treatment, yet its optimal measurement is unclear. Using dynamic contrast enhanced (DCE) MRI in knee OA patients before and after intraarticular steroid injection, we compared the responsiveness of static synovial volume measures to measures of dynamic changes in synovial enhancement, changes that are strongly related to synovial vascularity.

METHODS

Ninety three patients underwent DCE-MRI before and 1-2 weeks after intra-articular injection of 80 mg methylprednisolone. Synovium was segmented and volume, relative enhancement rate (RER), maximum relative enhancement (REmax), late relative enhancement (RElate) and pharmacokinetic parameters (K(trans), ve) were calculated. KOOS (​knee injury and osteoarthritis outcome score) pain score was recorded before and after injection. Standardized change scores were calculated for each parameter. Linear regression and Pearson's correlations were used to investigate the relationship between change in MRI parameters and change in pain.

RESULTS

The change in standardized score for the measures of synovial enhancement, RElate and REmax were -0.58 (95% CI -0.79 to -0.37) and -0.62 (95% CI -0.83 to -0.41) respectively, whereas the score for synovial volume was -0.30 (-0.52 to -0.09). Further, change in knee pain correlated more strongly with changes in enhancement (for both REmax and RElate, r = -0.27 (95% CI -0.45 to -0.07)) than with changes in synovial volume -0.15 (-0.35 to 0.05).

CONCLUSION

This study suggests DCE-MRI derived measures of synovial enhancement may be more sensitive to the response to treatment and more strongly associated with changes in pain than synovial volume and may be better outcomes for assessment of structural effects of treatment in OA.

High-temporospatial-resolution dynamic contrast-enhanced (DCE) wrist MRI with variable-density pseudo-random circular Cartesian undersampling (CIRCUS) acquisition: evaluation of perfusion in rheumatoid arthritis patients

This study is to evaluate highly accelerated three-dimensional (3D) dynamic contrast-enhanced (DCE) wrist MRI for assessment of perfusion in rheumatoid arthritis (RA) patients. A pseudo-random variable-density undersampling strategy, circular Cartesian undersampling (CIRCUS), was combined with k-t SPARSE-SENSE reconstruction to achieve a highly accelerated 3D DCE wrist MRI. Two healthy volunteers and 10 RA patients were studied. Two patients were on methotrexate (MTX) only (Group I) and the other eight were treated with a combination therapy of MTX and anti-tumor necrosis factor (TNF) therapy (Group II). Patients were scanned at baseline and 3 month follow-up. DCE MR images were used to evaluate perfusion in synovitis and bone marrow edema pattern in the RA wrist joints. A series of perfusion parameters was derived and compared with clinical disease activity scores of 28 joints (DAS28). 3D DCE wrist MR images were obtained with a spatial resolution of 0.3 × 0.3 × 1.5 mm(3) and temporal resolution of 5 s (with an acceleration factor of 20). The derived perfusion parameters, most notably transition time (dT) of synovitis, showed significant negative correlations with DAS28-ESR (r = -0.80, p < 0.05) and DAS28-CRP (r = -0.87, p < 0.05) at baseline and also correlated significantly with treatment responses evaluated by clinical score changes between baseline and 3 month follow-up (with DAS28-ESR r = -0.79, p < 0.05, and DAS28-CRP r = -0.82, p < 0.05). Highly accelerated 3D DCE wrist MRI with improved temporospatial resolution has been achieved in RA patients and provides accurate assessment of neovascularization and perfusion in RA joints, showing promise as a potential tool for evaluating treatment responses.

Validation of power Doppler versus contrast-enhanced magnetic resonance imaging quantification of joint inflammation in murine inflammatory arthritis

Contrast-enhancement magnetic resonance imaging (CE-MRI) of synovial volume is the radiographic gold standard to quantify joint inflammation; however, cost limits its use. Therefore, we examined if power Doppler-ultrasound (PD-US) outcomes of synovitis in tumor necrosis factor transgenic (TNF-Tg) mice correlate with CE-MRI. TNF-Tg mice underwent PD-US of their knees to measure the joint space volume (JSV) and power Doppler volume (PDV), and the results were correlated with synovial volume determined by CE-MRI. Immunohistochemistry for CD31 was performed to corroborate the PD signal. Synovial volume strongly correlated with both JSV and PDV (p < 0.01). CD31(+) blood vessels were observed in inflamed synovium proximal to the joint surface, which corresponded to areas of intense PD signals. JSV and PDV are valid measures of joint inflammation that correlate with synovial volume determined by CE-MRI and are associated with vascularity. Given the emergence of PD-US as a nonquantitative outcome of joint inflammation, we find JSV and PDV to be feasible and highly cost-effective for longitudinal studies in animal models. Furthermore, given the increasing use of PD-US in standard clinical practice, JSV and PDV could be translated to better quantify joint flare and response to therapy in patients with rheumatoid arthritis (RA).

Comparison of quantitative and semiquantitative dynamic contrast-enhanced MRI with respect to their correlation to delayed gadolinium-enhanced MRI of the cartilage in patients with early rheumatoid arthritis

OBJECTIVE

The objective of this study was to investigate the correlation between semiquantitative and quantitative dynamic contrast-enhanced (DCE) parameters with delayed gadolinium-enhanced magnetic resonance imaging (MRI) of the cartilage (dGEMRIC).

METHODS

Fifteen patients with early rheumatoid arthritis (RA) from the ArthroMark cohort were investigated at a 3-T MRI scanner. The metacarpophalangeal (MCP) joint of the index finger was examined with DCE-MRI and dGEMRIC. Semiquantitative and quantitative DCE perfusion parameters were calculated. The RA MRI score of the second MCP joint and the joint space width were measured.

RESULTS

Significant correlations were noted between both semiquantitative and quantitative DCE parameters and the RA MRI score of the second MCP joint. There was a significant negative correlation between DCE parameters and dGEMRIC. No association between joint space width and DCE parameters was observed.

CONCLUSIONS

Semiquantitative and quantitative analyses of perfusion are applicable to show that cartilage damage correlates with the inflammation activity despite the absence of joint space narrowing.

Power Doppler ultrasound phenotyping of expanding versus collapsed popliteal lymph nodes in murine inflammatory arthritis

Rheumatoid arthritis is a chronic inflammatory disease manifested by episodic flares in affected joints that are challenging to predict and treat. Longitudinal contrast enhanced-MRI (CE-MRI) of inflammatory arthritis in tumor necrosis factor-transgenic (TNF-Tg) mice has demonstrated that popliteal lymph nodes (PLN) increase in volume and contrast enhancement during the pre-arthritic “expanding” phase of the disease, and then suddenly “collapse” during knee flare. Given the potential of this biomarker of arthritic flare, we aimed to develop a more cost-effective means of phenotyping PLN using ultrasound (US) imaging. Initially we attempted to recapitulate CE-MRI of PLN with subcutaneous footpad injection of US microbubbles (DEFINITY®). While this approach allowed for phenotyping via quantification of lymphatic sinuses in PLN, which showed a dramatic decrease in collapsed PLN versus expanding or wild-type (WT) PLN, electron microscopy demonstrated that DEFINITY® injection also resulted in destruction of the lymphatic vessels afferent to the PLN. In contrast, Power Doppler (PD) US is innocuous to and efficiently quantifies blood flow within PLN of WT and TNF-Tg mice. PD-US demonstrated that expanding PLN have a significantly higher normalized PD volume (NPDV) versus collapsed PLN (0.553±0.007 vs. 0.008±0.003; p<0.05). Moreover, we define the upper (>0.030) and lower (<0.016) quartile NPDVs in this cohort of mice, which serve as conservative thresholds to phenotype PLN as expanding and collapsed, respectively. Interestingly, of the 12 PLN phenotyped by the two methods, there was disagreement in 4 cases in which they were determined to be expanding by CE-MRI and collapsed by PD-US. Since the adjacent knee had evidence of synovitis in all 4 cases, we concluded that the PD-US phenotyping was correct, and that this approach is currently the safest and most cost-effective in vivo approach to phenotype murine PLN as a biomarker of arthritic flare.

Comparison of OMERACT-RAMRIS scores and computer-aided dynamic magnetic resonance imaging findings of hand and wrist as a measure of activity in rheumatoid arthritis

The purpose of this study was to compare the value of conventional magnetic resonance imaging (MRI) finding of rheumatoid arthritis (RA) and computer-aided dynamic MRI measurements in predicting the activity of disease. The activity of the disease in 40 RA patients was evaluated by the disease activity score in 28 joints (DAS28). The conventional MRI of the wrists of all patients were scored for bone edema, synovitis and erosions, according to the criteria of RA-MRI scoring system (RAMRIS) developed by Outcome measures in rheumatology clinical trials (OMERACT) MR Imaging Group. Synovitis was also quantified by dynamic postcontrast MRI imaging using color coded maximum slope of increase maps and measurements of early enhancement rate (EER) and relative enhancement (RE). Twenty-two (55 %) patients with a score higher than 5.1 constituted the high disease activity group, 18 (45 %) patients with a score of 5.1 or less constituted moderate disease activity group. The dynamic MRI-EER score was the most significant parameter to differentiate between the groups (p = 0.001). Among OMERACT scores, only bone edema [p = 0.020 for wrist and p = 0.037 for metacarpophalangeal joints (MCP)] had a significant difference between the two groups. Dynamic MRI RE score and OMERACT scores for erosions and synovitis for both the wrist and MCP joints did not differ significantly between the two groups. Computer-aided dynamic MRI is a reliable, noninvasive method of evaluating the RA patients, which correlates with the DAS28 scores, at a higher significance than the OMERACT-RAMRIS scores.

Contrast-enhanced MRI of the subdeltoid, subacromial bursa in painful and painless rotator cuff tears

OBJECTIVE

Although shoulder pain is often associated with rotator cuff tears, many tears are asymptomatic and are not the cause of the patient's pain. This may explain the persistence of symptoms in some patients despite technically successful rotator cuff repair. It has been proposed that rotator cuff tears cause pain through subdeltoid/subacromial bursal inflammation. The aim of this study was to determine whether bursal inflammation seen on MRI is associated with pain in patients with rotator cuff tears of the shoulder.

METHODS

The shoulders of 255 patients were screened with ultrasound. 33 full-thickness rotator cuff tears (18 with shoulder pain and 15 without pain) were identified and subsequently studied using contrast-enhanced MRI of the shoulder. Enhancement of the subacromial bursa was scored independently by two musculoskeletal radiologists. Logistic regression was used to determine whether bursal enhancement was independently associated with pain.

RESULTS

There was a significant association between pain and age, with greater likelihood of pain in younger patients. Bursal enhancement was common in both painful and painless tears. No statistically significant link between pain and bursal enhancement was seen, even after accounting for age.

CONCLUSION

Although enhancement of the subdeltoid/subacromial bursa was common, no evidence was found to support the hypothesis that bursal enhancement is associated with pain in rotator cuff tears. It is therefore unlikely to determine reliably which patients would benefit from rotator cuff repair. Advances in knowledge Bursal enhancement and thickening does not reliably correlate with symptoms or presence of rotator cuff tear.

MRI of the wrist in juvenile idiopathic arthritis: proposal of a paediatric synovitis score by a consensus of an international working group. Results of a multicentre reliability study

BACKGROUND

MRI is a sensitive tool for the evaluation of synovitis in juvenile idiopathic arthritis (JIA).

OBJECTIVE

The purpose of this study was to introduce a novel MRI-based score for synovitis in children and to examine its inter- and intraobserver variability in a multi-centre study.

MATERIALS AND METHODS

Wrist MRI was performed in 76 children with JIA. On postcontrast 3-D spoiled gradient-echo and fat-suppressed T2-weighted spin-echo images, joint recesses were scored for the degree of synovial enhancement, effusion and overall inflammation independently by two paediatric radiologists. Total-enhancement and inflammation-synovitis scores were calculated.

RESULTS

Interobserver agreement was poor to moderate for enhancement and inflammation in all recesses, except in the radioulnar and radiocarpal joints. Intraobserver agreement was good to excellent. For enhancement and inflammation scores, mean differences (95 % CI) between observers were -1.18 (-4.79 to 2.42) and -2.11 (-6.06 to 1.83). Intraobserver variability (reader 1) was 0 (-1.65 to 1.65) and 0.02 (-1.39 to 1.44).

CONCLUSION

Intraobserver agreement was good. Except for the radioulnar and radiocarpal joints, interobserver agreement was not acceptable. Therefore, the proposed scoring system requires further refinement.

Diffusion-weighted MRI of bone marrow oedema, soft tissue oedema and synovitis in paediatric patients: feasibility and initial experience

BACKGROUND

MRI has become the mainstay of diagnostic imaging in paediatric rheumatology for lesion detection, differential diagnosis and therapy surveillance. MR imaging of synovitis, in particular, is indispensable for early diagnosis and follow-up in arthritis patients. We used diffusion-weighted MRI (DWI) as a new imaging modality in comparison to standard MRI sequences to study bone marrow oedema, soft-tissue oedema and synovitis in paediatric patients.

METHODS

A total of 52 patients (mean age 11 ± 5 years) with bone marrow oedema (n = 31), soft-tissue oedema (n = 20) and synovitis (n = 15) were examined with transversal diffusion-weighted single-shot echoplanar imaging in addition to standard MR sequences (T2W TIRM, T1W pre- and post-contrast). Diffusion-weighted images were used for lesion detection and apparent diffusion coefficient (ADC, unit × 10-3 mm2/s) values were measured with ROI technique on ADC maps.

RESULTS

In 50 of 52 patients, DWI delineated the lesion of interest corresponding to pathological signal increase on standard sequences. Mean ADC was 1.60 ± 0.14 (range 1.38 - 1.99) in osseous lesions, 1.72 ± 0.31 (range 1.43 - 2.56) in soft tissue oedema and 2.82 ± 0.24 (range 2.47 - 3.18) for joint effusion (ANOVA p < 0.001). No significant difference in mean ADC was seen for inflammatory vs. non-inflammatory lesions. Relative signal intensity of oedema was similar for DWI and T2W TIRM. DWI visualised synovial restricted diffusion with a mean ADC of 2.12 ± 0.45 in 12 of 15 patients with synovitis.

CONCLUSIONS

Diffusion-weighted MRI reliably visualises osseous and soft tissue oedema, as compared to standard sequences. DWI of synovitis is feasible in large joints and presents a novel approach to contrast-free imaging of synovitis. Whole-body DWI for chronic non-bacterial osteomyelitis should be evaluated in future studies.

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.

Evaluation of finger joint synovial vascularity in patients with rheumatoid arthritis using contrast-enhanced ultrasound with water immersion and a stabilized probe

PURPOSE.: To assess synovial microvascularity in finger joints with rheumatoid arthritis (RA) by contrast-enhanced ultrasound (CEUS), distinguishing between cases of active disease and those in remission; to standardize the technique for software analysis. METHODS.: Fifty-two finger joints of RA patients (26 with active disease and 26 in remission) were immersed in water and examined by CEUS using a fixed probe. Signal intensity curves were calculated with the software. RESULTS.: Contrast enhancement was detectable in all 26 patients with active RA (100%), but not in 25 of 26 patients in remission (96%); one of the latter patients (4%) showed minimal enhancement. The method's sensitivity and specificity in distinguishing active disease from remission were 100% and 96%. The grades of synovial enhancement correlated with clinical disease activity and software flow parameters. The peak contrast levels correlated with clinical activity, a peak of 9% representing the cutoff between remission and active disease. CONCLUSIONS.: CEUS with a fixed probe on finger joints immersed in water detected synovial vascularization in RA, producing results suitable for standardized software analysis and avoiding artifacts.

Dynamic contrast-enhanced 3-T magnetic resonance imaging: a method for quantifying disease activity in early polyarthritis

OBJECTIVE

To determine whether measurement of synovial enhancement and thickness quantification parameters with 3.0-Tesla magnetic resonance imaging (3-T MRI) can reliably quantify disease activity in patients with early polyarthritis.

MATERIALS AND METHODS

Eighteen patients (16 women, 2 men; mean age 46 years) with early polyarthritis with less than 12 months of symptoms were included. MRI examination using 3-T device was performed by a new approach including both wrists and hands simultaneously in the examination field-of-view. MRI scoring of disease activity included quantification of synovial enhancement with simple measurements such as rate of early enhancement (REE; REE(57) = S(57)/S(200), where S(57) and S(200) are the signal intensities 57 s and 200 s after gadolinium injection) and rate of relative enhancement (RE; RE = S(200) - S(0)). Both wrists and hands were scored according to the Rheumatoid Arthritis MRI Scoring System (RAMRIS) for synovitis. Disease activity was clinically assessed by the 28-joint Disease Activity Score (DAS28).

RESULTS

DAS28 score was strongly correlated with RE (r = 0.8331, p < 0.0001), REE (r = 0.8112, p < 0.0001), and RAMRIS score for synovitis (r = 0.7659, p < 0.0002). An REE score above 0.778 accurately identified patients with clinically active disease (sensitivity 92%; specificity 67%; p < 0.05). A statistically significant difference was observed in the RE, REE, and RAMRIS scores for synovitis between patients with active and inactive disease (p < 0.05).

CONCLUSIONS

Our findings support the use of 3-T dynamic contrast-enhanced MRI for precise quantification of disease activity and for discriminating active disease from inactive disease in early polyarthritis.

Quantifying synovitis in rheumatoid arthritis using computer-assisted manual segmentation with 3 Tesla MRI scanning

PURPOSE

To investigate the reliability, validity and feasibility of a computer-assisted manual segmentation method for determining the synovial membrane volume as a surrogate measure for synovitis in patients with rheumatoid arthritis (RA).

MATERIALS AND METHODS

The 3 Tesla (T) MRI scans were acquired in 22 early RA and 16 established RA patients. Synovial membrane volumes in postcontrast T1w axial images at three wrist joint regions were determined by two nonradiologist observers using a computer-assisted manual segmentation method.

RESULTS

Intraobserver reliability, measured by intraclass correlation coefficients (ICCs), was excellent in the early (ICC = 0.99) and established (ICC = 0.99) RA cohorts. Interobserver reliability (mean ICC [95% Confidence Interval]) was moderate to excellent in the early and established RA groups (ICCs = 0.87 [0.68,0.94] and 0.88 [0.66, 0.96], respectively). There was a strong correlation between the synovial membrane volumes derived by segmentation and the RA MRI scoring system (RAMRIS) scores for synovitis at all joints in the early (Spearman rho = 0.86-0.96) and established (Spearman rho = 0.85-0.93) RA cohorts. The entire segmentation technique took 19 to 21 min per patient.

CONCLUSION

Measurement of MRI synovitis using a computer-assisted manual segmentation method demonstrated excellent intraobserver and very good interobserver reliability, content validity (represented by its strong correlation with RAMRIS synovitis), and moderate feasibility.

Magnetic resonance imaging of inflammatory arthropathies of peripheral joints

As the treatment of inflammatory arthropathies has advanced with new therapies that can slow or even halt the development of disabling disease, early and accurate diagnosis has become imperative. Magnetic resonance (MR) imaging has proved to be very sensitive in the detection of erosions, but more importantly, it can demonstrate pre-erosive changes. Detection of synovitis and edema-like bone marrow lesions for initial diagnosis and as an indicator of disease progression can provide crucial information leading to therapeutic interventions before permanent joint damage occurs. Understanding the characteristic intra-articular and extra-articular MR imaging findings of the inflammatory arthritides allows the radiologist to provide appropriate consultations in the care of these patients. The MR appearances of both intra-articular and extra-articular findings of inflammatory arthritis are presented. Despite the advances in imaging, however, many of the MR findings remain nonspecific, and radiologists must avoid overdiagnosis by synthesizing all of the clinical information available into their interpretations.

Quantitative Power Doppler Ultrasonography Is a Sensitive Measure of Metacarpophalangeal Joint Synovial Vascularity in Rheumatoid Arthritis and Declines Significantly Following a 2-week Course of Oral Low-dose Corticosteroids

Objective.

To investigate the stability over 2 weeks of ultrasonographic assessments of synovial thickness and vascularity in all 10 metacarpophalangeal joints of subjects with rheumatoid arthritis (RA) with a range of disease activities as measured by the validated Disease Activity Score-28 joint score (DAS28-ESR). And in subjects with severe disease activity, to compare the sensitivity of these measurements, acute-phase markers, and vascular endothelial growth factor to change in response to 2 weeks of oral prednisolone (7.5 mg daily).

Methods.

A group of 38 subjects with RA were enrolled, 13 (mean DAS28 2.1), 14 (mean DAS28 5.2), and 11 (mean DAS28 5.7) meriting oral corticosteroid treatment. Synovial thickness and vascularity were assessed by ultrasonography at 3 timepoints. Images were ranked by semiquantitative scale. Vascularity was also measured by quantitative determination of the power Doppler area (PDA).

Results.

In the whole RA cohort, baseline indices of synovial thickness and vascularity correlated with DAS28, as did PDA (r = 0.42, p < 0.05). In the RA groups on stable therapy, synovial thickness and vascularity showed little variation over 2 weeks. In the corticosteroid group, PDA had fold changes of −1.9-fold (p < 0.05) after 1 week and −2.2-fold (p < 0.05) after 2 weeks. These were the largest fold changes of all measured variables.

Conclusion.

Ultrasonographic measures can differentiate disease severity in RA correlating closely with DAS28. Quantitative power Doppler signal was significantly reduced within 1 week of oral prednisolone, a rapid kinetic suggesting that PDA may have value as a sensitive early marker of therapeutic response.

Using magnetic resonance angiography to measure abnormal synovial blood vessels in early inflammatory arthritis: a new imaging biomarker?

OBJECTIVE

To ascertain whether magnetic resonance angiography (MRA) can reliably detect synovial neovascularization in subjects with early inflammatory arthritis.

METHODS

Subjects with 6 weeks to 6 months of clinical evidence of inflammatory hand arthritis had a radiograph, power Doppler ultrasound (PDU) scan, magnetic resonance imaging (MRI), and contrast enhanced MRA performed on the more symptomatic hand. Ultrasound examination of the wrist and 2nd-5th metacarpophalangeal (MCP) joints was scored for erosions, synovial thickening, and synovial blood flow. MRI were assessed using the OMERACT Rheumatoid Arthritis MRI Score (RAMRIS). MRA was used to assess the number of abnormal vessels in the 2nd-5th MCP and in the wrist.

RESULTS

Of 30 subjects, 66.7% showed abnormal vasculature on MRA in the MCP and/or wrist; mean number of abnormal vessels was 5.24 (range 0-22). Number of abnormal vessels on MRA was strongly correlated with degree of blood flow seen in the corresponding area on PDU (r = 0.79, p <or= 0.0001). The number of abnormal vessels was highly correlated with MRI MCP synovitis scores (r = 0.69, p <or= 0.0001), MRI wrist synovitis scores (r = 0.73, p <or= 0.0001), and ultrasound synovitis scores (r = 0.68, p <or= 0.0001).

CONCLUSION

In this cross-sectional pilot study, MRA identified abnormal vessels in patients with early inflammatory arthritis. This is the first report of MRA visualizing abnormal vessels in this patient population. If the degree of neovascularization in early inflammatory arthritis predicts disease course, MRA evidence of abnormal vessels could be a new imaging biomarker.

The role of dynamic contrast-enhanced MRI in the differential diagnosis of psoriatic and rheumatoid arthritis

OBJECTIVE

The purpose of this study was to investigate the role of dynamic contrast-enhanced MRI in the differential diagnosis of psoriatic and rheumatoid arthritis in the hand and wrist.

SUBJECTS AND METHODS

Forty-five consecutive patients (31 patients with rheumatoid arthritis and 14 patients with psoriatic arthritis) were examined in a 3-T whole-body MR unit. After contrast injection, a 3D encoded spoiled gradient-echo sequence was used for measurement of the time course of contrast-medium uptake in the synovial tissue. On the basis of the gained uptake curves, the rate of early enhancement was calculated after 35 and 52 seconds, and the relative enhancement rate was calculated after 35 seconds, 52 seconds, 3 minutes, and 15 minutes (late enhancement). Dynamic contrast-enhanced MRI rates of patients with rheumatoid arthritis and psoriatic arthritis were compared and correlated with laboratory and clinical data.

RESULTS

A statistically significant difference between the two groups was found regarding the relative enhancement rate after 15 minutes (p < 0.01). In contrast, no difference in relative enhancement rate was found 35 seconds, 52 seconds, or 3 minutes after contrast injection (p = 0.695, p = 0.573, and p = 0.278, respectively). Regarding the rate of early enhancement at 35 and 52 seconds, no significant difference between patients with rheumatoid arthritis and those with psoriatic arthritis was found. Significant correlations were found between inflammatory parameters and dynamic contrast-enhanced parameters in patients with rheumatoid arthritis but not in those with psoriatic arthritis.

CONCLUSION

Fifteen minutes after contrast injection, a statistically significant difference between rheumatoid arthritis and psoriatic arthritis was found in synovial enhancement that might play an important role in differentiating the two diseases.

Magnetic resonance imaging in osteoarthritis: which method best reflects synovial membrane inflammation? Correlations with clinical, macroscopic and microscopic features

OBJECTIVES

: To study synovial membrane (SM) inflammation near the patella with different magnetic resonance imaging (MRI) approaches performed using a T1-injected sequence in knee osteoarthritis (OA), and to compare MRI results with macroscopic, microscopic and clinical findings.

METHODS

Fifteen patients fulfilling American College of Rheumatology (ACR) criteria for knee OA and requiring joint lavage completed a functional index (Lequesne's functional index) and a pain visual analog scale (VAS). SM inflammation near the patella was assessed on axial fat saturation post-injected T1 MRI images using three different methods: (1) semi-quantitative score=MRI synovitis score; (2) synovial membrane volume (SMV) analysis; (3) SMV with low (SMVL) (<0.3%/s(-1)), intermediate (SMVI) (0.3%/s(-1) to 1%/s(-1)) and high (SMVH) (> or =1%/s(-1)) speed of enhancement. Chondral lesions and SM inflammation were macroscopically graded and SM biopsies performed for microscopic scoring.

RESULTS

All MRI approaches exhibited excellent intra- and inter-observer reproducibility. MRI synovitis score correlated well with macroscopic (r=0.61, P=0.003) and total microscopic scores (r=0.55, P=0.03). Correlations between SMV and macroscopic (r=0.60, P=0.02) and microscopic congestion (r=0.63, P=0.01) were good. SMVH was correlated only with microscopic congestion (r=0.79, P=0.01). Low SMV was associated with neither macroscopic nor microscopic scores. However, it did correlate well with pain-VAS score (r=0.61, P=0.03) and moderately with a functional index (r=0.46, P=0.10).

CONCLUSION

The three MRI approaches used here provided highly reproducible information on SM inflammation near the patella in knee OA. Compared to SMV, MRI synovitis score seems sufficient to assess synovial inflammation but high SMV is an appropriate indicator of vascular congestion, and low SMV reflects pain in knee OA.

Rheumatoid synovial inflammation: pixel-by-pixel dynamic contrast-enhanced MR imaging time-intensity curve shape analysis--a feasibility study

PURPOSE

To analyze the distribution of different shapes of time-intensity curves (TICs) in synovial tissue of patients with rheumatoid arthritis (RA) and to compare relative numbers of TIC shapes between patients with RA and healthy control subjects.

MATERIALS AND METHODS

This prospective study was approved by the institutional review board; patients and control subjects gave written informed consent. Dynamic contrast material-enhanced magnetic resonance (MR) imaging of the knee joint in five patients with early RA and in five control subjects was performed. Parametric maps showing seven TIC shape types were created. Spatial information of the synovial TIC shape distribution pattern and relative number of TIC shapes were calculated on a three-dimensional region of interest. Relative TIC shape numbers were compared by using a nonparametric Mann-Whitney U test.

RESULTS

Synovial enhancement in patients with RA consisted of type 2 TIC shapes (slow enhancement) with heterogeneous zones of types 3 (fast enhancement followed by plateau phase), 4 (fast enhancement followed by early washout phase), and 5 (fast enhancement followed by slow enhancement increase) TIC shapes, compared with almost only type 2 TIC shapes in control subjects. The heterogeneous zones were seen in the lateral and medial knee compartments and around the cruciate ligaments. A significantly higher relative number of type 4 TIC shapes was observed in the patient group compared with the control group (16.5% vs 6.9%, P = .008).

CONCLUSION

The pixel-by-pixel dynamic contrast-enhanced MR imaging TIC shape analysis may help distinguish patients with RA from control subjects on the basis of the relative number of type 4 TIC shapes. This study provides the rationale for future research to evaluate the utility of this approach in clinical practice.

Comparative analysis of synovial fluid and plasma proteomes in juvenile arthritis--proteomic patterns of joint inflammation in early stage disease

Synovial fluid is a potential source of novel biomarkers for many arthritic disorders involving joint inflammation, including juvenile idiopathic arthritis. We first compared the distinctive protein 'fingerprints' of local inflammation in synovial fluid with systemic profiles within matched plasma samples. The synovial fluid proteome at the time of joint inflammation was then evaluated across clinical subgroups to identify early disease associated proteins. We measured the synovial fluid and plasma proteomes using the two-dimensional fluorescence difference gel electrophoresis approach. Image analysis software was used to highlight the expression levels of joint and subgroup associated proteins across the study cohort (n = 32). A defined subset of 30 proteins had statistically significant differences (p < 0.05) between sample types such that synovial fluid could be differentiated from plasma. Furthermore distinctive synovial proteome expression patterns segregate patient subgroups. Protein expression patterns localized in the chronically inflamed joint therefore have the potential to identify patients more likely to suffer disease which will spread from a single joint to multiple joints. The proteins identified could act as criteria to prevent disease extension by more aggressive therapeutic intervention directed at an earlier stage than is currently possible.

Assessement of rheumatic diseases with computational radiology: current status and future potential

In recent years, several computational image analysis methods to assess disease progression in rheumatic diseases were presented. This review article explains the basics of these methods as well as their potential application in rheumatic disease monitoring, it covers radiography, sonography as well as magnetic resonance imaging in quantitative analysis frameworks.

The MRI view of synovitis and tenosynovitis in inflammatory arthritis: implications for diagnosis and management

MRI scanning is the current gold standard modality for imaging synovitis and tenosynovitis in patients with inflammatory arthritis. Inflamed synovial membrane within the joints and investing tendon sheaths appears thickened on T1-weighted sequences and enhances postcontrast. On T2-weighted sequences, synovitis and synovial effusions typically show a high signal. Studies have shown correlations between the degree of inflammation and vascularity of synovium obtained at biopsy and postcontrast enhancement on matching dynamic MRI scans. Scoring systems have been devised that are based on quantifying synovial membrane thickening and signal intensity on static postcontrast scans and have been validated in multireader settings. Moderate to high reliability has been demonstrated with trained readers and quantification of synovitis in this way is being used increasingly as an outcome measure in clinical trials to assess response to therapy. MRI-observed synovitis is almost invariable in those with active rheumatoid arthritis, but recent studies have also demonstrated its presence in patients in clinical remission, emphasizing the sensitivity of this technique and the importance of subclinical joint inflammation. MRI-observed synovitis has been validated against other imaging modalities, including power Doppler ultrasound, and has also been investigated in normal subjects (where mild enhancement can rarely occur). Studies over 1-2 years have suggested that MRI synovial membrane volume and postcontrast enhancement on dynamic imaging can predict the development of erosions. In the long term, an overall score of inflammation incorporating synovitis, tenosynovitis, and bone edema may be a more useful MRI predictor of aggressive erosive disease.

Magnetic resonance spin-labeling perfusion imaging of synovitis in inflammatory arthritis at 3.0 T

OBJECTIVE

The aim of this study was to test the feasibility of arterial spin labeling (ASL) perfusion imaging of synovitis in inflammatory joint diseases on a clinical 3.0 T whole-body scanner.

MATERIALS AND METHODS

Fifteen patients (geometric mean 47 years, range 8-69 years) with different types of inflammatory arthritis of the finger or wrist joints participated in the study. In addition to conventional spin-echo and dynamic contrast-enhanced FLASH3D sequences, a novel spin-labeling technique (FAIR-TrueFISP) for quantitative assessment of tissue perfusion was applied. Perfusion maps were calculated pixel-wise by means of the extended Bloch equations.

RESULTS

Perfusion maps showed good image quality with clear visualization of hyperaemia in synovitis. The computed perfusion maps corresponded best to subtraction images of the dynamic series from 30 to 60 s after contrast-medium injection. The quantitative perfusion values of synovitis showed a good correlation with the disease activity. Perfusion values for inflamed synovium in phase of high activity were up to 230 ml/100 g tissue/min.

CONCLUSION

The proposed modality allows for the assessment of disease activity in arthritis without the application of contrast-medium offering a new tool for therapy monitoring. As the technique provides quantitative information on hyperaemia, it potentially offers new insights in the pathophysiology of arthritic diseases.

What magnetic resonance imaging has told us about the pathogenesis of rheumatoid arthritis--the first 50 years

Modern imaging modalities, including magnetic resonance imaging (MRI), are valuable diagnostic and therapy monitoring tools in rheumatoid arthritis (RA). This article reviewed how these imaging modalities have greatly improved our understanding of pathogenic mechanisms in RA, namely the link between inflammation and damage. For example, traditional paradigms regarding the mechanisms of joint destruction, including the idea that synovitis and damage are uncoupled, have been challenged. As the power of MRI increases, there is a need to define normality since apparently normal joints occasionally exhibit MRI evidence of synovitis in the absence of symptoms.

Quantitative assessment of synovial vascularity using contrast-enhanced power Doppler ultrasonography: correlation with histologic findings and mr imaging findings in arthritic rabbit knee model

Objective

To validate contrast-enhanced power Doppler ultrasonography (PD US) for the evaluation of synovial vascularity in an arthritic rabbit knee model in correlation with MR and histological findings.

Materials and Methods

Power Doppler ultrasonography was performed for carrageenin-induced arthritic left knee and control right knee of 13 rabbits, first without and then with sonic contrast agent enhancement (Levovist, Schering, Berlin Germany), followed by gadolinium-enhanced MR imaging. Synovial vascularity was quantitatively assessed by calculating the color pixel area in power Doppler sonography using a computer-aided image analysis program and by grading the enhancement on MR images: grade 1, enhancement of knee joint is less than one-third of the area; grade 2, one-third to two-thirds enhancement; and grade 3, more than two-thirds enhancement. Microvessel density (MVD) was measured on slides stained immunohistochemically for CD31 antigen for histological assessment.

Results

The mean area of color pixels in PD US changed from 4.37 to 16.42 mm² in the arthritic knee after enhancement (p < 0.05), whereas it changed from 0.77 to 2.31 mm² in the control knee (p < 0.05). Arthritic knees had greater power Doppler signal than control knees both before and after contrast administration (p < 0.05). The average MVD was 88 in arthritic knees and 46 in control knees. MVDs correlated with color pixel areas of contrast-enhanced power Doppler imaging in arthritic knees. In MR grading of arthritic knees, five were grade 2 and eight were grade 3. MVD and PD US revealed no significant difference between grade 2 and 3 arthritic knees (p > 0.05).

Conclusion

Sonic contrast-enhanced PD US improves the visualization of synovial vascularity and allows quantitative measurement in experimentally induced rabbit arthritic knees.

Evaluation of the vascular status of autogenous hamstring tendon grafts after anterior cruciate ligament reconstruction in humans using magnetic resonance angiography

The purpose of this study is to evaluate the vascular status of autogenous semitendinosus grafts after anterior cruciate ligament reconstruction in humans using magnetic resonance angiography. Twelve patients (mean age, 24.3 years) who underwent anterior cruciate ligament reconstruction with the 4-strand semitendinosus tendon were studied. All patients underwent contrast-enhanced magnetic resonance angiography and second-look arthroscopy in their reconstructed knees on an average of 15.8 months (range 9-22 months) after surgery. Blood vessels to the graft were visualised and contrast medium enhancement for visualising the femoral tunnel, graft, and tibial tunnel was evaluated. Magnetic resonance angiography showed that a branch of the middle genicular artery extended to the upper side of the graft through the posterior capsule and that branches of the inferior genicular artery ended at the lower side of the graft in all patients. These were consistent with the actual findings of the second-look arthroscopy. We found contrast medium enhancement in the femoral and tibial tunnels in all patients. The effect of enhancement at 9 months after ACL reconstruction was higher than that at 22 months. The graft showed enhancement patterns in the posterior portion of the femoral side and the anterior portion of the tibial side. This study demonstrated that the branches of the middle and inferior genicular arteries provide blood supply to the graft, which may influence the maturation of the graft. The revascularisation of the bone tunnels could play an important role in the healing of the ligament-bone tunnel junction.

Changes underlying the dynamic contrast-enhanced MRI response to treatment in rheumatoid arthritis

OBJECTIVE

Dynamic contrast-enhanced MRI of patients with rheumatoid arthritis has shown a decrease in the early enhancement rate (EER) of synovitis after treatment. The purpose of this work was to investigate the underlying changes.

METHODS

3D dynamic contrast-enhanced images were acquired from 13 patients before and 1-2 weeks after anti-TNF alpha treatment. The EER of the inflamed synovium was measured. The T1 relaxation time of the synovitis was calculated from images at different flip angles. The time course of the arrival of gadolinium at the radial artery was determined. The gadolinium enhancement of the inflamed synovium was modeled to calculate the fractional plasma volume (vp), the fractional extravascular, extracellular fluid volume (ve), and the volume transfer constant (Ktrans). Pre- and post-treatment values were compared and the dependence of the EER on each parameter was assessed.

RESULTS

There was a decrease in the EER measured over 26 s after treatment (29%, p = 0.002). Reductions in T1 (12%, p = 0.001), Ktrans (31%, p = 0.002), and vp (43%, p = 0.01) contributed to this; however, the EER was relatively insensitive to changes in ve.

CONCLUSIONS

The decrease in EER after anti-TNF alpha treatment is largely caused by reductions in the volume transfer constant Ktrans, the fractional plasma volume vp, and the T1 relaxation time. Only the contributions from Ktrans and vp directly reflect synovial vascularity.

Longitudinal assessment of synovial, lymph node, and bone volumes in inflammatory arthritis in mice by in vivo magnetic resonance imaging and microfocal computed tomography

OBJECTIVE

To develop longitudinal 3-dimensional (3-D) measures of outcomes of inflammation and bone erosion in murine arthritis using contrast-enhanced magnetic resonance imaging (CE-MRI) and in vivo microfocal computed tomography (micro-CT) and, in a pilot study, to determine the value of entry criteria based on age versus synovial volume in therapeutic intervention studies.

METHODS

CE-MRI and in vivo micro-CT were performed on tumor necrosis factor-transgenic (TNF-Tg) mice and their wild-type littermates to quantify the synovial and popliteal lymph node volumes and the patella and talus bone volumes, respectively, which were validated histologically. These longitudinal outcome measures were used to assess the natural history of erosive inflammatory arthritis. We also performed anti-TNF versus placebo efficacy studies in TNF-Tg mice in which treatment was initiated according to either age (4-5 months) or synovial volume (3 mm(3) as detected by CE-MRI). Linear regression was performed to analyze the correlation between synovitis and focal erosion.

RESULTS

CE-MRI demonstrated the highly variable nature of TNF-induced joint inflammation. Initiation of treatment by synovial volume produced significantly larger treatment effects on the synovial volume (P = 0.04) and the lymph node volume (P < 0.01) than did initiation by age. By correlating the MRI and micro-CT data, we were able to demonstrate a significant relationship between changes in synovial and patellar volumes (R(2) = 0.75, P < 0.01).

CONCLUSION

In vivo CE-MRI and micro-CT 3-D outcome measures are powerful tools that accurately demonstrate the progression of erosive inflammatory arthritis in mice. These methods can be used to identify mice with arthritis of similar severity before intervention studies are initiated, thus minimizing heterogeneity in outcome studies of chronic arthritis seen between genetically identical littermates.