Diffusion tensor anisotropy magnetic resonance imaging: a new tool to assess synovial inflammation

Imaging-based measures of synovitis in knee osteoarthritis: A scoping review and narrative synthesis

Background

Synovitis has emerged as a tissue target of importance in OA research and is commonly evaluated with medical imaging.

Objectives

The purpose of this scoping review was to identify and describe the medical imaging techniques and definitions used by knee OA researchers to assess synovitis, summarize their advantages and disadvantages, and identify opportunities for future work.

Eligibility criteria

We included full-text peer-reviewed English publications including adults diagnosed with knee OA. Studies were included if one or more medical imaging modalities were used to assess synovitis in the knee.Studies of inflammatory arthritis, joint replacement, and synovial joints other than the knee were excluded. Animal studies and literature syntheses were also excluded.

Sources

MEDLINE, SCOPUS, and Google scholar databases were systematically searched for publications (2000-2023) using the following medical subject headings (MeSH): "osteoarthritis, knee", "magnetic resonance imaging", "ultrasonography", "synovitis".

Results

1154 articles were identified from searching medical databases. After removal of duplicates, abstract screening, and full text reading, 251 articles were included in the final review. MRI is the most common modality employed to assess knee synovitis, followed by US imaging. Varied imaging techniques used in the assessment of joint synovitis may be targeting divergent constructs of synovial remodeling and inflammation, which complicates interpretation of results.

Conclusions

There is no consensus on the best method for imaging of knee synovitis in OA. Future work may benefit from the evaluation of synovitis separate from joint effusion, and their associations with histologic findings to discriminate between features of synovial inflammation and remodeling.

Musculoskeletal manifestations in Tuberculosis

Musculoskeletal Tuberculosis (TB) affects the bones, joints and soft tissues and accounts for 1-3 % of TB cases worldwide. The onset of symptoms is usually insidious and nonspecific. It may lead to irreversible joint damage, deformities or neurological manifestations necessitating surgical and rehabilitative corrections due to delayed diagnosis and prolonged latency in the initiation of definitive medical treatment. The axial skeleton, particularly the thoracic and lumbar regions, is the most commonly involved site, followed by the hips and knees in peripheral joints. Given the rising prevalence of TB in developing countries and the emergence of drug-resistant strains, understanding musculoskeletal TB's pathophysiology, clinical manifestations, and management strategies remains critical for improving patient outcomes. In addition, non-tuberculous mycobacterial infections, para-infectious manifestation, and achieving adequate disease control in a setting of immune-mediated inflammatory disorders pose significant diagnostic and therapeutic challenges.

Factors influencing diffusion tensor imaging of knee cartilage in children ages 6-12 years: a prospective study

BACKGROUND

Magnetic resonance diffusion tensor imaging (DTI) has recently been used to evaluate the developing cartilage of children, but the influencing factors have not been well studied.

OBJECTIVE

The objective of this study was to investigate the influence of the diffusion gradient strength (b value), diffusion gradient direction, age and sex on knee cartilage DTI in healthy children aged 6-12 years.

MATERIALS AND METHODS

A total of 30 healthy child volunteers, with an average age of 8.9 ± 1.6 (mean ± standard deviation) years, were enrolled in this study. They were categorized into three groups according to their age range: 6-8 years, 8-10 years and 10-12 years, ensuring equal sex distribution in each group (5 boys and 5 girls). These volunteers underwent routine left knee joint magnetic resonance imaging (MRI) and serial DTI scans. DTI parameters were altered as follows: when b value = 600 s/mm2, diffusion gradient direction was set to 6, 15, 25, 35 and 45; and when diffusion gradient direction = 25, b value was set to 300, 600, 900 and 1200 s/mm2. The values of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were separately acquired using image post-processing techniques. The correlation between various b values, diffusion gradient directions, age and sex on the one hand and FA and ADC values on the other, was investigated.

RESULTS

(1) When diffusion gradient direction was fixed and the b value was varied, both FA and ADC exhibited a decreasing trend as the b value increased (P < 0.001). (2) When the b value was fixed and diffusion gradient direction was varied, the FA of knee cartilage showed a decreasing trend with increasing diffusion gradient direction (P < 0.001). (3) The FA value increased with age (P < 0.05).

CONCLUSION

The b value, diffusion gradient direction value and age exert a significant impact on both FA and ADC values in MR DTI of knee cartilage in children aged 6-12 years. In order to obtain a stable DTI, it is recommended to select a b value ≥ 600 s/mm2 and a diffusion gradient direction ≥ 25 during scanning.

Advanced Magnetic Resonance Imaging and Molecular Imaging of the Painful Knee

Chronic knee pain is a common condition. Causes of knee pain include trauma, inflammation, and degeneration, but in many patients the pathophysiology remains unknown. Recent developments in advanced magnetic resonance imaging (MRI) techniques and molecular imaging facilitate more in-depth research focused on the pathophysiology of chronic musculoskeletal pain and more specifically inflammation. The forthcoming new insights can help develop better targeted treatment, and some imaging techniques may even serve as imaging biomarkers for predicting and assessing treatment response in the future. This review highlights the latest developments in perfusion MRI, diffusion MRI, and molecular imaging with positron emission tomography/MRI and their application in the painful knee. The primary focus is synovial inflammation, also known as synovitis. Bone perfusion and bone metabolism are also addressed.

Diffusion Tensor and Dynamic Contrast-Enhanced Magnetic Resonance Imaging Correlate with Molecular Markers of Inflammation in the Synovium

Objectives: It is difficult to capture the severity of synovial inflammation on imaging. Herein we hypothesize that diffusion tensor imaging (DTI) derived metrics may delineate the aggregation of the inflammatory cells and expression of inflammatory cytokines and dynamic contrast-enhanced (DCE) imaging may provide information regarding vascularity in the inflamed synovium. Patients and methods: Patients with knee arthritis (>3-months duration) underwent conventional (T2-weighted fast spin echo and spin echo T1-weighted images) as well as DTI and DCE MRI and thereafter arthroscopic guided synovial biopsy. DCE and DTI metrics were extracted from the masks of the segments of the inflamed synovium which enhanced on post-contrast T1-weighted MRI. These metrics were correlated with immunohistochemistry (IHC) parameters of inflammation on synovium. Statistical analysis: Pearson’s correlation was performed to study the relationship between DTI- and DCE-derived metrics, IHC parameters, and post-contrast signal intensity. Linear regression model was used to predict the values of IHC parameters using various DTI and DCE derived metrics as predictors. Results: There were 80 patients (52 male) with mean age 39.78 years and mean disease duration 19.82 months. Nineteen patients had tuberculosis and the rest had chronic undifferentiated monoarthritis (n = 31), undifferentiated spondyloarthropathy (n = 14), rheumatoid arthritis (n = 6), osteoarthritis (n = 4), reactive arthritis (n = 3), ankylosing spondylitis (n = 2), and juvenile idiopathic arthritis (n = 1). Fractional anisotropy (FA), a metric of DTI, had significant correlation with number of immune cells (r = 0.87, p < 0.01) infiltrating into the synovium and cytokines (IL-1β, r = 0.55, p < 0.01; TNF-α, r = 0.42, p < 0.01) in all patients and also in each group of patients and adhesion molecule expressed on these cells in all patients (CD54, r = 0.51, p < 0.01). DCE parameters significantly correlated with CD34 (blood flow, r = 0.78, p < 0.01; blood volume, r = 0.76, p < 0.01) in each group of patients, a marker of neo-angiogenesis. FA was the best predictor of infiltrating inflammatory cells, adhesion molecule and proinflammatory cytokines. Amongst the DCE parameters, blood volume, was best predictor of CD34. Conclusion: DTI and DCE metrics capture cellular and molecular markers of synovial inflammation in patients with chronic inflammatory arthritis.

Intravoxel incoherent motion (IVIM) MRI in pediatric patients with synovitis of the knee joint: a prospective pilot study

BACKGROUND

Diagnosing synovial inflammation by administration of gadolinium-based contrast agents is limited by invasiveness and possible side effects, especially in children and adolescents.

PURPOSE

We investigated diagnostic accuracy of diffusion-weighted (DWI) MRI with intravoxel incoherent motion (IVIM) imaging compared to contrast-enhanced MRI for detecting synovitis of the knee in a population of pediatrics and young adults. In addition we compared quantitative measures of synovial diffusion and perfusion to a group of healthy volunteers.

METHODS

In this prospective study, 8 pediatric patients with 10 symptomatic knees (6 girls and 2 boys, mean age 13 years) with known or suspected synovitis underwent pre- and post-contrast 3.0 T MRI of the knee joint and additional DWI sequences between October 2016 and July 2019. For comparison we enrolled 5 healthy young adults (2 women and 3 men, median age 27 years) with contrast-free MRI of both knees. Post-contrast T1w images and DWI images at b = 1000s/mm² with apparent diffusion coefficient (ADC) maps of patients were separately rated by two independent and blinded readers with different levels of experience for the presence or absence and degree of synovitis along with the level of confidence. We measured signal intensity on DWI of synovium, joint effusion and muscle with regions of interests and calculated the IVIM-parameters tissue diffusion coefficient (D) and perfusion fraction (f) for patients and volunteers.

RESULTS

All patients showed at least some synovial contrast enhancement, 8 (80%) children knees were diagnosed with synovitis on contrast-enhanced (= ce)-T1w, the diagnostic standard. Ratings by the first and second reader on ce-T1w and DWI showed full agreement (kappa = 1) in diagnosing synovitis and substantial agreement (k = 0,655) for the degree of synovial enhancement. Interobserver agreement on DWI showed fair agreement (k = 0,220) between both readers. Diagnostic confidence was lower on DWI. Mean D- and f-values of muscle was comparable between patients and volunteers. Effusion mean D was higher, mean f was lower, synovial mean D was lower, mean f higher in patients than in volunteers. All differences were statistically significant (p < 0.001).

CONCLUSIONS

Diffusion-weighted MRI with IVIM imaging remains a promising, though reader-dependent alternative to i.v. contrast-enhanced imaging in pediatric patients to reliably diagnose, or rule out, synovitis of the knee joint. We detected significantly restricted synovial diffusion and increased perfusion in patients compared to healthy volunteers.

TRIAL REGISTRATION

Ethical Comitee University Hospital Ulm, Nr. 320/16.

To Contrast or Not to Contrast? On the Role of Contrast Enhancement in Hand MRI Studies of Patients with Rheumatoid Arthritis

Currently, clinical indications for the application of gadolinium-based contrast agents (GBCA) in magnetic resonance imaging (MRI) are increasingly being questioned. Consequently, this study aimed to evaluate the additional diagnostic value of contrast enhancement in MRI of the hand in patients with rheumatoid arthritis (RA). Thirty-one patients with RA (mean age, 50 ± 14 years (range, 18–72 years)) underwent morphologic MRI scans on a clinical 3 T scanner. MRI studies were analyzed based on (1) the Rheumatoid Arthritis Magnetic Resonance Imaging Score (RAMRIS) and (2) the GBCA-free RAMRIS version, termed RAMRIS Sine-Gadolinium-For-Experts (RAMRIS-SAFE), in which synovitis and tenosynovitis were assessed using the short-tau inversion-recovery sequence instead of the post-contrast T1-weighted sequence. The synovitis subscores in terms of Spearman’s ρ, as based on RAMRIS and RAMRIS-SAFE, were almost perfect (ρ = 0.937; p < 0.001), while the tenosynovitis subscores were less strongly correlated (ρ = 0.380 p = 0.035). Correlation between the total RAMRIS and RAMRIS-SAFE was also almost perfect (ρ = 0.976; p < 0.001). Inter-rater reliability in terms of Cohen’s κ was high (0.963 ≤ κ ≤ 0.925). In conclusion, RAMRIS-SAFE as the GBCA-free version of the well-established RAMRIS is a patient-friendly and resource-efficient alternative for assessing disease-related joint changes in RA. As patients with RA are subject to repetitive GBCA applications, non-contrast imaging protocols should be considered.

Gadolinium-free assessment of synovitis using diffusion tensor imaging

The dynamic contrast-enhanced (DCE)-MRI parameter Ktrans can quantify the intensity of synovial inflammation (synovitis) in knees with osteoarthritis (OA), but requires the use of gadolinium-based contrast agent (GBCA). Diffusion tensor imaging (DTI) measures the diffusion of water molecules with parameters mean diffusivity (MD) and fractional anisotropy (FA), and has been proposed as a method to detect synovial inflammation without the use of GBCA. The purpose of this study is to (1) determine the ability of DTI to quantify the intensity of synovitis in OA by comparing MD and FA with our imaging gold standard Ktrans within the synovium and (2) compare DTI and DCE-MRI measures with the semi-quantitative grading of OA severity with the Kellgren-Lawrence (KL) and MRI Osteoarthritis Knee Score (MOAKS) systems, in order to assess the relationship between synovitis intensity and OA severity. Within the synovium, MD showed a significant positive correlation with Ktrans (r = 0.79, p < 0.001), while FA showed a significant negative correlation with Ktrans (r = -0.72, p = 0.0026). These results show that DTI is able to quantify the intensity of synovitis within the whole synovium without the use of exogenous contrast agent. Additionally, MD, FA, and Ktrans values did not vary significantly when knees were separated by KL grade (p = 0.15, p = 0.32, p = 0.41, respectively), while MD (r = 0.60, p = 0.018) and Ktrans (r = 0.62, p = 0.013) had a significant positive correlation and FA (r = -0.53, p = 0.043) had a negative correlation with MOAKS. These comparisons indicate that quantitative measures of the intensity of synovitis may provide information in addition to morphological assessment to evaluate OA severity. Using DTI to quantify the intensity of synovitis without GBCA may be helpful to facilitate a broader clinical assessment of the severity of OA.

Imaging of Synovial Inflammation in Osteoarthritis, From the AJR Special Series on Inflammation

Synovitis, inflammation of the synovial membrane, is a common manifestation in osteoarthritis (OA) and is recognized to play a role in the complex pathophysiology of OA. Increased recognition of the importance of synovitis in the OA disease process and potential as a target for treatment has increased the need for non-invasive detection and characterization of synovitis using medical imaging. Numerous imaging methods can assess synovitis involvement in OA with varying sensitivity and specificity as well as complexity. This article reviews the role of contrast-enhanced MRI, conventional MRI, novel unenhanced MRI, gray-scale ultrasound (US), and power Doppler US in the assessment of synovitis in patients with OA. The role of imaging in disease evaluation as well as challenges in conventional imaging methods are discussed. We also provide an overview into the potential utility of emerging techniques for imaging of early inflammation and molecular inflammatory markers of synovitis, including quantitative MRI, superb microvascular imaging, and PET. The potential development of therapeutic treatments targeting inflammatory features, particularly in early OA, would greatly increase the importance of these imaging methods for clinical decision making and evaluation of therapeutic efficacy.

Evaluation of Synovitis of Hand in Patients With Rheumatoid Arthritis Using Diffusion Kurtosis Magnetic Resonance Imaging: Initial Findings

OBJECTIVE

To explore the role of diffusion kurtosis magnetic resonance (MR) imaging in the noninvasive identification of synovitis in hand arthritis.

METHODS

A total of 30 patients with rheumatoid arthritis (RA) and 10 patients suspected of RA were enrolled in the prospective study. A 3.0-T MR imaging including the diffusion kurtosis MR imaging sequence (b = 0, 500, 1000, 1500, 2000 s·mm2) was performed. A total of 210 regions of interest were confirmed and diffusion kurtosis MR imaging parameters were generated. The suspected synovitis or effusion was scored on a scale of 0 (effusion) to 3 (mild, moderate, severe synovitis), according to RA-MR imaging scoring system. The performance of diffusion kurtosis MR imaging parameters (the apparent diffusion coefficient [ADC], diffusion coefficient [D], and kurtosis [K]) in distinguishing different synovitis scores was evaluated.

RESULTS

There were significant differences in ADC, D, and K values among different synovitis scores (all P < 0.001). Synovitis scores were negatively correlated with the ADC and D values significantly (r = -0.725, -0.757, respectively, all P < 0.001), but positively correlated with the K values significantly (r = 0.429, P < 0.001). The area under the curve values of D, ADC, and K values were 0.884, 0.874, and 0.728 for differentiating score 1-3 from score 0, respectively. Diffusion coefficient and ADC had similar diagnostic performance, and both were higher than K in detecting synovitis. No significant difference was found between the ADC and D values in detecting synovitis.

CONCLUSIONS

The diffusion kurtosis MR imaging may be feasible as a noninvasive method for the diagnosis and grading of synovitis in the hands of RA patients, and the D and ADC values showed similar diagnostic performance, both of which were higher than K values.

Detection of knee synovitis using non-contrast-enhanced qDESS compared with contrast-enhanced MRI

Background

To assess diagnostic accuracy of quantitative double-echo in steady-state (qDESS) MRI for detecting synovitis in knee osteoarthritis (OA).

Methods

Patients with different degrees of radiographic knee OA were included prospectively. All underwent MRI with both qDESS and contrast-enhanced T1-weighted magnetic resonance imaging (CE-MRI). A linear combination of the two qDESS images can be used to create an image that displays contrast between synovium and the synovial fluid. Synovitis on both qDESS and CE-MRI was assessed semi-quantitatively, using a whole-knee synovitis sum score, indicating no/equivocal, mild, moderate, and severe synovitis. The correlation between sum scores of qDESS and CE-MRI (reference standard) was determined using Spearman’s rank correlation coefficient and intraclass correlation coefficient for absolute agreement. Receiver operating characteristic analysis was performed to assess the diagnostic performance of qDESS for detecting different degrees of synovitis, with CE-MRI as reference standard.

Results

In the 31 patients included, very strong correlation was found between synovitis sum scores on qDESS and CE-MRI (ρ = 0.96, p < 0.001), with high absolute agreement (0.84 (95%CI 0.14–0.95)). Mean sum score (SD) values on qDESS 5.16 (3.75) were lower than on CE-MRI 7.13 (4.66), indicating systematically underestimated synovitis severity on qDESS. For detecting mild synovitis or higher, high sensitivity and specificity were found for qDESS (1.00 (95%CI 0.80–1.00) and 0.909 (0.571–1.00), respectively). For detecting moderate synovitis or higher, sensitivity and specificity were good (0.727 (95%CI 0.393–0.927) and 1.00 (0.800–1.00), respectively).

Conclusion

qDESS MRI is able to, however with an underestimation, detect synovitis in patients with knee OA.

Traumatic subaxial cervical spine injury - Improving initial evaluation through correlation of diffusion tensor imaging and subaxial cervical spine injury classification SLIC score

Background

Traumatic injury to spine and spinal cord represents a devastating condition, with a huge risk for permanent severe disabilities. Predicting the long-term outcome in this type of trauma is a very difficult task being under the influence of a wide spectrum of biomechanical and pathophysiological factors. The advent of magnetic resonance imaging (MRI) structural evaluation of the spinal cord brought critical supplementary data in the initial evaluation of these cases. Although edema and hemorrhage proved to be valuable in predicting the outcome, there is a well-documented discrepancy between MRI findings and clinical status.

Methods

We performed diffusion tensor imaging (DTI) MR in 22 symptomatic patients with traumatic cervical spine injuries (mean age 49.6 ± 16, range from 17 to 74 years, 20 males and 2 females). DTI parameters were computed in 15 patients. Regional apparent diffusion coefficient, fractional anisotropy (FA), and fiber length (FL) were calculated in the region of interest defined as the region of maximum structural MR alterations and in the normal cord (above or below the level of the injury). The values for normal and pathological cord were compared. The clinical deficit was assessed with ASIA and subaxial cervical spine injury classification (SLIC) scores. We looked at the correlation between the DTI measures and clinical scores.

Results

There is a highly significant difference between normal and pathological spinal cord for all DTI properties measured. There is also a strong correlation between DTI measures and SLIC clinical score, especially for FA. Significant results were obtained for CDA and FL as well although with lesser statistical power.

Conclusion

Our results suggest that DTI measures, especially FA, represent a strong indicator of the severity of the traumatic cervical cord injury. It correlates very well with SLCI score and can be used as an additional confirmation of the real degree of level lesioning and as a prognostic factor for the neurological outcome regardless of the choice of treatment.

Quantitative Imaging in Inflammatory Arthritis: Between Tradition and Innovation

Radiologic imaging is crucial for diagnosing and monitoring rheumatic inflammatory diseases. Particularly the emerging approach of precision medicine has increased the interest in quantitative imaging. Extensive research has shown that ultrasound allows a quantification of direct signs such as bone erosions and synovial thickness. Dual-energy X-ray absorptiometry and high-resolution peripheral quantitative computed tomography (CT) contribute to the quantitative assessment of secondary signs such as osteoporosis or lean mass loss. Magnetic resonance imaging (MRI), using different techniques and sequences, permits in-depth evaluations. For instance, the perfusion of the inflamed synovium can be quantified by dynamic contrast-enhanced imaging or diffusion-weighted imaging, and cartilage injury can be assessed by mapping (T1ρ, T2). Furthermore, the increased metabolic activity characterizing the inflammatory response can be reliably assessed by hybrid imaging (positron emission tomography [PET]/CT, PET/MRI). Finally, advances in intelligent systems are pushing forward quantitative imaging. Complex mathematical algorithms of lesions' segmentation and advanced pattern recognition are showing promising results.

Assessing neuraxial microstructural changes in a transgenic mouse model of early stage Amyotrophic Lateral Sclerosis by ultra-high field MRI and diffusion tensor metrics

OBJECTIVE

Cell structural changes are one of the main features observed during the development of amyotrophic lateral sclerosis (ALS). In this work, we propose the use of diffusion tensor imaging (DTI) metrics to assess specific ultrastructural changes in the central nervous system during the early neurodegenerative stages of ALS.

METHODS

Ultra-high field MRI and DTI data at 17.6T were obtained from fixed, excised mouse brains, and spinal cords from ALS (G93A-SOD1) mice.

RESULTS

Changes in fractional anisotropy (FA) and linear, planar, and spherical anisotropy ratios (CL, CP, and CS, respectively) of the diffusion eigenvalues were measured in white matter (WM) and gray matter (GM) areas associated with early axonal degenerative processes (in both the brain and the spinal cord). Specifically, in WM structures (corpus callosum, corticospinal tract, and spinal cord funiculi) as the disease progressed, FA, CL, and CP values decreased, whereas CS values increased. In GM structures (prefrontal cortex, hippocampus, and central spinal cord) FA and CP decreased, whereas the CL and CS values were unchanged or slightly smaller. Histological studies of a fluorescent mice model (YFP, G93A-SOD1 mouse) corroborated the early alterations in neuronal morphology and axonal connectivity measured by DTI.

CONCLUSIONS

Changes in diffusion tensor shape were observed in this animal model at the early, nonsymptomatic stages of ALS. Further studies of CL, CP, and CS as imaging biomarkers should be undertaken to refine this neuroimaging tool for future clinical use in the detection of the early stages of ALS.

Intravoxel incoherent motion magnetic resonance imaging of the knee joint in children with juvenile idiopathic arthritis

BACKGROUND

MRI of synovitis relies on use of a gadolinium-based contrast agent. Diffusion-weighted MRI (DWI) visualises thickened synovium but is of limited use in the presence of joint effusion.

OBJECTIVE

To investigate the feasibility and diagnostic accuracy of diffusion-weighted MRI with intravoxel incoherent motion (IVIM) for diagnosing synovitis in the knee joint of children with juvenile idiopathic arthritis.

MATERIALS AND METHODS

Twelve consecutive children with confirmed or suspected juvenile idiopathic arthritis (10 girls, median age 11 years) underwent MRI with contrast-enhanced T1-weighted imaging and DWI at 1.5 T. Read-out segmented multi-shot DWI was acquired at b values of 0 s/mm², 200 s/mm², 400 s/mm² and 800 s/mm². We calculated the IVIM parameters perfusion fraction (f) and tissue diffusion coefficient (D). Diffusion-weighted images at b=800 s/mm², f parameter maps and post-contrast T1-weighted images were retrospectively assessed by two independent readers for synovitis using the Juvenile Arthritis MRI Scoring system.

RESULTS

Seven (58%) children showed synovial hypertrophy on contrast-enhanced imaging. Diagnostic ratings for synovitis on DWI and on f maps were fully consistent with contrast-enhanced imaging, the diagnostic reference. Two children had equivocal low-confidence assessments on DWI. Median f was 6.7±2.0% for synovitis, 2.1±1.2% for effusion, 5.0±1.0% for muscle and 10.6±5.7% for popliteal lymph nodes. Diagnostic confidence was higher based on f maps in three (25%) children and lower in one child (8%), as compared to DWI.

CONCLUSION

DWI with IVIM reliably visualises synovitis of the knee joint. Perfusion fraction maps differentiate thickened synovium from joint effusion and hence increase diagnostic confidence.

Contrast-enhanced MRI of the knee in children unaffected by clinical arthritis compared to clinically active juvenile idiopathic arthritis patients

OBJECTIVES

To evaluate enhancing synovial thickness upon contrast-enhanced magnetic resonance imaging (MRI) of the knee in children unaffected by clinical arthritis compared with clinically active juvenile idiopathic arthritis (JIA) patients. A secondary objective was optimization of the scoring method based on maximizing differences on MRI between these groups.

METHODS

Twenty-five children without history of joint complaints nor any clinical signs of joint inflammation were age/sex-matched with 25 clinically active JIA patients with arthritis of at least one knee. Two trained radiologists, blinded for clinical status, independently evaluated location and extent of enhancing synovial thickness with the validated Juvenile Arthritis MRI Scoring system (JAMRIS) on contrast-enhanced axial fat-saturated T1-weighted MRI of the knee.

RESULTS

Enhancing synovium (≥2 mm) was present in 13 (52 %) unaffected children. Using the total JAMRIS score for synovial thickening, no significant difference was found between unaffected children and active JIA patients (p = 0.091). Additional weighting of synovial thickening at the JIA-specific locations enabled more sensitive discrimination (p = 0.011).

CONCLUSIONS

Mild synovial thickening is commonly present in the knee of children unaffected by clinical arthritis. The infrapatellar and cruciate ligament synovial involvement were specific for JIA, which-in a revised JAMRIS-increases the ability to discriminate between JIA and unaffected children.

KEY POINTS

• Synovial inflammation is the primary disease feature in juvenile idiopathic arthritis (JIA). • Appearance of the synovium on contrast-enhanced MRI in unaffected children is unknown. • Validation of existing scoring methods requires comparison between JIA and unaffected children. • Mild enhancing synovial thickening was detected in half of the unaffected children. • Location-weighting for JIA-specific locations increased discriminative value of the scoring methods (p = 0.011).

Quantifying synovial inflammation: Emerging imaging techniques

Imaging techniques to assess synovial inflammation includes radiography, ultrasound, computed tomography, magnetic resonance imaging (MRI) and recently positron emission tomography. The ideal objective of imaging approaches are to quantify synovial inflammation by capturing features such as synovial hyperplasia, neo-angiogenesis and infiltration of immune cells in the synovium. This may enable clinicians to estimate response to therapy by measuring the improvement in the inflammatory signals at the level of synovium. Ultrasound can provide information regarding thickening of the synovial membrane and can reveal increased synovial blood flow using power Doppler technique. Bone marrow edema and synovial membrane thickness on MRI scan may serve as indicators for arthritis progression. Enhancement of the synovium on dynamic contrast MRI may closely mirror the inflammatory activity in the synovium. Diffusion tensor imaging is an advance MRI approach that evaluates the inflammation related to cell infiltration or aggregation in an inflamed synovium. In this review, we summarize the newer imaging techniques and their developments to evaluate synovial inflammation.

Non-invasive and in vivo assessment of osteoarthritic articular cartilage: a review on MRI investigations

Early detection of knee osteoarthritis (OA) is of great interest to orthopaedic surgeons, rheumatologists, radiologists, and researchers because it would allow physicians to provide patients with treatments and advice to slow the onset or progression of the disease. Early detection can be achieved by identifying early changes in selected features of degenerative articular cartilage (AC) using non-invasive imaging modalities. Magnetic resonance imaging (MRI) is becoming the standard for assessment of OA. The aim of this paper was to review the influence of MRI on the selection, detection, and measurement of AC features associated with early OA. Our review of the literature indicates that the changes associated with early OA are in cartilage thickness, cartilage volume, cartilage water content, and proteoglycan content that can be accurately, consistently, and non-invasively measured using MRI. Choosing an MR pulse sequence that provides the capability to assess cartilage physiology and morphology in a single acquisition and advanced multi-nuclei MRI is desirable. The results of the review indicate that using an ultra-high magnetic strength, MR imager does not affect early OA detection. In conclusion, MRI is currently the most suitable modality for early detection of knee OA, and future research should focus on the quantitative evaluation of early OA features using advances in MR hardware, software, and data processing with sophisticated image/pattern recognition techniques.

The diagnostic accuracy of unenhanced MRI in the assessment of joint abnormalities in juvenile idiopathic arthritis

OBJECTIVES

To assess the diagnostic accuracy and reliability of MRI without contrast enhancement in the evaluation of JIA knee joint abnormalities.

METHODS

JIA patients with clinically active knee involvement were prospectively studied using an 1-T open-bore magnet. MRI features were independently evaluated by two readers using the JAMRIS system. The first reading included unenhanced images, whereas complete image sets were available for the second reading.

RESULTS

Imaging findings from 73 patients were analysed. Agreement between Gd-enhanced (+Gd) and Gd-unenhanced (-Gd) MRI scores of bone marrow changes, cartilage lesions and bone erosions was good concerning sensitivity, specificity, negative predictive value and positive predictive value. Inter-observer agreement was good for both -Gd and +Gd scores (ICC = 0.91-1.00, 0.93-1.00, respectively). Regarding the assessment of synovial hypertrophy, specificity of -Gd was high (0.97), but the sensitivity of unenhanced MRI was only 0.62. Inter-reader agreement for +Gd MRI was ICC = 0.94; however, omitting post-Gd acquisitions increased inter-reader variation (ICC = 0.86).

CONCLUSIONS

If Gd-enhanced MRI is the reference standard, omitting Gd contrast medium is irrelevant for the assessment of bone marrow changes, cartilage lesions and bone erosions as joint abnormalities in JIA. Omitting intravenous Gd in the MRI assessment of joints in JIA is inadvisable, because it decreases the reliability of detecting synovial disease.

KEY POINTS

• Magnetic resonance imaging is increasingly used to assess juvenile idiopathic arthritis. • Synovial hypertrophy, a marker of JIA activity, is well shown by MRI. • Omitting intravenous contrast medium decreases the reliability of synovial hypertrophy scores. • Bone marrow, cartilage and erosions can be reliably evaluated without contrast enhancement. • In the evaluation of JIA disease activity, unenhanced MRI is inadvisable.

The pathogenesis of rheumatoid arthritis in radiological studies. Part II: Imaging studies in rheumatoid arthritis

Early diagnosis of rheumatoid arthritis followed by early initiation of treatment, prevent the destruction of joints and progression to disability in the majority of patients. A traditional X-ray fails to capture early inflammatory changes, while late changes (e.g. erosions) appear after a significant delay, once 20–30% of bone mass has been lost. Sonography and magnetic resonance imaging studies have shown that erosions are seen in the first 3 months from the appearance of symptoms in 10–26% of patients, while in 75% they are seen in the first 2 years of the disease. Power Doppler ultrasound and dynamic magnetic resonance studies allow for qualitative, semiquantitative and quantitative monitoring of the vascularization of the synovium. In addition, magnetic resonance enables assessment of the bone marrow. The ultrasonographic examination using a state-of-the-art apparatus with a high-frequency probe allows for images with great spatial resolution and for the visualization of soft tissues and bone surfaces. However, the changes seen in ultrasonography (synovial pathologies, the presence of exudate, tendons changes, cartilage and bone lesions, pathologies of tendon attachments and ligaments – enthesopathies) are not only specific for rheumatoid arthritis and occur in other rheumatic diseases. Qualitative methods are sufficient for diagnosing the disease through ultrasound or magnetic resonance imaging. Whereas semiquantitative and quantitative scales serve to monitor the disease course – efficacy of conservative treatment and qualification for radioisotope synovectomy or surgical synovectomy – and to assess treatment efficacy.

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.

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.

Emerging MRI methods in rheumatoid arthritis

New MRI techniques have been developed to assess not only the static anatomy of synovial hyperplasia, bone changes and cartilage degradation in patients with rheumatoid arthritis (RA), but also the activity of the physiological events that cause these changes. This enables an estimation of the rate of change in the synovium, bone and cartilage as a result of disease activity or in response to therapy. Typical MRI signs of RA in the pre-erosive phase include synovitis, bone marrow edema and subchondral cyst formation. Synovitis can be assessed by T2-weighted imaging, dynamic contrast-enhanced MRI or diffusion tensor imaging. Bone marrow edema can be detected on fluid-sensitive sequences such as short-tau inversion recovery or T2-weighted fast-spin echo sequences. Detection of small bone erosions in the early erosive phase using T1-weighted MRI has sensitivity comparable to CT. Numerous MRI techniques have been developed for quantitative assessment of potentially pathologic changes in cartilage composition that occur before frank morphologic changes. In this Review, we summarize the advances and new directions in the field of MRI, with an emphasis on their current state of development and application in RA.

Correlation of CSF proinflammatory cytokines with MRI in tuberculous meningitis

RATIONALE AND OBJECTIVES

To demonstrate the correlation of proinflammatory cytokines (PCs), intercellular adhesion molecule (sICAM-1), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1beta (IL-1beta) in CSF of tuberculous meningitis (TBM) patients with magnetic resonance imaging (MRI) including diffusion tensor imaging (DTI) and also to look for the changes in imaging parameters after antitubercular treatment (ATT) in these patients.

MATERIALS AND METHODS

Forty patients with TBM (median age, 27.7 years) and 30 age-/sex-matched controls were included in this study. PCs were quantified from the CSF of TBM patients at the time of hospital admission (baseline). MRI including DTI was performed at the time of baseline study and 6 months after ATT.

RESULTS

Significant positive correlation of PCs with fractional anisotropy (FA) values and post-contrast signal intensity (PCSI) collected from cerebral cortical regions was observed in TBM patients. A significant positive correlation of FA values with PCSI was also observed at both time points in patient groups. At baseline study significantly high FA values were observed in patients compared to controls. Significantly decreased FA values and PCSI were observed in the patients after 6 months of ATT compared to the baseline study.

CONCLUSIONS

Results of this study suggest that the DTI-derived anisotropy have the potential to delineate meningeal inflammation and it may be used in assessment of therapeutic response in TBM patients as an additional method to conventional imaging.