A rapid, novel method of volumetric assessment of MRI-detected subchondral bone marrow lesions in knee osteoarthritis

Bone marrow lesions in osteoarthritis: biomarker or treatment target? A narrative review

Osteoarthritis (OA) is a leading cause of pain, functional impairment, and disability in older adults. However, there are no effective treatments to delay and reverse OA. Magnetic resonance imaging (MRI) can assess structural abnormalities of OA by directly visualizing damage and inflammatory reactions within the tissues and detecting abnormal signals in the subchondral bone marrow region. While some studies have shown that bone marrow lesions (BMLs) are one of the early signs of the development of OA and predict structural and symptomatic progression of OA, others claimed that BMLs are prevalent in the general population and have no role in the progression of OA. In this narrative review, we screened and summarized studies with different designs that evaluated the association of BMLs with joint symptoms and structural abnormalities of OA. We also discussed whether BMLs may serve as an imaging biomarker and a treatment target for OA based on existing clinical trials.

A Comprehensive Review on MRI-based Knee Joint Segmentation and Analysis Techniques

Using magnetic resonance imaging (MRI) in osteoarthritis pathogenesis research has proven extremely beneficial. However, it is always challenging for both clinicians and researchers to detect morphological changes in knee joints from magnetic resonance (MR) imaging since the surrounding tissues produce identical signals in MR studies, making it difficult to distinguish between them. Segmenting the knee bone, articular cartilage and menisci from the MR images allows one to examine the complete volume of the bone, articular cartilage, and menisci. It can also be used to assess certain characteristics quantitatively. However, segmentation is a laborious and time-consuming operation that requires sufficient training to complete correctly. With the advancement of MRI technology and computational methods, researchers have developed several algorithms to automate the task of individual knee bone, articular cartilage and meniscus segmentation during the last two decades. This systematic review aims to present available fully and semi-automatic segmentation methods for knee bone, cartilage, and meniscus published in different scientific articles. This review provides a vivid description of the scientific advancements to clinicians and researchers in this field of image analysis and segmentation, which helps the development of novel automated methods for clinical applications. The review also contains the recently developed fully automated deep learning-based methods for segmentation, which not only provides better results compared to the conventional techniques but also open a new field of research in Medical Imaging.

Quantitative bone marrow lesion, meniscus, and synovitis measurement: current status

Imaging plays a pivotal role in osteoarthritis research, particularly in epidemiological and clinical trials of knee osteoarthritis (KOA), with the ultimate goal being the development of an effective drug treatment for future prevention or cessation of disease. Imaging assessment methods can be semi-quantitative, quantitative, or a combination, with quantitative methods usually relying on software to assist. The software generally attempts image segmentation (outlining of relevant structures). New techniques using artificial intelligence (AI) or deep learning (DL) are currently a frequent topic of research. This review article provides an overview of the literature to date, focusing primarily on the current status of quantitative software-based assessment techniques of KOA using magnetic resonance (MR) imaging. We will concentrate on the imaging evaluation of three specific structural imaging biomarkers: bone marrow lesions (BMLs), meniscus, and synovitis consisting of effusion synovitis (ES) and Hoffa's synovitis (HS). A brief clinical and imaging background review of osteoarthritis evaluation, particularly relating to these three structural markers, is provided as well as a general summary of the software methods. A summary of the literature with respect to each KOA assessment method will be presented overall as well as with respect to each specific biomarker individually. Novel techniques, as well as future goals and directions using quantitative imaging assessment, will be discussed.

3D MRI in Osteoarthritis

Osteoarthritis (OA) is among the top 10 burdensome diseases, with the knee the most affected joint. Magnetic resonance imaging (MRI) allows whole-knee assessment, making it ideally suited for imaging OA, considered a multitissue disease. Three-dimensional (3D) MRI enables the comprehensive assessment of OA, including quantitative morphometry of various joint tissues. Manual tissue segmentation on 3D MRI is challenging but may be overcome by advanced automated image analysis methods including artificial intelligence (AI). This review presents examples of the utility of 3D MRI for knee OA, focusing on the articular cartilage, bone, meniscus, synovium, and infrapatellar fat pad, and it highlights several applications of AI that facilitate segmentation, lesion detection, and disease classification.

The association between change in bone marrow lesion size and change in tibiofemoral cartilage volume and knee symptoms

OBJECTIVE

To describe the association between change in subchondral bone marrow lesions (BMLs) and change in tibiofemoral cartilage volume and knee symptoms in patients with symptomatic knee OA.

METHODS

In total, 251 participants (mean 61.7 years, 51% female) were included. Tibiofemoral cartilage volume was measured at baseline and 24 months, and BML size at baseline, 6 and 24 months. Knee pain and function scores were evaluated at baseline, 6 and 24 months. Change in total and compartment-specific BML size was categorized according to the Least Significance Criterion. Linear mixed-effects models were used to evaluate the associations of change in BMLs over 6 and 24 months with change in cartilage volume over 24 months and knee symptoms over 6 and 24 months.

RESULTS

Total BML size enlarged in 26% of participants, regressed in 31% and remained stable in 43% over 24 months. Compared with stable BMLs in the same compartment, enlarging BMLs over 24 months were associated with greater cartilage loss (difference: -53.0mm3, 95% CI: -100.0, -6.0), and regressing BMLs were not significantly associated with reduced cartilage loss (difference: 32.4mm3, 95% CI: -8.6, 73.3) over 24 months. Neither enlargement nor regression of total BML size over 6 and 24 months was associated with change in knee pain and function over the same time intervals.

CONCLUSIONS

In subjects with symptomatic knee osteoarthritis and BMLs, enlarging BMLs may lead to greater cartilage loss but regressing lesions are not associated with reduced cartilage loss while neither is associated with change in knee symptoms.

The relation of oral bisphosphonates to bone marrow lesion volume among women with osteoarthritis

OBJECTIVE

Bone marrow lesions (BMLs) contribute to pain and progression of knee OA. Bisphosphonates may be a potential disease-modifier through amelioration of BMLs. We sought to determine the effect of oral bisphosphonates on BML volume over 12 months.

DESIGN

Women in the Osteoarthritis Initiative who newly initiated an oral bisphosphonate were propensity-score matched to non-initiators. BML volume was assessed using sagittal turbo spin echo fat-suppressed intermediate-weighted MR images at the index date and 12 months later. A validated semi-automated process was used to segment subchondral OA-related BMLs to determine total volume of BMLs based on number of voxels within the outlined area of interest. Mean change in BML volume over 12 months among bisphosphonate initiators was compared with non-initiators using multiple linear regression.

RESULTS

145 bisphosphonate initiators were identified, who were well-matched to their comparators. The difference in mean change in total BML volume between the two groups, regardless of presence of baseline BMLs, was not significant (P = 0.4, 95% CI -156.6 to +354.2). The proportion of participants with decreased, increased, or unchanged BML volumes over the 12 months were similar in both groups. Among those with baseline BMLs, bisphosphonate initiators had a greater proportion with a decrease in BML volume compared with stable or increased BML volume than non-initiators (P = 0.03).

CONCLUSIONS

In this 'real-world' setting of women starting bisphosphonates, we found no clear evidence of benefit on BML volume over a 12-month period, though a trend towards a decrease in BML volume was noted.

Effect of cane use on bone marrow lesion volume in people with medial tibiofemoral knee osteoarthritis: randomized clinical trial

OBJECTIVE

To evaluate effects of daily cane use for 3 months on medial tibiofemoral bone marrow lesion (BML) volumes in people with medial tibiofemoral osteoarthritis (OA).

DESIGN

In this randomized controlled trial (RCT), 79 participants with medial tibiofemoral OA were randomized to either a cane group (using a cane whenever walking) or control group (not using any gait aid) for 3 months. The cane group received a single training session by a physiotherapist, using a biofeedback cane to teach optimal technique and body weight support and motor learning principles to facilitate retention of learning. The primary outcome was change in total medial tibiofemoral BML volume (per unit bone volume) measured from magnetic resonance imaging (MRI) at 3 months. Secondary outcomes were BML volumes (per unit bone volume) of the medial tibia and femur, and patient-reported outcomes of overall knee pain, knee pain on walking, physical function, perceived global symptom changes and health-related quality of life. MRI analyses were performed by a blinded assessor.

RESULTS

Seventy-eight participants (99%) completed the primary outcome. Mean (standard deviation) daily cane use was 2.3 (1.7) hours over 3 months. No evidence of between-group differences was found for change in total medial tibiofemoral BML volume (mean difference: -0.0010 (95% confidence intervals: -0.0022, 0.0003)). Most secondary outcomes showed minimal differences between groups.

CONCLUSION

Daily use of a cane during walking for 3 months aiming to reduce knee joint loading did not change medial tibiofemoral BML volumes compared to no use of gait aids.

CLINICAL TRIAL REGISTRATION

Australian New Zealand Clinical Trial Registry (ACTRN12614000909628).

Contribution of synovial macrophages to rat advanced osteoarthritis pain resistant to cyclooxygenase inhibitors

Most advanced knee osteoarthritis (OA) patients experience chronic pain resistant to cyclooxygenase (COX) inhibitors. However, the cells and molecules involved in this advanced OA pain remain poorly understood. In this study, we developed a rat model of advanced knee OA by modification of the monoiodoacetate-induced OA pain model and examined involvement of synovial macrophages in advanced OA pain. Cyclooxygenase inhibitors, such as celecoxib and naproxen, and a steroid were ineffective, but an opioid and anti-nerve growth factor (NGF) antibody was effective for pain management in the advanced OA model. Similar to advanced OA patients, histological analysis indicated severe bone marrow damages, synovitis, and cartilage damage and an increase of macrophages with high expression of interleukin-1β, NGF, nitric oxide synthase (NOS) 1, NOS2, and COX-2 in the knee joint of the advanced OA model. Intravenous injection of clodronate liposomes depleted synovial macrophages, which decreased the level of not only proinflammatory mediator interleukin-1β but also NGF in the knee joint, leading to pain suppression in the advanced OA model. These data suggest the involvement of synovial macrophages in advanced knee OA pain resistant to COX inhibitors by increasing proinflammatory mediators, and that drugs targeting synovial macrophages might have potent analgesic effects.

Synovial fluid pro-inflammatory profile differs according to the characteristics of knee pain

OBJECTIVE

The role of inflammation and pain in osteoarthritis (OA) is not fully understood. We evaluated the association between pro-inflammatory biomarkers and pain.

METHODS

We used baseline data and samples from a randomized controlled trial of colchicine for symptomatic knee OA. Severity of pain of the more symptomatic knee was assessed by National Health and Nutrition Examination Survey-I (NHANES-I) criterion and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain index. Pains on movement and at rest were self-reported on an 11-point Likert scale. Severity of radiographic tibiofemoral OA was assessed by Kellgren and Lawrence (KL) grade. Concentrations of synovial fluid (sf) IL-1β, IL-6, IL-8, TNFα, C-terminal telopeptides of Type I collagen (CTXI) and C-telopeptide of Type II collagen (CTXII), as well as urinary (u) CTXII were measured.

RESULTS

Of the 109 patients enrolled in the study, 70 patients (70% women) with synovial fluid obtained by direct aspiration were included for analysis. The mean ± SD age and body mass index (BMI) of the patients were 57.6 ± 8.3 years and 28.8 ± 5.2 kg/m². After adjustment for age, sex, and BMI, sf IL-6 and IL-8 were statistically significantly associated with 11-point pain on movement, but not with pain at rest. No significant associations were observed with WOMAC pain scores. sf IL-1β (analyzed as detectable/non-detectable) was inversely associated with pain. In contrast, after adjustment, Sf TNFα was associated with WOMAC total pain and both pain on movement and at rest. sf/u CTXII was associated with radiographic severity, but not with knee pain.

CONCLUSIONS

This study provides indication that OA pain mechanisms may differ according to the characteristics of the pain.

Associations between MRI features versus knee pain severity and progression: Data from the Vancouver Longitudinal Study of Early Knee Osteoarthritis

Objective

To determine associations between features of osteoarthritis (OA) on MRI and knee pain severity and knee pain progression.

Design

Baseline, 3.3- and 7.5-year assessments were performed for 122 subjects with baseline knee pain (age 40–79), sample-weighted for population (with knee pain) representativeness. MRIs were scored for: osteophytes (0:absent to 3:large); cartilage (0:normal to 4:full thickness defect; 0/1 collapsed); subchondral sclerosis (0:none to 3:>50% of site), subchondral cyst (0:absent to 3:severe), bone marrow lesions (0:none to 3:≥50% of site); and meniscus (0:normal to 3:maceration/resection), in 6–8 regions each. Per feature, scores were averaged across regions. Effusion/synovitis (0:absent to 3:severe) was analyzed as ≥2 vs. <2.

Linear models predicted WOMAC knee pain severity (0–100), and binary models predicted 10+ (minimum perceptible clinical improvement [MPCI]) and 20+ (minimum clinically important difference [MCID]) increases. Models were adjusted for age, sex, BMI (and follow-up time for longitudinal models).

Results

Pain severity was associated with osteophytes (7.17 per unit average; 95% CI = 3.19, 11.15) and subchondral sclerosis (11.03; 0.68, 21.39). MPCI-based pain increase was associated with osteophytes (odds ratio per unit average 3.20; 1.36, 7.55), subchondral sclerosis (5.69; 1.06, 30.44), meniscal damage (1.68; 1.08, 2.61) and effusion/synovitis ≥2 (2.25; 1.07, 4.71). MCID-based pain increase was associated with osteophytes (3.79; 1.41, 10.20) and cartilage defects (2.42; 1.24, 4.74).

Conclusions

Of the features investigated, only osteophytes were consistently associated with pain cross-sectionally and longitudinally in all models. This suggests an important role of bone in early knee osteoarthritis.

Impact of Cane Use on Bone Marrow Lesion Volume in People With Medial Knee Osteoarthritis (CUBA Trial)

BACKGROUND

No effective cure exists for knee osteoarthritis (OA). Low-burden self-management strategies that can slow disease progression are needed. Bone marrow lesions (BMLs) are a source of knee pain and accelerate cartilage loss. Importantly, they may be responsive to biomechanical off-loading treatments.

OBJECTIVE

The study objective is to investigate whether, in people with medial tibiofemoral OA, daily cane use for 12 weeks reduces the volume of medial tibiofemoral BMLs and improves pain, physical function, and health-related quality of life.

DESIGN

This study will be an assessor-masked, 2-arm, parallel-group, multisite randomized controlled trial.

SETTING

The community will serve as the setting for this study.

PARTICIPANTS

The study participants will be people who are 50 years old or older and have medial tibiofemoral OA and at least 1 medial tibiofemoral BML.

INTERVENTION

The participants will be allocated to either the cane group (using a cane daily whenever walking for 12 weeks) or the control group (not using any gait aid for 12 weeks).

MEASUREMENTS

Outcomes will be measured at baseline and 13 weeks. The primary outcome will be total medial tibiofemoral BML volume measured from magnetic resonance imaging. Secondary outcomes will include BML volume of the medial tibia and/or femur, knee pain overall and on walking, physical function, participant-perceived global change, and health-related quality of life. Additional measures will include physical activity, cointerventions, adverse events, participation, participant demographics, cane training process measures and feasibility, barriers to and facilitators of cane use, and loss to follow-up.

LIMITATIONS

People who are morbidly obese will not be included because of difficulties with magnetic resonance imaging.

CONCLUSIONS

The findings of this study will help to determine whether cane use can alter disease progression in people with medial tibiofemoral OA and/or influence clinical symptoms. This study may directly influence clinical guidelines for the management of knee OA.

Bone contusion progression from traumatic knee injury: association of rate of contusion resolution with injury severity

BACKGROUND

Bone contusions are frequently encountered in magnetic resonance imaging (MRI) evaluation of knee anterior cruciate ligament (ACL) injuries. Their role as indicators of injury severity remains unclear, primarily due to indeterminate levels of joint injury forces and to a lack of preinjury imaging.

PURPOSE

The purpose of this study was to 1) quantify bone contusion pathogenesis following traumatic joint injuries using fixed imaging follow-ups, and 2) assess the feasibility of using longitudinal bone contusion volumes as an indicator of knee injury severity.

STUDY DESIGN

Prospective sequential MRI follow-ups of a goat cohort exposed to controlled stifle trauma in vivo were compared to parallel clinical MRI follow-ups of a human ACL tear patient series.

METHODS

Reproducible cartilage impact damage of various energy magnitudes was applied in a survival goat model, coupled with partial resection of anterior portions of medial menisci. Both emulate injury patterns to the knee osteochondral structures commonly encountered in human ACL injury imaging as well as instability from resultant ligament laxity. Longitudinal clinical MRI sequences portrayed stifle bone contusion evolution through 6 months after the inciting event.

RESULTS

In the first 2 weeks, biological response variability dominated the whole-joint response with no apparent correlation to trauma severity. Control goats subjected to partial meniscectomy alone exhibited minimal bone response. Thereafter, 0.6 J impact bone contusions portrayed a faster rate of resolution than those induced by 1.2 J cartilage impacts.

CONCLUSION

Bone contusion sizes combined with time of persistence are likely better measures of joint injury severity than isolated bone contusion volume.

Preliminary validation of the Knee Inflammation MRI Scoring System (KIMRISS) for grading bone marrow lesions in osteoarthritis of the knee: data from the Osteoarthritis Initiative

Objective

Bone marrow lesions (BML) are an MRI feature of osteoarthritis (OA) offering a potential target for therapy. We developed the Knee Inflammation MRI Scoring System (KIMRISS) to semiquantitatively score BML with high sensitivity to small changes, and compared feasibility, reliability and responsiveness versus the established MRI Osteoarthritis Knee Score (MOAKS).

Methods

KIMRISS incorporates a web-based graphic overlay to facilitate detailed regional BML scoring. Observers scored BML by MOAKS and KIMRISS on sagittal fluid-sensitive sequences. Exercise 1 focused on interobserver reliability in Osteoarthritis Initiative observational data, with 4 readers (two experienced/two new to KIMRISS) scoring BML in 80 patients (baseline/1 year). Exercise 2 focused on responsiveness in an open-label trial of adalimumab, with 2 experienced readers scoring BML in 16 patients (baseline/12 weeks).

Results

Scoring time was similar for KIMRISS and MOAKS. Interobserver reliability of KIMRISS was equivalent to MOAKS for BML status (ICC=0.84 vs 0.79), but consistently better than MOAKS for change in BML: Exercise 1 (ICC 0.82 vs 0.53), Exercise 2 (ICC 0.90 vs 0.32), and in new readers (0.87–0.92 vs 0.32–0.51). KIMRISS BML was more responsive than MOAKS BML: post-treatment BML improvement in Exercise 2 reached statistical significance for KIMRISS (SRM −0.69, p=0.015), but not MOAKS (SRM −0.12, p=0.625). KIMRISS BML also more strongly correlated to WOMAC scores than MOAKS BML (r=0.80 vs 0.58, p<0.05).

Conclusions

KIMRISS BML scoring was highly feasible, and was more reliable for assessment of change and more responsive to change than MOAKS BML for expert and new readers.

Integration of accelerated MRI and post-processing software: a promising method for studies of knee osteoarthritis

OBJECTIVE

Magnetic resonance imaging (MRI) is a widely used imaging modality for studies of knee osteoarthritis (OA). Compared to radiography, MRI offers exceptional soft tissue imaging and true three-dimensional (3D) visualization. However, MRI is expensive both due to the cost of acquisition and evaluation of the images. The goal of our study is to develop a new method to address the cost of MRI by combining innovative acquisition methods and automated post-processing software.

METHODS

Ten healthy volunteers were scanned with three different MRI protocols: A standard 3D dual-echo steady state (DESS) pulse sequence, an accelerated DESS (DESS_Acc), acquired at approximately half the time compared to DESS, and a multi-echo time DESS (DESS_MTE), which is capable of producing measurements of T2 relaxation time. A software tool was used to measure cartilage volume. Accuracy was quantified by comparing DESS to DESS_Acc and DESS_MTE and precision was measured using repeat readings and acquisitions. T2 precision was determined using duplicate DESS_MTE acquisitions. Intra-class correlation coefficients (ICCs), root-mean square standard deviation (RMSSD), and the coefficient of variation (CoV) were used to quantify accuracy and precision.

RESULTS

The accuracies of DESS_Acc and DESS_MTE were CoV = 3.7% and CoV = 6.6% respectively, while precision was 3.8%, 3.0%, and 3.1% for DESS, DESS_Acc and DESS_MTE. T2 repositioning precision was 5.8%.

CONCLUSION

The results demonstrate that accurate and precise quantification of cartilage volume is possible using a combination of substantially faster MRI acquisition and post-processing software. Precise measurements of cartilage T2 and volume can be made using the same acquisition.

Validity and responsiveness of a new measure of knee osteophytes for osteoarthritis studies: data from the osteoarthritis initiative

PURPOSE

To validate a novel quantitative MRI method to measure osteophyte volume.

METHODS

90 subjects were selected from the Progression Cohort of the Osteoarthritis Initiative (OAI) at baseline and 48 months, and analyzed using a semi-automated software tool. Marginal osteophyte volume was calculated for four compartments of the central weight-bearing region of the tibiofemoral joint. Standardized response mean (SRM) for change in volume was used to quantify responsiveness. Concurrent validity was assessed via a comparison with MRI Osteoarthritis Knee Score (MOAKS) using Kruskal-Wallis analysis and Spearman's correlation coefficient. Intra- and inter-reader reliability was assessed on a subset of 20 knees using intra-class correlation coefficients (ICCs) and the root mean square standard deviation (RMSSD).

RESULTS

The average change in osteophyte volume (ΔV) was 196 mm(3) (SD = 272 mm(3)), and the baseline to 48-month SRM was 0.72. An increase in osteophyte volume was observed for 84% (76/90) of the subjects. Kruskal-Wallis analysis across the four MOAKS osteophyte categories was significant for medial and lateral compartments of both the tibia and femur (P < 0.001 for all). The intra-reader ICC was 0.98, and RMSSD was 82 mm(3), while inter-reader ICC was 0.97 and RMSSD was 91 mm(3). A statistically significant positive correlation was observed between osteophyte volume and several MOAKS cartilage and BML scores. The reader time was approximately 10 min per knee.

CONCLUSIONS

The method is responsive, efficient, and precise, making it practical for use in large cohort studies and observational research.

The Influence of Joint Loading on Bone Marrow Lesions in the Knee: A Systematic Review With Meta-analysis

BACKGROUND

Bone marrow lesions (BMLs) are considered as predictors of pain, disability, and structural progression of knee osteoarthritis. The relationship between knee loading and BMLs is not yet completely understood.

PURPOSE

To summarize the available evidence regarding the relationship between joint loading and the prevalence and progression of BMLs in the tibiofemoral joint.

STUDY DESIGN

Meta-analysis.

METHODS

Three databases (PubMed, Web of Science, and The Cochrane Library) were systematically screened for studies encompassing BMLs and changes in knee loading. A methodological quality assessment was conducted, and a meta-analysis computing overall odds ratios (ORs) was performed where possible.

RESULTS

A total of 29 studies involving 7641 participants were included. Mechanical loading was categorized as body weight and composition, compartmental load, structural lesion, and physical activity. High compartmental loads and structural lesions increased the risk for BMLs (overall ORs ranging from 1.56 [95% CI, 1.13-2.15] to 8.2 [95% CI, 4.4-15.1]; P = .006). Body weight increased the risk for BMLs to a lesser extent (overall OR, 1.03; 95% CI, 1.01-1.05; P = .007). Contradictory results for the effect of physical activity on BMLs were found.

CONCLUSION

Augmented compartmental loads and structural lesions increased the risk of the presence or progression of BMLs. Body weight increased the risk for BMLs to a lesser extent. Contradictory results for the effect of physical activity on BMLs may be explained by a dose-response relationship, knee alignment, and structural lesions.

CLINICAL RELEVANCE

It has been shown that unloading the knee temporarily may induce beneficial effects on osteoarthritis-related structural changes. Therefore, an early recognition of BMLs in the aging athlete's knee may provide information to counter the onset and aggravation of symptomatic knee osteoarthritis by reducing the knee load.

A systematic review of the relationship between subchondral bone features, pain and structural pathology in peripheral joint osteoarthritis

INTRODUCTION

Bone is an integral part of the osteoarthritis (OA) process. We conducted a systematic literature review in order to understand the relationship between non-conventional radiographic imaging of subchondral bone, pain, structural pathology and joint replacement in peripheral joint OA.

METHODS

A search of the Medline, EMBASE and Cochrane library databases was performed for original articles reporting association between non-conventional radiographic imaging-assessed subchondral bone pathologies and joint replacement, pain or structural progression in knee, hip, hand, ankle and foot OA. Each association was qualitatively characterised by a synthesis of the data from each analysis based upon study design, adequacy of covariate adjustment and quality scoring.

RESULTS

In total 2456 abstracts were screened and 139 papers were included (70 cross-sectional, 71 longitudinal analyses; 116 knee, 15 hip, six hand, two ankle and involved 113 MRI, eight DXA, four CT, eight scintigraphic and eight 2D shape analyses). BMLs, osteophytes and bone shape were independently associated with structural progression or joint replacement. BMLs and bone shape were independently associated with longitudinal change in pain and incident frequent knee pain respectively.

CONCLUSION

Subchondral bone features have independent associations with structural progression, pain and joint replacement in peripheral OA in the hip and hand but especially in the knee. For peripheral OA sites other than the knee, there are fewer associations and independent associations of bone pathologies with these important OA outcomes which may reflect fewer studies; for example the foot and ankle were poorly studied. Subchondral OA bone appears to be a relevant therapeutic target.

SYSTEMATIC REVIEW

PROSPERO registration number: CRD 42013005009.

Measurement of bone marrow lesions by MR imaging in knee osteoarthritis using quantitative segmentation methods--a reliability and sensitivity to change analysis

Background

Longitudinal assessment of bone marrow lesions (BMLs) in knee osteoarthritis (KOA) by MRI is usually performed using semi-quantitative grading methods. Quantitative segmentation methods may be more sensitive to detect change over time. The purpose of this study was to evaluate and compare the validity and sensitivity to detect changes of two quantitative MR segmentation methods for measuring BMLs in KOA, one computer assisted (CAS) and one manual (MS) method.

Methods

Twenty-two patients with KOA confined to the medial femoro-tibial compartment obtained MRI at baseline and follow-up (median 334 days in between). STIR, T1 and fat saturated T1 post-contrast sequences were obtained using a 1.5 T system. The 44 sagittal STIR sequences were assessed independently by two readers for quantification of BML. The signal intensities (SIs) of the normal bone marrow in the lateral femoral condyles and tibial plateaus were used as threshold values. The volume of bone marrow with SIs exceeding the threshold values (BML) was measured in the medial femoral condyle and tibial plateau and related to the total volume of the condyles/plateaus.

The 95% limits of agreement at baseline were used to determine the sensitivity to change.

Results

The mean threshold values of CAS and MS were almost identical but the absolute and relative BML volumes differed being 1319 mm³/10% and 1828 mm³/15% in the femur and 941 mm³/7% and 2097 mm³/18% in the tibia using CAS and MS, respectively. The BML volumes obtained by CAS and MS were significantly correlated but the tissue changes measured were different. The volume of voxels exceeding the threshold values was measured by CAS whereas MS included intervening voxels with normal SI.

The 95% limits of agreement were narrower by CAS than by MS; a significant change of relative BML by CAS was outside the limits of -2.0%-4.7% whereas the limits by MS were -6.9%-8.2%. The BML changed significantly in 13 knees using CAS and in 10 knees by MS.

Conclusion

CAS was a reliable method for measuring BML and more sensitive to detect changes over time than MS. The BML volumes measured by the two methods differed but were significantly correlated.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2474-15-447) contains supplementary material, which is available to authorized users.

Osteoarthritis year in review 2014: imaging

PURPOSE

This narrative review covers original publications related to imaging in osteoarthritis (OA) published in English between April 2013 and March 2014. In vitro data, animal studies and studies with less than 20 observations were not included.

METHODS

To extract relevant studies, an extensive PubMed database search was performed based on, but not limited to the query terms "Osteoarthritis" in combination with "MRI", "Imaging", "Radiography", "Ultrasound", "Computed Tomography" and "Nuclear Medicine". Publications were sorted according to relevance based on potential impact to the OA research community with the overarching goal of a balanced overview covering all aspects of imaging. Focus was on publications in high impact special interest journals. The literature will be presented in a methodological fashion covering radiography, ultrasound, compositional and morphologic Magnetic resonance imaging (MRI), and from an anatomic perspective including bone, muscle, meniscus and synovitis.

RESULTS AND CONCLUSIONS

Imaging research in OA in the last year was characterized by a strong focus on MRI-based studies dealing with epidemiological and methodological aspects of the disease. Ultrastructural tissue assessment specifically of cartilage and meniscus using compositional MRI is evolving further. Additional subsets of the large publicly available Osteoarthritis Initiative (OAI) MRI dataset are being analyzed at present and have been published with muscle analyses coming increasingly into the focus of the community. Bone parameters were evaluated using varying technology and a persistent interest in inflammatory disease manifestations has been noted. Other modalities than MRI have been less explored. To date most OA imaging research is still focused on the knee joint.

Clinical and translational potential of MRI evaluation in knee osteoarthritis

Magnetic resonance imaging (MRI) has become an increasingly important imaging technique in osteoarthritis (OA) research, and is widely used in the ongoing endeavor to understand the pathogenesis of OA and to develop structure and disease-modifying OA drugs. MRI offers semiquantitative, quantitative and compositional evaluation of knee OA, and enables visualization of tissues that are not seen by radiography, including but not limited to cartilage, meniscus, bone marrow lesions, synovitis, and muscles. It is now recognized that contrast-enhanced MRI enables more accurate evaluation of synovitis than MRI without contrast. Because of its ability to visualize multiple pain-related tissue pathology in three dimensions, MRI is the best modality for imaging of OA.