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

Automatic Segmentation of Bone Marrow Lesions on MRI Using a Deep Learning Method

Bone marrow lesion (BML) volume is a potential biomarker of knee osteoarthritis (KOA) as it is associated with cartilage degeneration and pain. However, segmenting and quantifying the BML volume is challenging due to the small size, low contrast, and various positions where the BML may occur. It is also time-consuming to delineate BMLs manually. In this paper, we proposed a fully automatic segmentation method for BMLs without requiring human intervention. The model takes intermediate weighted fat-suppressed (IWFS) magnetic resonance (MR) images as input, and the output BML masks are evaluated using both regular 2D Dice similarity coefficient (DSC) of the slice-level area metric and 3D DSC of the subject-level volume metric. On a dataset with 300 subjects, each subject has a sequence of 36 IWFS MR images approximately. We randomly separated the dataset into training, validation, and testing sets with a 70%/15%/15% split at the subject level. Since not every subject or image has a BML, we excluded the images without a BML in each subset. The ground truth of the BML was labeled by trained medical staff using a semi-automatic tool. Compared with the ground truth, the proposed segmentation method achieved a Pearson's correlation coefficient of 0.98 between the manually measured volumes and automatically segmented volumes, a 2D DSC of 0.68, and a 3D DSC of 0.60 on the testing set. Although the DSC result is not high, the high correlation of 0.98 indicates that the automatically measured BML volume is strongly correlated with the manually measured BML volume, which shows the potential to use the proposed method as an automatic measurement tool for the BML biomarker to facilitate the assessment of knee OA progression.

Increased Host Bone Marrow Edema on 6-Month MRI Is a Risk Factor for Osteochondral Allograft Failure

PURPOSE

To evaluate the presence of host bone marrow edema (BME) surrounding osteochondral allograft (OCA) plugs on routine 6-month postoperative magnetic resonance imaging (MRI) and to determine whether such BME is correlated with subsequent failure.

METHODS

The present study was approved under our institutional review board-approved database (#2020-2123). We included patients who underwent cartilage repair with OCA for focal chondral and osteochondral defects of the distal femur by 2 senior surgeons between January 2016 and May 2021 with minimum 2-year follow-up. OCA is frequently performed with concomitant procedures, and therefore ligament reconstruction, meniscal surgery, and osteotomy were not exclusion criteria. Failure was defined as (1) poor clinical outcome with graft collapse on follow-up MRI or second-look arthroscopy, (2) primary OCA removal or revision, or (3) conversion to unicompartmental or total knee arthroplasty. Routine MRI scans were performed at 6 ± 2 months postoperatively. All postoperative MRI scans were reviewed from our imaging record by 2 blinded fellowship-trained orthopaedic surgeons. Patients were divided for analyses into 2 groups: BME ≥10 cm3 versus BME <10 cm3.

RESULTS

Of the 85 patients eligible for the study, 56 patients (30 female, mean age 31.69 ± 11.34 years) had a minimum 2-year follow-up. Nonfailure cases had a mean clinical follow-up of 3.13 ± 0.93 years. The mean time from surgery to failure in our cohort was 1.67 ± 0.91 years. There were 12 (21.4%) patients with BME ≥10 cm³ and 44 (78.6%) patients with BME <10 cm³. No statistically significant differences were found between groups when compared for sex, age, body mass index, OCA size, time to MRI, mean follow-up, number of plugs, graft location, diagnosis, previous surgeries, or concomitant procedures. All OCA failures of the study cohort were in the BME ≥10 cm³ group, representing 50% of this group (P < .001). Kaplan-Meier survival analysis with the log-rank test demonstrated significant difference in survival distributions between groups (P < .001). Patients who ultimately failed had a mean BME volume of 18.49 ± 5.82 cm3, while the nonfailure group had a mean volume of 4.66 ± 4.97 cm3 (P < .001). Cutoff values around 10 cm³ in receiver operating characteristic curve analysis demonstrated 100% sensitivity and close to 90% specificity for OCA failure diagnosis.

CONCLUSION

Host BME with a volume greater than 10 cm³ on 6-month postoperative MRI is predictive of an increased subsequent failure rate after OCA transplantation with a failure rate of 50%.

LEVEL OF EVIDENCE

Level III, cohort study.

Comprehensive Study on Scoring and Grading Systems for Predicting the Severity of Knee Osteoarthritis

Knee Osteoarthritis (KOA) is a degenerative joint ailment characterized by cartilage loss, which can be seen using imaging modalities and converted into imaging features. The older population is the most affected by knee OA, which affects 16% of people worldwide who are 15 years of age and older. Due to cartilage tissue degradation, primary knee OA develops in older people. In contrast, joint overuse or trauma in younger people can cause secondary knee OA. Early identification of knee OA, according to research, may be a successful management tactic for the condition. Scoring scales and grading systems are important tools for the management of knee osteoarthritis as they allow clinicians to measure the progression of the disease's severity and provide suggestions on suitable treatment at identified stages. The comprehensive study reviews various subjective and objective knee evaluation scoring systems that effectively score and grade the KOA based on where defects or changes in articular cartilage occur. Recent studies reveal that AI-based approaches, such as that of DenseNet, integrating the concept of deep learning for scoring and grading the KOA, outperform various state-of-the-art methods in order to predict the KOA at an early stage.

Larger bone marrow lesion volume before medial open-wedge high tibial osteotomy correlates with better improvement of clinical scores in patients with knee osteoarthritis

PURPOSE

This study evaluated the clinical outcomes of medial open-wedge high tibial osteotomy (MOWHTO) and bone marrow lesion (BML) scores and volumes. The hypotheses were that quantitative BML volume is more associated with clinical outcomes of MOWHTO than qualitative BML evaluations, and pre-operative BML volume is associated with the improvement of clinical outcomes.

METHODS

Patients who underwent MOWHTO were retrospectively enrolled. The Knee Injury and Osteoarthritis Outcome Score (KOOS) was recorded before the initial surgery and at plate removal surgery. Using pre-operative short-time inversion recovery magnetic resonance imaging, BMLs were evaluated using three qualitative scores, reflecting the maximum length, proportion, and intensity of BML. For quantification, BMLs of the femur and tibia were separately defined as lesions with a threshold greater than the mean signal intensity plus two standard deviations, using the corresponding lateral condyles as controls. The association between the KOOS scales and BML scores/volume was evaluated using Spearman's correlation coefficient. Multivariate linear regression analyses for post-operative KOOS scales were performed using the tibial BML volume as one of the four independent variables.

RESULTS

The final analysis included 40 MOWHTO cases. Two qualitative BML scores correlated only with pre-operative KOOS sports. Femoral and tibial BML volumes were correlated with post-operative KOOS QOL (ρ = 0.40, p = 0.01) and sports (ρ = 0.36, p = 0.02), respectively. Tibial BML volume was significantly correlated with all five delta KOOS scales (ρ = 0.39-0.51, p = 0.01-0.001), however, femoral BML volume was only correlated with delta KOOS QOL (ρ = 0.41, p = 0.01). In multivariate analyses, tibial BML volume was a significant positive predictor for every post-operative KOOS scale, while post-operative % mechanical axis was also a positive significant variable, except post-operative KOOS pain.

CONCLUSION

Tibial BML volume was positively correlated with one post-operative KOOS scale and all delta KOOS scales. A larger pre-operative tibial BML and appropriate alignment correction were associated with a better post-operative KOOS scales. Pre-operative large BML had no negative influence on post-operative clinical outcomes; hence, surgeons need not hesitate to perform MOWHTO in patients with large BMLs in the medial condyles.

LEVEL OF EVIDENCE

Retrospective case series, Level IV.

Quantitative and semi-quantitative assessment of synovitis on MRI and the relationship with symptoms in symptomatic knee osteoarthritis

Objectives

Synovitis in symptomatic knee OA (KOA) is common and is associated with joint symptoms. Optimal synovial measurement on MRI is, however, unclear. Our aims were to examine the relationship between MRI measures of synovitis and knee symptoms in symptomatic KOA.

Methods

Data from a randomized, multicentre, placebo-controlled trial (UK-VIDEO) of vitamin-D therapy in symptomatic KOA were utilized. Participants reported knee symptoms using WOMAC at baseline and annually. On contrast-enhanced (CE) MRI, synovial thickness was measured using established, semi-quantitative methods whilst synovial tissue volume (STV) was assessed as absolute STV (aSTV) and relative to the width of femoral condyle (rSTV). STV of the infrapatellar region was also assessed. Associations between synovial measures and symptoms were analysed using multiple linear regression modelling.

Results

No linear association was observed between knee symptoms and synovitis thickness scores. Whole-joint aSTV (0.88, 95% CI: 0.17, 1.59) and infrapatellar aSTV (5.96, 95% CI: 1.22, 10.7) were positively associated with knee pain. Whole-joint rSTV had a stronger association with pain (7.96, 95% CI: 2.60, 13.33) and total scores (5.63, 95% CI: 0.32, 10.94). Even stronger associations were found for infrapatellar rSTV with pain (55.47, 95% CI: 19.99, 90.96), function (38.59, 95% CI: 2.1, 75.07) and total scores (41.64, 95% CI: 6.56, 76.72).

Conclusions

Whole-joint and site-specific infrapatellar STV measures on CE-MRI were associated with knee pain, respectively. Volumes relative to the size of the femoral condyle may be promising outcome measures in KOA trials.

The effect of intra-articular glucocorticosteroids and exercise on symptoms and bone marrow lesions in knee osteoarthritis: a secondary analysis of results from a randomized controlled trial

OBJECTIVE

To evaluate if the relative volume of bone marrow lesions (BMLs) changed in patients with knee osteoarthritis (OA) during a therapeutic study.

DESIGN

This study is a sub-study to a larger clinical trial which compared the clinical effects of intra-articular corticosteroid injection in knee OA to placebo injection, both given prior to exercise therapy. Clinical assessment using the Knee injury and Osteoarthritis Outcome Score (KOOS) and magnetic resonance imaging (MRI) examinations with BML assessments were performed at baseline and follow-up after 14 weeks and 26 weeks, respectively. The BML volume was determined using a computer assisted method focusing on participants with valid baseline and follow-up MRI examinations. Any changes in BML and KOOS were analyzed and investigated for associations.

RESULTS

Fifty participants received steroid and placebo injection, respectively, of which 41 and 45 had complete MRI examinations at week 14, and 36 and 33 at week 26, respectively. All participants received 12 weeks of exercise. A significant change in relative BML volume was observed between the corticosteroid group and the placebo group after 14 weeks [-1.1% vs 2.7%; between-group difference, 3.8% (95% CI 0.5-7.0)] but not after 26 weeks [0.8% vs 1.6%; between-group difference, 0.8% (95% CI -2.8 to 4.4)]. No significant association was found between changes in relative BML volume and KOOS.

CONCLUSIONS

Despite the statistically significant difference in BML volume at 14 weeks after corticosteroid injection and 12 weeks exercise therapy compared to placebo injection and exercise, there is very little evidence on a relationship between corticosteroids and BML volume.

EU CLINICAL TRIALS REGISTER

EudraCT number: 2012-002607-18.

Risk factors for joint replacement in knee osteoarthritis; a 15-year follow-up study

BACKGROUND

To evaluate whether clinical, radiographic or MRI findings are associated with long term risk for total knee arthroplasty (TKA) in persons with knee osteoarthritis.

METHODS

We performed a follow-up analysis of 100 persons with knee osteoarthritis who participated in a clinical trial between 2000 and 2002. Clinical data as well as radiography and MRI of the inclusion knee were obtained in all participants. Data on TKA procedures were extracted from The Danish National Patient Register. Clinical, radiographic and MRI findings were analyzed for associations with subsequent TKA.

RESULTS

During a mean follow-up period of 15 years, 66% received a TKA in the included knee (target knee); 37% also received a TKA in the other knee. The degree of joint space narrowing was highly associated with subsequent TKA (adjusted odds ratio (OR) 5.0 (95% confidence interval (95% CI) 2.6 - 9.9)) as was a radiological sum score comprising joint space narrowing, osteophytes, subchondral sclerosis and cysts (adjusted OR 1.7 (95% CI 1.3 - 2.1)). MRI detected bone marrow lesions, synovitis and effusion were similarly associated with subsequent TKA with an adjusted OR of 2.3 (95% CI 1.3 - 4.0), 2.8 (95% CI 1.5 - 5.2) and 1.9 (95% CI 1.2 - 3.1), respectively. Increased body mass index (BMI) was not associated with subsequent TKA in the target knee but was associated with TKA in the other knee (OR 2.3 (95% CI 1.2 - 4.3).

CONCLUSIONS

Radiographic findings including joint space narrowing and MRI detected bone marrow lesions, synovitis and effusion were all significantly associated with the long term risk of TKA in persons with knee osteoarthritis.

Assessment of subchondral bone marrow lesions in knee osteoarthritis by MRI: a comparison of fluid sensitive and contrast enhanced sequences

Background

Bone marrow lesions (BMLs) in knee osteoarthritis (OA) can be assessed using fluid sensitive and contrast enhanced sequences. The association between BMLs and symptoms has been investigated in several studies but only using fluid sensitive sequences. Our aims were to assess BMLs by contrast enhanced MRI sequences in comparison with a fluid sensitive STIR sequence using two different segmentation methods and to analyze the association between the MR findings and disability and pain.

Methods

Twenty-two patients (mean age 61 years, range 41–79 years) with medial femoro-tibial knee OA obtained MRI and filled out a WOMAC questionnaire at baseline and follow-up (median interval of 334 days). STIR, dynamic contrast enhanced-MRI (DCE-MRI) and fat saturated T1 post-contrast (T1 CE FS) MRI sequences were obtained. All STIR and T1 CE FS sequences were assessed independently by two readers for STIR-BMLs and contrast enhancing areas of BMLs (CEA-BMLs) using manual segmentation and computer assisted segmentation, and the measurements were compared. DCE-MRIs were assessed for the relative distribution of voxels with an inflammatory enhancement pattern, N_voxel, in the bone marrow. All findings were compared to WOMAC scores, including pain and overall symptoms, and changes from baseline to follow-up were analyzed.

Results

The average volume of CEA-BML was smaller than the STIR-BML volume by manual segmentation. The opposite was found for computer assisted segmentation where the average CEA-BML volume was larger than the STIR-BML volume. The contradictory finding by computer assisted segmentation was partly caused by a number of outliers with an apparent generally increased signal intensity in the anterior parts of the femoral condyle and tibial plateau causing an overestimation of the CEA-BML volume.

Both CEA-BML, STIR-BML and N_voxel were significantly correlated with symptoms and to a similar degree. A significant reduction in total WOMAC score was seen at follow-up, but no significant changes were observed for either CEA-BML, STIR-BML or N_voxel.

Conclusions

Neither the degree nor the volume of contrast enhancement in BMLs seems to add any clinical information compared to BMLs visualized by fluid sensitive sequences. Manual segmentation may be needed to obtain valid CEA-BML measurements.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-1336-9) contains supplementary material, which is available to authorized users.