Relationship between subchondral bone microstructure and articular cartilage in the osteoarthritic knee using 3T MRI

Using Radiomics to Detect Subtle Architecture Changes of Cartilage and Subchondral Bone in Chronic Lateral Ankle Instability Patients Based on MRI PD-FS Images

RATIONALE AND OBJECTIVES

To use radiomics to detect the subtle changes of cartilage and subchondral bone in chronic lateral ankle instability (CLAI) patients based on MRI PD-FS images.

MATERIALS AND METHODS

A total of 215 CLAI patients and 186 healthy controls were included and randomly split into a training set (n=281, patients/controls=151/130) and an independent test set (n=120, patients/controls=64/56). They underwent ankle MRI examinations. On sagittal PD-FS images, eight cartilage regions and their corresponding subchondral bone regions were drawn. Radiomics models of cartilage, subchondral bone and combined cartilage and subchondral bone were built to differentiate CLAI patients from controls. A receiver operating characteristic curve (ROC) was used to assess the model's performance.

RESULTS

In the test dataset, the cartilage model yielded an area under the curve (AUC) of 0.0.912 (95% confidence interval (CI): 0.858-0.965, p<0.001), a sensitivity of 0.859, a specificity of 0.893, a negative predictive value (NPV) of 0.848, and a positive predictive value (PPV) of 0.902. The subchondral bone model yielded an AUC of 0.837 (95% CI: 0.766-0.907, p<0.001), a sensitivity of 0.875, a specificity of 0.714, an NPV of 0.833, and a PPV of 0.778. For the combined model, the AUC was 0.921 (95% CI: 0.863-0.972, p<0.001), sensitivity was 0.844, specificity was 0.911, NPV was 0.836, and PPV was 0.915, whose AUC was higher than those of both the cartilage model and the subchondral bone model.

CONCLUSION

The combined radiomics model achieved satisfying performance in detecting potential early architectural changes in cartilage and subchondral bone for CLAI patients.

Conventional MRI-derived subchondral trabecular biomarkers and their association with knee cartilage volume loss as early as 1 year: a longitudinal analysis from Osteoarthritis Initiative

OBJECTIVE

To study associations between MRI-derived subchondral trabecular biomarkers obtained from conventional MRI sequences and knee cartilage loss over 12 and 24 months, using the FNIH osteoarthritis (OA) biomarkers consortium.

MATERIALS AND METHODS

Data of the 600 subjects in the FNIH OA biomarkers consortium (a nested case-control study within Osteoarthritis Initiative [OAI]) were extracted from the online database. Baseline knee MRI (intermediate-weighted (IW) sequences) were evaluated to determine conventional MRI-derived trabecular thickness (cTbTh) and bone-to-total ratio (cBV/TV). The measurements for medial and lateral volumes of cartilages using baseline, 12-, and 24-month knee MRI were extracted from the OAI database, and cartilage volume loss over 12 and 24 months of follow-up were determined using Relative Change Index. The association between conventional MRI-based subchondral trabecular biomarkers and cartilage volume loss were studied using logistic regression models, adjusted for relevant confounders including age, sex, body mass index (BMI), vitamin D use, Kellgren Lawrence grade (KLG), and tibiofemoral alignment.

RESULTS

Higher medial cTbTh and cBV/TV at baseline were associated with increased odds of medial tibial cartilage volume loss over 12 months (ORs: 1.01 [1.00-1.02] and 1.24 [1.10-1.39] per 1-SD change) and 24 months (ORs: 1.01 [1.00-1.02] and 1.22 [1.08-1.37], per 1-SD change). No significant association was observed between medial subchondral trabecular biomarkers and lateral tibial or femoral (medial or lateral) cartilage volume loss over the first and second follow-up years.

CONCLUSIONS

Conventional MRI-derived subchondral trabecular biomarkers (higher medial cTbTh and cBV/TV) may be associated with increased medial tibial cartilage volume loss as early as 1 year.

Radiomics analysis using MR imaging of subchondral bone for identification of knee osteoarthritis

Background

To develop a magnetic resonance imaging (MRI)-based radiomics predictive model for the identification of knee osteoarthritis (OA), based on the tibial and femoral subchondral bone, and compare with the trabecular structural parameter-based model.

Methods

Eighty-eight consecutive knees were scanned with 3T MRI and scored using MRI osteoarthritis Knee Scores (MOAKS), in which 56 knees were diagnosed to have OA. The modality of sagittal three-dimensional balanced fast-field echo sequence (3D BFFE) was used to image the subchondral bone. Four trabecular structural parameters (bone volume fraction [BV/TV], trabecular thickness [Tb.Th], trabecular separation [Tb.Sp], and trabecular number) and 93 radiomics features were extracted from four regions of the lateral and medial aspects of the femur condyle and tibial plateau. Least absolute shrinkage and selection operator (LASSO) was used for feature selection. Machine learning-based support vector machine models were constructed to identify knee OA. The performance of the models was assessed by area under the curve (AUC) of the receiver operator characteristic (ROC). The correlation between radiomics features and trabecular structural parameters was analyzed using Pearson’s correlation coefficient.

Results

Our radiomics-based classification model achieved the AUC score of 0.961 (95% confidence interval [CI], 0.912–1.000) when distinguishing between normal and knee OA, which was higher than that of the trabecular parameter-based model (AUC, 0.873; 95% CI, 0.788–0.957). The first-order, texture, and Laplacian of Gaussian-based radiomics features correlated positively with Tb.Th and BV/TV, but negatively with Tb.Sp (P < 0.05).

Conclusions

Our results suggested that our MRI-based radiomics models can be used as biomarkers for the classification of OA and are superior to the conventional structural parameter-based model.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-022-03314-y.

Quantifying the Human Subchondral Trabecular Bone Microstructure in Osteoarthritis with Clinical CT

Osteoarthritis (OA) is characterized by critical alterations of the subchondral bone microstructure, besides the well-known cartilaginous changes. Clinical computed tomography (CT) detection of quantitative 3D microstructural subchondral bone parameters is applied to monitor changes of subchondral bone structure in different stages of human OA and is compared with micro-CT, the gold standard. Determination by clinical CT (287 µm resolution) of key microstructural parameters in tibial plateaus with mild-to-moderate and severe OA reveals strong correlations to micro-CT (35 µm), high inter- and intraobserver reliability, and small relative differences. In vivo, normal, mild-to-moderate, and severe OA are compared with clinical CT (331 µm). All approaches detect characteristic expanded trabecular structure in severe OA and fundamental microstructural correlations with clinical OA stage. Multivariate analyses at various in vivo and ex vivo imaging resolutions always reliably separate mild-to-moderate from severe OA (except mild-to-moderate OA from normal), revealing a striking similarity between 287 µm clinical and 35 µm micro-CT. Thus, accurate structural measurements using clinical CT with a resolution near the trabecular dimensions are possible. Clinical CT offers an opportunity to quantitatively monitor subchondral bone microstructure in clinical and experimental settings as an advanced tool of investigating OA and other diseases affecting bone architecture.

Early Emergent and Progressive Aberrant Subchondral Bone Remodeling Coupled with Aggravated Cartilage Degeneration in Developmental Dysplasia of the Hip

OBJECTIVE

Developmental dysplasia of the hip (DDH) is the most common skeletal development in children and could result in secondary osteoarthritis. This study aims to clarify the alternations of subchondral trabecular bone remodeling and microstructural properties during the development of DDH, and the potential influence of these alternations on the overlying cartilage degeneration and DDH progression.

DESIGN

Traditional straight-leg swaddling method was adopted to establish DDH model in newborn Sprague Dawley rats. Hip joint specimens from normal or DDH rats were used. Typical features of DDH in radiological examination were observed by x-ray analysis. Micro-computed tomography analysis was applied to evaluate the microstructural properties of subchondral bone at postnatal weeks 2, 4, and 6. Histological and immunohistochemical analyses were adopted to appraise subchondral bone remodeling activity and cartilage degeneration. The associations among subchondral bone, articular cartilage, and DDH severity were analyzed via multiple linear regression analysis.

RESULTS

Compared with control group, the subchondral bone in DDH group displayed a gradual trend of deteriorated microstructure and worsening biomechanical properties along with aberrant bone remodeling, which might be responsible for the inhibition of stress transmission from the articular cartilage to the subchondral bone and thus leading to the cartilage degeneration and accelerated DDH progression.

CONCLUSIONS

Our findings indicate that alternations of subchondral trabecular bone in a time-dependent manner could contribute to the DDH progression and the amelioration on subchondral bone might be a favorable therapeutic candidate for DDH.

Assessment of Bone Microarchitecture in Fresh Cadaveric Human Femurs: What Could Be the Clinical Relevance of Ultra-High Field MRI

MRI could be applied for bone microarchitecture assessment; however, this technique is still suffering from low resolution compared to the trabecular dimension. A clear comparative analysis between MRI and X-ray microcomputed tomography (μCT) regarding microarchitecture metrics is still lacking. In this study, we performed a comparative analysis between μCT and 7T MRI with the aim of assessing the image resolution effect on the accuracy of microarchitecture metrics. We also addressed the issue of air bubble artifacts in cadaveric bones. Three fresh cadaveric femur heads were scanned using 7T MRI and µCT at high resolution (0.051 mm). Samples were submitted to a vacuum procedure combined with vibration to reduce the volume of air bubbles. Trabecular interconnectivity, a new metric, and conventional histomorphometric parameters were quantified using MR images and compared to those derived from µCT at full resolution and downsized resolutions (0.102 and 0.153 mm). Correlations between bone morphology and mineral density (BMD) were evaluated. Air bubbles were reduced by 99.8% in 30 min, leaving partial volume effects as the only source of bias. Morphological parameters quantified with 7T MRI were not statistically different (p > 0.01) to those computed from μCT images, with error up to 8% for both bone volume fraction and trabecular spacing. No linear correlation was found between BMD and all morphological parameters except trabecular interconnectivity (R2 = 0.69 for 7T MRI-BMD). These results strongly suggest that 7T MRI could be of interest for in vivo bone microarchitecture assessment, providing additional information about bone health and quality.

Effective protein extraction combined with data independent acquisition analysis reveals a comprehensive and quantifiable insight into the proteomes of articular cartilage and subchondral bone

OBJECTIVE

The objectives of this study was to establish a sensitive and reproducible method to map the cartilage and subchondral bone proteomes in quantitative terms, and mine the proteomes for proteins of particular interest in the pathogenesis of osteoarthritis (OA). The horse was used as a model animal.

DESIGN

Protein was extracted from articular cartilage and subchondral bone samples from three horses in triplicate by pressure cycling technology or ultrasonication. Digested proteins were analysed by data independent acquisition based mass spectrometry. Data was processed using a pre-established spectral library as reference database (FDR 1%).

RESULTS

We identified to our knowledge the hitherto most comprehensive quantitative cartilage (1758 proteins) and subchondral bone (1482 proteins) proteomes in all species presented to date. Both extraction methods were sensitive and reproducible and the high consistency of the identified proteomes (>97% overlap) indicated that both methods preserved the diversity among the extracted proteins. Proteome mining revealed a substantial number of quantifiable cartilage and bone matrix proteins and proteins involved in osteogenesis and bone remodeling, including ACAN, BGN, PRELP, FMOD, COMP, ACP5, BMP3, BMP6, BGLAP, TGFB1, IGF1, ALP, MMP3, and collagens. A number of proteins, including COMP and TNN, were identified in different protein isoforms with potential unique biological roles.

CONCLUSION

We have successfully developed two sensitive and reproducible non-species specific workflows enabling a comprehensive quantitative insight into the proteomes of cartilage and subchondral bone. This facilitates the prospect of investigating the molecular events at the osteochondral unit in the pathogenesis of OA in future projects.

Radiomics Feature Analysis of Cartilage and Subchondral Bone in Differentiating Knees Predisposed to Posttraumatic Osteoarthritis after Anterior Cruciate Ligament Reconstruction from Healthy Knees

Objectives

To introduce a new implementation of radiomics analysis for cartilage and subchondral bone of the knee and to compare the performance of the proposed models to classic T2 relaxation time in distinguishing knees predisposed to posttraumatic osteoarthritis (PTOA) after anterior cruciate ligament reconstruction (ACLR) and healthy controls.

Methods

114 patients following ACLR after at least 2 years and 43 healthy controls were reviewed and allocated to training (n = 110) and testing (n = 47) cohorts. Radiomics models are built for cartilage and subchondral bone regions of different compartments: lateral femur (LF), lateral tibia (LT), medial femur (MF), and medial tibia (MT) and combined models of four compartments on T2 mapping images. The model performance of discrimination between patients and controls was illustrated with the receiver operating characteristic curve and compared with a classic T2 value-based model.

Results

The T2 value model of cartilage yielded moderate predictive performance in discerning patients and controls, with an AUC of 0.731 (95% confidence interval, 0.556–0.875) in the testing cohort, while the radiomics signature of cartilage and subchondral bone of different compartments demonstrated excellent performance, with AUCs of 0.864–0.979. Furthermore, the combined model reported an even better performance, with AUCs of 0.977 (95% confidence interval, 0.919–1.000) for the cartilage and 0.934 (95% confidence interval, 0.865–0.994) for the subchondral bone in the testing cohort.

Conclusion

The radiomics features of the cartilage and subchondral bone may be able to provide powerful tools with more sensitive detection than T2 values in differentiating knees at risk for PTOA after ACLR from healthy knees.

Survey of MRI Usefulness for the Clinical Assessment of Bone Microstructure

Bone microarchitecture has been shown to provide useful information regarding the evaluation of skeleton quality with an added value to areal bone mineral density, which can be used for the diagnosis of several bone diseases. Bone mineral density estimated from dual-energy X-ray absorptiometry (DXA) has shown to be a limited tool to identify patients' risk stratification and therapy delivery. Magnetic resonance imaging (MRI) has been proposed as another technique to assess bone quality and fracture risk by evaluating the bone structure and microarchitecture. To date, MRI is the only completely non-invasive and non-ionizing imaging modality that can assess both cortical and trabecular bone in vivo. In this review article, we reported a survey regarding the clinically relevant information MRI could provide for the assessment of the inner trabecular morphology of different bone segments. The last section will be devoted to the upcoming MRI applications (MR spectroscopy and chemical shift encoding MRI, solid state MRI and quantitative susceptibility mapping), which could provide additional biomarkers for the assessment of bone microarchitecture.

Assessment of 3-T MRI using susceptibility-weighted imaging to detect and evaluate intra- or periarticular blood metabolites and meniscal tears of the knee

Purpose

The purpose of this study was to assess the suitability of susceptibility-weighted imaging (SWI) sequences using the 3T MRI-unit for assessment of potential intraarticular pathologies in patients with acute and chronic torsion trauma of the knee joint.

Material and methods

Sixty-three patients with subacute and chronic rotary knee joint trauma of either the left or right knee were studied using an Achieva MRI 3T device (Philips, Amsterdam, Netherlands). Ground truth was set by two expert radiologists with seven and 10 years of experience in musculoskeletal imaging. Readings were performed separately for meniscus and joint space including synovia, ligaments, and periarticular soft tissue. Haemorrhage was defined as any lesion that was either T1 or SWI positive, without proton density (PD)-hypointensity (calcification). A lesion was defined as any pathology/variant with any signal positivity of either T1, PD, or SWI.

Results

A total of 63 patients were included (F : M = 22 : 41). The median age of the cohort was 29 years (range 13 to 71 years). Thirty-nine patients showed a meniscal tear, and only three of them (7.7%) demonstrated a meniscal haemorrhage. A total of 18 patients suffered from a periarticular injury, and 16 patients (88.9%) demonstrated a concomitant periarticular haemorrhage.

Conclusions

These data suggest that SWI can be used for the diagnosis of intra- or periarticular blood metabolites because their potential have an impact on mechanical conflict with the surface of the knee joints, in particular the cartilage and their effect on malacic lesions, but it performs poorly in the detection of meniscal pathologies.

Osteoarthritis year in review 2018: imaging

PURPOSE

To provide a narrative review of the most relevant original research published in 2017/2018 on osteoarthritis imaging.

METHODS

The PubMed database was used to recover all relevant articles pertaining to osteoarthritis and medical imaging published between 1 April 2017 and 31 March 2018. Review articles, case studies and in vitro or animal studies were excluded. The original publications were subjectively sorted based on relevance, novelty and impact.

RESULTS AND CONCLUSIONS

The publication search yielded 1,155 references. In the assessed publications, the most common imaging modalities were radiography (N = 708) and magnetic resonance imaging (MRI) (355), followed by computed tomography (CT) (220), ultrasound (85) and nuclear medicine (17). An overview of the most important publications to the osteoarthritis (OA) research community is presented in this narrative review. Imaging studies play an increasingly important role in OA research, and have helped us to understand better the pathophysiology of OA. Radiography and MRI continue to be the most applied imaging modalities, while quantitative MRI methods and texture analysis are becoming more popular. The value of ultrasound in OA research has been demonstrated. Several multi-modality predictive models have been developed. Deep learning has potential for more automatic and standardized analyses in future OA imaging research.