Quantitative T2 mapping of the patella at 3.0T is sensitive to early cartilage degeneration, but also to loading of the knee

Time-Resolved Quantification of Patellofemoral Cartilage Deformation in Response to Loading and Unloading via Dynamic MRI With Prospective Motion Correction

BACKGROUND

In vivo cartilage deformation has been studied by static magnetic resonance imaging (MRI) with in situ loading, but knowledge about strain dynamics after load onset and release is scarce.

PURPOSE

To measure the dynamics of patellofemoral cartilage deformation and recovery in response to in situ loading and unloading by using MRI with prospective motion correction.

STUDY TYPE

Prospective.

SUBJECTS

Ten healthy male volunteers (age: [31.4 ± 3.2] years).

FIELD STRENGTH/SEQUENCE

T1-weighted RF-spoiled 2D gradient-echo sequence with a golden angle radial acquisition scheme, augmented with prospective motion correction, at 3 T.

ASSESSMENT

In situ knee loading was realized with a flexion angle of approximately 40° using an MR-compatible pneumatic loading device. The loading paradigm consisted of 2 minutes of unloaded baseline followed by a 5-minute loading bout with 50% body weight and an unloading period of 38 minutes. The cartilage strain was assessed as the mean distance between patellar and femoral bone-cartilage interfaces as a percentage of the initial (pre-load) distance.

STATISTICAL TESTS

Wilcoxon signed-rank tests (significance level: P < 0.05), Pearson correlation coefficient (r).

RESULTS

The cartilage compression and recovery behavior was characterized by a viscoelastic response. The elastic compression ([-12.5 ± 3.1]%) was significantly larger than the viscous compression ([-7.6 ± 1.5]%) and the elastic recovery ([10.5 ± 2.1]%) was significantly larger than the viscous recovery ([6.1 ± 1.8]%). There was a significant residual offset strain ([-3.6 ± 2.3]%) across the cohort. A significant negative correlation between elastic compression and elastic recovery was observed (r = -0.75).

DATA CONCLUSION

The in vivo cartilage compression and recovery time course in response to loading was successfully measured via dynamic MRI with prospective motion correction. The clinical relevance of the strain characteristics needs to be assessed in larger subject and patient cohorts.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY: Stage 1.

T2 Mapping of Patellar Cartilage After a Single First-Time Episode of Traumatic Lateral Patellar Dislocation

BACKGROUND

In most cases, lateral patellar dislocation (LPD) is accompanied by chondral injury and may initiate gradual degeneration of patellar cartilage, which might be detected with a T2 mapping, a well-established method for cartilage lesions assessment.

PURPOSE

To examine short-term consequences of single first-time LPD in teenagers by T2 mapping of the patellar-cartilage state.

STUDY TYPE

Prospective.

POPULATION

95 patients (mean age: 15.1 ± 2.3; male/female: 46/49) with first-time, complete, traumatic LPD and 51 healthy controls (mean age: 14.7 ± 2.2, male/female: 29/22).

FIELD STRENGTH/SEQUENCE

3.0 T; axial T2 mapping acquired using a 2D turbo spin-echo sequence.

ASSESSMENT

MRI examination was conducted 2-4 months after first LPD. T2 values were calculated in manually segmented cartilage area via averaging over three middle level slices in six cartilage regions: deep, intermediate, superficial layers, and medial lateral parts.

STATISTICAL TESTS

ANOVA analysis with Tukey's multiple comparison test, one-vs.-rest logistic regression analysis. The threshold of significance was set at P < 0.05.

RESULTS

In lateral patellar cartilage, a significant increase in T2 values was found in deep and intermediate layers in both patient groups with mild (deep: 34.7 vs. 31.3 msec, intermediate: 38.7 vs. 34.6 msec, effect size = 0.55) and severe (34.8 vs. 31.3 msec, 39.1 vs. 34.6 msec, 0.55) LPD consequences as compared to controls. In the medial facet, only severe cartilage damage showed significant prolongation of T2 times in the deep layer (34.3 vs. 30.7 msec, 0.55). No significant changes in T2 values were found in the lateral superficial layer (P = 0.99), whereas mild chondromalacia resulted in a significant decrease of T2 in the medial superficial layer (41.0 vs. 43.8 msec, 0.55).

DATA CONCLUSION

The study revealed substantial difference in T2 changes after LPD between medial and lateral areas of patellar cartilage.

EVIDENCE LEVEL

2 TECHNICAL EFFICACY STAGE: 2.

Morphological and Quantitative Parametric MRI Follow-up of Cartilage Changes Before and After Intra-articular Injection Therapy in Patients With Mild to Moderate Knee Osteoarthritis: A Randomized, Placebo-Controlled Trial

BACKGROUND

Intra-articular injections are routinely used for conservative treatment of knee osteoarthritis (OA). The detailed comparative therapeutic effects of these injections on cartilage tissue are still unclear.

OBJECTIVE

The aim of this study was to detect and compare knee cartilage changes after intra-articular injection of glucocorticoid, hyaluronic acid, or platelet-rich plasma (PRP) to placebo using quantitative (T2 and T2* mapping) and morphological magnetic resonance imaging parameters in patients with mild or moderate osteoarthritis.

MATERIALS AND METHODS

In a double-blinded, placebo-controlled, single-center trial, knees with mild or moderate osteoarthritis (Kellgren-Lawrence grade 1-3) were randomly assigned to an intra-articular injection with 1 of these substances: glucocorticoid, hyaluronic acid, PRP, or placebo. Cartilage degeneration on baseline and follow-up magnetic resonance imaging scans (after 3 and 12 months) was assessed by 2 readers using quantitative T2 and T2* times (milliseconds) and morphological parameters (modified Outerbridge grading, subchondral bone marrow edema, subchondral cysts, osteophytes).

RESULTS

One hundred twenty knees (30 knees per treatment group) were analyzed with a median patient age of 60 years (interquartile range, 54.0-68.0 years). Interreader reliability was good for T2 (ICC, 0.76; IQR, 0.68-0.83) and T2* (ICC, 0.83; IQR, 0.76-0.88) measurements. Morphological parameters showed no significant changes between all groups after 3 and 12 months. T2 mapping after 12 months showed the following significant ( P = 0.001-0.03) changes between groups in 6 of 14 compartments: values after PRP injection decreased compared with glucocorticoid in 4 compartments (complete medial femoral condyle and central part of lateral condyle) and compared with placebo in 2 compartments (anterior and central part of medial tibial plateau); values after glucocorticoid injection decreased compared with placebo in 1 compartment (central part of medial tibial plateau). No significant changes were seen for T2 and T2* times after 3 months and T2* times after 12 months. No correlation was found between T2/T2* times and Kellgren-Lawrence grade, age, body mass index, or pain (Spearman ρ, -0.23 to 0.18).

CONCLUSIONS

Platelet-rich plasma injection has a positive long-term effect on cartilage quality in the medial femoral compartment compared to glucocorticoid, resulting in significantly improved T2 values after 12 months. For morphological cartilage parameters, injections with glucocorticoid, PRP, or hyaluronic acid showed no better effect in the short or long term compared with placebo.

Preclinical Cartilage Changes of the Knee Joint in Adolescent Competitive Volleyball Players: A Prospective T2 Mapping Study

PURPOSE

To investigate the potential effects of volleyball as a competitive sport in adolescence on the cartilage of knee joints using T2 mapping in MRI and identification of preclinical cartilage changes. Volleyball as an impact sport often leads to damage of the knee joint cartilage in adulthood. As T2 mapping is widely available and highly capable of detecting cartilage changes prior to conventional MRI sequences, such a detection may allow adolescent volleyball players to change their training regime before structural damage can occur to the cartilage and pose the risk of osteoarthritis.

MATERIALS AND METHODS

Comparative study of the patellar, femoral, and tibial cartilage of 60 knee joints using T2 mapping on 3 T MRI. In each case, both knees of 15 adolescent competitive volleyball athletes were compared with 15 controls.

RESULTS

In the group of competitive athletes, more focal cartilage changes were detected in the medial facet of the patellofemoral cartilage and in the medial femoral condyle of the knee joint cartilage (p = .01 and p <.05, respectively). Furthermore, the latter showed a diffused increase in maximal T2 mapping values (p <.04 right and p = .05 left). The distribution of changes seems to further depend on the player's position.

CONCLUSION

In adolescent volleyball players in competitive sports, T2 mapping demonstrates early cartilage changes in both the patellofemoral and medial femoral cartilages. The distribution of lesions depends on the player's position. Since the cascade from T2 relaxation time increase to conspicuous cartilage damage is well established, early counter-regulation (e. g., adapted training profile, targeted physiotherapy, and appropriate muscle building training) has the potential to prevent later damage.

KEY POINTS

· Volleyball as a competitive sport in adolescence leads to preclinical knee cartilage changes.. · Cartilage changes are both focal and diffuse.. · Jumping-intensive player positions seem to show more patellofemoral and running-intensive more condylar cartilage changes.. · Early detection of these changes could prevent progression to cartilage damage through adapted training..

CITATION FORMAT

· Roth C, Hirsch F, Sorge I et al. Preclinical Cartilage Changes of the Knee Joint in Adolescent Competitive Volleyball Players: A Prospective T2 Mapping Study. Fortschr Röntgenstr 2023; 195: 913 - 923.

Quantitative Analysis of Supraspinatus Tendon Pathologies via T2/T2* Mapping Techniques with 1.5 T MRI

The aim of this study was to quantitatively assess supraspinatus tendon pathologies with T2/T2* mapping techniques, which are sensitive to biochemical changes. Conventional magnetic resonance imaging (MRI) and T2/T2* mapping techniques were applied to 41 patients with shoulder pathology, and there were also 20 asymptomatic cases included. The patients were divided into two groups: tendinosis and rupture. The supraspinatus tendon was divided into medial, middle, and lateral sub-regions, and the T2/T2* values were measured in both the coronal and sagittal planes for intergroup comparison. Intra-class and inter-class correlation coefficients (ICCs) were calculated to assess test reproducibility. Receiver operating characteristic (ROC) analysis was used to determine the cut-off value in each group. A total of 61 patients (27 males and 34 females)-including 20 asymptomatic individuals, 20 with tendinosis, and 21 with rupture-were evaluated using T2/T2* mapping techniques. In the rupture group, there were significant differences in the values of the lateral region (p < 0.001), as well as in the middle and medial regions (p < 0.05) of the supraspinatus tendon compared to the tendinosis and asymptomatic groups. These were determined using both T2* and T2 mapping in both the coronal and sagittal plane measurements. In the tendinosis group, there were significant differences in the values of the lateral region with T2* mapping (p < 0.001) in both the coronal and sagittal planes, and also with the T2 mapping in the coronal plane (p < 0.05) compared to the asymptomatic groups. The cut-off values for identifying supraspinatus pathology ranged from 85% to 90% for T2 measurements and above 90% for T2* measurements in both planes of the lateral section. The ICC values showed excellent reliability (ICC > 0.75) for all groups. In conclusion, T2 and T2* mapping techniques with 1.5 T MRI can be used to assess tendon rupture and tendinosis pathologies in the supraspinatus tendon. For an accurate evaluation, measurements from the lateral region in both the coronal and sagittal planes are more decisive.

Improved accuracy and precision of fat-suppressed isotropic 3D T2 mapping MRI of the knee with dictionary fitting and patch-based denoising

PURPOSE

To develop an isotropic three-dimensional (3D) T2 mapping technique for the quantitative assessment of the composition of knee cartilage with high accuracy and precision.

METHODS

A T2-prepared water-selective isotropic 3D gradient-echo pulse sequence was used to generate four images at 3 T. These were used for three T2 map reconstructions: standard images with an analytical T2 fit (AnT2Fit); standard images with a dictionary-based T2 fit (DictT2Fit); and patch-based-denoised images with a dictionary-based T2 fit (DenDictT2Fit). The accuracy of the three techniques was first optimized in a phantom study against spin-echo imaging, after which knee cartilage T2 values and coefficients of variation (CoV) were assessed in ten subjects in order to establish accuracy and precision in vivo. Data given as mean ± standard deviation.

RESULTS

After optimization in the phantom, whole-knee cartilage T2 values of the healthy volunteers were 26.6 ± 1.6 ms (AnT2Fit), 42.8 ± 1.8 ms (DictT2Fit, p < 0.001 versus AnT2Fit), and 40.4 ± 1.7 ms (DenDictT2Fit, p = 0.009 versus DictT2Fit). The whole-knee T2 CoV reduced from 51.5% ± 5.6% to 30.5 ± 2.4 and finally to 13.1 ± 1.3%, respectively (p < 0.001 between all). The DictT2Fit improved the data reconstruction time: 48.7 ± 11.3 min (AnT2Fit) versus 7.3 ± 0.7 min (DictT2Fit, p < 0.001). Very small focal lesions were observed in maps generated with DenDictT2Fit.

CONCLUSIONS

Improved accuracy and precision for isotropic 3D T2 mapping of knee cartilage were demonstrated by using patch-based image denoising and dictionary-based reconstruction.

KEY POINTS

• Dictionary T2 fitting improves the accuracy of three-dimensional (3D) knee T2 mapping. • Patch-based denoising results in high precision in 3D knee T2 mapping. • Isotropic 3D knee T2 mapping enables the visualization of small anatomical details.

Ultra-small superparamagnetic iron oxide nanoparticles for intra-articular targeting of cartilage in early osteoarthritis

Early diagnosis of osteoarthritis (OA) is critical for effective cartilage repair. However, lack of blood vessels in articular cartilage poses a barrier to contrast agent delivery and subsequent diagnostic imaging. To address this challenge, we proposed to develop ultra-small superparamagnetic iron oxide nanoparticles (SPIONs, 4 nm) that can penetrate into the matrix of articular cartilage, and further modified with the peptide ligand WYRGRL (particle size, 5.9 nm), which allows SPIONs to bind to type II collagen in the cartilage matrix and increase the retention of probes. Type II collagen in the cartilage matrix is gradually lost with the progression of OA, consequently, the binding of peptide-modified ultra-small SPIONs to type II collagen in the OA cartilage matrix is less, thus presenting different magnetic resonance (MR) signals in OA group from the normal ones. By introducing the AND logical operation, damaged cartilage can be differentiated from the surrounding normal tissue on T1 and T2 AND logical map of MR images, and this was also verified in histology studies. Overall, this work provides an effective strategy for delivering nanosized imaging agents to articular cartilage, which could potentially be used to diagnosis joint-related diseases such as osteoarthritis.

Advances in osteoarthritis imaging

PURPOSE OF REVIEW

Imaging plays a pivotal role for diagnosis, follow-up and stratification of osteoarthritis patients in clinical trials and research. We aim to present an overview of currently available and emerging imaging techniques for osteoarthritis assessment and provide insight into relevant benefits and pitfalls of the different modalities.

RECENT FINDINGS

Although radiography is considered sufficient for a structural diagnosis of osteoarthritis and is commonly used to define eligibility of patients for participation in clinical trials, it has inherent limitations based on the projectional nature of the technique and inherent challenges regarding reproducibility in longitudinal assessment. MRI has changed our understanding of the disease from 'wear and tear' of cartilage to a whole organ disorder. MRI assessment of structural changes of osteoarthritis includes semi-quantitative, quantitative and compositional evaluation. Ultrasound is helpful in evaluating the degree of synovitis and has value in the assessment particularly of the patella-femoral joint. Recent development of computed tomography technology including weight-bearing systems has led to broader application of this technology in a research context.

SUMMARY

Advances in MRI technology have resulted in a significant improvement in understanding osteoarthritis as a multitissue disease.

Imaging in Osteoarthritis

Osteoarthritis (OA) is the most frequent form of arthritis with major implications on both individual and public health care levels. The field of joint imaging, and particularly magnetic resonance imaging (MRI), has evolved rapidly due to the application of technical advances to the field of clinical research. This narrative review will provide an introduction to the different aspects of OA imaging aimed at an audience of scientists, clinicians, students, industry employees, and others who are interested in OA but who do not necessarily focus on OA. The current role of radiography and recent advances in measuring joint space width will be discussed. The status of cartilage morphology assessment and evaluation of cartilage biochemical composition will be presented. Advances in quantitative three-dimensional morphologic cartilage assessment and semi-quantitative whole-organ assessment of OA will be reviewed. Although MRI has evolved as the most important imaging method used in OA research, other modalities such as ultrasound, computed tomography, and metabolic imaging play a complementary role and will also be discussed.

Advanced compositional imaging T2 mapping sequence in detection of stages of medial knee joint compartments articular cartilage degeneration

Background

The predictive value of the new imaging sequences, especially T2 mapping in assessment of articular cartilage abnormalities of the medial knee compartments in patients with medial knee pain. The purpose of this study is to evaluate the additional value of T2 mapping over using a baseline standard knee MRI to detect cartilage lesions of the medial compartments in patients representing with medial knee pain.

Results

The study included 60 patients presented with medial knee pain, where divided into two groups ; control group (20 volunteers) with age range from 19 to 41 years old 26.80 ± 8.05 (mean ± SD) and patients (40 candidates) with age range from 13 to 57 years old with a mean age 33.00 ± 14.1 (mean ± SD).

Conclusion

On adding T2 mapping sequence to the routine MRI of the knee, the sensitivity for detecting knee cartilage lesions was increased, especially in the detection of early cartilage degeneration at the medial compartment.

Compositional MR imaging including T2 mapping plays an important role in the assessment of early and potentially reversible cartilage damage especially among the young population.

7-Tesla MRI Evaluation of the Knee, 25 Years after Cartilage Repair Surgery: The Influence of Intralesional Osteophytes on Biochemical Quality of Cartilage

OBJECTIVE

To evaluate the morphological and biochemical quality of cartilage transplants and surrounding articular cartilage of patients 25 years after perichondrium transplantation (PT) and autologous chondrocyte transplantation (ACT) as measured by ultra-high-field 7-Tesla (7T) magnetic resonance imaging (MRI) and to present these findings next to clinical outcome.

DESIGN

Seven PT patients and 5 ACT patients who underwent surgery on the femoral condyle between 1986 and 1996 were included. Patient-reported outcome measures (PROMs) were assessed by the clinical questionnaires: Knee injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC), and Visual Analogue Scale (VAS) for knee pain. The morphological (MOCART score) and biochemical quality (glycosaminoglycans [GAGs] content and collagen integrity) of cartilage transplants and surrounding articular cartilage were analyzed by 7T MRI. The results of the PT and ACT patients were compared. Finally, a detailed morphological analysis of the grafts alone was performed.

RESULTS

No statistically significant difference was found for the PROMs and MOCART scores of PT and ACT patients. Evaluation of the graft alone showed poor repair tissue quality and high prevalence of intralesional osteophyte formation in both the PT and ACT patients. Penetration of the graft surface by the intralesional osteophyte was related to biochemically damaged opposing tibial cartilage; GAG content was significantly lower in patients with an osteophyte penetrating the graft surface.

CONCLUSIONS

Both PT and ACT patients have a high incidence of intralesional osteophyte formation 25 years after surgery. The resulting biochemical damage to the opposing tibial cartilage might be dependent on osteophyte morphology.

Exploration of MRI T2 Mapping Image Application in Articular Disc Displacement of the Temporomandibular Joint in Adolescents

Purpose

To explore the application of magnetic resonance imaging (MRI) T2 mapping technique in clinical practice through morphological and quantitative analysis of T2 mapping sequences in adolescents with temporomandibular disorders (TMDs) and control groups comprising healthy participants.

Patients and Methods

A total of 45 and 63 patients, who had articular disc displacement with and without reduction, respectively, were assigned to the experimental groups, and 57 participants with normal articular discs of the temporomandibular joint were considered as the control group. All participants in the three groups underwent MRI. T2 mapping was performed in the oblique sagittal plane. The regions of interest (ROIs) for the T2 relaxation time maps of the disc were selected manually. The performance of morphological and structural changes and quantitative parameters in MRI T2 mapping image artifacts were statistically compared.

Results

In the control group, the mean T2 value was 39.284 ±5.634 ms, in the group of disc displacement with reduction, the mean T2 value was 33.634 ±4.235 ms, and in the group of disc displacement without reduction, the mean T2 value was 30.982 ±3.205 ms. The T2 mapping values of the experimental groups, together with different morphological structures, were significantly lower than were those of the control group.

Conclusion

MRI T2 mapping enables a more accurate evaluation of TMD severity. Sequentially, it helps provide a more reliable medical imaging basis for classifying diagnosis and evaluation in clinical practice.

Compositional MRI of the Hip: Reproducibility, Effect of Joint Unloading, and Comparison of T2 Relaxometry with Delayed Gadolinium-Enhanced Magnetic Resonance Imaging of Cartilage

OBJECTIVE

Our aim was to compare T2 with delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) in the hip and assess the reproducibility and effect of joint unloading on T2 mapping.

DESIGN

Ten individuals at high risk of developing hip osteoarthritis (SibKids) underwent contemporaneous T2 mapping and dGEMRIC in the hip (10 hips). Twelve healthy volunteers underwent T2 mapping of both hips (24 hips) at time points 25, 35, 45, and 55 minutes post offloading. Acetabular and femoral cartilage was manually segmented into regions of interest. The relationship between T2 and dGEMRIC values from anatomically corresponding regions of interests was quantified using Pearson's correlation. The reproducibility of image analysis for T2 and dGEMRIC, and reproducibility of image acquisition for T2, was quantified using the intraclass correlation coefficient (ICC), root mean square coefficient of variance (RMSCoV), smallest detectable difference (SDD), and Bland-Altman plots. The paired t test was used to determine if difference existed in T2 values at different unloading times.

RESULTS

T2 values correlated most strongly with dGEMRIC values in diseased cartilage (r = -0.61, P = <0.001). T2 image analysis (segmentation) reproducibility was ICC = 0.96 to 0.98, RMSCoV = 3.5% to 5.2%, and SDD = 2.2 to 3.5 ms. T2 values at 25 minutes unloading were not significantly different to longer unloading times (P = 0.132). SDD for T2 image acquisition reproducibility was 7.1 to 7.4 ms.

CONCLUSIONS

T2 values in the hip correlate well with dGEMRIC in areas of cartilage damage. T2 shows high reproducibility and values do not change beyond 25 minutes of joint unloading.

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.

Magnetic resonance imaging for non-invasive clinical evaluation of normal and regenerated cartilage

With the development of tissue engineering and regenerative medicine, it is much desired to establish bioimaging techniques to monitor the real-time regeneration efficacy in vivo in a non-invasive way. Herein, we tried magnetic resonance imaging (MRI) to evaluate knee cartilage regeneration after implanting a biomaterial scaffold seeded with chondrocytes, namely, matrix-induced autologous chondrocyte implantation (MACI). After summary of the T2 mapping and the T1-related delayed gadolinium-enhanced MRI imaging of cartilage (dGEMRIC) in vitro and in vivo in the literature, these two MRI techniques were tried clinically. In this study, 18 patients were followed up for 1 year. It was found that there was a significant difference between the regeneration site and the neighboring normal site (control), and the difference gradually diminished with regeneration time up to 1 year according to both the quantitative T1 and T2 MRI methods. We further established the correlation between the quantitative evaluation of MRI and the clinical Lysholm scores for the first time. Hence, the MRI technique was confirmed to be a feasible semi-quantitative yet non-invasive way to evaluate the in vivo regeneration of knee articular cartilage.

Quantitative T2 mapping of the glenohumeral joint cartilage in asymptomatic shoulders and shoulders with increasing severity of rotator cuff pathology

•

Glenohumeral cartilage T2 values were correlated to increasing rotator cuff pathology severity.

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Massive tear versus lesser injury differences were most evident in superior humeral cartilage.

•

Sagittal T2 mapping best captures superior humeral head cartilage change in massive tear patients.

Purpose

To examine the relationship between glenohumeral cartilage T2 mapping values and rotator cuff pathology.

Method

Fifty-nine subjects (age 48.2 ± 13.5 years, 15 asymptomatic volunteers and 10 tendinosis, 13 partial-thickness tear, 8 full-thickness tear, and 13 massive tear patients) underwent glenohumeral cartilage T2 mapping. The humeral head cartilage was segmented in the sagittal and coronal planes. The glenoid cartilage was segmented in the coronal plane. Group means for each region were calculated and compared between the groups.

Results

Massive tear group T2 values were significantly higher than the asymptomatic group values for the humeral head cartilage included in the sagittal (45 ± 7 versus 32 ± 4 ms, p <  .001) and coronal (44 ± 6 versus 38 ± 1 ms, p =  0.01) plane images. Mean T2 was also significantly higher for massive than full-thickness tears (45 ± 7 versus 38 ± 5 ms, p =  0.02), massive than partial-thickness tears (45 ± 7 versus 34 ± 4 ms, p <  0.001), and massive tears than tendinosis (45 ± 7 versus 35 ± 4 ms, p =  0.001) in the sagittal-images humeral head region and significantly higher for massive tears than asymptomatic shoulders (44 ± 6 versus 38 ± 1 ms, p =  0.01) in the coronal-images humeral head region.

Conclusion

Humeral head cartilage T2 values were significantly positively correlated with rotator cuff pathology severity. Massive rotator cuff tear patients demonstrated significantly higher superior humeral head cartilage T2 mapping values relative to subjects with no/lesser degrees of rotator cuff pathology.

Evaluation of Knee Cartilage Diurnal, Activity, and BMI-Related Variations Using Quantitative T2 Mapping MRI and Fitbit Activity Tracking

The aim of this study is to evaluate diurnal variation in knee cartilage 3 Tesla magnetic resonance imaging (MRI) T2 mapping relaxation times, as well as activity- and body mass index (BMI)-dependent variability, using quantitative analysis of T2 values from segmented regions of the weight-bearing articular surfaces of the medial and lateral femoral condyles and tibial plateaus. Ten healthy volunteers' daily activity (steps) were tracked with Fitbit pedometers. Sagittal MRI T2 maps were obtained in the morning and afternoon on days 2 and 3. Mean T2 values were analyzed for variation related to the number of steps taken (activity), time of day (diurnal variation), and BMI using mixed effect model. Significant (albeit small) differences in the medial femoral and medial tibial cartilage regions were identified between morning and afternoon scans (diurnal variation). Daily activity did not result in significant changes and increasing BMI only demonstrated a slight increase in T2 values for the lateral tibial plateau. These findings suggest that it may be necessary to control diurnal variation when using quantitative MRI T2 mapping to assess articular cartilage longitudinally in healthy participants. Further investigation is needed to confirm these findings and determine if they also apply to symptomatic patients.

Magnetic resonance fingerprinting of the pancreas at 1.5 T and 3.0 T

Magnetic resonance imaging of the pancreas is increasingly used as an important diagnostic modality for characterisation of pancreatic lesions. Pancreatic MRI protocols are mostly qualitative due to time constraints and motion sensitivity. MR Fingerprinting is an innovative acquisition technique that provides qualitative data and quantitative parameter maps from a single free-breathing acquisition with the potential to reduce exam times. This work investigates the feasibility of MRF parameter mapping for pancreatic imaging in the presence of free-breathing exam. Sixteen healthy participants were prospectively imaged using MRF framework. Regions-of-interest were drawn in multiple solid organs including the pancreas and T1 and T2 values determined. MRF T1 and T2 mapping was performed successfully in all participants (acquisition time:2.4-3.6 min). Mean pancreatic T1 values were 37-43% lower than those of the muscle, spleen, and kidney at both 1.5 and 3.0 T. For these organs, the mean pancreatic T2 values were nearly 40% at 1.5 T and < 12% at 3.0 T. The feasibility of MRF at 1.5 T and 3 T was demonstrated in the pancreas. By enabling fast and free-breathing quantitation, MRF has the potential to add value during the clinical characterisation and grading of pathological conditions, such as pancreatitis or cancer.

Synthetic MRI is not yet ready for morphologic and functional assessment of patellar cartilage at 1.5Tesla

PURPOSE

The purpose of this study was to compare morphologic assessment and relaxometry of patellar hyaline cartilage between conventional sequences (fast spin-echo [FSE] T2-weighted fat-saturated and T2-mapping) and synthetic T2 short-TI inversion recovery (STIR) and T2 maps at 1.5T magnetic resonance imaging (MRI).

METHOD

The MRI examinations of the knee obtained at 1.5T in 49 consecutive patients were retrospectively studied. There were 21 men and 28 women with a mean age of 45±17.7 (SD) years (range: 18-88 years). Conventional and synthetic acquisitions were performed, including T2-weighted fat-saturated and T2-mapping sequences. Two radiologists independently compared patellar cartilage T2-relaxation time on conventional T2-mapping and synthetic T2-mapping images. A third radiologist evaluated the patellar cartilage morphology on conventional and synthetic T2-weighted images. The presence of artifacts was also assessed. Interobserver agreement for quantitative variables was assessed using intraclass correlation coefficient (ICC).

RESULTS

In vitro, conventional and synthetic T2 maps yielded similar mean T2 values 58.5±2.3 (SD) ms and 58.8±2.6 (SD) ms, respectively (P=0.414) and 6% lower than the expected experimental values (P=0.038). Synthetic images allowed for a 15% reduction in examination time compared to conventional images. On conventional sequences, patellar chondropathy was identified in 35 patients (35/49; 71%) with a mean chondropathy grade of 4.8±4.8 (SD). On synthetic images, 28 patients (28/49; 57%) were diagnosed with patellar chondropathy, with a significant 14% difference (P=0.009) and lower chondropathy scores (3.7±4.9 [SD]) compared to conventional images. Motion artifacts were more frequently observed on synthetic images (18%) than on conventional ones (6%). The interobserver agreement was excellent for both conventional and synthetic T2 maps (ICC>0.83). Mean cartilage T2 values were significantly greater on synthetic images (36.2±3.8 [SD] ms; range: 29-46ms) relative to conventional T2 maps (31.8±4.1 [SD] ms; range: 26-49ms) (P<0.0001).

CONCLUSION

Despite a decrease in examination duration, synthetic images convey lower diagnostic performance for chondropathy, greater prevalence of motion artifacts, and an overestimation of T2 values compared to conventional MRI sequences.

Alterations in articular cartilage T2 star relaxation time following mechanical disorders: in vivo canine supraspinatus tendon resection models

Background

The role of altered joint mechanics on cartilage degeneration in in vivo models has not been studied successfully due to a lack of pre-injury information. We aimed 1) to develop an accurate in vivo canine model to measure the changes in joint loading and T2 star (T2*) relaxation time before and after unilateral supraspinatus tendon resections, and 2) to find the relationship between regional variations in articular cartilage loading patterns and T2* relaxation time distributions.

Methods

Rigid markers were implanted in the scapula and humerus of tested dogs. The movement of the shoulder bones were measured by a motion tracking system during normal gaits. In vivo cartilage contact strain was measured by aligning 3D shoulder models with the motion tracking data. Articular cartilage T2* relaxation times were measured by quantitative MRI scans. Articular cartilage contact strain and T2* relaxation time were compared in the shoulders before and 3 months after the supraspinatus tendon resections.

Results

Excellent accuracy and reproducibility were found in our in vivo contact strain measurements with less than 1% errors. Changes in articular cartilage contact strain exhibited similar patterns with the changes in the T2* relaxation time after resection surgeries. Regional changes in the articular cartilage T2* relaxation time exhibited positive correlations with regional contact strain variations 3 months after the supraspinatus resection surgeries.

Conclusion

This is the first study to measure in vivo articular cartilage contact strains with high accuracy and reproducibility. Positive correlations between contact strain and T2* relaxation time suggest that the articular cartilage extracellular matrix may responds to mechanical changes in local areas.

Radiofrequency Chondroplasty May Not Have A Long-Lasting Effect in the Treatment of Concomitant Grade II Patellar Cartilage Defects in Humans

The effect of radiofrequency chondroplasty on cartilage tissue is not well studied. This prospective pilot study investigates the effect of radiofrequency chondroplasty on International Cartilage Repair Society (ICRS) grade II patellar cartilage defects using high-resolution magnetic resonance imaging (MRI) with T2 mapping. Six consecutive patients were treated for ICRS grade II patellar cartilage defects using radiofrequency chondroplasty. Before surgery and at defined follow-ups (2 weeks, 4 and 12 months) a high-resolution morphological 3 Tesla MRI with quantitative T2 mapping was performed. At baseline MRI, global T2 values of cartilage defects were increased (46.8 ms ± 9.7) compared to healthy cartilage (35.2 ms ± 4.5) in the same knee which served as reference. Two weeks after treatment, global T2 values (39.2 ms ± 7.7) of the defect areas decreased. However, global T2 values of the defect areas increased beyond the preoperative levels at 4 months (47.4 ms ± 3.1) and 12 months (51.5 ms ± 5.9), respectively. Zonal T2 mapping revealed that the predominant changes in T2 values occurred at the superficial cartilage layer. T2 mapping appears to be an ideal method to monitor cartilage degeneration after chondroplasty. Based on the small sample size of this pilot study, radiofrequency chondroplasty may cause cartilage damage and may not have a long-lasting effect in the treatment of grade II patellar cartilage defects. In five out of six patients, postoperative cartilage damage was observed on quantitative MRI. This study was therefore terminated before completion. We recommend only addressing the pathology which indicated arthroscopy and leaving concomitant cartilage lesions untreated.

Multiparametric Mapping Magnetic Resonance Imaging of Pancreatic Disease

Background

Current magnetic resonance imaging (MRI) of pancreatic disease is qualitative in nature. Quantitative imaging offers several advantages, including increased reproducibility and sensitivity to detect mild or diffuse disease. The role of multiparametric mapping MRI in characterizing various tissue types in pancreatic disease such as chronic pancreatitis (CP) and pancreatic ductal adenocarcinoma (PDAC) has rarely been evaluated.

Purpose

To evaluate the feasibility of multiparametric mapping [T1, T2, and apparent diffusion coefficient (ADC)] in defining tissue characteristics that occur in CP and PDAC to improve disease diagnosis.

Materials and Methods:

Pancreatic MRI was performed in 17 patients with PDAC undergoing therapy, 7 patients with CP, and 29 healthy volunteers with no pancreatic disease. T1 modified Look-Locker Inversion Recovery (T1 MOLLI), T2-prepared gradient-echo, and multi-slice single-shot echo-planar diffusion weighted imaging (SS-EPI DWI) sequences were used for data acquisition. Regions of interest (ROIs) of pancreas in PDAC, CP, and control subjects were outlined by an experienced radiologist. One-way analysis of variance (ANOVA) was used to compare the difference between groups and regions of the pancreas, and Tukey tests were used for multiple comparison testing within groups. Receiver operator characteristic (ROC) curves were analyzed, and the areas under the curves (AUCs) were calculated using single parameter and combined parameters, respectively.

Results

T1, T2, and ADC values of the entire pancreas among PDAC, CP, and control subjects; and between upstream and downstream portions of the pancreas in PDAC patients were all significantly different (p < 0.05). The AUC values were 0.90 for T1, 0.55 for T2, and 0.71 for ADC for independent prediction of PDAC. By combining T1, T2, and ADC, the AUC value was 0.94 (sensitivity 91.54%, specificity 85.81%, 95% CI: 0.92–0.96), which yielded higher accuracy than any one parameter only (p < 0.001).

Conclusion

Multiparametric mapping MRI is feasible for the evaluation of the differences between PDAC, CP, and normal pancreas tissues. The combination of multiple parameters of T1, T2, and ADC provides a higher accuracy than any single parameter alone in tissue characterization of the pancreas.

Potential predictive value of axial T2 mapping at 3 Tesla MRI in patients with untreated patellar cartilage defects over a mean follow-up of four years

OBJECTIVE

The objective was to demonstrate the potential of axial T2 mapping for quantification of untreated early-stage patellar cartilage lesions over time and to assess its capability as a potential predictive marker for future progression.

STUDY DESIGN & METHODS

Thirty patients (mean age, 36.7 ± 11.1 years; 16 males), with early-stage patellar cartilage defects (≤ICRS grade 2) at baseline and no treatment during follow up (4.0 ± 1.6 years) were enrolled. Morphological cartilage changes over time were subdivided into a Progression, Non-Progression Group and Regression Group. Quantitative analysis of cartilage defects and healthy reference was performed by means of global and zonal T2 mapping (deep and superficial cartilage T2 values) at both time points. Statistical evaluation included analysis of variance (ANOVA), paired t Test's and ROC analysis.

RESULTS

The Progression Group (N = 11) had significantly higher global T2 values at baseline (57.4 ± 7.8 ms) than patients without (N = 17) (40.6 ± 6.9 ms) (P < 0.01). Furthermore the Non-Progression Group showed only a minor increase in global T2 relaxation times to 43.1 ± 7.9 ms (P = 0.07) at follow up, whereas in the progression group global (68,7 ± 19 ms: P = 0.02) and superficial T2 values (65,8 ± 8.2-79.8 ± 24.4 ms; P = 0.03) increased significantly. T2 values for healthy reference cartilage remained stable. In 2 patients an improvement in ICRS grading was observed (Regression Group) with decreasing T2 values. The ROC analysis showed an area under the curve of 0.92 (95%CI 0.82-1.0). At a cut-off value of 47.15 ms, we found a sensitivity of 92% (false-positive rate of 18%) for future progression of cartilage defects.

CONCLUSIONS

This study provides evidence regarding the possible potential of axial T2 mapping as a tool for quantification and prediction of patellar cartilage defect progression in untreated defects.

Quantitative ultrashort echo time magnetization transfer (UTE-MT) for diagnosis of early cartilage degeneration: comparison with UTE-T2* and T2 mapping

Background

To investigate the feasibility of using quantitative ultrashort echo time magnetization transfer (UTE-MT) technique in diagnosing early cartilage degeneration and to compare the technique's diagnostic efficacy with UTE-T2* mapping and T2 mapping.

Methods

Twenty human anterolateral condyle specimens with degeneration were obtained from volunteers undergoing total knee arthroplasty (TKA); they then underwent magnetic resonance (MR) scan on a clinical 3.0T scanner (GE, MR750). Seventy-two regions of interest (ROI) were manually drawn on specimens for UTE-MT, UTE-T2*, and T2 measurement, and the corresponding cartilage-bone regions were further divided into degeneration classifications of normal (n=11, Mankin scores 0-1), mild (n=28, Mankin scores 2-5), moderate (n=21, Mankin scores 6-9), and severe (n=12, Mankin scores 10-14) based on histological measures of degeneration (i.e., Mankin scores) as a reference standard. Differences among groups and correlations between quantitative MR parameters and Mankin scores were assessed using analysis of variance (ANOVA), Tamhane-T2, LSD, Kruskal-Wallis tests, and Spearman's correlation coefficient. The receiver-operating characteristic (ROC) curve was used to compare the diagnostic efficacy of different quantitative MR parameters for the detection of mild cartilage degeneration.

Results

The UTE magnetization transfer ratio (UTE-MTR) in the normal group was significantly different from the mild group (P=0.021), moderate group (P<0.001), and severe group (P<0.001). Significant differences were observed in the T2* values between both the normal group and the moderate group (P<0.032), and between the normal group and the severe group (P<0.001). For T2 values, the only significant difference was observed between the severe group and the normal group (P=0.011). The UTE-MTR, UTE-T2*, and T2 values were all significantly correlated with Mankin scores: UTE-MTR values were strongly (r=-0.678, P<0.001) correlated, UTE-T2* values were markedly correlated (r=-0.501, P<0.001), and T2 values were weakly correlated (r=0.337, P=0.004) correlated with Mankin scores. The diagnostic efficacy of UTE-MTR (AUC =0.828, P=0.002) was better than UTE T2* mapping and T2 mapping (AUC =0.604, P=0.318; AUC =0.644, P=0.165, respectively) for the diagnosis of early cartilage degeneration.

Conclusions

UTE-MTR values were strongly correlated with histological grades of cartilage degeneration, and its diagnostic efficacy was better than both UTE T2* mapping and T2 mapping in detecting early cartilage degeneration. Once the clinical potential of the technique has been confirmed, UTE-MT may provide a promising imaging biomarker with potential application in a more comprehensive diagnosis and monitoring of cartilage degeneration.

Using Cartilage MRI T2-Mapping to Analyze Early Cartilage Degeneration in the Knee Joint of Young Professional Soccer Players

OBJECTIVE

To evaluate and characterize the appearance of articular cartilage in the tibiofemoral joint of young professional soccer players using T2-relaxation time evaluation on magnetic resonance imaging (MRI).

DESIGN

In this study, we included 57 male adolescents from the youth academy of a professional soccer team. The MRI scans were acquired of the knee joint of the supporting leg. An "early unloading" (minute 0) and "late unloading" (minute 28) T2-sequence was included in the set of images. Quantitative T2-analysis was performed in the femorotibial joint cartilage in 4 slices with each 10 regions of interest (ROIs). Statistical evaluation, using Wilcoxon signed-rank tests, was primarily performed to compare the T2 values of the "early unloading" and "late unloading."

RESULTS

When comparing "early unloading" with "late unloading," our findings showed a significant increase of T2-relaxation times in the weightbearing femoral cartilage of the medial (P < 0.001) and lateral (P < 0.001) compartment of the knee and in the tibial cartilage of the medial compartment (P < 0.001).

CONCLUSION

In this study, alterations of the cartilage were found with a maximum in the medial condyle where the biomechanical load of the knee joint is highest, as well as where most of the chronic cartilage lesions occur. To avoid chronic damage, special focus should be laid on this region.

MRI T2 and T1ρ relaxation in patients at risk for knee osteoarthritis: a systematic review and meta-analysis

Background

Magnetic resonance imaging (MRI) T2 and T1ρ relaxation are increasingly being proposed as imaging biomarkers potentially capable of detecting biochemical changes in articular cartilage before structural changes are evident. We aimed to: 1) summarize MRI methods of published studies investigating T2 and T1ρ relaxation time in participants at risk for but without radiographic knee OA; and 2) compare T2 and T1ρ relaxation between participants at-risk for knee OA and healthy controls.

Methods

We conducted a systematic review of studies reporting T2 and T1ρ relaxation data that included both participants at risk for knee OA and healthy controls. Participant characteristics, MRI methodology, and T1ρ and T2 relaxation data were extracted. Standardized mean differences (SMDs) were calculated within each study. Pooled effect sizes were then calculated for six commonly segmented knee compartments.

Results

55 articles met eligibility criteria. There was considerable variability between scanners, coils, software, scanning protocols, pulse sequences, and post-processing. Moderate risk of bias due to lack of blinding was common. Pooled effect sizes indicated participants at risk for knee OA had lengthened T2 relaxation time in all compartments (SMDs from 0.33 to 0.74; p < 0.01) and lengthened T1ρ relaxation time in the femoral compartments (SMD from 0.35 to 0.40; p < 0.001).

Conclusions

T2 and T1ρ relaxation distinguish participants at risk for knee OA from healthy controls. Greater standardization of MRI methods is both warranted and required for progress towards biomarker validation.

Electronic supplementary material

The online version of this article (10.1186/s12891-019-2547-7) contains supplementary material, which is available to authorized users.

Quantification of patellofemoral cartilage deformation and contact area changes in response to static loading via high-resolution MRI with prospective motion correction

BACKGROUND

Higher-resolution MRI of the patellofemoral cartilage under loading is hampered by subject motion since knee flexion is required during the scan.

PURPOSE

To demonstrate robust quantification of cartilage compression and contact area changes in response to in situ loading by means of MRI with prospective motion correction and regularized image postprocessing.

STUDY TYPE

Cohort study.

SUBJECTS

Fifteen healthy male subjects.

FIELD STRENGTH

3 T.

SEQUENCE

Spoiled 3D gradient-echo sequence augmented with prospective motion correction based on optical tracking. Measurements were performed with three different loads (0/200/400 N).

ASSESSMENT

Bone and cartilage segmentation was performed manually and regularized with a deep-learning approach. Average patellar and femoral cartilage thickness and contact area were calculated for the three loading situations. Reproducibility was assessed via repeated measurements in one subject.

STATISTICAL TESTS

Comparison of the three loading situations was performed by Wilcoxon signed-rank tests.

RESULTS

Regularization using a deep convolutional neural network reduced the variance of the quantified relative load-induced changes of cartilage thickness and contact area compared to purely manual segmentation (average reduction of standard deviation by ∼50%) and repeated measurements performed on the same subject demonstrated high reproducibility of the method. For the three loading situations (0/200/400 N), the patellofemoral cartilage contact area as well as the mean patellar and femoral cartilage thickness were significantly different from each other (P < 0.05). While the patellofemoral cartilage contact area increased under loading (by 14.5/19.0% for loads of 200/400 N), patellar and femoral cartilage thickness exhibited a load-dependent thickness decrease (patella: -4.4/-7.4%, femur: -3.4/-7.1% for loads of 200/400 N).

DATA CONCLUSION

MRI with prospective motion correction enables quantitative evaluation of patellofemoral cartilage deformation and contact area changes in response to in situ loading. Regularizing the manual segmentations using a neural network enables robust quantification of the load-induced changes.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:1561-1570.

Patient respiratory-triggered quantitative T2 mapping in the pancreas

Background

Long acquisition times and motion sensitivity limit T₂ mapping in the abdomen. Accelerated mapping at 3 T may allow for quantitative assessment of diffuse pancreatic disease in patients during free‐breathing.

Purpose

To test the feasibility of respiratory‐triggered quantitative T₂ analysis in the pancreas and correlate T₂‐values with age, body mass index, pancreatic location, main pancreatic duct dilatation, and underlying pathology.

Study Type

Retrospective single‐center pilot study.

Population

Eighty‐eight adults.

Field Strength/Sequence

Ten‐fold accelerated multiecho‐spin‐echo 3 T MRI sequence to quantify T₂ at 3 T.

Assessment

Two radiologists independently delineated three regions of interest inside the pancreatic head, body, and tail for each acquisition. Means and standard deviations for T₂ values in these regions were determined. T₂‐value variation with demographic data, intraparenchymal location, pancreatic duct dilation, and underlying pancreatic disease was assessed.

Statistical Tests

Interreader reliability was determined by calculating the interclass coefficient (ICCs). T₂ values were compared for different pancreatic locations by analysis of variance (ANOVA). Interpatient associations between T₂ values and demographical, clinical, and radiological data were calculated (ANOVA).

Results

The accelerated T₂ mapping sequence was successfully performed in all participants (mean acquisition time, 2:48 ± 0:43 min). Low T₂ value variability was observed across all patients (intersubject) (head: 60.2 ± 8.3 msec, body: 63.9 ± 11.5 msec, tail: 66.8 ± 16.4 msec). Interreader agreement was good (ICC, 0.82, 95% confidence interval: 0.77–0.86). T₂‐values differed significantly depending on age (P < 0.001), location (P < 0.001), main pancreatic duct dilatation (P < 0.001), and diffuse pancreatic disease (P < 0.03).

Data Conclusion

The feasibility of accelerated T₂ mapping at 3 T in moving abdominal organs was demonstrated in the pancreas, since T₂ values were stable and reproducible. In the pancreatic parenchyma, T₂‐values were significantly dependent on demographic and clinical parameters.

Level of Evidence: 4

Technical Efficacy: Stage 1

J. Magn. Reson. Imaging 2019;50:410–416.

Simultaneous fat-free isotropic 3D anatomical imaging and T2 mapping of knee cartilage with lipid-insensitive binomial off-resonant RF excitation (LIBRE) pulses

BACKGROUND

Improved knee cartilage morphological delineation and T₂ mapping precision necessitates isotropic 3D high-resolution and efficient fat suppression.

PURPOSE

To develop and assess an isotropic 3D lipid-insensitive T₂ mapping technique of the knee for improved cartilage delineation and precise measurement of T₂ relaxation times.

STUDY TYPE

Prospective.

PHANTOM/SUBJECTS

Phantoms (n = 6) used in this study were designed to mimic the T₁ and T₂ relaxation times of cartilage and fat. The study cohort comprised healthy volunteers (n = 7) for morphometry and T₂ relaxation time measurements.

FIELD STRENGTH/SEQUENCE

A high-resolution isotropic 3D T₂ mapping technique that uses sequential T₂ -prepared segmented gradient-recalled echo (Iso3DGRE) images and lipid-insensitive binomial off-resonant radiofrequency (RF) excitation (LIBRE) at 3T.

ASSESSMENT

Numerical simulations and phantom experiments were performed to optimize the LIBRE pulse. Phantom studies were carried out to test the accuracy of the technique against reference standard spin-echo (SE) T₂ mapping. Subsequently, T₂ maps with and without LIBRE pulses were acquired in knees of healthy volunteers and the T₂ relaxation time values in different cartilage compartments were compared.

STATISTICAL TESTS

A two-tailed paired Student's t-test was used to compare the average T₂ values and the relative standard deviations (inverse measurement of the precision) obtained with and without LIBRE pulses.

RESULTS

A LIBRE pulse of 1 msec suppressed fat with an RF excitation frequency offset of 1560 Hz and optimal RF excitation angle of 35°. These results were corroborated by phantom and knee experiments. Robust and homogeneous fat suppression was obtained (a fat signal-to-noise ratio (SNR) decrease of 86.4 ± 2.4%). In phantoms, T₂ values were found in good agreement when comparing LIBRE-Iso3DGRE with SE (slope 0.93 ± 0.04, intercept 0.11 ± 1.6 msec, R² >0.99). In vivo, LIBRE excitation resulted in more precise T₂ estimation (23.7 ± 7.4%) than normal excitation (30.5 ± 9.9%, P < 0.0001).

DATA CONCLUSION

Homogeneous LIBRE fat signal suppression was achieved with a total RF pulse duration of 1 msec, allowing for the removal of chemical shift artifacts and resulting in improved cartilage delineation and precise T₂ values.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;49:1275-1284.

Maturation-Related Changes in T2 Relaxation Times of Cartilage and Meniscus of the Pediatric Knee Joint at 3 T

OBJECTIVE

The objective of our study was to use a T2 mapping sequence performed at 3 T to investigate changes in the composition and microstructure of the cartilage and menisci of the pediatric knee joint during maturation.

MATERIALS AND METHODS

This retrospective study was performed of MRI examinations of 76 pediatric knees without internal derangement in 72 subjects (29 boys [mean age, 12.5 years] and 43 girls [mean age, 13.0 years]) who were evaluated with a sagittal T2 mapping sequence. T2 relaxation time values were quantitatively measured in eight cartilage subregions and in the medial and lateral menisci. Wilcoxon rank sum and Kruskal-Wallis tests were used to analyze the relationship between cartilage and meniscus T2 relaxation time values and sex and skeletal maturation, respectively. A multivariate linear regression model was used to investigate the independent association between cartilage T2 relaxation time values and age, weight, and body mass index (BMI [weight in kilograms divided by the square of height in meters]).

RESULTS

There were no significant sex differences (p = 0.26-0.91) in T2 relaxation time values for cartilage or meniscus. T2 relaxation time values in each individual cartilage subregion significantly decreased (p < 0.001) with progressive maturation. T2 relaxation time values in the lateral meniscus significantly increased (p = 0.001) with maturation, whereas T2 relaxation time values in the medial meniscus did not significantly change (p = 0.82). There was a significant association (p < 0.001) between cartilage T2 relaxation time values and age independent of weight and BMI, but no significant association between cartilage T2 relaxation time values and weight (p = 0.06) and BMI (p = 0.20) independent of age.

CONCLUSION

Cartilage T2 relaxation time values significantly decreased in all cartilage subregions and meniscus T2 relaxation time values significantly increased in the lateral meniscus during maturation. These changes in T2 relaxation time values reflect age-related changes in tissue composition and microstructure.

Quantitative mapping of glenohumeral cartilage in asymptomatic subjects using 3 T magnetic resonance imaging

OBJECTIVE

The purpose of this study was to develop quantitative T2 mapping methodology in asymptomatic shoulders for the entire mappable region of the glenohumeral cartilage in the coronal and sagittal planes, to assess the feasibility and limitations of the development of a diagnostic tool for future application in symptomatic patients.

MATERIALS AND METHODS

Twenty-one asymptomatic volunteers underwent sagittal and coronal glenohumeral T2 mapping, as the spherical geometry of the humeral head obviates the need to evaluate the entire glenohumeral cartilage in a single plane. The humeral head cartilage orthogonal to the mapping plane was manually segmented in the sagittal and coronal planes, whereas the glenoid cartilage was segmented in the coronal plane. Cartilage T2 summary statistics were calculated and coverage in each mapping plane was qualitatively assessed.

RESULTS

The mean ± standard deviation of the glenoid cartilage T2 was 38 ± 2 ms. The coronal and sagittal mapping planes captured different regions of the humeral head with some overlap: inferior-medial to superior-lateral versus superior/superior-lateral to anterior-lateral and posterior-lateral respectively. The mean humeral head cartilage T2 in the coronal plane was 41 ± 3 ms, which was significantly different (p < 0.05) from the sagittal plane mean of 34 ± 2 ms.

CONCLUSION

This study measured characteristic glenoid and humeral head cartilage T2 values over the area mappable with two planes. Importantly, this study demonstrated that two-dimensional mapping in a single plane or two combined planes cannot capture the entirety of the semi-spherical humeral head cartilage. This highlights the need for three-dimensional T2 mapping techniques in the shoulder.

T2* Mapping of the Hip in Asymptomatic Volunteers with Normal Cartilage Morphology: An Analysis of Regional and Age-Dependent Distribution

Objective To assess age-dependent and regional differences in T2* relaxation measurements in hip joint cartilage of asymptomatic volunteers at 3 T. Design Three age cohorts (cohort 1: age 20-30 years, 15 individuals; cohort 2: age 30-40 years, 17 individuals; cohort 3: age 40-50 years, 15 individuals) were enrolled. T2* values were obtained in the central and peripheral cartilage of the acetabulum and the femoral head in 7 regions (anterior to superior and posterior). Results T2* did not differ among age cohorts in acetabular cartilage (cohort 1: 24.65 ± 6.56 ms, cohort 2: 24.70 ± 4.83 ms, cohort 3: 25.81 ± 5.10 ms, P = 0.10) and femoral head cartilage (cohort 1: 27.08 ± 8.24 ms, cohort 2: 25.90 ± 7.82 ms, cohort 3: 26.50 ± 5.61 ms, P = 0.34). Analysis of the regional T2* distribution pattern indicates increased T2* values in the anterior, anterior-superior, superior-anterior, and the posterior-superior aspects of acetabular and femoral head cartilage. For acetabular cartilage, higher values were observed in the central region (25.90 ± 4.80 ms vs. 24.21 ± 4.05 ms, P < 0.0001) whereas femoral head cartilage did not reveal such differences (26.62 ± 5.74 ms vs. 26.37 ± 5.89 ms, P = 0.44). Conclusions The T2* analysis of presumably healthy hip joint cartilage does not seem to be stratified according to age in this population. Regional T2* variation throughout hip joint cartilage is apparent in this modality.

Investigations of Cartilage Matrix Degeneration in Patients with Early-Stage Femoral Head Necrosis

Background

The purpose of this study was to explore changes in cartilage matrix in early-stage femoral head necrosis (FHN).

Material/Methods

Femoral head samples of patients with early FHN were collected during total hip arthroplasty (THA), high-field 7.0T MRI scans were performed in vitro, and the average T2 values were calculated. Cartilage samples were obtained from the weight-bearing area (FHN group) and non-weight-bearing area (Control group), divided into 3 equal parts and used for biochemical analysis, histopathological staining, and gene expression analysis.

Results

T2 mapping of the femoral head specimens showed that the density distribution of cartilage surface was not uniform, and the average T2 value increased unevenly. Histological staining demonstrated that the number of chondrocytes was significantly decreased and they were irregularly arranged, SO staining was lost, and collagen fiber arrangement was slightly more irregular on the cartilage surface in the FHN group. The biochemical results in the FHN group showed that the water content increased significantly and the DNA content decreased significantly, while no significant changes in GAG and total collagen contents were detected. Gene expression analysis in the FHN group showed that SOX9 expression was significantly down-regulated, while COL10A1 and RUNX2 expressions were significantly up-regulated. The expression of ACAN and COL2A1 were decreased and COL1A1 was increased, but there was no significant difference compared with the Control group.

Conclusions

Taken together, the results of this study suggest that patients with early-stage FHN tend to have cartilage matrix degeneration, which provides new ideas for studying the pathogenesis of FHN and selecting treatment strategies.

T2 mapping and post-contrast T1 (dGEMRIC) of the patellar cartilage: 12-year follow-up after patellar stabilizing surgery in childhood

Background

Cartilage degeneration has been reported after recurrent patellar dislocation. However, effects of surgical stabilization in childhood have not yet been described.

Purpose

To examine the cartilage quality in very young adults operated with a patellar stabilizing procedure due to recurrent patellar dislocation in childhood, and evaluate if cartilage quality correlates with clinical parameters and patient-reported outcomes.

Material and Methods

Seventeen patients were investigated ≥ 5 years (mean = 11.6 years) after patellar stabilizing surgery in childhood. Pre-contrast T2 relaxation times were analyzed in four superficial and four deep patellar cartilage regions of both knees. Two hours after 0.2 mM/kg Gd-DTPA² i.v., post-contrast T1 (T1(Gd)) was analyzed in the same regions. Patient-reported outcomes (KOOS, Kujala, and Tegner scores) and recurrence rates were evaluated.

Results

Comparing operated to healthy side, neither T2 nor dGEMRIC differed between the operated and the reference knee regarding the superficial half of the cartilage. In the deep half of the cartilage, T1(Gd) was shorter in the central part of the cartilage, whereas T2 was longer medially (P < 0.05). A low score in the KOOS subscales Symptom and Sports & Recreation, was correlated to the degenerative changes detected by T1(Gd) (r = 0.5, P = 0.041).

Conclusion

In general, our findings demonstrate good cartilage quality 12 years after patellar stabilizing surgery during childhood. The subtle changes in T2 and T1(Gd) in the deep cartilage layer may be a result of altered biomechanics, although very early degenerative changes cannot be excluded. The short T1(Gd) centrally may reflect lower glycosaminoglycan content, whereas the increase in T2 medially indicates increased cartilage hydration.

Intraoperative validation of quantitative T2 mapping in patients with articular cartilage lesions of the knee

OBJECTIVE

The aim of this study was to compare T2 relaxation times of knee cartilage with intraoperative results for the assessment of early osteoarthritis (OA) and to define T2 values for the differentiation between healthy and degenerated cartilage.

DESIGN

Twenty-one patients with cartilage lesions or moderate OA were examined using 3T magnetic resonance imaging (MRI). In this prospective study, a total of 882 regions of interest (ROIs) were examined by a sagittal, multi-echo, spin-echo T2 sequence and a morphological high-resolution three-dimensional, fat-saturated proton-density space sequence. Cartilage lesions were identified arthroscopically, graded by the International Cartilage Repair Society (ICRS) score in 42 defined ROIs per patient and consecutively compared with mean T2 values using analysis of variance and Spearman's rank correlation test. Receiver operating characteristics (ROC) curves were developed to identify threshold T2 values to differentiate between the ICRS grades.

RESULTS

A total of 882 ROIs were examined and graduated in ICRS score 0 (67.3%), 1 (25.2%), 2 (6.2%) and the merged ICRS 3 and 4 (1.0%). T2 values increased with increasing grade of cartilage damage with a statistically significant positive correlation between T2 values and ICRS scores. A T2 value threshold of 47.6 ms was identified to differentiate between ICRS score 0 (normal) and all other grades (ROC curve analysis).

CONCLUSION

T2 mapping might provide a diagnostic tool for the detection of early knee-joint cartilage damage and for the non-invasive differentiation between ICRS grades by MRI in clinical practice.

Intra-articular Injection of Mesenchymal Stem Cells and Platelet-Rich Plasma to Treat Patellofemoral Osteoarthritis: Preliminary Results of a Long-Term Pilot Study

PURPOSE

To assess the feasibility and safety of concomitant intra-articular (IA) knee injection of mesenchymal stem cells (MSCs) and platelet-rich plasma (PRP) under fluoroscopic guidance to treat patellofemoral osteoarthritis (OA).

MATERIALS AND METHODS

This prospective study included 19 consecutive patients referred for fluoroscopically guided IA MSC and PRP injection for symptomatic patellofemoral chondropathy in which conservative treatment had failed. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score and magnetic resonance (MR) data, including T2 mapping sequence, were prospectively collected before and 6 months after treatment. Clinical data without MR imaging were collected until 12 months after the procedure.

RESULTS

WOMAC scores were significantly lower after IA injection of MSCs and PRP at 6 months and during 12-months follow-up compared with baseline (mean score decreased from 34.3 to 14.2; P < .0018). Patients reported no complications. Concerning MR imaging follow-up, there were no significant differences in grade, surface, or T2 value of the chondral lesions (P > .375).

CONCLUSIONS

IA injection of MSCs and PRP in early patellofemoral OA appears to allow functional improvement.

T2* Mapping for Hip Joint Cartilage Assessment: Pre-MRI Exercise and Time of Imaging Do Not Bias the T2* Measurement in Asymptomatic Volunteers

Objective To identify if the time of day and pre-imaging exercise matter while performing T2* mapping of hip joint cartilage at 3 T. Design Nine asymptomatic healthy volunteers (mean age 27.4 ± 4.0 years) with no obvious morphological evidence of cartilage damage were enrolled. The MRI protocol included a double-echo steady state (DESS) sequence for morphological cartilage assessment and a multi-echo data image combination sequence for the T2* measurement. T2* values were obtained between 8 and 11 a.m., between 3 and 6 p.m., and after 50 knee-bends at several time points of each measurement (0, 15, 30, 45, 60 minutes). Results We observed no differences ( P = 0.47) between the T2* values obtained in the morning (T2* = 22.9 ± 3.0 ms) and those measured in the afternoon (T2* = 23.2 ± 3.2 ms). We also observed no statistically significant differences between the T2* values at different time points ( P = 0.67) or after 50 knee-bends ( P = 0.43). Conclusions Timing of the scan and pre-imaging exercise clearly did not matter in this modality. This study consolidates the value of T2* imaging in hip joint cartilage that seems to be independent of diurnal effects and physical activity prior to MRI.

T2* mapping of subtalar cartilage: Precision and association between anatomical variants and cartilage composition

Hindfoot arthritis is an important contributor to foot pain and physical disability. While the subtalar joint (STJ) is most frequently affected, anatomical variants such as facet configuration were suggested to further STJ cartilage deterioration. T2* mapping enables detection of ultra-structural cartilage change, particularly in thin cartilage layers, but its feasibility in the STJ has not yet been evaluated. The purpose of this study was to evaluate segmentation consistency and inter-scan short-term precision error of T2* mapping of talocalcaneal cartilage and to investigate the relationship between facet configuration and STJ T2* values. Using 3Tesla morphological magnetic resonance imaging, STJ configuration was categorized according to the degree of fusion between anterior, medial, or posterior facets. Subsequently, two repeats of multi-echo gradient recalled echo sequences were performed to obtain T2* maps with repositioning. Segmentation consistency of T2* values attained an ICC of 0.90 (95%CI 0.69-0.99). Precision errors comprised a coefficient of variation (CV) ranging 0.01-0.05, corresponding to a root mean square CV of 0.03-0.04. A 2-joint configuration type (i.e., fused anterior-medial facets) was significantly associated with a decrease in posterior facet T2* values (β = -0.6, p = 0.046). STJ T2* mapping is a reliable method requiring at least a 4% difference within people to enable detection of significant change. Anatomical variants in STJ configuration were associated with T2* values with the more stable 3-joint types exhibiting more favorable cartilage outcomes. Longer-term larger-scaled studies focusing on arthritis pathology are needed to further support the use of T2* mapping in hindfoot disease monitoring. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1969-1976, 2016.

Comparison of T2* relaxation times of articular cartilage of the knee in elite professional football players and age-and BMI-matched amateur athletes

OBJECTIVE

Recent investigation has underlined the potential of quantitative MR imaging to be used as a complementary tool for the diagnosis of cartilage degeneration at an early state. The presented study analyses T2* relaxation times of articular cartilage of the knee in professional athletes and compares the results to age- and BMI (Body Mass Index)-matched healthy amateur athletes.

MATERIALS AND METHODS

22 professional football players and 22 age- and BMI-matched individuals were underwent knee Magnetic Resonance Imaging (MRI) at 3T including qualitative and quantitative analysis. Qualitative analysis included e.g. meniscal tears, joint effusion and bone edema. For quantitative analysis T2* (22 ET: 4.6-53.6ms) measurements in 3D data acquisition were performed. Deep and superficial layers of 22 predefined cartilage segments were analysed. All data sets were postprocessed using a dedicated software tool. Statistical analysis included Student t-test, confidence intervals and a random effects model.

RESULTS

In both groups, T2* relaxation times were significantly higher in the superficial compared to the deep layers (p<0.001). Professional athletes had significantly higher relaxation times in eight superficial and three deep cartilage layers in the predefined cartilage segments (p<0.05). Highly significant differences were found in the weight-bearing segments of the lateral superficial femoral condyle (p<0.001).

CONCLUSION

Elevated T2* values in cartilage layers of professional football players compared to amateur athletes were noted. The effects seem to predominate in superficial cartilage layers.

Influence of acupuncture in treatment of knee osteoarthritis and cartilage repairing

As two major non-operative methods, physiotherapy and acupuncture have been proved to be safe and effective in osteoarthritis (OA) treatment. However, only a little study focused on functions of both methods on cartilage repairing. The main goal of this research is to prove and compare effectiveness of acupuncture and physiotherapy on OA, and to explore their possible efficacy on cartilage repairing. One hundred knees of 50 participants with knee osteoarthritis (KOA) were randomly divided into acupuncture group and physiotherapy group. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) was used to evaluate the motor function of knee joints, followed by MRI scanning to measure T2 values in ten cartilage sub-regions in tibiofemoral joints. Significant lower scores of total WOMAC and three subscales on the 4th weekend were observed in both groups than those of the baseline (P < 0.01). For acupuncture group, scores of total WOMAC and three subscales for pain, stiffness and physical function on 4th weekend were significantly lower than those of the physiotherapy group (P < 0.01 and P < 0.05). T2 values in anterior medial tibial sub-region (MTa) and anterior lateral tibial sub-region (LTa) were significantly lower in acupuncture group on 4th weekend than those of the baseline (P < 0.05). No significant difference in T2 values was detected in physiotherapy group. These results indicate that acupuncture represents certain clinical effect on KOA which is superior compared with physiotherapy, and hint the possible roles of acupuncture in promoting cartilage repairing.

T2 mapping of articular cartilage of the glenohumeral joint at 3.0 T in healthy volunteers: a feasibility study

OBJECTIVE

The purpose of this study was to assess the T2 values of the glenohumeral joint cartilage in healthy asymptomatic individuals at 3.0 T and to analyze the T2 profile of the humeral cartilage.

MATERIALS AND METHODS

This prospective study was approved by our institutional review board and written informed consent was obtained. Thirteen subjects (mean age, 28.6 years; age range, 24-33 years) were included and underwent multiecho spin-echo T2-weighted MR imaging and T2 mapping was acquired. Regions of interest were placed on the humeral cartilage and glenoid cartilage on oblique coronal images. T2 profiles of humeral cartilage were measured from the bone-cartilage interface to the articular surface. Intra-observer agreement was analyzed using intraclass correlation coefficient (ICC).

RESULTS

All 13 joints showed normal appearance on conventional T2-weighted images. The mean T2 values of humeral and glenoid cartilage were 50.5 ± 12.1 and 49.0 ± 9.9 ms, respectively. Intra-observer agreement was good, as determined by ICC (0.736). Longer T2 values were observed at the articular surface with a tendency to decrease toward the bone-cartilage interface. The mean cartilage T2 value was 69.03 ± 21.2 ms at the articular surface and 46.99 ± 19.6 ms at the bone-cartilage interface.

CONCLUSION

T2 values of the glenohumeral joint cartilage were similar to reported values of cartilage in the knee. The T2 profile of normal humeral cartilage showed a spatial variation with an increase in T2 values from the subchondral bone to the articular surface.

The immediate effect of long-distance running on T2 and T2* relaxation times of articular cartilage of the knee in young healthy adults at 3.0 T MR imaging

OBJECTIVE

To quantitatively assess the immediate effect of long-distance running on T2 and T2* relaxation times of the articular cartilage of the knee at 3.0 T in young healthy adults.

METHODS

30 healthy male adults (18-31 years) who perform sports at an amateur level underwent an initial MRI at 3.0 T with T2 weighted [16 echo times (TEs): 9.7-154.6 ms] and T2* weighted (24 TEs: 4.6-53.6 ms) relaxation measurements. Thereafter, all participants performed a 45-min run. After the run, all individuals were immediately re-examined. Data sets were post-processed using dedicated software (ImageJ; National Institute of Health, Bethesda, MD). 22 regions of interest were manually drawn in segmented areas of the femoral, tibial and patellar cartilage. For statistical evaluation, Pearson product-moment correlation coefficients and confidence intervals were computed.

RESULTS

Mean initial values were 35.7 ms for T2 and 25.1 ms for T2*. After the run, a significant decrease in the mean T2 and T2* relaxation times was observed for all segments in all participants. A mean decrease of relaxation time was observed for T2 with 4.6 ms (±3.6 ms) and for T2* with 3.6 ms (±5.1 ms) after running.

CONCLUSION

A significant decrease could be observed in all cartilage segments for both biomarkers. Both quantitative techniques, T2 and T2*, seem to be valuable parameters in the evaluation of immediate changes in the cartilage ultrastructure after running.

ADVANCES IN KNOWLEDGE

This is the first direct comparison of immediate changes in T2 and T2* relaxation times after running in healthy adults.

A comparison of multi-echo spin-echo and triple-echo steady-state T2 mapping for in vivo evaluation of articular cartilage

OBJECTIVES

To assess the clinical relevance of T2 relaxation times, measured by 3D triple-echo steady-state (3D-TESS), in knee articular cartilage compared to conventional multi-echo spin-echo T2-mapping.

METHODS

Thirteen volunteers and ten patients with focal cartilage lesions were included in this prospective study. All subjects underwent 3-Tesla MRI consisting of a multi-echo multi-slice spin-echo sequence (CPMG) as a reference method for T2 mapping, and 3D TESS with the same geometry settings, but variable acquisition times: standard (TESSs 4:35min) and quick (TESSq 2:05min). T2 values were compared in six different regions in the femoral and tibial cartilage using a Wilcoxon signed ranks test and the Pearson correlation coefficient (r). The local ethics committee approved this study, and all participants gave written informed consent.

RESULTS

The mean quantitative T2 values measured by CPMG (mean: 46±9ms) in volunteers were significantly higher compared to those measured with TESS (mean: 31±5ms) in all regions. Both methods performed similarly in patients, but CPMG provided a slightly higher difference between lesions and native cartilage (CPMG: 90ms→61ms [31%],p=0.0125;TESS 32ms→24ms [24%],p=0.0839).

CONCLUSIONS

3D-TESS provides results similar to those of a conventional multi-echo spin-echo sequence with many benefits, such as shortening of total acquisition time and insensitivity to B1 and B0 changes.

KEY POINTS

• 3D-TESS T 2 mapping provides clinically comparable results to CPMG in shorter scan-time. • Clinical and investigational studies may benefit from high temporal resolution of 3D-TESS. • 3D-TESS T 2 values are able to differentiate between healthy and damaged cartilage.

High-Resolution Methods for Diagnosing Cartilage Damage In Vivo

Advances in current clinical modalities, including magnetic resonance imaging and computed tomography, allow for earlier diagnoses of cartilage damage that could mitigate progression to osteoarthritis. However, current imaging modalities do not detect submicrometer damage. Developments in in vivo or arthroscopic techniques, including optical coherence tomography, ultrasonography, bioelectricity including streaming potential measurement, noninvasive electroarthrography, and multiphoton microscopy can detect damage at an earlier time point, but they are limited by a lack of penetration and the ability to assess an entire joint. This article reviews current advancements in clinical and developing modalities that can aid in the early diagnosis of cartilage injury and facilitate studies of interventional therapeutics.