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To develop an ultrafast and robust MR parameter mapping network using deep learning.We design a deep learning framework called SuperMAP that directly converts a series of undersampled (both in k-space and parameter-space) parameter-weighted images into several quantitative maps, bypassing the conventional exponential fitting procedure. We also present a novel technique to simultaneously reconstruct T1rho and T2 relaxation maps within a single scan. Full data were acquired and retrospectively undersampled for training and testing using traditional and state-of-the-art techniques for comparison. Prospective data were also collected to evaluate the trained network. The performance of all methods is evaluated using the parameter qualification errors and other metrics in the segmented regions of interest.SuperMAP achieved accurate T1rho and T2 mapping with high acceleration factors (R = 24 and R = 32). It exploited both spatial and temporal information and yielded low error (normalized mean square error of 2.7% at R = 24 and 2.8% at R = 32) and high resemblance (structural similarity of 97% at R = 24 and 96% at R = 32) to the gold standard. The network trained with retrospectively undersampled data also works well for the prospective data (with a slightly lower acceleration factor). SuperMAP is also superior to conventional methods.Our results demonstrate the feasibility of generating superfast MR parameter maps through very few undersampled parameter-weighted images. SuperMAP can simultaneously generate T1rho and T2 relaxation maps in a short scan time.

Background: The association between activity level after anterior cruciate ligament (ACL) reconstruction (ACLR) and development of posttraumatic osteoarthritis (PTOA) remains unclear. This study investigated the relationship of patient-reported outcomes and progressive cartilage degenerative changes at 3 years after ACLR. Hypothesis: Higher activity levels, as measured by Marx scores, are significantly correlated with early cartilage degeneration after ACLR. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 35 patients (16 women; mean age, 31.0 ± 7.6 years) with isolated ACLR and without pre-existing arthritis were prospectively enrolled. Patients reported Marx activity scores and Knee injury and Osteoarthritis Outcome Score (KOOS) scores and underwent T1ρ magnetic resonance imaging (MRI) preoperatively, 6 months, 1 year, 2 years, and 3 years after ACLR with soft tissue graft (22 autograft). The change in cartilage relaxation times between preoperative and 3-year imaging was used to identify cartilage degeneration, defined as an increase in T1ρ values by 14.3%. Correlation between Marx activity levels, KOOS scores, and T1ρ degeneration was performed with the Spearman rank test. The Fisher exact test was used to test for association between Marx activity score cutoffs and degeneration. The Student t test was used to compare Whole-Organ Magnetic Resonance Imaging Score (WORMS) and T1ρ relaxation times. Significance was defined as P < .05. Results: Sixteen patients (45.7%) showed evidence of cartilage degeneration at 3 years, most frequently in the medial compartment (n = 12; 34%). Higher Marx activity scores at 3 years correlated with cartilage degeneration in the medial femur (rho = 0.34; P = .045), and medial tibia (rho = 0.43; P = .01). A Marx score of 11 or greater at 3 years was significantly associated with medial compartment degeneration ( P = .03), with a positive predictive value of 52.6%. No Marx score cutoff at years 1 or 2 predicted future cartilage degeneration. The KOOS Quality of Life score was inversely correlated with cartilage degeneration (rho = 0.38; P = .02). WORMS did not correlate with degeneration of the medial compartment. Conclusion: Increased activity at 3 years after ACLR was significantly associated with increased risk of medial compartment PTOA. While further research is needed to fully define these relationships, patients may be counseled that return to Marx activity levels of greater than 11 may be associated with a higher risk of medial compartment cartilage degeneration.

Joint coordination variability during walking that is associated with patellofemoral joint cartilage degeneration after anterior cruciate ligament reconstruction are not well understood. The purpose of this study was to assess between-limb differences in joint coordination variability and to determine the relationship of coordination variability with postoperative patellofemoral joint cartilage composition. Thirty-five patients underwent bilateral gait analysis and a magnetic resonance exam of the reconstructed knee joint at 6 months post anterior cruciate ligament reconstruction. Vector coding was used to assess coordination variability during the early (1%–33%), mid (34%–66%), and late (67%–100%) stance phase. The T1ρ/T2 mapping was used to evaluate the glycosaminoglycan–collagen matrix of the patellar and femoral trochlear cartilage. Compared with the uninjured limb, the reconstructed limb exhibited higher hip sagittal/knee sagittal plane coordination variability during midstance as well as higher knee sagittal/ankle sagittal plane coordination variability during both mid and late stance. The hip sagittal/knee sagittal plane coordination variability during midstance predicted 14.6% of the variance in patellar cartilage T1ρ values within the reconstructed limb. In addition, sex of participants was able to predict 32.4% and 13.7% of the variance in femoral trochlea T1ρ and T2 values, respectively. The study results demonstrate that a multijoint mechanism may be associated with early patellofemoral joint cartilage degeneration at 6 months after anterior cruciate ligament reconstruction.

MRI-based cartilage compositional analysis shows biochemical and microstructural changes at early stages of osteoarthritis before changes become visible with structural MRI sequences and arthroscopy. This could help with early diagnosis, risk assessment, and treatment monitoring of osteoarthritis. Spin-lattice relaxation time constant in rotating frame (T1ρ) and T2 mapping are the MRI techniques best established for assessing cartilage composition. Only T2 mapping is currently commercially available, which is sensitive to water, collagen content, and orientation of collagen fibers, whereas T1ρ is more sensitive to proteoglycan content. Clinical application of cartilage compositional imaging is limited by high variability and suboptimal reproducibility of the biomarkers, which was the motivation for creating the Quantitative Imaging Biomarkers Alliance (QIBA) Profile for cartilage compositional imaging by the Musculoskeletal Biomarkers Committee of the QIBA. The profile aims at providing recommendations to improve reproducibility and to standardize cartilage compositional imaging. The QIBA Profile provides two complementary claims (summary statements of the technical performance of the quantitative imaging biomarkers that are being profiled) regarding the reproducibility of biomarkers. First, cartilage T1ρ and T2 values are measurable at 3.0-T MRI with a within-subject coefficient of variation of 4%–5%. Second, a measured increase or decrease in T1ρ and T2 of 14% or more indicates a minimum detectable change with 95% confidence. If only an increase in T1ρ and T2 values is expected (progressive cartilage degeneration), then an increase of 12% represents a minimum detectable change over time. The QIBA Profile provides recommendations for clinical researchers, clinicians, and industry scientists pertaining to image data acquisition, analysis, and interpretation and assessment procedures for T1ρ and T2 cartilage imaging and test-retest conformance. This special report aims to provide the rationale for the proposed claims, explain the content of the QIBA Profile, and highlight the future needs and developments for MRI-based cartilage compositional imaging for risk prediction, early diagnosis, and treatment monitoring of osteoarthritis. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Kijowski in this issue.

The purpose of this proof-of-concept study was to develop three-dimensional patient-specific mechanobiological knee joint models to simulate alterations in the fixed charged density (FCD) around cartilage lesions during the stance phase of the walking gait. Two patients with anterior cruciate ligament (ACL) reconstructed knees were imaged at 1 and 3 years after surgery. The magnetic resonance imaging (MRI) data were used for segmenting the knee geometries, including the cartilage lesions. Based on these geometries, finite element (FE) models were developed. The gait of the patients was obtained using a motion capture system. Musculoskeletal modeling was utilized to calculate knee joint contact and lower extremity muscle forces for the FE models. Finally, a cartilage adaptation algorithm was implemented in both FE models. In the algorithm, it was assumed that excessive maximum shear and deviatoric strains (calculated as the combination of principal strains), and fluid velocity, are responsible for the FCD loss. Changes in the longitudinal T1ρ and T2 relaxation times were postulated to be related to changes in the cartilage composition and were compared with the numerical predictions. In patient 1 model, both the excessive fluid velocity and strain caused the FCD loss primarily near the cartilage lesion. T1ρ and T2 relaxation times increased during the follow-up in the same location. In contrast, in patient 2 model, only the excessive fluid velocity led to a slight FCD loss near the lesion, where MRI parameters did not show evidence of alterations. Significance: This novel proof-of-concept study suggests mechanisms through which a local FCD loss might occur near cartilage lesions. In order to obtain statistical evidence for these findings, the method should be investigated with a larger cohort of subjects.

Background: There is growing evidence suggesting a link between patellofemoral joint (PFJ) osteoarthritis in anterior cruciate ligament (ACL)–reconstructed knees and altered joint alignment. Purpose: To determine whether patellar alignment differs between participants with and without ACL reconstruction (ACLR) and to identify possible associations between patellar alignment and PFJ osteoarthritis features over 3 years. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 37 participants with ACLR (sex, 23 male; mean ± SD age, 28.1 ± 7.4 years) and 20 healthy controls (13 male; 30.4 ± 4.8 years) participated. Patients underwent magnetic resonance imaging: (1) sagittal T2-weighted fat-saturated fast spin echo images to calculate patellar alignment, (2) sagittal 3-dimensional intermediate-weighted fast spin echo Cube sequence for clinical morphological grading (modified Whole-Organ Magnetic Resonance Imaging Score [WORMS]), and (3) sagittal combined T1ρ/T2 mapping sequence for performing voxel-based relaxometry. Patellar alignment of the ACLR knees were assessed at 6 months (baseline). One-way analysis of variance was used to compare patellar alignment among the ACLR (at 6 months), contralateral, and control knees. Within the ACLR group, a logistic regression model was used to identify if patellar alignment measures at baseline were risk factors for worsening of PFJ structural changes over 3 years. Statistical parametric mapping was used to evaluate the longitudinal associations between patellar alignment and cartilage relaxation times at 3 years. Results: When compared with control knees, ACLR knees exhibited a laterally and anteriorly displaced patella ( P = .045 and P = .041), less flexion ( P = .031), and less lateral spin ( P = .012). Furthermore, excessive lateral displacement was a significant predictor of worsening of WORMS ( P = .050). Lateral displacement was positively correlated with increased T1ρ and T2 in the patellar and trochlear cartilage at 3 years. Patellar lateral spin revealed similar negative findings. Conclusion: Participants with ACLR exhibited a laterally and anteriorly displaced patella, less flexion, and less lateral spin when compared with healthy controls. Excessive patellar lateral displacement was the strongest predictor to the development of PFJ osteoarthritis features longitudinally.

The purpose of this study was to analyze the relationship between postsurgical tibial translation (TT) and tibial rotation (TR) with cartilage matrix changes using quantitative magnetic resonance imaging, specifically voxel-based relaxometry with T1ρ and T2 mapping sequences. Knee magnetic resonance imaging's (MRI's) of 51 patients with unilateral anterior cruciate ligament injury, no concomitant ligamentous injury, history of osteoarthritis (OA), and previous knee surgery were scanned prior to surgery. Thirty-four patients completed follow-up MRI scans at 6-month, 1- and 2-year post-reconstruction and were included in this study. Knee biomechanics, T1ρ, and T2 were calculated using an in-house Matlab program. Compared to the contralateral knee, the injured knee demonstrated significantly increased anterior TT at baseline (P < .001), 6-month (P < .001), 1- (P = .001), and 2-year (P < .001). Furthermore, patients were divided into groups based on TT at 6-month. When compared to patients with normal TT, those with increased anterior TT at 6-month displayed significantly longer T1ρ and T2 relaxation times in 10.4% and 7.4% of the voxels in the injured medial tibia at 1-year, respectively, as well as 12.4% and 9.8% of the voxels in the injured medial tibia at 2-year, respectively. Our results demonstrate an association between abnormal tibiofemoral position and early degradative changes to the articular cartilage matrix of the injured knee. Clinical significance: These findings suggest that altered tibiofemoral position following ACL reconstruction is associated with early degeneration of knee cartilage. Future prospective studies employing longer follow-up times are warranted to evaluate the relationship between abnormal tibiofemoral position and the early onset of posttraumatic OA.

Purpose Fully automatic tissue segmentation is an essential step to translate quantitative MRI techniques to clinical setting. The goal of this study was to develop a novel approach based on the generative adversarial networks for fully automatic segmentation of knee cartilage and meniscus. Theory and methods Defining proper loss function for semantic segmentation to enforce the learning of multiscale spatial constraints in an end-to-end training process is an open problem. In this work, we have used the conditional generative adversarial networks to improve segmentation performance of convolutional neural network, such as UNet alone by overcoming the problems caused by pixel-wise mapping based objective functions, and to capture cartilage features during the training of the network. Furthermore, the Dice coefficient and cross entropy losses were incorporated to the loss functions to improve the model performance. The model was trained and tested on 176, 3D DESS (double-echo steady-state) knee images from the Osteoarthritis Initiative data set. Results The proposed model provided excellent segmentation performance for cartilages with Dice coefficients ranging from 0.84 in patellar cartilage to 0.91 in lateral tibial cartilage, with an average Dice coefficient of 0.88. For meniscus segmentation, the model achieves 0.89 Dice coefficient for lateral meniscus and 0.87 Dice coefficient for medial meniscus. The results are superior to previously published automatic cartilage and meniscus segmentation methods based on deep learning models such as convolutional neural network. Conclusion The proposed UNet-conditional generative adversarial networks based model demonstrated a fully automated segmentation method with high accuracy for knee cartilage and meniscus.

Three-dimensional (3D) magnetic resonance imaging (MRI) of the knee is widely used in musculoskeletal (MSK) imaging. Currently, 3D sequences are most commonly used for morphological imaging. Isotropic 3D MRI provides higher out-of-plane resolution than standard two-dimensional (2D) MRI, leading to reduced partial volume averaging artifacts and allowing for multiplanar reconstructions in any plane with any thickness from a single high-resolution isotropic acquisition. Specifically, isotropic 3D fast spin-echo imaging, with options for tissue weighting similar to those used in multiplanar 2D FSE imaging, is of particular interest to MSK radiologists. New applications for 3D spatially encoded sequences are also increasingly available for clinical use. These applications offer advantages over standard 2D techniques for metal artifact reduction, quantitative cartilage imaging, nerve imaging, and bone shape analysis. Emerging fast imaging techniques can be used to overcome the long acquisition times that have limited the adoption of 3D imaging in clinical protocols.

The aims of this case-control study were to: (1) Identify cartilage locations and volumes at risk of osteoarthritis (OA) using subject-specific finite element (FE) models; (2) Quantify the relationships between the simulated biomechanical parameters and T2 and T1ρ relaxation times of magnetic resonance imaging (MRI). We created subject-specific FE models for seven patients with anterior cruciate ligament (ACL) reconstruction and six controls based on a previous proof-of-concept study. We identified locations and cartilage volumes susceptible to OA, based on maximum principal stresses and absolute maximum shear strains in cartilage exceeding thresholds of 7 MPa and 32%, respectively. The locations and volumes susceptible to OA were compared qualitatively and quantitatively against 2-year longitudinal changes in T2 and T1ρ relaxation times. The degeneration volumes predicted by the FE models, based on excessive maximum principal stresses, were significantly correlated (r = 0.711, p < 0.001) with the degeneration volumes determined from T2 relaxation times. There was also a significant correlation between the predicted stress values and changes in T2 relaxation time (r = 0.649, p < 0.001). Absolute maximum shear strains and changes in T1ρ relaxation time were not significantly correlated. Five out of seven patients with ACL reconstruction showed excessive maximum principal stresses in either one or both tibial cartilage compartments, in agreement with follow-up information from MRI. Expectedly, for controls, the FE models and follow-up information showed no degenerative signs. Our results suggest that the presented modelling methodology could be applied to prospectively identify ACL reconstructed patients at risk of biomechanically driven OA, particularly by the analysis of maximum principal stresses of cartilage.

Background: MRI acceleration using deep learning (DL) convolutional neural networks (CNNs) is a novel technique with great promise. Increasing the number of convolutional layers may allow for more accurate image reconstruction. Studies on evaluating the diagnostic interchangeability of DL reconstructed knee magnetic resonance (MR) images are scarce. The purpose of this study was to develop a deep CNN (DCNN) with an optimal number of layers for accelerating knee magnetic resonance imaging (MRI) acquisition by 6-fold and to test the diagnostic interchangeability and image quality of nonaccelerated images versus images reconstructed with a 15-layer DCNN or 3-layer CNN. Methods: For the feasibility portion of this study, 10 patients were randomly selected from the Osteoarthritis Initiative (OAI) cohort. For the interchangeability portion of the study, 40 patients were randomly selected from the OAI cohort. Three readers assessed meniscal and anterior cruciate ligament (ACL) tears and cartilage defects using DCNN, CNN, and nonaccelerated images. Image quality was subjectively graded as nondiagnostic, poor, acceptable, or excellent. Interchangeability was tested by comparing the frequency of agreement when readers used both accelerated and nonaccelerated images to frequency of agreement when readers only used nonaccelerated images. A noninferiority margin of 0.10 was used to ensure type I error = 80%. A logistic regression model using generalized estimating equations was used to compare proportions; 95% confidence intervals (CIs) were constructed. Results: DCNN and CNN images were interchangeable with nonaccelerated images for all structures, with excess disagreement values ranging from -2.5% [95% CI: (-6.1, 1.1)] to 3.0% [95% CI: (-0.1, 6.1)]. The quality of DCNN images was graded higher than that of CNN images but less than that of nonaccelerated images [excellent/acceptable quality: DCNN, 95% of cases (114/120); CNN, 60% (72/120); nonaccelerated, 97.5% (117/120)]. Conclusions: Six-fold accelerated knee images reconstructed with a DL technique are diagnostically interchangeable with nonaccelerated images and have acceptable image quality when using a 15-layer CNN. National Institutes of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [R21EB020861]; Society of Skeletal Radiology (SSR) Research Seed Grant ("Highly Accelerated Knee MRI using a Novel Deep Convolutional Neural Network Algorithm: A Multi-Reader Comparison Study") This work was supported in part by the National Institutes of Health R21EB020861. This study was also partially supported by a Society of Skeletal Radiology (SSR) Research Seed Grant ("Highly Accelerated Knee MRI using a Novel Deep Convolutional Neural Network Algorithm: A Multi-Reader Comparison Study").

PURPOSE: To investigate (i) the frequency and natural evolution of meniscal ramp lesions (MRLs) on MRI in subjects with acute ACL-tear and (ii) to compare knee cartilage compositional degeneration between subjects with MRLs and subjects without meniscal pathology over 2 years. MATERIALS AND METHODS: Fifty-seven subjects with ACL tears (32 females; age 32.6±8.3y; BMI 24.5±3.5kg/m(2)) from a prospective study were screened for the presence of MRLs. Morphological (high-resolution 3D fast spin-echo) and compositional (T1ρ and T2-mapping) MRI was performed prior to and 2-years after ACL-reconstruction. Follow-up MR images were assessed for changes in the signal-intensity of the MRLs and the presence of meniscal tears. Differences of compositional parameters were compared between subjects with MRLs and without meniscal lesions using an Independent Samples t Tests. RESULTS: MRLs were found in 16% (9/56) of the subjects with ACL tears at baseline. Only one subject with MRLs developed a posterior horn meniscal tear over 2 years. In 12 knees no meniscal tears were found, which were defined as controls. Most interestingly, cartilage ΔT1ρ of the medial femur and medial tibia increased significantly more in subjects with MRLs compared to controls (mean difference, MF=6.0±0.8 vs. 2.3±0.6, p=0.004 and MT=4.4±1.4 vs. 0.4±0.6, p=0.027) and medial femur ΔT2 over 2 years increased significantly more in MRL than in control knees (5.1±2.5 ms vs. 2.2±1.9 ms, p=0.012). CONCLUSION: Subjects with ACL-tear presented MRLs in 16% of cases. Compared to controls without meniscal lesions knees with MRLs demonstrated accelerated degeneration of cartilage composition in the medial knee compartment over 2-years.

T1 ρ and T2 magnetic resonance imaging (MRI) may allow for a noninvasive assessment of ligamentization after anterior cruciate ligament (ACL) reconstruction. We hypothesized that ACL graft T1 ρ and T2 relaxation times would decrease over time, that T1 ρ and T2 relaxation times would be inversely correlated with Knee Osteoarthritis Outcome Scores (KOOS), and that T1 ρ and T2 values would be lower for autograft relative to allograft reconstruction. Thirty-nine patients (age: 30.5 ± 8.2 years) were followed prospectively after ACL reconstruction with hamstring autograft (N = 27) or soft-tissue allograft (N = 12). Magnetic resonance (MR) imaging and KOOS surveys were completed at 6, 12, 24, and 36 months after surgery. ACL graft was segmented to define T1 ρ and T2 relaxation times. Relaxation times were compared between time points with ANOVA tests. Log-transformed autograft and allograft relaxation times were compared with the Student t tests. The relationship between KOOS and relaxation times at 24 months was investigated with Spearman's rank correlation. ACL graft T1 ρ relaxation times were significantly higher at 6 months relative to 12 months (P = .042), 24 months (P

PURPOSE OF REVIEW: To provide an overview on recent technical development for quantifying marrow composition using magnetic resonance imaging (MRI) and spectroscopy (MRS) techniques, as well as a summary on recent findings of interrelationship between marrow adipose tissue (MAT) and skeletal health in the context of osteoporosis. RECENT FINDINGS: There have been significant technical advances in reliable quantification of marrow composition using MR techniques. Cross-sectional studies have demonstrated a negative correlation between MAT and bone, with trabecular bone associating more strongly with MAT than cortical bone. However, longitudinal studies of MAT and bone are limited. MAT contents and composition have been associated with prevalent vertebral fracture. The evidence between MAT and clinical fracture is more limited, and, to date, no studies have reported on the relationship between MAT and incident fracture. SUMMARY: Increasing evidence suggests a dynamic role of marrow fat in skeletal health. Reliable non-invasive quantification of marrow composition will facilitate developing novel treatment strategies for osteoporosis.

ObjectivesTo assess (i) normal imaging anatomy of the popliteomeniscal fascicles, (ii) prevalence and natural evolution of popliteomeniscal fascicle tears (PMFT) in subjects with traumatic anterior cruciate ligament (ACL) tears over 2 years and (iii) compare knee cartilage degeneration in subjects with and without PMFT longitudinally.Methods57 subjects with ACL tears were screened for PMFT. Morphological (high-resolution 3D fast spin-echo) and compositional (T1ρ and T2 mapping) MR imaging was performed prior to and 2 years after ACL reconstruction. Differences of morphological and compositional parameters were compared between subjects with and without PMFT using logistic regression, adjusting for age, sex and BMI.ResultsIn 24% (n = 14) of the subjects with ACL tear a PMFT was detected on baseline MRI. One subject with PMFT developed a meniscal tear over 2 years. Cartilage ∆T1ρ of the lateral femur increased significantly more in subjects with isolated PMFT compared to controls (mean difference, 2.0 ± 2.9 vs. -1.3 ± 1.6, p = 0.027).ConclusionPMFT detected by MRI are a common finding in subjects with ACL tears. Subjects with these defects showed higher compositional cartilage deterioration compared to controls, over 2 years in the lateral femoral compartment, indicating accelerated cartilage degeneration.Key points• Popliteomeniscal fascicle lesions are a common finding in subjects with ACL tears. • Progression to a meniscal tear over 2 years is not frequent. • Anteroinferior popliteomeniscal fascicle is injured most frequently. • Patients with popliteomeniscal fascicle lesions showed accelerated cartilage degeneration.

Background: Abnormal frontal plane gait mechanics are known risk factors for knee osteoarthritis, but their role in early cartilage degeneration after anterior cruciate ligament reconstruction (ACLR) is not well understood. Hypothesis/Purpose: The objective was to evaluate the association of frontal plane gait mechanics with medial knee cartilage magnetic resonance (MR) relaxation times over 1 year in patients with ACLR and controls. It was hypothesized that (1) there will be an increase in frontal plane medial knee loading and medial knee MR relaxation times over time in the patients with ACLR, and (2) increases in frontal plane medial knee loading will be associated with an increase in medial knee MR relaxation times. Study Design: Case-control study; Level of evidence, 3. Methods: Patients with ACLR (n = 37) underwent walking gait analyses and bilateral quantitative MR imaging (MRI) before surgery and at 6 and 12 months after ACLR. Healthy control participants (n = 13) were evaluated at baseline and 12 months. Gait variables included peak knee adduction moment (KAM), KAM impulse, and peak knee adduction angle. MRI variables included medial femur and medial tibia whole compartment and subregional T1ρ and T2 relaxation times. Statistical analyses included a comparison of changes over time for gait and MRI variables, correlations between changes in gait and MRI variables over time, and differences in change in MRI variables in patients who showed an increase versus decrease in KAM impulse. Results: There were significant increases in medial T1ρ (Δ 4%-11%) and T2 (Δ 2%-10%) relaxation times from baseline to 6 months for both knees in the ACLR group and in KAM (Δ 13%) for the injured knee. From baseline to 6 months, patients who had an increase in KAM impulse in the injured knee had a greater increase in medial T1ρ and T2 relaxation times as compared with those who did not have an increase in KAM impulse. Longitudinal changes for the control group were not significant. Conclusion: There is an increase in medial knee relaxation times over the first 6 months after ACLR. People with an increase in medial knee loading show an increase in medial knee relaxation times when compared with those who do not have an increase in medial knee loading over the first 6 months.

BackgroundThe factors that contribute to the abnormal knee kinematics after anterior cruciate ligament (ACL) injury and ACL reconstruction remain unclear. Bone shape has been implicated in the development of hip and knee osteoarthritis, although there is little knowledge about the effects of bone shape on knee kinematics after ACL injury and after ACL reconstruction. QUESTIONS/QUESTIONS: (1) What is the relationship between bony morphology with alterations in knee kinematics after ACL injury? (2) Are baseline bone shape features related to abnormal knee kinematics at 12 months after ACL reconstruction?MethodsThirty-eight patients (29 ± 8 years, 21 men) were prospectively followed after acute ACL injury and before ligamentous reconstruction. Patients were excluded if there was a history of prior knee ligamentous injury, a history of inflammatory arthritis, associated meniscal tears that would require repair, or any prior knee surgery on either the injured or contralateral side. In total, 54 patients were recruited with 42 (78%) patients completing 1-year followup and four patients excluded as a result of incomplete or unusable imaging data. MR images were obtained for the bilateral knees at two time points 1 year apart for both the injured (after injury but before reconstruction and 1 year after reconstruction) and contralateral uninjured knees. Kinematic MRI was performed with the knee loaded with 25% of total body weight, and static images were obtained in full extension and in 30° of flexion. The side-to-side difference (SSD) between tibial position in the extended and flexed positions was determined for each patient. Twenty shape features, referred to as modes, for the tibia and femur each were extracted independently from presurgery scans with the principal component analysis-based statistical shape modeling algorithm. Spearman rank correlations were used to evaluate the relationship between the SSD in tibial position and bone shape features with significance defined as p < 0.05. Each of the shape features (referred to as the bone and mode number such as Femur 18 for the 18th unique femoral bone shape) associated with differences in tibial position was then investigated by modeling the mean shape ± 3 SDs.ResultsTwo of the 20 specific femur bone shape features (Femur 10, Femur 18) and two of the 20 specific tibial bone shape features (Tibia 19, Tibia 20) were associated with an increasingly anterior SSD in the tibial position for the patients with ACL injury before surgical treatment. The shape features described by these modes include the superoinferior height of the medial femoral condyle (Femur 18; ρ = 0.33, p = 0.040); the length of the anterior aspect of the lateral tibial plateau (Tibia 20; ρ = -0.35, p = 0.034); the sphericity of the medial femoral condyle (Femur 10; ρ = -0.52, p < 0.001); and tibial slope (Tibia 19; ρ = 0.34; p = 0.036). One year after surgical treatment, there were two of 20 femoral shape features that were associated with SSD in the tibial position in extension (Femur 10, Femur 18), one of 20 femoral shape features associated with SSD in the tibial position in flexion (Femur 10), and three of 20 tibial shape features associated with SSD in the tibial position in flexion (Tibia 2, Tibia 4, Tibia 19). The shape features described by these modes include the sphericity of the medial femoral condyle (Femur 10; ρ = -0.38, p = 0.020); the superoinferior height of the medial femoral condyle (Femur 18; ρ = 0.34, p = 0.035); the height of the medial tibial plateau (Tibia 2; ρ = -0.32, p = 0.048); the AP length of the lateral tibial plateau (Tibia 4; ρ = -0.37, p = 0.021); and tibial slope (Tibia 19; ρ = 0.34, p = 0.038).ConclusionsWe have observed multiple bone shape features in the tibia and the femur that may be associated with abnormal knee kinematics after ACL injury and ACL reconstruction. Future directions of research will include the influence of bony morphology on clinical symptoms of instability in patients with and without ACL reconstruction and the long-term evaluation of these shape factors to better determine specific contributions to posttraumatic arthritis and graft failure.Level of evidenceLevel II, therapeutic study.

Background: Osteoarthritis of the medial tibiofemoral joint (MTFJ) is prevalent among patients undergoing anterior cruciate ligament reconstruction (ACLR). Magnetic resonance T1ρ and T2 relaxation times provide noninvasive methods to quantify early cartilage degeneration. Altered sagittal-plane gait biomechanics have been observed after ACLR, but their associations with longitudinal changes in MTFJ cartilage T1ρ and T2 remain unclear. Hypothesis/Purpose: To examine whether the peak knee flexion moment (KFM), knee flexion angle (KFA), and vertical ground-reaction force (vGRF) during gait are associated with prospective changes in medial tibiofemoral cartilage T1ρ and T2 in ACL-reconstructed knees and to compare these gait characteristics between patients undergoing ACLR and healthy control participants. We hypothesized that a higher KFM, KFA, and vGRF would be associated with greater increases in cartilage relaxation times and that patients undergoing ACLR would demonstrate altered gait characteristics compared with healthy controls. Study Design: Controlled laboratory study. Methods: Thirty-three patients undergoing ACLR underwent gait analysis before and 6 months and 1 year after ACLR and knee magnetic resonance imaging (MRI) before and 6 months, 1 year, and 2 years after ACLR. Twelve healthy controls underwent knee MRI and gait analysis at baseline and 1 year. Cartilage T1ρ and T2 were calculated for the medial tibia and medial femoral condyle. Linear regressions were used to evaluate associations between gait characteristics and changes in cartilage relaxation times from before ACLR to follow-up time points. Independent t tests were used to compare differences in gait between patients undergoing ACLR and control participants. Results: A higher KFM and KFA before ACLR were related to greater increases in medial femoral condyle T1ρ and T2 at 6 months after ACLR. Similarly, a higher KFM, KFA, and vGRF at 6 months were associated with greater increases in medial tibia and medial femoral condyle T1ρ and T2 at 1 and 2 years after ACLR. Gait characteristics at 1 year were not associated with changes in cartilage relaxation times at 2 years after ACLR. Compared with healthy controls, patients undergoing ACLR demonstrated a lower KFM at 6 months after ACLR. Conclusion/Clinical Relevance: The findings of this study revealed that a higher KFM, KFA, and vGRF during gait, especially at 6 months after ACLR, were associated with greater deterioration of MTFJ cartilage health at later time points.

Purpose To develop a novel technique for reliable quantification of bone marrow fat content and composition using in vivo MR spectroscopy (MRS). Methods An MRS quantification method combining both advantages of Voigt line shape model and time-domain analysis was developed. The proposed method was tested using computer-simulated data and in vivo data acquired at lumbar vertebral bodies of 23 subjects (age, 83.8 ± 3.7 y; male, n = 13; female, n = 10) from L1 to L4. Reliability and reproducibility were calculated for the quantification results. Comparisons between the proposed method and some conventional methods were conducted. Results Low mean absolute percentage errors and low mean coefficients of variation for computer simulations suggest that the proposed method is accurate and precise. By using this method, marrow fat content can be quantified reliably, even for data with low spectral resolution and low signal-to-noise ratio (SNR). Unsaturation level can be reliably quantified for data with moderate spectral resolution and moderate SNR. Results obtained from in vivo data using the proposed method demonstrated better model fit than conventional methods. Conclusion The method proposed in this study has better performance than conventional methods in the quantification of bone marrow MRS data and has great potential for wide applications of studying marrow fat content and composition. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine.

To assess the impact of cyclops lesions with MRI in patients treated for anterior cruciate ligament (ACL) tears on clinical outcome.In 113 patients (age 29.8 ± 10.5y; 55 females; BMI 24.8 ± 3.7 kg/mCyclops lesions were found in 25% (28/113), 27% (20/75) and 33% (11/33) of patients after 6-months, 1- and 2-years, respectively. The lesion volume did not change significantly (P 0.05) between time points, measuring 0.65 ± 0.59, 0.81 ± 0.70 and 0.72.9 ± 0.96 cmNeither presence nor size of cyclops lesions within the first 2-years after ACL surgery were associated with inferior clinical outcome.• Cyclops lesions had a prevalence of 25% in patients after ACL reconstruction. • Subjects with cyclops lesions did not have an inferior clinical outcome. • Cyclops lesions developed within the first 6 months after surgery. • The size of cyclops lesions did not significantly change over a period of 2 years.

BackgroundTo evaluate the longitudinal changes of bone marrow edema-like lesions (BMELs) in patients after anterior cruciate ligament (ACL) reconstruction and to investigate the effect of BMELs on cartilage matrix composition changes measured using MR T1ρ and T2 mapping.MethodsPatients with acute ACL tear were enrolled in a prospective study. MR imaging was performed at baseline (before surgeries) and at 6-month, 1-year and 2-year after ACL reconstruction. MR imaging included sagittal high-resolution, 3D fast spin-echo (CUBE) sequences for BMEL evaluation, and 3D T1ρ mapping and T2 mapping for cartilage assessment. BMELs were assessed using whole-organ magnetic resonance imaging score (WORMS), and the volume of BMELs was measured by a semi-automatic method. Generalized estimating equation (GEE) was used to explore association between BMELs at baseline and cartilage changes during follow-up.ResultsFifty four patients were included in the present study and 39 patients had completed 2-year follow-up. BMELs were noted in 42 injured knees (77.8%) with 105 lesions and in 7 contralateral knees (13.0%) with 9 lesions (χ2=45.763, P

Purpose To evaluate the feasibility of MR T1ρ in assessing radiocarpal cartilage matrix changes following rheumatoid arthritis (RA) treatment. Materials and Methods Five healthy controls and nine RA patients were studied: three RA patients with low disease activity that were treated with methotrexate (MTX) alone and six with active disease despite MTX treatment who were additionally treated with certolizumab pegol, an anti-tumor necrosis factor biologic. Wrist 3 Tesla MRI were acquired at baseline and 3-month follow-up. T1ρ were quantified for lunar, radius, and scaphoid cartilage. Reproducibility was evaluated using coefficients of variation (CV). Longitudinal changes were evaluated with t-test and relationships between T1ρ with clinical, MRI, and patient-reported outcomes were evaluated with Spearman's rho. Results Scan/re-scan CVs of T1ρ values were all

The current study looks to: (i) investigate postural stability following anterior cruciate ligament (ACL) reconstruction, as assessed by Y-Balance Test, by comparing single-leg balance of the injured limb against those of controls and the uninjured limb; (ii) analyze the relationship between postural stability symmetry with localized cartilage matrix changes and the Knee Injury and Osteoarthritis Outcome Score (KOOS). Bilateral knee MRI of 36 patients who underwent ACL reconstruction were performed before surgery, 6 months, 1 year, and 2 years, postoperatively. Postural stability was evaluated based on Y-Balance Test at 1 and 2 years. ACL patients were also split into three groups based on postural stability symmetry at 2 years and symmetry thresholds associated with elevated risks of lower extremity injury. Voxel-based relaxometry employing analysis of covariance was used to analyze localized differences in cartilage composition at all time-points (using quantitative magnetic resonance [MR] T1ρ and T2 mapping) between the three groups. The ACL patients displayed no significant deficits in postural stability. Compared with symmetric patients, those with asymmetric postural stability at 2 years had significantly prolonged cartilage T1ρ-indicating deterioration of the cartilage matrix-specifically in the injured knee's medial tibia as early as 6-month post-reconstruction. Prolonged T1ρ in asymmetric patients persisted up to 2 years, where the group also reported worse KOOS. Our results demonstrate an association between early stages of cartilage matrix deterioration and postural stability symmetry that may manifest in elevated lower extremity injury risk and worse patient-reported outcomes. Quantitative MR, in combination with local analysis performed with voxel-based relaxometry, is a tool to further study this relationship. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:1132-1140, 2020.

PURPOSE: To investigate compositional changes of knee cartilage at the site of newly appearing cartilage lesions and the surrounding cartilage 1–4 years prior to lesion onset using quantitative T2-measurements. METHODS: Fifty-seven cartilage plates with newly appearing cartilage lesions from 45 knees (cases) and 52 plates from 26 control knees from the OAI cohort (controls) were evaluated. Using MRI T2-mapping, composition of local (the site of future lesions) and surrounding cartilage (remainder of the cartilage plate) was assessed 1–4 years prior to lesion onset. Analogous cartilage ROIs in control plates without cartilage lesions were assessed over 1–4 years. Mixed models were used to compare T2-means and change rates between local and surrounding cartilage within cases and controls, and to compare change rates in local and surrounding cartilage between cases and controls, adjusting for covariates. RESULTS: Four years prior to lesion onset, we found that local cartilage ROIs had higher T2-values compared to the surrounding cartilage. No such differences were found in control plates. In cases mean local T2-values were persistantly elevated compared to the surrounding cartilage prior to lesion onset reaching significance 1 year prior (+2.94ms, p=0.012). T2-values of the surrounding cartilage were also persistantly higher in cases compared to controls, reaching significance 2 years prior to lesion onset (+3.61ms, p=0.003). CONCLUSION: The findings of our study support the concept of compositional cartilage changes as a mechanism for cartilage degradation and that both diffuse and focal changes of cartilage composition within a cartilage plate precede the development of cartilage lesions.

Background:An altered tibial position is still present despite anterior cruciate ligament (ACL) reconstruction. It has been demonstrated that an abnormal tibial position after an ACL injury may play a role in subsequent injuries to the meniscus, which can lead to early cartilage degeneration.Purpose:To determine changes in both the tibial position and the meniscal matrix present before and after ACL reconstruction as well as to evaluate the association between these 2 variables in ACL-injured knees 3 years after reconstruction.Study Design:Cohort study; Level of evidence, 2.Methods:Bilateral knee magnetic resonance imaging (MRI) of 32 patients with unilateral ACL injuries was performed before reconstruction; 13 control participants also underwent MRI. Follow-up MRI was performed up to 3 years after surgery. Tibial position, internal tibial rotation, and T1ρ and T2 values of the menisci were calculated using an in-house MATLAB program. Student t tests and multiple linear regression were used to compare differences between injured, uninjured, and control knees as well as to assess correlations between the tibial position at 3 years and 3-year changes in quantitative MRI meniscal relaxation values.Results:The tibial position of injured knees was more anterior than that of uninjured knees at baseline, 6 months, and 1, 2, and 3 years ( P < .05 for all). The T1ρ and T2 values of the menisci of injured knees were greater than those of uninjured and control knees in the posterior lateral and posterior medial horns up to 1 and 2 years after surgery, respectively ( P < .05 for all). The tibial position at 3 years was associated with increased T2 values from baseline to 3 years in the posterior medial horn (β = 0.397; P = .031) and anterior medial horn (β = 0.360; P = .040).Conclusion:Results of the current study indicate that there is a persistently altered tibial position after ACL reconstruction. Initial preoperative meniscal abnormalities show prolonged but gradual improvement. Additionally, correlations between the tibial position and changes in the medial meniscal matrix suggest that the tibial position may play a role in the increased susceptibility to medial meniscal tears seen after reconstruction. The development of newer surgical techniques must address a persistently altered tibial position. Quantitative MRI is an effective instrument to evaluate meniscal matrix changes and can serve as an early radiological tool for meniscal injuries.

Finite element modelling can be used to evaluate altered loading conditions and failure locations in knee joint tissues. One limitation of this modelling approach has been experimental comparison. The aims of this proof-of-concept study were: 1) identify areas susceptible to osteoarthritis progression in anterior cruciate ligament reconstructed patients using finite element modelling; 2) compare the identified areas against changes in TTwo patient-specific finite element models of knee joints with anterior cruciate ligament reconstruction were created. The knee geometry was based on clinical magnetic resonance imaging and joint loading was obtained via motion capture. We evaluated biomechanical parameters linked with cartilage degeneration and compared the identified risk areas against TThe risk areas identified by the finite element models matched the follow-up magnetic resonance imaging findings. For Patient 1, excessive values of maximum principal stresses and shear strains were observed in the posterior side of the lateral tibial and femoral cartilage. For Patient 2, high values of maximum principal stresses and shear strains of cartilage were observed in the posterior side of the medial joint compartment. For both patients, increased TFinite element models with patient-specific geometries and motions and relatively simple material models of tissues were able to identify areas susceptible to post-traumatic knee osteoarthritis. We suggest that the methodology presented here may be applied in large cohort studies.

Use of knee joint finite element models for diagnostic purposes is challenging due to their complexity. Therefore, simpler models are needed for studies where a high number of patients need to be analyzed, without compromising the results of the model. In this study, more complex, kinetic (forces and moments) and simpler, kinetic-kinematic (forces and angles) driven finite element models were compared during the stance phase of gait. Patella and tendons were included in the most complex model, while they were absent in the simplest model. The greatest difference between the most complex and simplest models was observed in the internal-external rotation and axial joint reaction force, while all other rotations, translations and joint reaction forces were similar to one another. In terms of cartilage stresses and strains, the simpler models behaved similarly with the more complex models in the lateral joint compartment, while minor differences were observed in the medial compartment at the beginning of the stance phase. We suggest that it is feasible to use kinetic-kinematic driven knee joint models with a simpler geometry in studies with a large cohort size, particularly when analyzing cartilage responses and failures related to potential overloads.

Objective.To investigate the correlation between changes in radiological quantitative assessment with changes in clinical and functional assessment from baseline to 3 months in patients with rheumatoid arthritis (RA).Methods.Twenty-eight patients with RA [methotrexate (MTX) and anti-tumor necrosis factor–α (TNF-α) group with high disease activity (n = 18); and MTX group with low disease activity (n = 10)] underwent assessments at baseline and 3 months: clinical [28-joint count Disease Activity Score (DAS28)], functional [Health Assessment Questionnaire (HAQ) and Michigan Hand Outcome Questionnaire (MHQ)], and imaging-based [3 Tesla magnetic resonance imaging (MRI) and high-resolution peripheral quantitative computed tomography (HR-pQCT)]. MR images were evaluated semiquantitatively [RA MRI scoring (RAMRIS)] and quantitatively for the volume of synovitis and bone marrow edema (BME) lesions. Erosion volumes were measured using HR-pQCT.Results.After 3 months, the anti-TNF-α group demonstrated an improvement in disease activity through DAS28, HAQ, and MHQ. MRI showed significant decreases in synovitis and BME volume for the anti-TNF-α group, and significant increases in the MTX group. HR-pQCT showed significant decreases in bone erosion volume for the anti-TNF-α group, and significant increases in the MTX group. No significance was observed using RAMRIS. Changes in synovitis, BME, and erosion volumes, but not RAMRIS, were significantly correlated with changes in DAS28, HAQ, and MHQ.Conclusion.Quantitative measures were more sensitive than semiquantitative grading when evaluating structural and inflammatory changes with treatment, and were associated with patient clinical and functional outcomes. Multimodality imaging with 3T MRI and HR-pQCT may provide promising biomarkers that help determine disease progression and therapy response.

Level of evidence5 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2019.

Purpose To investigate the longitudinal changes in landing mechanics and knee kinematics for patients both before and 3 years after anterior cruciate ligament reconstruction (ACLR) and to investigate the association between changes in landing mechanics and magnetic resonance knee kinematics. Methods Thirty-one ACLR patients were included in the study. All patients underwent magnetic resonance imaging and biomechanical analysis of a drop-landing task using the injured knee and contralateral knee preoperatively and at 6 months and 3 years after ACLR. For evaluations of knee joint anteroposterior laxity, tibial position was calculated using quantitative loaded magnetic resonance methods. Results The ACLR knee exhibited a significantly lower peak vertical ground reaction force and peak external knee flexion moment and angle at 6 months compared with the contralateral knee; however, the differences were resolved at 3 years. Tibial position was significantly more anterior on the injured side, and the side-to-side difference (SSD) in tibial position exhibited a significant increase from 6 months to 3 years. Among ACLR knees, a greater SSD in peak knee flexion moment at 6 months was associated with an increase in the SSD in anterior tibial translation from 6 months to 3 years. Conclusions Although landing mechanics and clinical outcomes recovered in patients with ACLR in this study, anteroposterior translation failed to be restored at 3 years after surgery. In addition, patients who have low knee flexion moments in early stages could have greater anteroposterior laxity. Clinical Relevance Because of the adverse consequences of abnormal knee kinetics on anterior laxity after ACLR, efforts to improve knee movement patterns should be initiated.

Summary Objective To evaluate differences in meniscal T1ρ and T2 quantification in patients with acute anterior cruciate ligament (ACL) injuries and to determine correlations of these differences with MR morphological grading and patient-reported outcomes. Design Bilateral knees of 52 patients with acute ACL injury and 20 healthy controls were scanned using 3 T magnetic resonance imaging (MRI) T1ρ and T2 mapping in this prospective study. Quantitative analysis of the meniscus was performed in anterior and posterior horns of the lateral and medial menisci. Morphological meniscal damage was assessed using modified whole-organ MRI scores (WORMS). Measurements were compared between injured, uninjured contralateral, and control knees using a mixed-effects regression model. Correlations between meniscal T1ρ/T2, WORMS and Knee Injury and Osteoarthritis Outcome Scores (KOOS) were examined using partial correlation analysis. Results Mean meniscal T1ρ and T2 values were significantly higher in ACL-injured knees compared to control and contralateral knees. Menisci of ACL-injured knees without tears, including those limited to modified meniscal WORMS grade 0, also had significantly higher T1ρ and T2 values compared to menisci of uninjured knees. Within ACL-injured knees, T1ρ and T2 values showed significant positive associations with meniscal WORMS and significant negative associations with KOOS. Conclusion Acute ACL injuries are associated with significantly increased meniscal T1ρ and T2 values in both patients with and without meniscal lesions or tears, suggesting quantitative MRI provides more sensitive measures of meniscal differences compared to traditional morphological MRI sequences. Correlation between meniscal T1ρ/T2 and KOOS suggest that quantitative MRI is reflective of the extent of patients' clinical symptoms.

Purpose Quantitative T1ρ imaging is beneficial for early detection for osteoarthritis but has seen limited clinical use due to long scan times. In this study, we evaluated the feasibility of accelerated T1ρ mapping for knee cartilage quantification using a combination of compressed sensing (CS) and data-driven parallel imaging (ARC-Autocalibrating Reconstruction for Cartesian sampling). Methods A sequential combination of ARC and CS, both during data acquisition and reconstruction, was used to accelerate the acquisition of T1ρ maps. Phantom, ex vivo (porcine knee), and in vivo (human knee) imaging was performed on a GE 3T MR750 scanner. T1ρ quantification after CS-accelerated acquisition was compared with non CS-accelerated acquisition for various cartilage compartments. Results Accelerating image acquisition using CS did not introduce major deviations in quantification. The coefficient of variation for the root mean squared error increased with increasing acceleration, but for in vivo measurements, it stayed under 5% for a net acceleration factor up to 2, where the acquisition was 25% faster than the reference (only ARC). Conclusion To the best of our knowledge, this is the first implementation of CS for in vivo T1ρ quantification. These early results show that this technique holds great promise in making quantitative imaging techniques more accessible for clinical applications. Magn Reson Med, 2015. © 2015 Wiley Periodicals, Inc.

Background Multiple techniques are used for femoral tunnel drilling in ACL reconstruction, including the Mini-two Incision Method (MT) and Anteromedial Portal Technique (AM). Both techniques allow for independent placement of the femoral tunnel, though there are no reports comparing kinematics and cartilage health after these reconstructions. We hypothesized that both techniques would result in the restoration of normal knee kinematics and show no evidence of early cartilage degeneration. Methods A total of 20 patients were evaluated one year after ACL reconstruction, including 10 patients after MT and 10 patients after AM. MR-imaging was acquired bilaterally with the knee loaded in extension and flexion to evaluate the kinematics of the reconstructed knee compared with the normal knee. Quantitative cartilage imaging was obtained and compared with 10 matched control subjects. The Marx Activity Rating Scale and KOOS survey were administered. Results The tibia was positioned significantly more anteriorly in extension and flexion relative to the contralateral knee for the MT group. The tibial position in the AM group was not significantly different from the patient's contralateral knee. T 1 ρ values in the central-medial tibia were significantly elevated in the MT group compared with the Control group. KOOS Symptom scores were significantly better for the MT group compared with the AM group. Conclusions We have observed in vivo differences in knee kinematics and early cartilage degeneration between patients following MT and AM ACL reconstructions. Both techniques allow for anatomic ACL reconstruction, though the MT group shows significant early differences compared with the patient's normal knee. Level of evidence Level III — retrospective comparative study

Purpose To develop and compare with the classical region of interest (ROI)-based approach a fully automatic, local, and unbiased way of studying the knee T1ρ relaxation time by creating an atlas and using voxel-based relaxometry (VBR) in osteoarthritis (OA) and anterior cruciate ligament (ACL) subjects. Materials and Methods In this study 110 subjects from two cohorts: 1) Mild OA 40 patients with mild-OA Kellgren–Lawrence (KL) ≤ 2 and 15 controls KL ≤ 1; 2) ACL cohort (a model for early OA): 40 ACL-injured patients imaged prior to ACL reconstruction and 1-year postsurgery and 15 controls are analyzed. All the subjects were acquired at 3T with a protocol that includes: 3D-FSE (CUBE) and 3D-T1ρ. A nonrigid registration technique was applied to align all the images on a single template. This allows for performing VBR to assess local statistical differences of T1ρ values using z-score analysis. VBR results were compared with those obtained with classical ROI-based technique. Results ROI-based results from atlas-based segmentation were consistent with classical ROI-based method (coefficient of variation [CV] = 3.83%). Voxel-based group analysis revealed local patterns that were overlooked by the ROI-based approach; eg, VBR showed posterior lateral femur and posterior lateral tibia significant T1ρ elevations in ACL-injured patients (sample mean z-score=9.7 and 10.3). Those elevations were overlooked by the classical ROI-based approach (sample mean z-score=1.87 and −1.73) Conclusion VBR is a feasible and accurate tool for the local evaluation of the biochemical composition of knee articular cartilage. VBR is capable of detecting specific local patterns on T1ρ maps in OA and ACL subjects. J. Magn. Reson. Imaging 2015.

Author(s): Wyatt, Cory; Guha, Aditi; Venkatachari, Anand; Li, Xiaojuan; Krug, Roland; Kelley, Douglas E; Link, Thomas; Majumdar, Sharmila | Abstract: Background/objectiveT1ρ and T2 relaxation mapping in knee cartilage have been used extensively at 3 Tesla (T) as markers for proteoglycan and collagen, respectively. The objective of this study was to evaluate the feasibility of T1ρ and T2 imaging of knee cartilage at 7T in comparison to 3T and to evaluate the ability of T1ρ and T2 to determine differences between normal and osteoarthritis (OA) patients.Materials and methodsTwenty patients, seven healthy patients (Kellgren-Lawrencen=n0), and 13 patients with signs of radiographic OA (Kellgren-Lawrencengn0) were scanned at 3T and 7T. The knee cartilage was segmented into six compartments and the T1ρ and T2 values were fit using a two-parameter model. Additionally, patients were stratified by the presence of cartilage lesions using the modified Whole Organ Magnetic Resonance Imaging Score classification of the knee. One-way analysis of variance was used to compare the healthy and OA groups at 3T and 7T. The specific absorption ratio was kept under Food and Drug Administration limits during all scans.ResultsT1ρ and T2 values at 3T and 7T were significantly higher in the lateral femoral condyle and patella in patients with OA. However, more regions were significant or approached significance at 7T compared with 3T, with the differences between healthy and OA patients also larger at 7T. The signal to noise ratio across all cartilage and meniscus compartments was 60% higher on average at 7T compared to 3T.ConclusionT1ρ imaging at 7T has been established as a viable imaging method for the differentiation of degenerated cartilage despite previous concerns over specific absorption rate and imaging time. The potential increased sensitivity of T1ρ and T2 imaging at 7T may be useful for future studies in the development of OA.

Summary Purpose (1) To identify bone-shape changes from baseline to 3-years after anterior cruciate ligament reconstruction (ACLR). (2) to assess association between changes in bone-shape from baseline to 6-months and changes in cartilage matrix and patient functions and symptoms from baseline to 3-years after ACLR. Methods Bilateral knees of 30 patients with unilateral ACL injuries were scanned at baseline, 6-months, 1-, 2-, and 3-years after ACLR. Bilateral knees of 13 controls were scanned at baseline, 1- and 3-years. Mean T1ρ and T2 values of each cartilage compartment were computed. Bone shape was quantified using statistical shape modeling (SSM) and 3D-MRI. Patient functions and symptoms were evaluated using Knee Injury and Osteoarthritis Outcome Score (KOOS). Results Statistically significant changes were observed in Femur 2 (medial femoral condyle [MF] shape), Femur 6 (intercondylar notch width), Tibia 1 (tibia plateau area), and Tibia 7 (medial tibia slope) over 3-years after ACLR. Statistically significant differences were observed between injured and control knees in several modes. Statistically significant correlations were found between changes in bone shape (ΔFemur 6, ΔFemur 8 [trochlea inclination and MF height], ΔTibia 1) from baseline to 6-months and that of cartilage T1ρ and T2 and KOOS from baseline to 3-years after ACLR. Conclusion Bone shape remodeling occurs after ACLR, and early bone shape changes (within 6 months) correlated with cartilage matrix and patient outcomes at 3-years after ACLR. Bone shape can be a promising imaging biomarker that stratifies patients at high risk for post-traumatic osteoarthritis (PTOA).

Summary Objective To evaluate the longitudinal changes in meniscal T1ρ/T2 signal post-reconstruction in patients with acute anterior cruciate ligament (ACL) injury and to investigate the association with T1ρ/T2 signal in articular knee cartilage. Method In this prospective study, knees of 37 patients with ACL-injury and reconstruction in addition to 13 healthy controls were scanned using magnetic resonance imaging (MRI) T1ρ/T2 mapping. Quantitative analysis of the meniscus was performed in the anterior/posterior horns of lateral/medial meniscus fourteen sub-compartments of cartilage spanning the medial/lateral area of the tibia and femoral condyles. Meniscus T1ρ/T2 signals were compared between injured, contralateral and control knees at baseline, 6-months, 1-year and 2-years using t -tests for cross-sectional comparisons and a mixed model for longitudinal comparisons. Pearson-partial correlations between meniscal and cartilage T1ρ/T2 were evaluated. Results There was a significant decrease of T1ρ/T2 signal in the posterior horn of lateral meniscus (PHLAT) of injured knees during a 2-year period. In the posterior horn of medial meniscus (PHMED), T1ρ/T2 signal of injured knees was significantly elevated at all time points post-reconstruction compared to contralateral and control knees. Within injured knees, PHMED T1ρ/T2 signal showed significant positive correlations with medial tibia (MT) cartilage T1ρ/T2 signal at all time points. Conclusion A significant decrease in PHLAT T1ρ/T2 signal by 2-years suggests potential tissue recovery after ACL-injury. Elevated T1ρ/T2 signal in the PHMED of injured knees at 2-years correlating with knee cartilage T1ρ/T2 signal elevations suggests involvement of the PHMED in subacute cartilage degeneration after ACL-injury and reconstruction.

Background: Anterior cruciate ligament tears can lead to posttraumatic osteoarthritis. In addition to biomechanical factors, changes in biochemical profiles within the knee joint after injury and anterior cruciate ligament reconstruction (ACLR) may play a role in accelerating joint degeneration. Hypothesis/Purpose: It was hypothesized that cartilage matrix composition after ACLR is associated with the degree of inflammatory response after initial injury. This study evaluated the association between the inflammatory response after injury—as indicated by cytokine, metalloproteinase, and cartilage degradation marker concentrations in synovial fluid—and articular cartilage degeneration, measured by T1ρ and T2 quantitative magnetic resonance imaging up to 3 years after ACLR. Study Design: Cohort study; Level of evidence, 2. Methods: Twenty-six subjects from a longitudinal cohort study who underwent ACLR at a mean 8.5 weeks after injury (range, 4-19 weeks) had synovial fluid aspirated at the time of surgery. Immunoassays quantified biomarkers in synovial fluid. T1ρ and T2 values of articular cartilage were calculated with magnetic resonance scans acquired prior to surgery and at 6 months and 1, 2, and 3 years after surgery. Pearson correlation coefficients were calculated among the various biomarkers. K-means clustering was used to group subjects with similar biomarker profiles. Generalized estimating equations were used to find the overall differences in T1ρ and T2 values throughout these first 3 years after surgery between the clusters while controlling for other factors. Results: Significant and strong correlations were observed between several cytokines (interleukin 6 [IL-6], IL-8, IL-10, and tumor necrosis factor α) and 2 matrix metalloproteinases (MMP-1 and MMP-3) ( P < .05). Moderate correlations were found among combinations of C-terminal crosslinked telopeptide type II collagen, N-terminal telopeptide, cartilage oligomeric matrix protein, and sulfated glycosaminoglycan ( P < .05). Two clusters were generated, 1 of which was characterized by lower concentrations of cytokines (IL-6, IL-8, IL-10, tumor necrosis factor α) and MMP-1 and MMP-3 and higher sulfated glycosaminoglycan. This cluster was associated with significantly higher T1ρ and T2 values in the medial tibial and patellar cartilage over the first 3 years after ACLR. Conclusion: At the time of ACLR surgery, profiles of synovial fluid inflammatory cytokines, degradative enzymes, and cartilage breakdown products show promise as predictors of abnormal cartilage tissue integrity (increased T1ρ and T2 values) throughout the first 3 years after surgery. Clinical Relevance: The results suggest an intricate relationship between inflammation and cartilage turnover, which can in turn be influenced by timing after injury and patient factors.

PURPOSE: The purpose of this study was to investigate the changes in landing biomechanics over a three-year period and its correlation with cartilage degenerative changes in the medial tibiofemoral joint of the knee after anterior cruciate ligament reconstruction (ACLR) using magnetic resonance (MR) T1(ρ) mapping. METHODS: Thirty-one ACL injured patients underwent magnetic resonance imaging (MRI) of the injured knee prior to ACLR and three years after ACLR as well as biomechanical analysis of a drop-landing task at six months and three years after ACLR. Sixteen healthy individuals were recruited and underwent knee MRI and biomechanical assessment during a drop-landing task. T(1ρ) cartilage relaxation times were calculated for the medial femur and tibia. RESULTS: ACLR patients exhibited increased peak vertical ground reaction forces (VGRF), VGRF impulse, peak knee flexion moment (KFM) and KFM impulse from six months to three years (P

Although one study showed minimal progression of erosions in patients with rheumatoid arthritis (RA) one year after TNFα inhibition therapy, no studies have investigated very early bone changes after initiation of anti-TNFα treatment. We investigated the effects of 3-month anti-TNFα treatment on bone erosion progression and bone microarchitecture in RA patients using high-resolution peripheral quantitative computed tomography (HR-pQCT). Patients with RA (n = 27) (17 in the anti-TNFα and 10 in the MTX-only group) underwent assessment of disease activity score in 28 joints (DAS-28), radiographs, 3-T magnetic resonance imaging (MRI) and HR-pQCT of metacarpophalangeal and wrist joints at baseline and 3 months. HR-pQCT-derived erosion volume, joint volume/width and bone microarchitecture were computed and joint destruction was assessed using Sharp and RAMRIS scorings on radiographs and MRI, respectively. Overall, 73 erosions were identified by HR-pQCT at baseline. Over 3 months, the anti-TNFα group had decreased mean erosion volume; increased erosion volume was observed in one clinical non-responder. The MTX-only group in contrast, trended toward increasing erosion volume despite low disease activity. In the anti-TNFα group, joint-space width and volume of MCP joints decreased significantly and was positively correlated with erosion volume changes (R 2 = 0.311, p = 0.013; R 2 = 0.527, p = 0.003, respectively). In addition, erosion volume changes were significantly negatively correlated with changes in trabecular bone mineral density (R 2 = 0.353, p = 0.020) in this group. We observed significant correlation between percentage change in erosion volume and change in DAS-28 erythrocyte sedimentation rate and C-reactive protein CRP scores (R 2 = 0.558, p

Osteoarthritis of the medial tibiofemoral joint (MTFJ) is prevalent among patients undergoing anterior cruciate ligament reconstruction (ACLR). Magnetic resonance TControlled laboratory study.Thirty-three patients undergoing ACLR underwent gait analysis before and 6 months and 1 year after ACLR and knee magnetic resonance imaging (MRI) before and 6 months, 1 year, and 2 years after ACLR. Twelve healthy controls underwent knee MRI and gait analysis at baseline and 1 year. Cartilage TA higher KFM and KFA before ACLR were related to greater increases in medial femoral condyle TThe findings of this study revealed that a higher KFM, KFA, and vGRF during gait, especially at 6 months after ACLR, were associated with greater deterioration of MTFJ cartilage health at later time points.

Background: Quantitative magnetic resonance (qMR) can be used to measure macromolecules in tissues and is a potential method of observing early cartilage changes in the development of posttraumatic osteoarthritis. Hypothesis/Purpose: We hypothesized that specific patient and surgical factors affecting cartilage matrix composition after anterior cruciate ligament (ACL) reconstruction (ACLR) can be detected using T1ρ and T2 relaxation times. Our purpose was to demonstrate this ability in a multicenter feasibility study. Study Design: Case series; Level of evidence, 4. Methods: A total of 54 patients who underwent ACLR underwent bilateral MRI at baseline before surgery and 6 months postoperatively. Operative findings were recorded. T1ρ and T2 relaxation times were calculated for 6 cartilage regions: the medial femur, lateral femur, medial tibia, lateral tibia, patella, and trochlea. A paired t test compared relaxation times at baseline and 6 months, univariate regression identified regions that influenced patient-reported outcome measures, and analysis of covariance was used to determine the surgical factors that resulted in elevated relaxation times at 6 months. Results: The injured knee had significantly prolonged T1ρ and T2 relaxation times in the tibiofemoral compartment at baseline and 6 months but had shorter values in the patellofemoral compartment compared with the uninjured knee. Prolonged T1ρ and T2 times at 6 months were noted for both the injured and uninjured knees. At 6 months, prolongation of T1ρ and T2 times in the tibial region was associated with lower patient-reported outcome measures. ACLR performed within 30 days of injury had significantly shorter T1ρ times in the tibial regions, and lateral meniscal tears treated with repair had significantly shorter T1ρ times than those treated with excision. Conclusion: Prolonged relaxation times in multiple regions demonstrate how the injury affects the entire joint after an ACL tear. Changes observed in the uninjured knee may be caused by increased loading during rehabilitation, especially in the patellofemoral articular cartilage and distal femur. Relaxation times in the tibial regions may be predictive of patient symptoms at 6 months. These same regions are affected by surgical timing as early as 30 days after injury, but this may partially be reflective of the severity of the preoperative injury and the choice of treatment of meniscal tears.

Purpose To accelerate T1ρ quantification in cartilage imaging using combined compressed sensing with iterative locally adaptive support detection and JSENSE. Methods To reconstruct T1ρ images from accelerated acquisition at different time of spin-lock (TSLs), we propose an approach to combine an advanced compressed sensing (CS) based reconstruction technique, LAISD (locally adaptive iterative support detection), and an advanced parallel imaging technique, JSENSE. Specifically, the reconstruction process alternates iteratively among local support detection in the domain of principal component analysis, compressed sensing reconstruction of the image sequence, and sensitivity estimation with JSENSE. T1ρ quantification results from accelerated scans using the proposed method are evaluated using in vivo knee cartilage data from bilateral scans of three healthy volunteers. Results T1ρ maps obtained from accelerated scans (acceleration factors of 3 and 3.5) using the proposed method showed results comparable to conventional full scans. The T1ρ errors in all compartments are below 1%, which is well below the in vivo reproducibility of cartilage T1ρ reported from previous studies. Conclusion The proposed method can significantly accelerate the acquisition process of T1ρ quantification on human cartilage imaging without sacrificing accuracy, which will greatly facilitate the clinical translation of quantitative cartilage MRI. Magn Reson Med, 2015. © 2015 Wiley Periodicals, Inc.

Purpose To describe three quantification methods for magnetic resonance imaging (MRI)-based knee kinematic evaluation and to report on the reproducibility of these algorithms. Materials and Methods T2-weighted, fast-spin echo images were obtained of the bilateral knees in six healthy volunteers. Scans were repeated for each knee after repositioning to evaluate protocol reproducibility. Semiautomatic segmentation defined regions of interest for the tibia and femur. The posterior femoral condyles and diaphyseal axes were defined using the previously defined tibia and femur. All segmentation was performed twice to evaluate segmentation reliability. Anterior tibial translation (ATT) and internal tibial rotation (ITR) were calculated using three methods: a tibial-based registration system, a combined tibiofemoral-based registration method with all manual segmentation, and a combined tibiofemoral-based registration method with automatic definition of condyles and axes. Intraclass correlation coefficients and standard deviations across multiple measures were determined. Results Reproducibility of segmentation was excellent (ATT = 0.98; ITR = 0.99) for both combined methods. ATT and ITR measurements were also reproducible across multiple scans in the combined registration measurements with manual (ATT = 0.94; ITR = 0.94) or automatic (ATT = 0.95; ITR = 0.94) condyles and axes. Conclusion The combined tibiofemoral registration with automatic definition of the posterior femoral condyle and diaphyseal axes allows for improved knee kinematics quantification with excellent in vivo reproducibility. J. Magn. Reson. Imaging 2015;42:533–538.

To investigate the reliability and validity of computer-aided automated and manual quantification as well as semiquantitative analysis for MRI synovitis, bone marrow edema-like lesions, erosion and cartilage loss of the wrist in rheumatoid arthritis (RA) compared to the OMERACT-RAMRIS. Wrist MRI was performed at 3 T in 16 patients with RA. Synovial volume and perfusion, bone marrow edema-like lesion (BMEL) volume, signal intensity and perfusion, and erosion dimensions were measured manually and using an in-house-developed automated software algorithm; findings were correlated with the OMERAC-RAMRIS gradings. In addition, a semiquantitative MRI cartilage loss score system was developed. Intraclass correlation coefficients (ICCs) were used to test the reproducibility of these quantitative and semiquantitative techniques. Spearman correlation coefficients were calculated between lesion quantifications and RAMRIS and between the MRI cartilage score and radiographic Sharp van der Heijde joint space narrowing scores. The intra- and interobserver ICCs were excellent for synovial, BMEL and erosion quantifications and cartilage loss grading (all >0.89). The synovial volume, BMEL volume and signal intensity, and erosion dimensions were significantly correlated with the corresponding RAMRIS (r = 0.727 to 0.900, p < 0.05). Synovial perfusion parameter maximum enhancement (Emax) was significantly correlated with synovitis RAMRIS (r = 0.798). BMEL perfusion parameters were not correlated with the RAMRIS BME score. Cartilage loss gradings from MRI were significantly correlated with the Sharp joint space narrowing scores (r = 0.635, p = 0.008). The computer-aided, manual and semiquantitative methods presented in this study can be used to evaluate MRI pathologies in RA with excellent reproducibility. Significant correlations with standard RAMRIS were found in the measurements using these methods.

summary Objective: The objective of this study was to evaluate the effects of mechanical loading on knee articular cartilage T1r and T2 relaxation times in patients with and without osteoarthritis (OA). Design: Magnetic resonance (MR) images were acquired from 137 subjects with and without knee OA under two conditions: unloaded and loaded at 50% body weight. Three sequences were acquired: a high-resolution 3D-CUBE, a T1r relaxation time, and a T2 relaxation time sequences. Cartilage regions of interest included: medial and lateral femur (MF, LF); medial and lateral tibia (MT, LT), laminar analysis (superficial and deep layers), and subcompartments. Changes in relaxation times in response to loading were evaluated. Results: In response to loading, we observed significant reductions in T1r relaxation times in the MT and LT. In both the MF and LF, loading resulted in significant decreases in the superficial layer and significant increases in the deep layer of the cartilage for T1r and T2. All subcompartments of the MT and LT showed significant reduction in T1r relaxation times. Reductions were larger for subjects with OA (range: 13e19% change) when compared to healthy controls (range: 3e13% change). Conclusions: Loading of the cartilage resulted in significant changes in relaxation times in the femur and tibia, with novel findings regarding laminar and subcompartmental variations. In general, changes in relaxation times with loading were larger in the OA group suggesting that the collageneproteoglycan matrix of subjects with OA is less capable of retaining water, and may reflect a reduced ability to dissipate loads.