Layer-specific femorotibial cartilage T2 relaxation time in knees with and without early knee osteoarthritis: Data from the Osteoarthritis Initiative (OAI)

Anterior cruciate ligament injury and age affect knee cartilage T2 but not thickness

OBJECTIVE

To investigate the effect of unilateral anterior cruciate ligament (ACL) injury on cartilage thickness and composition, specifically laminar transverse relaxation time (T2) by magnetic resonance imaging (MRI), in younger and older participants and to compare within-person side differences in these parameters between ACL-injured and healthy controls.

DESIGN

Quantitative double-echo steady-state 3 Tesla MRI-sequences were acquired in both knees of 85 participants in four groups: 20-30 years: healthy, HEA20-30, n = 24; ACL-injured, ACL20-30, n = 23; 40-60 years: healthy, HEA40-60, n = 24; ACL-injured, ACL40-60, n = 14 (ACL injury 2-10 years prior to study inclusion). Weight-bearing femorotibial cartilages were manually segmented; cartilage T2 and thickness were computed using custom software. Mean and side differences in subregional cartilage thickness, superficial and deep cartilage T2 were compared within and between groups using non-parametric statistics.

RESULTS

Cartilage thickness did not differ within or between groups. Only the side difference in medial femorotibial cartilage thickness was greater in ACL20-30 than in HEA20-30. Deep zone T2 was longer in the ACL-injured than in the contralateral uninjured knees and than in healthy controls, especially in the lateral compartment. Most ACL-injured participants had side differences in femorotibial deep zone T2 above the threshold derived from controls.

CONCLUSION

In the ACL-injured knee, early compositional differences in femorotibial cartilage (T2) appear to occur in the deep zone and precede cartilage thickness loss. These results suggest that monitoring laminar T2 after ACL injury may be useful in diagnosing and monitoring early articular cartilage changes.

Assessment of articular cartilage of ankle joint in stable and unstable unilateral weber type-B/SER-type ankle fractures shortly after trauma using T2 relaxation time

Background

Early detection of post-traumatic cartilage damage in the ankle joint in magnetic resonance images can be difficult due to disturbances to structures usually appearing over time.

Purpose

To study the articular cartilage of unilateral Weber type-B/SER-type ankle fractures shortly post-trauma using T2 relaxation time.

Material and Methods

Fifty one fractured ankles were gathered from consecutively screened patients, compiled initially for RCT studies, and treated at Oulu University Hospital and classified as stable (n = 28) and unstable fractures (n = 23) based on external-rotation stress test: medial clear space of ≥5 mm was interpreted as unstable. A control group of healthy young individuals (n = 19) was also gathered. All ankles were imaged on average 9 (range: 1 to 25) days after injury on a 3.0T MRI unit for T2 relaxation time assessment, and the cartilage was divided into sub-regions for comparison.

Results

Control group displayed significantly higher T2 values in tibial cartilage compared to stable (six out of nine regions, p-values = .003-.043) and unstable (six out of nine regions, p-values = .001-.037) ankle fractures. No differences were detected in talar cartilage. Also, no differences were observed between stable and unstable fractures in tibial or talar cartilage.

Conclusions

Lower T2 relaxation times of tibial cartilage in fractured ankles suggest intact extra cellular matrix (ECM) of the cartilage. Severity of the ankle fracture, measured by ankle stability, does not seem to increase ECM degradation immediately after trauma.

Spatial Gradients of Quantitative MRI as Biomarkers for Early Detection of Osteoarthritis: Data From Human Explants and the Osteoarthritis Initiative

BACKGROUND

Healthy articular cartilage presents structural gradients defined by distinct zonal patterns through the thickness, which may be disrupted in the pathogenesis of several disorders. Analysis of textural patterns using quantitative MRI data may identify structural gradients of healthy or degenerating tissue that correlate with early osteoarthritis (OA).

PURPOSE

To quantify spatial gradients and patterns in MRI data, and to probe new candidate biomarkers for early severity of OA.

STUDY TYPE

Retrospective study.

SUBJECTS

Fourteen volunteers receiving total knee replacement surgery (eight males/two females/four unknown, average age ± standard deviation: 68.1 ± 9.6 years) and 10 patients from the OA Initiative (OAI) with radiographic OA onset (two males/eight females, average age ± standard deviation: 57.7 ± 9.4 years; initial Kellgren-Lawrence [KL] grade: 0; final KL grade: 3 over the 10-year study).

FIELD STRENGTH/SEQUENCE

3.0-T and 14.1-T, biomechanics-based displacement-encoded imaging, fast spin echo, multi-slice multi-echo T2 mapping.

ASSESSMENT

We studied structure and strain in cartilage explants from volunteers receiving total knee replacement, or structure in cartilage of OAI patients with progressive OA. We calculated spatial gradients of quantitative MRI measures (eg, T2) normal to the cartilage surface to enhance zonal variations. We compared gradient values against histologically OA severity, conventional relaxometry, and/or KL grades.

STATISTICAL TESTS

Multiparametric linear regression for evaluation of the relationship between residuals of the mixed effects models and histologically determined OA severity scoring, with a significance threshold at α = 0.05.

RESULTS

Gradients of individual relaxometry and biomechanics measures significantly correlated with OA severity, outperforming conventional relaxometry and strain metrics. In human explants, analysis of spatial gradients provided the strongest relationship to OA severity (R2  = 0.627). Spatial gradients of T2 from OAI data identified variations in radiographic (KL Grade 2) OA severity in single subjects, while conventional T2 alone did not.

DATA CONCLUSION

Spatial gradients of quantitative MRI data may improve the predictive power of noninvasive imaging for early-stage degeneration.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 1.

Is Laminar Cartilage Composition as Determined by T2 Relaxometry Associated with Incident and Worsening of Cartilage or Bone Marrow Abnormalities?

OBJECTIVE

To test the hypothesis that superficial cartilage composition (T2) is associated with subsequent incidence or worsening of cartilage damage, and deep T2 with that of bone marrow lesions (BMLs) in knees without radiographic osteoarthritis (ROA).

DESIGN

A total of 201 knees from the Osteoarthritis Initiative without ROA were included: 78 from the healthy reference cohort, 60 without ROA but with risk factors, and 63 without ROA but with contralateral ROA. Year 1 (Y1) superficial and deep cartilage T2 were derived in the medial and lateral (weightbearing) femur (MF/LF) and tibia (MT/LT), using sagittal multiecho spin echo magnetic resonance images. Cartilage and BMLs were assessed in the medial (MFTJ) and lateral femorotibial joint (LFTJ) at Y1 and 3 years later. Binary logistic regression statistics were applied.

RESULTS

Incidence or worsening of cartilage damage was more frequent (MFTJ 15%, LFTJ 13%) than incidence or worsening of BMLs (6.0%, 4.5%). In knees with incident or worsening cartilage lesions in the MF and LT, deep layer T2 in the same plate was elevated (MF, 43.6 ± 4.0 vs. 41.3 ± 3.8 ms, P = 0.047; LT, 33.8 ± 2.3 vs. 32.0 ± 2.2 ms, P = 0.008) compared to those without. In knees with incident or worsening of BMLs in the LFTC and LT, superficial layer T2 was elevated (LFTJ, 49.6 ± 4.8 vs. 46.7 ± 3.1 ms; LT, 47.4 ± 4.9 vs. 44.0 ± 3.3 ms, both Ps = 0.04).

CONCLUSIONS

Contrary to our hypothesis, increased deep layer cartilage T2 was associated with subsequent worsening of cartilage damage, whereas superficial layer T2 was related to subsequent BML worsening. Yet, this relationship was observed in some, but not in all cartilage plates.

Histological Analysis of Cartilage Defects Repaired with an Autologous Human Stem Cell Construct 48 Weeks Postimplantation Reveals Structural Details Not Detected by T2-Mapping MRI

OBJECTIVE

The aim of this study was to elucidate the efficacy of T2-mapping MRI and correlation with histology for the evaluation of tissue repair quality following the first-in-human implantation of an autologous tissue engineered construct.

DESIGN

We directly compared the results of T2-mapping MRI of cartilage repair tissue with the histology of a biopsy specimen from the corresponding area at 48 weeks postoperatively in 5 patients who underwent the implantation of a scaffold-free tissue-engineered construct generated from autologous synovial mesenchymal stem cells to repair an isolated cartilage lesion. T2 values and histological scores were compared at each of 2 layers of equally divided halves of the repair tissue (upper and lower zones).

RESULTS

Histology showed that the repair tissue in the upper zone was dominated by fibrous tissue and the ratio of hyaline-like matrix increased with the depth of the repair tissue. There were significant differences between upper and lower zones in histological scores. Conversely, there were no detectable statistically significant differences in T2 value detected among zones of the repair tissue, but zonal differences were detected in corresponding healthy cartilage. Accordingly, there were no correlations detected between histological scores and T2 values for each repair cartilage zone.

CONCLUSION

Discrepancies in the findings between T2 mapping and histology suggest that T2 mapping was limited in ability to detect details in the architecture and composition of the repair cartilage.

Reproducibility of an Automated Quantitative MRI Assessment of Low-Grade Knee Articular Cartilage Lesions

OBJECTIVE

The goal of this study was to assess the reproducibility of an automated knee cartilage segmentation of 21 cartilage regions with a model-based algorithm and to compare the results with manual segmentation.

DESIGN

Thirteen patients with low-grade femoral cartilage defects were included in the study and were scanned twice on a 7-T magnetic resonance imaging (MRI) scanner 8 days apart. A 3-dimensional double-echo steady-state (3D-DESS) sequence was used to acquire MR images for automated cartilage segmentation, and T2-mapping was performed using a 3D triple-echo steady-state (3D-TESS) sequence. Cartilage volume, thickness, and T2 and texture features were automatically extracted from each knee for each of the 21 subregions. DESS was used for manual cartilage segmentation and compared with automated segmentation using the Dice coefficient. The reproducibility of each variable was expressed using standard error of measurement (SEM) and smallest detectable change (SDC).

RESULTS

The Dice coefficient for the similarity between manual and automated segmentation ranged from 0.83 to 0.88 in different cartilage regions. Test-retest analysis of automated cartilage segmentation and automated quantitative parameter extraction revealed excellent reproducibility for volume measurement (mean SDC for all subregions of 85.6 mm³), for thickness detection (SDC = 0.16 mm) and also for T2 values (SDC = 2.38 ms) and most gray-level co-occurrence matrix features (SDC = 0.1 a.u.).

CONCLUSIONS

The proposed technique of automated knee cartilage evaluation based on the segmentation of 3D MR images and correlation with T2 mapping provides highly reproducible results and significantly reduces the segmentation effort required for the analysis of knee articular cartilage in longitudinal studies.

Characterizing the transient response of knee cartilage to running: Decreases in cartilage T2 of female recreational runners

Cartilage transmits and redistributes biomechanical loads in the knee joint during exercise. Exercise-induced loading alters cartilage hydration and is detectable using quantitative magnetic resonance imaging (MRI), where T₂ relaxation time (T₂ ) is influenced by cartilage collagen composition, fiber orientation, and changes in the extracellular matrix. This study characterized short-term transient responses of healthy knee cartilage to running-induced loading using bilateral scans and image registration. Eleven healthy female recreational runners (33.73 ± 4.22 years) and four healthy female controls (27.25 ± 1.38 years) were scanned on a 3T GE MRI scanner with quantitative 3D double-echo in steady-state before running over-ground (runner group) or resting (control group) for 40 min. Subjects were scanned immediately post-activity at 5-min intervals for 60 min. T₂ times were calculated for femoral, tibial, and patellar cartilage at each time point and analyzed using a mixed-effects model and Bonferroni post hoc. There were immediate decreases in T₂ (mean ± SEM) post-run in superficial femoral cartilage of at least 3.3% ± 0.3% (p = .002) between baseline and Time 0 that remained for 25 min, a decrease in superficial tibial cartilage T₂ of 2.9% ± 0.4% (p = .041) between baseline and Time 0, and a decrease in superficial patellar cartilage T₂ of 3.6% ± 0.3% (p = .020) 15 min post-run. There were decreases in the medial posterior region of superficial femoral cartilage T₂ of at least 5.3 ± 0.2% (p = .022) within 5 min post-run that remained at 60 min post-run. These results increase understanding of transient responses of healthy cartilage to repetitive, exercise-induced loading and establish preliminary recommendations for future definitive studies of cartilage response to running.

Longitudinal Femoral Cartilage T2 Relaxation Time and Thickness Changes with Fast Sequential Radiographic Progression of Medial Knee Osteoarthritis-Data from the Osteoarthritis Initiative (OAI)

This study tested for longitudinal changes in femoral cartilage T2 relaxation time and thickness in fast-progressing medial femorotibial osteoarthritis (OA). From the Osteoarthritis Initiative (OAI) database, nineteen knees fulfilled the inclusion criteria, which included medial femorotibial OA and sequential progression from Kellgren–Lawrence grade (KL) 1 to KL2 to KL3 within five years. Median T2 value and mean thickness were calculated for six condylar volumes of interest (VOIs; medial/lateral anterior, central, posterior) and six sub-VOIs (medial/lateral anterior external, central, internal). T2 value and thickness changes between severity timepoints were tested using repeated statistics. T2 values increased between KL1 and KL2 and between KL1 and KL3 in the medial compartment (p ≤ 0.02), whereas both increases and decreases were observed between the same timepoints in the lateral compartment (p ≤ 0.02). Cartilage thickness decreased in VOI/subVOIs of the medial compartment from KL1 to KL2 and KL3 (p ≤ 0.014). Cartilage T2 value and thickness changes varied spatially over the femoral condyles. While all T2 changes occurred in the early radiographic stages of OA, thickness changes occurred primarily in the later stages. These data therefore support the use of T2 relaxation time analyses in methods of detecting disease-related change during early OA, a valuable period for therapeutic interventions.

Longitudinal changes in location-specific cartilage thickness and T2 relaxation-times after posterior cruciate ligament reconstruction for isolated and multiligament injury

BACKGROUND

Knee cartilage undergoes pathological changes after anterior cruciate ligament rupture. However, little is known about the development and progression of structural pathology after posterior cruciate ligament (PCL) injury. This study aimed to determine the location-specific longitudinal changes in knee cartilage morphology (thickness) and composition (T2 relaxation-times) after PCL rupture and reconstruction (PCLR) and compare these to uninjured controls.

METHODS

Fifteen adults (mean age 39 years (standard deviation 10), 12 men) with PCLR for isolated and multiligment injury had MRIs acquired at a minimum 5 years post-PCLR and 1 year later. Location-specific changes in knee cartilage thickness and T2 relaxation-times were determined quantitatively after segmentation, and compared with annualised cartilage changes in 13 active controls (mean age 45 years (standard deviation 4), 6 men).

FINDINGS

Following PCLR, the annual loss of cartilage thickness was greatest in the medial femoral condyle (mean -4.0%, 95% confidence interval [95% CI] -6.7, -1.4), medial tibia (mean -3.7%, 95% CI -6.1, -1.3), and patella (mean -3.2%, 95% CI -4.7, -1.6). In the medial femoral condyle and trochlea, the PCLR group lost significantly more cartilage thickness than uninjured controls (mean difference -3.7%, 95% CI -0.9, -6.5; and -1.8%, 95% CI -0.1, -3.6, respectively). Deep and superficial zone T2 relaxation-times were relatively constant over time, without longitudinal differences between PCLR and control knees.

INTERPRETATION

PCL reconstructed knees displayed substantially greater rates of cartilage loss in the medial tibiofemoral and patellofemoral compartments compared to uninjured controls, highlighting that the process of degeneration remains active many years after injury.

Layer-specific analysis of femorotibial cartilage t2 relaxation time based on registration of segmented double echo steady state (dess) to multi-echo-spin-echo (mese) images

OBJECTIVE

To develop and validate a 3D registration approach by which double echo steady state (DESS) MR images with cartilage thickness segmentations are used to extract the cartilage transverse relaxation time (T2) from multi-echo-spin-echo (MESE) MR images, without direct segmentations for MESE.

MATERIALS AND METHODS

Manual DESS segmentations of 89 healthy reference knees (healthy) and 60 knees with early radiographic osteoarthritis (early ROA) from the Osteoarthritis Initiative were registered to corresponding MESE images that had independent direct T2 segmentations. For validation purposes, (a) regression analysis of deep and superficial cartilage T2 was performed and (b) between-group differences between healthy vs. early ROA knees were compared for registered vs. direct MESE analysis.

RESULTS

Moderate to high correlations were observed for the deep (r = 0.80) and the superficial T2 (r = 0.81), with statistically significant between-group differences (ROA vs. healthy) of + 1.4 ms (p = 0.002) vs. + 1.3 ms (p < 0.001) for registered vs. direct T2 segmentation in the deep, and + 1.3 ms (p = 0.002) vs. + 2.3 ms (p < 0.001) in the superficial layer.

DISCUSSION

This registration approach enables extracting cartilage T2 from MESE scans using DESS (cartilage thickness) segmentations, avoiding the need for direct MESE T2 segmentations.

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.

T2 distribution profiles are a good way to show cartilage regional variabilities and cartilage insufficiency

OBJECTIVE

To use T2 relaxation time distribution profiles to assess inter-group regional differences along articular surfaces and to evaluate the feasibility of this analysis for comparison of cartilage insufficiency.

MATERIALS AND METHODS

Twelve pairs matched according to age and gender (12 healthy volunteers and 12 patients after anterior cruciate ligament reconstruction (ACLR)) underwent 3-T MRI. T2 maps were calculated from six time echo images of the mid-sagittal slice in the lateral and medial compartment. The femoral and tibial cartilage was analyzed by measuring T2 distribution profiles along the articular surfaces.

RESULTS

T2 distribution profiles were generated along the length of the articular surface in the femorotibial compartments. Differences in the T2 distribution profiles between the tibial and femoral cartilage as well as between the cartilage of the femoral condyles were identified in healthy individuals. T2 distribution profiles clearly demonstrated cartilage insufficiency in the weight-bearing areas for subjects in the ACLR group.

CONCLUSIONS

T2 distribution profiles can identify regional differences in femoral and tibial cartilage. The T2 distribution profile pattern is preserved with cartilage insufficiency, however, with important differences in T2 values for the ACLR group in weight-bearing areas.

Baseline structural tissue pathology is not strongly associated with longitudinal change in transverse relaxation time (T2) in knees without osteoarthritis

PURPOSE

To evaluate whether baseline MRI-defined structural abnormalities are associated with subsequent change in laminar femorotibial cartilage transverse relaxation time (T2) of participants without radiographic signs, symptoms or risk factors for knee osteoarthritis (OA).

METHOD

We studied all right knees with longitudinal MRI data of the refined Osteoarthritis Initiative Healthy Reference cohort. Baseline osteophytes, effusion-synovitis, Hoffa-synovitis, bone marrow lesions, cartilage lesions, and meniscus morphology and - extrusion were scored semiquantitatively from MR images by an expert reader. Deep and superficial layer cartilage T2 was computed in the medial and lateral femorotibial compartment (MFTC/LFTC) at baseline and at 1- and 4-year follow-up from multi-echo spin-echo MR images. Statistical analyses were performed using UNIANOVA.

RESULTS

82 participants (age 54.1 ± 7.2y, BMI 24.2 ± 3.0 kg/m²; 61% women, bilateral Kellgren-Lawrence 0) were studied. Number of baseline MRI pathologies was not significantly associated with longitudinal change in MFTC or LFTC cartilage T2 over 1 or 4 years. Feature-specific analyses suggested that presence of baseline MFTC osteophytes may be associated with prolongation in superficial MFTC cartilage T2 over one (0.8 vs. 0.0 ms, p = 0.02) and four years (2.3 vs. 0.9 ms, p = 0.01), and that MFTC meniscal damage or extrusion may be associated with prolongation in deep layer T2 times over the first year (0.7 vs. 2.1 ms, p = 0.02).

CONCLUSIONS

Our study does not provide evidence that, in knees without radiographic OA, baseline structural MRI abnormalities are strongly related to compositional progression during normal aging and/or the potentially earliest phases of the disease as measured by cartilage T2.

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.

Systematic review and meta-analysis of the reliability and discriminative validity of cartilage compositional MRI in knee osteoarthritis

OBJECTIVE

To assess reliability and discriminative validity of cartilage compositional magnetic resonance imaging (MRI) in knee osteoarthritis (OA).

DESIGN

The study was carried out per PRISMA recommendations. We searched MEDLINE and EMBASE (1974 - present) for eligible studies. We performed qualitative synthesis of reliability data. Where data from at least two discrimination studies were available, we estimated pooled standardized mean difference (SMD) between subjects with and without OA. Discrimination analyses compared controls and subjects with mild OA (Kellgren-Lawrence (KL) grade 1-2), severe OA (KL grade 3-4) and OA not otherwise specified (NOS) where not possible to stratify. We assessed quality of the evidence using Quality Appraisal of Diagnostic Reliability (QAREL) and Quality Assessment of Diagnostic Accuracy (QUADAS-2) tools.

RESULTS

Fifty-eight studies were included in the reliability analysis and 26 studies were included in the discrimination analysis, with data from a total of 2,007 knees. Intra-observer, inter-observer and test-retest reliability of compositional techniques were excellent with most intraclass correlation coefficients >0.8 and coefficients of variation <10%. T1rho and T2 relaxometry were significant discriminators between subjects with mild OA and controls, and between subjects with OA (NOS) and controls (P < 0.001). T1rho showed best discrimination for mild OA (SMD [95% CI] = 0.73 [0.40 to 1.06], P < 0.001) and OA (NOS) (0.60 [0.41 to 0.80], P < 0.001). Quality of evidence was moderate for both parts of the review.

CONCLUSIONS

Cartilage compositional MRI techniques are reliable and, in the case of T1rho and T2 relaxometry, can discriminate between subjects with OA and controls.

Conservatively treated knee injury is associated with knee cartilage matrix degeneration measured with MRI-based T2 relaxation times: data from the osteoarthritis initiative

OBJECTIVE

To investigate the association of cartilage degeneration with previous knee injuries not undergoing surgery, determined by morphologic and quantitative 3-T magnetic resonance imaging (MRI).

MATERIALS AND METHODS

We performed a nested cross-sectional study of right knee MRIs from participants in the Osteoarthritis Initiative (OAI) aged 45-79 with baseline Kellgren-Lawrence score of 0-2. Cases were 142 right knees of patients with self-reported history of injury limiting the ability to walk for at least 2 days. Controls were 426 right knees without history of injury, frequency-matched to cases on age, BMI, gender, KL scores and race (1:3 ratio). Cases and controls were compared using covariate-adjusted linear regression analysis, with the outcomes of region-specific T2 mean, laminar analysis and heterogeneity measured by texture analysis to investigate early cartilage matrix abnormalities and the Whole-Organ Magnetic Resonance Imaging Score (WORMS) to investigate morphologic knee lesions.

RESULTS

Compared to control subjects, we found significantly higher mean T2 values in the injury [lateral tibia (28.10 ms vs. 29.11 ms, p = 0.001), medial tibia (29.70 ms vs. 30.40 ms, p = 0.014) and global knee cartilage (32.73 ms vs. 33.29 ms, p = 0.005)]. Injury subjects also had more heterogeneous cartilage as measured by GLCM texture contrast, variance and entropy (p < 0.05 in 14 out of 18 texture parameters). WORMS gradings were not significantly different between the two groups (p > 0.05).

CONCLUSION

A history of knee injury not treated surgically is associated with higher and more heterogeneous T2 values, but not with morphologic knee abnormalities. Our findings suggest that significant, conservatively treated knee injuries are associated with permanent cartilage matrix abnormalities.

Sex- and age-dependence of region- and layer-specific knee cartilage composition (spin-spin-relaxation time) in healthy reference subjects

Compositional measures of articular cartilage are accessible in vivo by magnetic resonance imaging (MRI) based relaxometry and cartilage spin-spin transverse relaxation time (T2) has been related to tissue hydration, collagen content and orientation, and mechanical (functional) properties of articular cartilage. The objective of the current study was therefore to evaluate subregional variation, and sex- and age-differences, in laminar (deep and superficial) femorotibial cartilage T2 relaxation time in healthy adults. To this end, we studied the right knees of 92 healthy subjects from the Osteoarthritis Initiative reference cohort (55 women, 37 men; age range 45-78 years; BMI 24.4±3.1) without knee pain, radiographic signs, or risk factors of knee osteoarthritis in either knee. T2 of the deep and superficial femorotibial cartilages was determined in 16 femorotibial subregions, using a multi-echo spin-echo (MESE) MRI sequence. Significant subregional variation in femorotibial cartilage T2 was observed for the superficial and for the deep (both p<0.001) cartilage layer (Friedman test). Yet, layer- and region-specific femorotibial T2 did not differ between men and women, or between healthy adults below and above the median age (54 years). In conclusion, this first study to report subregional (layer-specific) compositional variation of femorotibial cartilage T2 in healthy adults identifies significant differences in both superficial and deep cartilage T2 between femorotibial subregions. However, no relevant sex- or age-dependence of cartilage T2 was observed between age 45-78 years. The findings suggest that a common, non-sex-specific set of layer-and region-specific T2 reference values can be used to identify compositional pathology in joint disease for this age group.