Assessment of Achilles Tendon Changes After Long‐Distance Running Using Ultrashort Echo Time Magnetization Transfer MR Imaging

Patellar tendon biomechanical and morphologic properties and their relationship to serum clinical variables in persons with prediabetes and type 2 diabetes

Tendon biomechanical properties and fibril organization are altered in patients with diabetes compared to healthy individuals, yet few biomarkers have been associated with in vivo tendon properties. We investigated the relationships between in vivo imaging-based tendon properties, serum variables, and patient characteristics across healthy controls (n = 14, age: 45 ± 5 years, body mass index [BMI]: 24 ± 1, hemoglobin A1c [HbA1c]: 5.3 ± 0.1%), prediabetes (n = 14, age: 54 ± 5 years, BMI: 29 ± 2; HbA1c: 5.7 ± 0.1), and type 2 diabetes (n = 13, age: 55 ± 3 years, BMI: 33 ± 2, HbA1c: 6.7 ± 0.3). We used ultrasound speckle-tracking and measurements from magnetic resonance imaging (MRI) to estimate the patellar tendon in vivo tangent modulus. Analysis of plasma c-peptide, interleukin-1β (IL-1β), IL-6, IL-8, tumor necrosis factor-α (TNF-α), adiponectin, leptin, insulin-like growth factor 1 (IGF-1), and C-reactive protein (CRP) was completed. We built regression models incorporating statistically significant covariates and indicators for the clinically defined groups. We found that tendon cross-sectional area normalized to body weight (BWN CSA) and modulus were lower in patients with type 2 diabetes than in healthy controls (p < 0.05). Our regression analysis revealed that a model that included BMI, leptin, high-density lipoprotein (HDL), low-density lipoprotein (LDL), age, and group explained ~70% of the variability in BWN CSA (R2 = 0.70, p < 0.001). For modulus, including the main effects LDL, groups, HbA1c, age, BMI, cholesterol, IGF-1, c-peptide, leptin, and IL-6, accounted for ~54% of the variability in modulus (R2 = 0.54, p < 0.05). While BWN CSA and modulus were lower in those with diabetes, group was a poor predicter of tendon properties when considering the selected covariates. These data highlight the multifactorial nature of tendon changes with diabetes and suggest that blood variables could be reliable predictors of tendon properties.

Achilles tendon and enthesis assessment using ultrashort echo time magnetic resonance imaging (UTE-MRI) T1 and magnetization transfer (MT) modeling in psoriatic arthritis

The purpose of this study is to investigate the use of ultrashort echo time (UTE) magnetic resonance imaging (MRI) techniques (T1 and magnetization transfer [MT] modeling) for imaging of the Achilles tendons and entheses in patients with psoriatic arthritis (PsA) compared with asymptomatic volunteers. The heels of twenty-six PsA patients (age 59 ± 15 years, 41% female) and twenty-seven asymptomatic volunteers (age 33 ± 11 years, 47% female) were scanned in the sagittal plane with UTE-T1 and UTE-MT modeling sequences on a 3-T clinical scanner. UTE-T1 and macromolecular proton fraction (MMF; the main outcome of MT modeling) were calculated in the tensile portions of the Achilles tendon and at the enthesis (close to the calcaneus bone). Mann-Whitney-U tests were used to examine statistically significant differences between the two cohorts. UTE-T1 in the entheses was significantly higher for the PsA group compared with the asymptomatic group (967 ± 145 vs. 872 ± 133 ms, p < 0.01). UTE-T1 in the tendons was also significantly higher for the PsA group (950 ± 145 vs. 850 ± 138 ms, p < 0.01). MMF in the entheses was significantly lower in the PsA group compared with the asymptomatic group (15% ± 3% vs. 18% ± 3%, p < 0.01). MMF in the tendons was also significantly lower in the PsA group compared with the asymptomatic group (17% ± 4% vs. 20% ± 5%, p < 0.01). Percentage differences in MMF between the asymptomatic and PsA groups (-16.6% and -15.0% for the enthesis and tendon, respectively) were higher than the T1 differences (10.8% and 11.7% for the enthesis and tendon, respectively). The results suggest higher T1 and lower MMF in the Achilles tendons and entheses in PsA patients compared with the asymptomatic group. This study highlights the potential of UTE-T1 and UTE-MT modeling for quantitative evaluation of entheses and tendons in PsA patients.

Correlations between elastic modulus and ultrashort echo time (UTE) adiabatic T1ρ relaxation time (UTE-Adiab-T1ρ) in Achilles tendons and entheses

Patients with psoriatic arthritis commonly have abnormalities of their entheses, which are the connections between tendons and bone. There are shortcomings with the use of conventional magnetic resonance imaging (MRI) sequences for the evaluation of entheses and tendons, whereas ultrashort echo time (UTE) sequences are superior for the detection of high signals, and can also be used for non-invasive quantitative assessments of these structures. The combination of UTE-MRI with an adiabatic-T1ρ preparation (UTE-Adiab-T1ρ) allows for reliable assessment of entheses and tendons with decreased susceptibility to detrimental magic angle effects. This study aimed to investigate the relationship between quantitative UTE-MRI measures and the biomechanical properties of Achilles tendons and entheses. In total, 28 tendon-enthesis sections were harvested from 11 fresh-frozen human cadaveric foot-ankle specimens (52 ± years old). Tendon-enthesis sections were scanned using the UTE-Adiab-T1ρ and UTE-T1 sequences on a clinical 3 T scanner. MRI-based measures and indentation tests were performed on the enthesis, transitional, and tensile tendon zones of the specimens. Hayes' elastic modulus showed significant inverse correlations (Spearman's) with UTE-Adiab-T1ρ in all zones (R= - 0.46, - 0.54, and - 0.61 in enthesis, transition, and tensile tendon zones, respectively). Oliver-Pharr's elastic modulus showed significant inverse correlations with UTE-Adiab-T1ρ in transition (R= - 0.52) and tensile tendon zone (R=- 0.60). UTE-T1 did not show significant correlations with the elastic modulus. UTE-MRI and elastic modulus were significantly lower in the tensile tendon compared with the enthesis regions This study highlights the potential of the UTE-Adiab-T1ρ technique for the non-invasive evaluation of tendons and enthuses.

Preliminary study on the assessment of early cartilage degeneration by quantitative ultrashort echo time magnetic resonance imaging in vivo

BACKGROUND

To investigate the feasibility of quantitative ultrashort echo time magnetic resonance imaging (UTE-MRI) techniques for assessing early cartilage degeneration in vivo.

METHODS

A total of 46 patients with knee pain due to osteoarthritis (OA) as the main complaint were recruited into the study. We performed MRI examinations with different quantitative UTE-MRI techniques, including UTE-based magnetization transfer (MT), UTE-adiabaticT1ρ, and UTE-T2* mapping on a 3.0T clinical magnetic resonance (MR) scanner (MR750; GE Healthcare, Milwaukee, WI, USA). Three regions of interest (ROIs) were manually drawn on the medial and lateral femoral condyles and the corresponding medial and lateral tibial plateaus, respectively. A total of 561 ROIs (12 ROIs for each knee) were finally included and divided into 3 groups according to the MRI Osteoarthritis Knee Score (MOAKS): normal (MOAKS 0, n=175), mild degeneration (MOAKS 1, n=283), and moderate degeneration (MOAKS 2, n=103). One-way analysis of variance (ANOVA) and Tamhane's T2 test were used to compare the differences of quantitative UTE-biomarkers among different groups. The analysis of Spearman's correlation was used to assess the correlation between the UTE-biomarkers and MOAKS grading. The diagnostic efficacy of different quantitative UTE-MRI techniques for detecting mild cartilage degeneration was evaluated using the receiver operating characteristic (ROC) curve.

RESULTS

The UTE-MT ratio (UTE-MTR) and the UTE-adiabatic T1ρ values had a moderate correlation with the MOAKS grading (r=-0.523, P<0.001; r=0.531, P<0.001, respectively), while the UTE-T2* was weakly correlated with the MOAKS grading (r=-0.396, P<0.001). For the normal group (MOAKS 0) and the mild group (MOAKS 1), the UTE-MTR values were 21.09%±3.03% and 17.30%±3.22%, respectively. The UTE-adiabatic T1ρ values were 30.43±6.26 ms and 35.05±8.78 ms for the normal group (MOAKS 0) and the mild group (MOAKS 1), respectively. With respect to the UTE-T2* values, the normal group (MOAKS 0) values were 21.49±3.96 ms and the mild group (MOAKS 1) values were 19.86±3.08 ms. All the differences between the 2 groups of the 3 UTE-MRI values were significant. The AUCs of the UTE-MTR, UTE-adiabatic T1ρ, and UTE-T2* mapping were 0.794, 0.732, and 0.651, respectively.

CONCLUSIONS

The quantitative UTE-MRI techniques (UTE-MT, UTE-adiabatic T1ρ, and UTE-T2* mapping) show great promise for assessing the early degeneration of articular cartilage in vivo, and the UTE-MT and UTE-adiabatic T1ρ values show better diagnostic efficacy than UTE-T2* mapping.