To study the longitudinal changes of cartilage ${\mathrm{T}}_{1\mathrm{\rho }}$ and ${\mathrm{T}}_2$ relaxation time measurements in hip-OA patients. A calibration study compared two scanner data, Scanner-1 (GE Discovery MR750 3.0T) with unilateral acquisition protocol and Scanner-2 (GE Signa Premier 3.0T) with bilateral acquisition protocol, using nine subjects(average age ​= ​40.33 ​± ​13.53 years, 5 females), including one hip-OA subject. Quantified parameters from the Scanner-2 were adjusted using voxel-based relaxometry(VBR) and Z-score normalization to reduce the inter-scanner variability. Eighteen hip-OA Subjects (age ​= ​53.11 ​± ​14.96 years, 12 females) were recruited to the longitudinal variability study from 2016, comprising five assessments at 1-year intervals. Baseline to 3rd-year data used unilateral acquisition with Scanner-1, while 4th-year data used bilateral acquisition with Scanner-2. A linear mixed-effects model(LME) assessed trajectory analyses, with acquisition year, age, sex, body mass index(BMI), and Kellgren-Lawrence(KL) score as predictor variables and cartilage mean ${\mathrm{T}}_{1\mathrm{\rho }}$ and ${\mathrm{T}}_2$ values as outcomes. VBR analysis after Z-score normalization showed that only a few of the whole cartilage voxels had significant differences in ${\mathrm{T}}_{1\mathrm{\rho }}($femur-2.36 ​% and acetabular-3.23 ​%) and ${\mathrm{T}}_2$ (femur-2.30 ​% and acetabular-2.94 ​%) values between the scanners. The LME analysis showed that the BMI predictor variable was significantly correlated with the femur ${\mathrm{T}}_{1\mathrm{\rho }}$ (p ​< ​0.0001) and ${\mathrm{T}}_2$ (p ​< ​0.0001) and acetabular ${\mathrm{T}}_{1\mathrm{\rho }}$ (p ​< ​0.0001) and ${\mathrm{T}}_2$ (p ​< ​0.0001) cartilage region. The calibration study demonstrated the effectiveness of VBR and Z-score normalization in reducing inter-scanner variability. The longitudinal study revealed a significant correlation between ${\mathrm{T}}_{1\mathrm{\rho }}$ and ${\mathrm{T}}_2$ values of the cartilage and BMI; also the ${\mathrm{T}}_{1\mathrm{\rho }}$ and ${\mathrm{T}}_2$ values increased over time in some of the cartilage subregions.

The current study investigated proximal femur bone shape asymmetry and its associations with cartilage composition and functional performance in individuals with hip osteoarthritis (OA). Forty-seven participants with hip OA (mean age: 53.77 ± 12.47 years; 22 females; BMI: 24.49 ± 4.0 kg/m²) were included in this study. Bilateral hip MRI was performed using a 3.0 T MR scanner with 3D proton density fat-saturated CUBE and MAPSS sequences. Automatic segmentation of the proximal femur was achieved using a U-Net framework refined through a human-in-the-loop annotation strategy, followed by three-dimensional bone shape analysis to quantify asymmetry. Cartilage relaxation times were assessed using atlas-based segmentation and quantification, while functional activity was evaluated according to OARSI-recommended criteria. The proposed proximal femur bone segmentation showed a DSC of 96.48% (95%-CI: 96.33–96.64) and Hausdorff Distance of 4.66 mm (95%-CI: 3.80–5.51). Increased bone shape asymmetry in the posterior–lateral–superior region of the proximal femur was associated with functional activity in the chair stand test (rho = −0.41; p = 0.006), and the anterior–lateral–inferior region demonstrated a comparatively higher significant positive correlation ($\mathrm{rho}=0.37$; p = 0.006) with the ${\mathrm{T}}_{1\mathrm{rho}}$values of the acetabular cartilage region. Overall, the findings indicate that region-specific proximal femoral bone shape asymmetry in hip OA is associated with cartilage characteristics and functional impairment, highlighting the potential value of bone shape features as imaging biomarkers relevant to clinical function.