Abstract
BACKGROUND: Microvascular dysfunction of the subchondral bone is thought to play a central role in juvenile osteochondritis dissecans (JOCD), but remains difficult to assess with conventional MRI. This study evaluated the diagnostic value of intravoxel incoherent motion MRI (IVIM-MRI) parameters in JOCD of the distal femoral condyle and explored their relationship with lesion morphology and stability. METHODS: In this single-center retrospective cross-sectional study, 57 skeletally immature patients (mean age 13.0 ± 2.0 years) with clinically and radiologically confirmed JOCD underwent bilateral knee IVIM-MRI. Quantitative parameters-apparent diffusion coefficient (ADC), perfusion fraction (f), and pseudodiffusion coefficient (D*)-were calculated for lesional and contralateral condyles. Lesion stability was classified on conventional MRI using the Hefti system. Morphological measurements and clinical scores (IKDC, KOOS-Child, Tegner) were recorded. Within-subject comparisons used Shapiro-Wilk testing, paired t-tests or Wilcoxon signed-rank tests, and effect sizes (Cohen's d). Diagnostic performance for discriminating stable versus unstable lesions was assessed with ROC analysis and multiparametric IVIM models. RESULTS: JOCD lesions showed significantly reduced perfusion fraction (0.178 ± 0.048 vs. 0.253 ± 0.043, p < 0.001) and ADC (1.178 ± 0.167 vs. 1.363 ± 0.100 × 10⁻³ mm²/s, p < 0.001) compared with contralateral tissue, with large effect sizes, indicating marked microvascular compromise and restricted diffusion. Perfusion fraction yielded high diagnostic accuracy for lesion instability (AUC = 0.91; optimal cutoff 0.20; sensitivity 88.6%, specificity 85.0%), while a combined IVIM model further improved classification accuracy to 94.7%. Correlations between IVIM parameters and baseline IKDC, KOOS-Child, and Tegner scores were weak and non-significant. Age-stratified analyses (≤ 12 vs. > 12 years) revealed no significant differences in microvascular metrics. Based on IVIM profiles, lesions were categorized into three microvascular patterns: preserved (Type I), compromised (Type II), and intermediate (Type III). CONCLUSIONS: IVIM-MRI provides quantitative, non-invasive biomarkers that sensitively characterize microvascular compromise in JOCD and support objective assessment of lesion stability. The prognostic utility of these biomarkers for clinical outcomes, however, remains uncertain and warrants validation in prospective studies with arthroscopic ground truth (ROCK classification) and longitudinal follow-up.