T 2 Clusters Are More Sensitive Than Mean T 2 Change to Detect Early and Longitudinal Changes in Anterior Cruciate Ligament Reconstructed and Healthy Knees

• Published in: Journal of magnetic resonance imaging Vol. 61; no. 6; pp. 2615 - 2629
• Main Authors: Pai S, Anoosha, Gatti, Anthony A., Black, Marianne S., Young, Katherine A., Desai, Arjun D., Barbieri, Marco, Asay, Jessica L., Sherman, Seth L., Gold, Garry E., Kogan, Feliks, Hargreaves, Brian A., Chaudhari, Akshay S.
• Format: Journal Article
• Language: English
• Published: United States 01.06.2025
• Subjects: Adult; Anterior Cruciate Ligament - diagnostic imaging; Anterior Cruciate Ligament - surgery; Anterior Cruciate Ligament Injuries - diagnostic imaging; Anterior Cruciate Ligament Reconstruction; Cartilage, Articular - diagnostic imaging; Case-Control Studies; Cluster Analysis; Female; Humans; Imaging, Three-Dimensional; Knee - diagnostic imaging; Knee Joint - diagnostic imaging; Longitudinal Studies; Magnetic Resonance Imaging - methods; Male; Middle Aged; Osteoarthritis, Knee - diagnostic imaging; post‐traumatic osteoarthritis; ACL‐reconstruction; T2 relaxometry; cluster analysis; femoral cartilage
• DOI: 10.1002/jmri.29689
• ISSN: 1053-1807

Post-traumatic osteoarthritis (PTOA) often follows anterior cruciate ligament reconstruction (ACLR), leading to early cartilage degradation. Change in mean T fails to capture subject-specific spatial-temporal variations, highlighting the need for robust quantitative methods for early PTOA detection and monitoring. Develop and apply 3D T cluster analysis to ACLR and healthy knees over 2.5 years. Longitudinal case-control study. ACLR and contralateral knees of 15 subjects (9 male/6 female, 37.7 ± 10 years) and right knee of 15 matched controls (9 male/6 female, 37.1 ± 12 years) were scanned at 3 weeks, 3, 9, 18, and 30 months post-ACLR. 3 T Quantitative double echo steady state sequence. "T cluster analysis" was developed, incorporating registration and thresholding methods to identify and quantify elevated T regions (T clusters, T C) in femoral cartilage. Percentage of cartilage covered by T clusters (T C ), mean cluster size (T C ), the number of clusters (T C ), and ΔT Mean (change in mean femoral cartilage T relative to visit 1) were computed for all knees. A linear mixed model assessed knee, time, and knee-time interaction effects on each outcome metric (P < 0.05), with effect sizes (η ) describing the sensitivity of these effects to longitudinal changes. T C (η  = 0.22), T C , (η  = 0.14), and T C (η  = 0.51) showed significant and systematic difference between knees (ACLR > contralateral > control). T C (η  = 0.24), T C (η  = 0.17), and T C (η  = 0.11) showed significant longitudinal change across all knees. Specifically, ACLR knees exhibited a significant increase in T C (η  = 0.21), T C (η  = 0.13), and a decrease in T C (η  = 0.07) with time. ΔT Mean showed significant difference between knees (η  = 0.15), increase with time (η  = 0.04), with no significant knee-time interaction (η  = 0.00, P = 0.772 [contralateral], P = 0.482 [control]). T C metrics are more sensitive than ΔT Mean for longitudinal monitoring of femoral cartilage post ACLR. Our findings suggest potential merging of T clusters overtime, forming larger areas of cartilage degradation in ACLR knees. 1 TECHNICAL EFFICACY: Stage 2.