Age and Gender‐Dependence of Single‐and Bi‐Exponential T1ρ MR Parameters in Knee Ligaments.

Background: There is limited understanding of differences in the composition and structure of ligaments between healthy males and females, and individuals of different ages. Females present higher risk for ligament injuries than males and there are conflicting reports on its cause. This study looks into T1ρ parameters for an explanation as it relates to proteoglycan, collagen, and water content in these tissues. Purpose: To investigate gender‐related and age‐related differences in T1ρ parameters in knee joint ligaments in healthy volunteers using a T1ρ‐prepared zero echo‐time (ZTE)‐based pointwise‐encoding time‐reduction with radial acquisition (T1ρ‐PETRA) sequence. Study Type: Prospective. Population: The study group consisted of 22 healthy subjects (11 females, ages: 41 ± 18 years, and 11 males, ages: 41 ± 14 years) with no known inflammation, trauma, or pain in the knee joint. Field Strength/Sequence: A T1ρ‐prepared 3D‐PETRA sequence was used to acquire fat‐suppressed images with varying spin‐lock lengths (TSLs) of the knee joint at 3T. Assessment: Monoexponential, biexponential, and stretched‐exponential 3D‐PETRA‐T1ρ parameters were measured in the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), and patellar tendon (PT) by manually drawing ROIs over the entirety of the tissues. Statistical Tests: Mann–Whitney U‐tests were used to compare 3D‐PETRA‐T1ρ parameters in the ACL, PCL, and PT between males and females. Spearman correlation coefficients were used to determine the association between age and T1ρ parameters. Statistical significance was defined as P < 0.05. Results: Significant correlations with age were found the three ligaments with most of the measured T1ρ parameters (rs = 0.28–0.74) with the exception of the short fraction in the PCL (P = 0.18), and the short relaxation time in the ACL (P = 0.58) and in the PCL (P = 0.14). Data Conclusion: 3D‐PETRA‐T1ρ can detect age‐related differences in monoexponential, biexponential, and stretched‐exponential T1ρ parameters in three ligaments of healthy volunteers, which are thought to be related to changes in tissue composition and structure during the aging process. Level of Evidence: 2 Technical Efficacy: Stage 1 [ABSTRACT FROM AUTHOR]