3-T MRI mapping is a valid in vivo method of quantitatively evaluating the anterior cruciate ligament: rater reliability and comparison across age

• Published in: Skeletal radiology Vol. 49; no. 3; pp. 443 - 452
• Main Authors: Anz, Adam W., Edison, Jos, Denney, Thomas S., Branch, Eric A., Walz, Christopher R., Brock, Kenny V., Goodlett, Michael D.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.03.2020; Springer; Springer Nature B.V
• Subjects: Age; Anterior cruciate ligament; Clinical trials; Comparative studies; Correlation coefficients; Imaging; In vivo methods and tests; Knee; Magnetic resonance imaging; Mapping; Measurement methods; Medicine; Medicine & Public Health; Methods; Nuclear Medicine; Orthopedics; Pathology; Radiology; Reliability analysis; Scientific Article; Soft tissues; Variance analysis; ACL; Magnetic resonance imaging; T2 relaxation time; Structural properties
• ISSN: 0364-2348; 1432-2161
• DOI: 10.1007/s00256-019-03301-1

Objective As biologic augmentation methods emerge, objective measures of soft tissues are necessary for developmental study. The purpose of this study was to develop a quantitative MRI mapping protocol for the ACL. The objectives were (1) to provide age-based T2 relaxation, T2* relaxation, and volume values in healthy individuals, (2) to establish the intra-rater and inter-rater reliability of ACL mapping, and (3) to determine whether 3-T or 7-T MRI is more appropriate for future clinical trials. Materials and methods Thirty healthy participants, aged 18–62, asymptomatic for knee pathology and without history of knee injury underwent both a 3-T and 7-T MRI. Manual image mapping of the anterior cruciate ligament was performed by two observers and processed to obtain T2, T2*, and volume values. Analysis of variance and two-way random effects model were used to calculate statistical significance and intraclass correlation coefficients. Results Across all participants, 3-T and 7-T mean T2, T2* and volume values were 37.1 ± 7.9 and 39.7 ± 6.2 ms ( p  = 0.124), 10.9 ± 1.3 and 10.9 ± 0.9 ms ( p  = 0.981), and 2380 ± 602 and 2484 ± 736 mm 3 ( p  = 0.551), respectively. The T2, T2*, and volume did not vary between age cohorts ( p  > 0.05). Excellent inter-rater and intra-rater reliability regarding T2 and T2* values was found. While ACL volume exhibited good inter-rater reliability and excellent intra-rater reliability. Conclusions T2 relaxation values and ACL volume do not vary with age and therefore can be used as a quantifiable, non-invasive method to assess ACL graft maturation. 7-T MRI analysis was not superior to 3-T MRI analysis, suggesting that 3-T MRI is practical and capable for future comparative studies.