Meniscus tear is a known risk factor for osteoarthritis (OA). Quantitative assessment of meniscus degeneration, prior to surface break-down, is important to identification of early disease potentially amenable to therapeutic interventions. This work examines the diagnostic potential of ultrashort echo time-enhanced T2∗ (UTE-T2∗) mapping to detect human meniscus degeneration in vitro and in vivo in subjects at risk of developing OA.
UTE-T2∗ maps of 16 human cadaver menisci were compared to histological evaluations of meniscal structural integrity and clinical magnetic resonance imaging (MRI) assessment by a musculoskeletal radiologist. In vivo UTE-T2∗ maps were compared in 10 asymptomatic subjects and 25 ACL-injured patients with and without concomitant meniscal tear.
In vitro, UTE-T2∗ values tended to be lower in histologically and clinically normal meniscus tissue and higher in torn or degenerate tissue. UTE-T2∗ map heterogeneity reflected collagen disorganization. In vivo, asymptomatic meniscus UTE-T2∗ values were repeatable within 9% (root-mean-square average coefficient of variation). Posteromedial meniscus UTE-T2∗ values in ACL-injured subjects with clinically diagnosed medial meniscus tear (n=10) were 87% higher than asymptomatics (n=10, P<0.001). Posteromedial menisci UTE-T2∗ values of ACL-injured subjects without concomitant medial meniscal tear (n=15) were 33% higher than asymptomatics (P=0.001). Posterolateral menisci UTE-T2∗ values also varied significantly with degree of joint pathology (P=0.001).
Significant elevations of UTE-T2∗ values in the menisci of ACL-injured subjects without clinical evidence of subsurface meniscal abnormality suggest that UTE-T2∗ mapping is sensitive to sub-clinical meniscus degeneration. Further study is needed to determine whether elevated subsurface meniscus UTE-T2∗ values predict progression of meniscal degeneration and development of OA.