Abstract
STUDY DESIGN: Cross-sectional. OBJECTIVE: To assess the distribution of the ultra-short time-to-echo (UTE) disc sign (UDS) and its association with disc degeneration, other magnetic resonance imaging (MRI) phenotypes, pain, and disability profiles. SUMMARY OF BACKGROUND DATA: Disc degeneration has been conventionally assessed by T2-weighted (T2W) signal intensity on MRI; however, its clinical utility has been questionable. UTE MRI assesses short T2 components. The authors have identified a new imaging biomarker on UTE-the UDS. METHODS: One hundred eight subjects were recruited. T2W MRI assessed disc degeneration and other phenotypes, and T1-rho MRI values represented quantitative proteoglycan disc profiles of L1-S1. UDS was detected on UTE (i.e., hyper-/hypointense disc band). A UDS score (cumulative number of UDS levels) and T2W summated lumbar degenerated scores (cumulative disc degeneration score) were assessed. Subject demographics, chronic low back pain (LBP), and disability profiles (Oswestry Disability Index: ODI) were obtained. RESULTS: UDS was noted in 39.8% subjects, 61.4% occurred at the lower lumbar spine and 39.5% had multilevel UDS. UDS subjects had significantly greater severity and extent of disc degeneration, and Modic changes (P < 0.05). By disc levels, a higher prevalence of disc degeneration/displacement, Modic changes, and spondylolisthesis were noted in UDS discs than non-UDS discs (P < 0.05). T1-rho values were also lower in UDS discs (P = 0.022). The majority of UDS could not be detected on T2W. The UDS score significantly correlated with worse ODI scores (r = 0.311; P = 0.001), whereas T2W cumulative disc degeneration score did not (r = 0.13; P = 0.19). LBP subjects exhibited more multilevel UDS (P < 0.015) but not on T2W MRI (P = 0.53). The UDS score was significantly related to LBP (P = 0.009), whereas T2W cumulative disc degeneration score was not (P = 0.127). CONCLUSION: This is the first study to report "UDS" in humans. UDS is a novel imaging biomarker that is highly associated with degenerative spine changes, chronic LBP, and disability than conventional T2W MRI. LEVEL OF EVIDENCE: 2.