Ultrashort Echo Time Magnetization Transfer MR Imaging of Lumbar Nerve Roots in Patients With Disc Herniation

ABSTRACT Background Lumbar disc herniation (LDH) causes compositional alterations within compressed nerve roots, resulting in low back pain (LBP). The ultrashort echo time magnetization transfer technique (UTE‐MT) facilitates assessment of macromolecular changes in collagen‐ or myelin‐rich tissues in nerve roots. Purpose To assess lumbar nerve root composition in LDH using UTE‐MT. Study Type Prospective. Population One hundred and seventy‐six participants (age range, 20–89; 72 females) with LDH. Field Strength/Sequence 3T/UTE‐MT, Carr‐Purcell‐Meiboom‐Gill (CPMG). Assessment UTE‐MT ratio (UTE‐MTR) and T 2 value in compressed nerve roots (determined on axial T 2 ) were evaluated by UTE‐MT and CPMG in LDH patients (L4/5‐L5/S1). Additionally, pain and functionality were evaluated using the visual analog scale (VAS) and Oswestry Disability Index (ODI). Statistical Tests Linear regression and Bland–Altman assessed UTE‐MT reproducibility. One‐way ANOVA assessed the statistical significance of UTE‐MTR and T 2 measures between compressed and intact nerve roots. ROC and DCA evaluated diagnostic performance and clinical value of UTE‐MTR and T 2 in discriminating between compressed and intact nerve roots. Linear regression correlated UTE‐MTR and T 2 with pain and functionality scores. The p value < 0.05 was considered significant. Results Significant increases in UTE‐MTR and decreases in T 2 values in compressed nerve roots compared to intact ones. High AUC values for UTE‐MTR (0.912 at L4/5 and 0.900 at L5/S1) highlighted its superior ability to distinguish between compressed and intact nerve roots, outperforming T 2 (AUCs of 0.840 and 0.790, respectively) in cohort discrimination. Strong significant positive correlations were found between UTE‐MTR and VAS ( R 2 = 0.63) and ODI ( R 2 = 0.62), while T 2 values showed moderate significant negative correlations with VAS ( R 2 = 0.32) and ODI ( R 2 = 0.32) for the measurement of the most severely compressed nerve roots (determined on axial T 2 ). Data Conclusion UTE‐MT technique can detect macromolecular alterations in the compressed nerve roots of patients diagnosed with LDH. Level of Evidence 1. Technical Efficacy Stage 2.