<p>Supplementary file: results of analysis focused on disc L4/5.</p><p>With analysis focused on disc L4/5 (n=50) only, the relationship between NP relaxation times and 8-level grading is shown in Suppl Fig 1. The quadratic coefficient (±SE) was</p><p>3.35±0.56 (P<0.0001, R2=0.78) for T1rho relaxation time; and 4.67±0.65 (p<0.0001,</p><p>R2=0.83) for T2 relaxation time. There was no significant trend difference for the T1rho and T2 values decrease over degeneration grade increase (P =0.13). When only grades</p><p>2/8~5/8 were analyzed, the quadratic coefficient (±SE) was 6.58±1.66 (P =0.0003,</p><p>R2=0.79) for T1rho relaxation time; and 6.99±2.22 (P =0.003, R2=0.76) for T2 relaxation time, with no significant trend difference for the T1rho and T2 values decrease over degeneration grade increase (P =0.88). The relationship between NP relaxation times and</p><p>5-level grading is shown in Suppl Fig 2. The quadratic coefficient (±SE) was 4.55±1.46</p><p>(P <0.0031, R2=0.76) and for T1rho relaxation time; and 7.36±1.70 (P <0.0001, R2=</p><p>0.81) for T2 relaxation time. There was no significant trend difference for the T1rho and</p><p>T2 values decrease over degeneration grade increase (P =0.21). </p><p>The relationship between AF relaxation times and 8-level grading is shown in Suppl Fig</p><p>3. For T1rho relaxation time, as the degeneration grade increased from 1/8 to 5/8, relaxation time decreased. On the other hand, the trend of T2 relaxation time decrease was much flatter. The slope (±SE) was -2.92±0.50 (P <0.0001, R2=0.41) for T1rho relaxation time; and -1.22±0.55 (P <0.0001, R2= 0.09) for T2 relaxation time. There was significant difference for the slopes of T1rho and T2 value decrease over disc degeneration (P =0.02). The relationship between AF relaxation times and 5-level grading is shown in Suppl Fig 4. For T1rho relaxation time, as the degeneration grade increased, relaxation time decreased. On the other hand, the trend of T2 relaxation time decrease over disc degeneration increase was much flatter. The slope (± SE) was</p><p>-4.23±0.74 (P <0.0001, R2=0.40) for T1rho relaxation time; and -1.57±0.82 (P =0.06,</p><p>R2= 0.07) for T2 relaxation time. There was significant difference for the slopes of T1rho and T2 value (P =0.02).</p><p>Supplementary Fig 1 (A, B): A: Nucleus pulposus T1rho relaxation time vs 8-level disc degeneration grading. B: Nucleus pulposus T2 relaxation time vs 8-level disc degeneration grading. Supplementary Fig 2 (A, B): A: Nucleus pulposus T1rho relaxation time vs 5-level disc degeneration grading. B: Nucleus pulposus T2 relaxation time vs 5-level disc degeneration grading.</p><p>Supplementary Fig 3 (A, B): A: Annulus fibrosus T1rho relaxation time vs 8-level disc degeneration grading. B: Annulus fibrosus T2 relaxation time vs 8-level disc degeneration grading. Supplementary Fig 4 (A, B): A: Annulus fibrosus T1rho relaxation time vs 5-level disc degeneration grading. B: Annulus fibrosus T2 relaxation time vs 5-level disc degeneration grading.</p>