| Objective:To clarify the sensitivity and efficacy of T1ρ and T2 Mapping for the lumbar intervertebral disc degeneration(IVDD)and comparison of their diagnostic efficacy.To explore whether long-term static overload(sedentary and prolonged-standing)has different effects on lumbar intervertebral discs.Methods:We included 25 taxis drivers(13 males and 12 females)in the sedentary group,16 salesclerks(7 males and 9 females)in the prolonged-standing group,and 22volunteers(13 males and 9 females)in the non-sedentary/prolonged-standing group,with all three groups aged 20-45 years.The sedentary group and the prolonged-standing group were divided into two groups according to the comprehensive scale of daily working hours length and working-age: working hours≤25000 hours(15 cases were sedentary,7 cases were standing),and working hours> 25000 hours(10 cases were sedentary,9 cases were standing).Another group of55 volunteers(28 males and 27 females,aged 46-77 years)were collected.The L1/2-L5/S1 intervertebral discs were scanned by GE Discovery 750 W 3.0T Magnetic Resonance Imaging(MRI).The scanning sequence included conventional lumbar MRI,sagittal T1ρ sequence,and T2 Mapping sequence.Lumbar discs were graded according to Pfirrmann grading on T2 weighted images(T2WI),T1ρ maps,and T2 Mapping of the disc nucleus pulposus(NP),anterior annulus fibrosus(AAF),and posterior annulus fibrosus(PAF)were measured in the post-processing workstation.The T1ρ values and T2 values of the AAF,NF,and PAF with different Pfirrmann grades,different occupational load groups,different ages,and genders were analyzed statistically.Results:There were significant differences in T1ρ values between the AAF,NP,and PAF in Pfirrmann grades I-IV lumbar discs.There were no significant differences in T2 values between the AAF and PAF of Pfirrmann grades I-II,T2 values of grades I-II(NP)and grades II-IV(NP,AAF,and PAF)lumbar disc was significantly different.The T1ρ values and T2 values of the AAF,NP,and PAF were all negatively correlated with the Pfirrmann grade.T1ρ values of NP and PAF were positively correlated with T2 values.Both T1ρ values and T2 values were high efficiencies in Pfirrmann grade I-IV discs,and T1ρ values were superior to T2 values with diagnostic efficacy exception of comparable efficacy in Pfirrmann grades III-IV(NP).Compared with the non-sedentary/prolonged-standing group,T1ρ values were lower in L1/2(NP),L2/3(NP),L4/5(NP),and T2 values were lower in L1/2(NP,PAF),L2/3(PAF),L4/5(NP),L5/S1(NP)in the prolonged-standing group;Compared with the non-sedentary/prolonged-standing group,T1ρ values were lower in L4/5(NP),L5/S1(NP,PAF),and T2 values were lower in L4/5(NP),L5/S1(NP)in the sedentary group;Compared with the sedentary group and prolonged-standing group,T1ρ values were lower in L1/2(NP),L2/3(NP),and T2 values were lower in L1/2(NP,PAF),L2/3(NP,PAF)in the prolonged-standing group;Both T1ρ values and T2 values were lower in L5/S1(NP)in the sedentary group;In the non-sedentary/prolonged-standing group,L5/S1(NP,PAF)had the lowest T1ρ values and L5/S1(PAF)had the lowest T2 values.In the prolonged-standing group,there were no significant differences in T1ρ values and T2 values between L1/2-L5/S1 discs.In the sedentary group,T1ρ values and T2 values of L5/S1(NP,AAF,and PAF)were lower than L1/2,L2/3,and L3/4.The T1ρ values of L4/5(NP)were lower than L1/2,L2/3,and L3/4,and the T2 values of L4/5(NP,AAF,and PAF)were lower than L1/2,L2/3,and L3/4.T1ρ values and T2 values of L5/S1(NP,PAF)were both lower than L4/5.Compared with working hours≤25000 hours,the T1ρ values of L3/4,L4/5(NP,AAF,and PAF),and T2 values of L3/4(AAF,PAF),L4/5(NP,AAF,and PAF)were lower in the working hours>25000 hours sedentary group;Compared with working hours≤25000 hours,the T1ρ values of L1/2(AAF,PAF),L2/3(AAF,PAF),L3/4(NP),and T2 values of L2/3(AAF),L3/4(NP)were lower in the working hours>25000 hours prolonged-standing group.Within the group of volunteers older than 45 years: L1/2 and L2/3(NP,AAF,and PAF)T1ρ values were higher than L4/5 and L5/S1,L1/2(NP,AAF,and PAF),L2/3(PAF)T2 values were higher than L4/5 and L5/S1.There were weak negative correlations between T1ρ values and age in L2/3(NP),L3/4(NP),L4/5(NP,AAF,and PAF).There were weak negative correlations between T2 values and age in L2/3(NP,AAF),L3/4(NP,PAF),L4/5(NP,PAF).Conclusions:1.Both T1ρ and T2 Mapping technologies have great capacities to diagnose IVDD,and the diagnostic ability of T1ρ is superior to T2 Mapping.2.Both T1ρ and T2 values were negatively correlated with Pfirrmann grade,with the grade of disc degeneration worsened,T1ρ and T2 values decreased.The diagnostic efficacy of the NP was superior to that of the AF.3.The effects of sedentary on L4/5 and L5/S1 degeneration were more significant,while the effects of prolonged-standing on L1/2-L5/S1 were more uniform and showed less severe degeneration. |
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