T2-mapping For Evaluation Of Ozone Ablation In Lumbar Discs With Rabbits Model

Objective: To study the value of T2 mapping for non-invasivequantitative monitoring of ozone ablation in intervertebral disc.Methods: Lumbar disc imaging were performed preoperatively in 48health 6-month-age New Zealand rabbits with sagittal T2WI and T2-mappingsequences in 1.5T MRI scanner. The rabbits were randomly divided into 6Groups ( 8 rabbits in each group including 6 rabbits for experimental animalsand 2 rabbits for reserve candidates)，which included 4 experimental groupsand 2 control groups. Ozone ( 2ml O2-O3) with different concentration wereinjected to the nucleus pulposus of L2-3, L3-4 and L4-5 disc respectively inexperimental groups including group A (80ug/ml), group B (60ug/ml), groupC (40ug/ml), group D (20ug/ml). Air (2ml) was injected in Control group Eand nothing was injected in group F (blank control). Each 2 rabbits imagedwith the same sequences in each group were killed on 1st week, 4th week and8th week respectively after interventional procedures for the proteoglycancontents and pathological observation. The correlation between T2 values andproteoglycan contents, degenerative scores were analyzed with SPSS 17.0software.Results:T2 values of lumbar disc on the 1st,4th and 8th week after interventionalprocedures were lower than those on pre-procedures in Group A, B, and C(P<0.01). In Group D, although there was a statistical significant difference inT2 values between at 1st week and on pre-procedures, P<0.01, no difference were found in T2 values between on the 4th, 8th week after interventionalprocedures and on pre-procedures, P>0.05. In Group E and F, No differencein T2 values were found between on the 1st, 4th and 8th week afterinterventional procedures and on pre-procedures (P>0.05). Although therewere no statistical significance difference in T2 values on 1st, 4th and 8thweek within each groups including group A, B, E and F (P>0.05), differencewere found within group C and group D, P<0.05. There were significantdifference in T2 values on the 1st, 4th and 8th week after interventionalprocedure respectively among different Ozone concentration groups includinggroup A, B, C and D, p<0.05; Difference were found in proteoglycan contenton the 1st, 4th and 8th week after interventional procedure respectivelyamong all groups, P<0.01. The proteoglycan contents in group A are thelowest than that in other groups. There were significant difference indegeneration degree on the 1st, 4th and 8th week after interventionalprocedure respectively among all groups, P<0.05. The positive correlationwere found between T2 values and proteoglycan contents (rS =0.867, p<0.01).There was a negative correlation between T2 values and degenerationscores (rS=﹣0.847, p<0.01).Conclusion: T2-mapping imaging could be used as a non-invasivequantitative monitoring tool for lumbar disc after ozone ablation.