|ECR 2013 / C-0541|
|MR imaging assessment of the lumbar disc herniation treated with oxygen-ozone(O2-O3) discolysis: Role of DWI and related ADC versus intervertebral disc volumetric analysis for detecting response to treatment|
Comparison of Study and Control Group - At the presentation, the study and control groups (Table 1), were not significantly different (P=0.58 to P=0.74) in terms of demographic data( sex, age, disc level affected and BMI). For 11 patients from the study group, no matching control subject could be found, resulting in 66 matched pairs(Table 1). The treatment at 2 months was a success in 15(19.5%) of 77 study group patients (95% CI: 11.3%, 30.08%) and in 14(18.1%) of 77 control group patients (95% CI: 10.3%, 28.6%) with no statistically significant difference in terms of success rate (χ2=0.028, P=.86)(Fig.2). Even at 4 months after treatment there was no statistically significant difference in success rate(χ2=0.98, P=.32) with a success in 31(40.2%) of 77 study group patients (95% CI: 29.2%, 52.05%) and in 25(32.4%) of 77 control group patients (95% CI: 22.2%, 44.09%)(Fig.2). Only 6 months after treatment, the success rate difference between the two groups was statistically significant(χ2=31,31, P<.001) and in particular 58(75,3%) of 77 study group patients(95% CI: 64,1%, 84,4%) compared with 30(38,9%) of 77 control group patients(95% CI: 28,04%, 50,7%)(Fig.3). The power estimation was .99 (very good) and the effect size was 0.42. During or after the procedures, no major or minor complications were observed.
Quantitative image Analysis - In the study and control groups, disc and herniation volume reductions evaluated with IDVA, were significantly more frequent in the responders group than in the non responders group. Student’s T test showed a statistically significant reduction at around 6 months of follow-up(p < 0.05) after treatment, with an average reduction of whole discs with herniation volumes around 4-5% (Table 2). Corresponding DWI-ADC analysis of intervertebral discs, before and after treatment, showed statistically significant difference between responders and non responders in terms of reduction in water diffusion(Fig.4) quantified by the corresponding value of the apparent diffusion coefficient(ADC) in particular in the follow-up of the second month of the study group(p < 0.05) (Table. 2).
Diagnostic accuracy - In our study, by plotting ROC curve areas(Table 3) from observed findings in the second month of follow-up, we determined that accuracies for predicting shrinkage of lumbar disc herniation treated with oxygen-ozone(O2-O3) discolysis of DWI-ADC and IDVA were 0,81 and 0.68 respectively. DWI-ADC obtained the best results with sensitivity of 82%, specificicy of 70%, positive predictive value of 94% and negative predictive value of 41% when an ADC value of 2.10 x 10 -3 mm 2 / sec was used as a threshold value for differentiating a positive or negative response to treatment.
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