Introduction

AS is a chronic irreversible inflammatory disease with unknown etiology[1], characterized by axial bone inflammation and rigidity, which mainly affects young and middle-aged men[2]. Monitoring the alterations in BME of the sacroiliac joint is vital for evaluating the progression of AS patients' condition and the efficacy of medications [3]. Accurate and non-invasive imaging can enable AS patients to receive precise diagnosis and early treatment [3]. Therefore, this study mainly discussed the application value of MRI T2 mapping, DWI and SPARCC scores in evaluating the bone marrow edema in sacroiliarthritis of patients with AS in the active inflammatory stages[4]. Furthermore, provide a better imaging program for clinicians to aid in the early diagnosis of AS and in evaluating the efficacy of treatments.

Methods

Thirty patients （23 males, aged 30.40±6.00 years）with AS who received biologics from September 2021 to January2023 were included as the patient group, and 32 healthy individuals (15 males , aged 27.53±7.28 years)were included as the control group. Routine MRI, T2 mapping and DWI sequences of Sacroiliac joint were performed in AS patients before treatment, 6 months after treatment with biological agents, and so as to control group. The paired sample t-test was employed to compare the mean T2 values, ADC values and SPARCC scores before and 6 months following AS treatment, as well as between the treatment and control groups, respectively. A Correlation ROC curve was constructed to evaluate the diagnostic efficacy of SPARCC score, DWI and T2mapping before and after AS treatment. Binary Logistic regression was used to analyze the correlation diagnostic efficacy of pairwise combination and combination of the three quantitative values.

Results

The SPARCC score, ADC value and T2 value following AS treatment exhibited significant decrement compared to their pre-treatment counterparts, were significantly lower than those before AS treatment, and these differences were statistically significant (P <0.001)(Figure1). The sensitivity of ADC before and after treatment was the highest (96.7%), the specificity was 70.0%, and the area under the curve was about 0.908 (95% confidence interval: 0.837-0.980), P < 0.001. The diagnostic sensitivity of the combined ADC and T2 values before and after AS treatment was 86.7%, the specificity was the highest (93.3%), and the area under the curve was the largest (about 0.927 (95% confidence interval: 0.852-1.001), P < 0.001(Table、figure2).

Discussion

In this study, the ADC and T2 values decreased after treatment, indicating that DWI and T2 mapping can effectively evaluate water molecule changes of BME [5,6]. The combined use of DWI and T2 mapping can more accurately assess the diffusion motion and content changes of water molecules in BME under the sacroiliac joint in AS [7], thus providing high value for evaluating the therapeutic effect of AS[8]. The effectiveness of SPARCC score is slightly lower when used alone to evaluate the therapeutic effect of AS or when combined with other quantitative MRI parameters to evaluate its therapeutic effect.

Conclusions

The combination of DWI and T2 mapping demonstrated superior efficacy in assessing drug efficacy in AS sacroiliac arthritis. The diagnostic efficiency of DWI alone is better than that of SPARCC score combined with T2 mapping.

Acknowledgements

Associate Professor Song Lingling of Guizhou Medical University, thanks to the experts of the Imaging Technology Group of the Affiliated Hospital of Guizhou Medical University, thanks to all the members of the skeletal muscle system group for their help and support.

References

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