The Evaluation Value Of DWI In Ankylosing Spondylitis Activity

Objective: To investigate the best b value of sacroiliac joint in 1.5T magnetic resonance imaging(DWI)by comparing the difference of diffusion weighted imaging(DWI)and ADC value,and lay a foundation for later research on ankylosing spondylitis sacroiliac arthritis.Methods: Twenty healthy volunteers aged 15 to 35 years old(14 males and 6 females)were randomly selected for routine MRI scan of the sacroiliac joint and different b values(b=0,400,600,800s/mm2(DWI)were used to observe the ADC value of the sacroiliac joint at different b values,and the ADC values of the bone marrow area(sacral side and ilium side)of the sacroiliac joint under the two kinds of b values were measured.Compair the difference in the mean of the ADC values under the three b values.Results: After comparison,it was found that when the b value was 400s/mm2 and600s/mm2,the image was clear and the sacroiliac joint was well compared with the surrounding tissue.When the b value was 800s/mm2,the sacroiliac joint showed less clear and contrast with the surrounding tissue decline.Both sides of the sacroiliac joint surface bone marrow area of the ADC value with the b value increased gradually decreased.There were significant differences in ADC values between the right iliac side,the right sacral side,the left sacral side and the left iliac lateral joint under the three kinds of b values.There was no significant difference in the ADC value between the two sacral and iliac joints.When the b value of 400s/mm2,both sides of thesacroiliac joint surface bone marrow area of the larger the dispersion of the ADC value;b value of 600s/mm2 and 800s/mm2 when the dispersion is relatively small.Conclusion: When b value is 600s/mm2,DWI image is clearer,ADC value dispersion is small,600s/mm2 is 1.5T magnetic resonance DWI shows sacroiliac joint appropriate b value.6Objective: To evaluate the value of DWI in the regulation of sacroiliac arthritis inankylosing spondylitis(AS);and to explore the value of total spinal diffusion weighted imaging in the evaluation of ankylosing spondylitis activity.Methods: A total of 76 patients with clinically diagnosed AS were enrolled in the Wanyan Medical College Yijishan Hospital from October 2015 to December 2016.According to the clinical ankylosing spondylitis activity score(BASDAI)and laboratory examination(erythrocyte sedimentation rate,C reaction Protein,etc.)were divided into stable group(32 cases)and active group(44 cases).Twenty healthy volunteers were selected as control group.All the subjects underwent routine MR and DWI examination of sacroiliac joint,and the ADC values of sacroiliac joint were obtained.(DWI and ADC images with abnormal high signal area were obtained by routine;No abnormality was taken as the mean ADC value of the sacral side and the iliac bone on both sides of the joint).At the same time,all patients with AS were scored using the Canadian Spine Osteoarthritis Research Association(SPARCC)sacroiliac joint scoring system.The ADC value of the sacroiliac joint between the three groups was compared by using the variance analysis.Analysis of ADC significance in detecting the activity of AS by using the receiver characteristic curve(ROC curve).The Spearman correlation coefficient was used to analyze the ADC value of the sacroiliac joint and the SPARCC Score and its clinical BASDAI score,ESR and C-reactive protein correlation.In addition,34 patients with active AS and 20 healthy volunteers were enrolled in the whole spine diffusion weighted imaging.To analyze the involvement of sacroiliac jointand spine,and spine-related inflammatory lesions in AS patients combined with conventional image.The ADC values of inflammatory vertebrae were measured of AS patients,and the ADC value of normal vertebral body was measured.The difference of ADC value between the vertebral body and the normal vertebral body was compared by t test.Results:(1)The median ADC value of sacroiliac joint was 1278.50×10-6mm2/s in the active group,483.70×10-6mm2/s in the stable group and 478.46×10-6mm2/s in the control group(P <0.01).There was significant difference between the active group and the stable group,the active group and the control group(P <0.01).There was no significant difference between the stable group and the control group(P> 0.05).(2)ROC curve analysis showed that the optimal critical ADC value was 1010.5×10-6mm2/ s(the area under the curve was 0.941,the sensitivity was 84.1% and the specificity was 90.6%)in the active and stable groups of AS patients.(3)The ADC value and SPARCC score of sacroiliac joint in AS patients were positively correlated with clinical BASDAI score,ESR and CRP.The ADC value and SPARCC score of sacroiliac joint in AS patients were significantly correlated with clinical BASDAI scores(r=0.797,0.748,P <0.01),and the ADC value of sacroiliac joint was significantly correlated with SPARCC score(r = 0.889,P <0.01).Among the 34 cases of sacroiliac joint and the whole spine DWI active AS patients,13 cases only sacroiliac joint inflammatory lesions were seen,7 cases only spine inflammatory lesions were seen,14 cases of sacroiliac joint and spine inflammatory lesions were seen.Among the 21 cases withing spine inflammatory lesions in AS patients,male 20 cases,female 1 case,male and female spine inflammation positive rate was statistically significant;10 cases with only thoracic involved,3 cases with only lumbar involved,8 cases with thoracic and lumbar spine involved,lesions are located in the lower thoracic and upper lumbar spine.The ADC value of vertebral spine was1169.76±259.22×10-6mm2/s,and the ADC value of normal vertebral body was475.47±53.75×10-6mm2/s,the difference was statistically significant(t=12.18,P<0.05).Conclusion:ADC value and SPARCC score can be used as an important index to evaluate the activity of sacroiliac arthritis.SPARCC score is relatively cumbersome and can only give semi-quantitative assessment,and DWI was sensitive to bone marrow edema,imaging speed is fast,and can be measured by measuring the ADC value of the lesion quantitative analysis,and then determine the degree of sacroiliac joint inflammation activity,DWI is the AS patients with sacroiliac joint examination of the ideal choice.On the basis of sacroiliac joint examination in patients with AS scan on the whole spine scan can be more comprehensive and reliable assessment of AS activity.