Ankylosing Spondylitis: A Study Of The Value Of Dynamic Enhanced MRI In Assessing Its Activity And Imaging Characteristics Of Spinal Fractures In The Advanced Stage

Objective1.To test contrast to findings of both diffusion-weighted imaging(DWI)and dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI)in terms of the visual assessment of activity in sacroiliitis of ankylosing spondylitis(AS)patients.2.To explore injury mechanism and imaging manifestations of patients with AS and spinal fracture so as to reduce missed diagnosis and misdiagnosis.Materials and methods1.32 patients(18 males and 14 females)with AS in our hospital were enrolled prospectively according to the standard of diagnostic criteria for AS revised in 1984.All of the,were evaluated with MRI and clinical activity markers including C-reactive protein(CRP),erythrocyte sedimentation rate(ESR)and Bath Ankylosing Spondylitis Disease Activity Index(BASDAI)scores.According to these clinical data,We divided the patients with AS into resting phase group and active phase group and analyzed the MRI findings of each groups using the quantitative parameters of DCE-MRI including contrast transfer coefficient(Ktrans)and apparent diffusion coefficient(ADC)of DWI,and then the differences of quantitative data between the two groups were compared.Spearman correlation analysis was performed between the parameters and markers of clinical activity including ESR,CRP and BASDAI scores.2.Image and clinical data of 15 cases with AS and spinal fracture as well as 37 cases with common spinal fracture were reviewed retrospectively and analyzed subsequently.Results1.Among the 32 patients,18 patients(10males and 8 females)were in active phase group and the other 14 patients(8 males and 6 females)were in resting phase group.We observed a significant difference in the DCE parameters Ktrans and ADC values between the two groups(P= 0.02 for Ktrans,P= 0.002 for ADC).The Ktrans values and ADC values were the higher in patients with active sacroiliitis than patients with resting stage sacroiliitis.We found a statistically significant correlation between the Ktrans values and BASDAI scores(r= 0.55,P=0.001),the CRP levels(r=0.351,P=0.049)or ESR levels(r=0.373,P=0.036).Only between the ADC values and BASDAI scores(r=0.503,p=0.003)or ESR levels(r=0.383,p=0.031)could we find a statistically significant correlation.Besides,there was a statistically significant correlation between Ktrans values and ADC values(r=0.352,p=0.048)..2.(1)Among the patients with AS,there were 11 cases who had explicit trauma history,there were 9 cases whose imaging findings were three column fracture,there were 7 cases who had spinal canal compression or spinal cord injury,and there were 6 cases whose fracture lines were across the intervertebral disk.Among the patients with common spinal fracture,the corresponding number were 3 6,4,5,0 in sequence.(2)Statistic analysis findings:There were significant differences between AS fracture group and common fracture group in trauma history(?2=4.565,P<0.05),three column fracture(?2=11.274,P<0.05),spinal canal compression or spinal cord injury(?2=4.873,P<0.05)and traversing the intervertebral disk(?2=13.041,P<0.05).Conclusion1.Quantitative DCE-MRI parameters and ADC values of DWI can be used to differentiate active sacroiliitis and resting stage sacroiliitis.The DCE-MRI parameters are good visual imaging markers of activity in patients with AS and have a better consistency with clinical activity markers than ADC values.2.There are obvious differences between patients with AS and spinal fracture and patients with common spinal fracture in injury mechanism.X-ray,CT and MRI could complement each other with their respective advantages in the diagnosis of AS with spinal fracture.Taking full advantage of the differences and choosing appropriate imaging examinations are conducive to reduce missed diagnosis and misdiagnosis.