Active Sacroiliitis In Patients With Axial Spondyloarthritis: Evaluation With DWI, ~1H-MRS

PurposeTo evaluate the value of DWI and 1H-MRS to detect active inflammatory changes in the sacroiliac joint (SIJ) of patients with axial Spondyloarthritis (SpA) according to DWI and 1H-MRS of SIJ in the healthy volunteers and the patients with axial SpA active sacroiliitis, SIJ (or sacroiliitis) to observe the manifestation of DWI and 1H-MRS and to get some idea of the characteristics of molecular imaging in the SIJ (or sacroiliitis).Objects and MethodsDWI,1H-MRS,conventional MRI examinations were done oblique coronary on bilateral SIJs of 19 participants,involving 11 healthy volunteers(the control group) and 8 patients(the case group) underwent clinical and conventional MRI evaluation for axial SpA active sacroiliitis.The conventional MRI,DWI,ADC and EADC images were transmitted to two experienced radiology doctors respectively at the workstation, and then finished the imaging reading,evaluation and the data(ADC values and EADC values) measurement blinded.The spectrum data was first processed with the LCModel software, then the position of the water peak and the lipid peak were observed, and finally the water to lipid area ratio (WLR) was made a record.The experimental data was input and analyzed by SPSS19.0 statistics software. 1. In the control group, at b values of 100s/mm~2 and 300s/mm~2, satisfactory DWI images of SIJ were obtained, and the display rate was 100%; at b values of 300s/mm~2, it could provide a more satisfactory image than at b values of 100s/mm~2 or 600s/mm~2.2. In the control group, the periarticularly bone marrow in the SIJ showed a higher or lower signal on the DWI image, hypointense signal on the ADC image and hyperintense signal on the EADC image. The periarticularly bone marrow oedema showed a hyperintense signal on the DWI and ADC images while hopyintense signal on the EADC image.3. At b values of 100s/mm~2, the ADC values of only the right iliac and right sacral periarticularly bone marrow in the case group were higher than those in the control group while EADC values were lower, there were a statistical difference between the groups(P<0.05). At b values of 300s/mm~2, the ADC values of the periarticularly bone marrow at each side in the case group were significantly higher than those in the control group while EADC values were lower, the difference were statistically significant (P <0.01). Using the STIR sequeces as the reference standard, for b values of 100s/mm~2, the area under the ROC curve (Az) of the ADC values and the EADC values in diagnosis axial SpA active sacroiliitis were 0.784 (P<0.01) and 0.748 (P<0.01) respectively, with a certain diagnostic capability. ADC values at 1.72×10-3mm~2/s and EADC values at 0.20 were the best critical point, and their sensitivity (81.0%,76.2%) and specificity (82.0%,73.0%) were high. For b values of 300s/mm~2, Az of the ADC values and the EADC values in diagnosis axial SpA active sacroiliitis were 0.974 (P<0.01) and 0.972 (P<0.01) respectively, it had a better diagnostic capability. ADC values at 0.95×10-3mm~2/s and EADC values at 0.36 were the best critical point, and their sensitivity (100.0%,95.2%) and specificity (91.0%,89.0%) were high. At b values of 300s/mm~2, ADC values and EADC values had a higher diagnostic values in axial SpA active sacroiliitis.4. All the subjects got satisfactory SIJ spectrograms which contained several metabolin peaks: methyl peak at 0.9 ppm, methylene peak at 1.3 ppm,1.6 ppm,Results 2.0 ppm, ethenyl peak at 5.3 ppm and the water peak at the 4.7 ppm.WLR of the active inflammatory group was higher than those of the control group and the inactive group, there was a significant difference between the two groups. However, WLR of the control group and the inactive group were close, there was no statistical significance between them. Using the STIR sequeces as the reference standard, Az of WLR in diagnosis axial SpA active sacroiliitis were 0.929 (P<0.01), it had a better diagnostic capability. WLR at 0.77 was the best critical point, and its sensitivity (83.3%) and specificity (92.3%) were high.Conclusion1. B values of 300s/mm~2 is the basic in measuring the ACD values and EADC values as it can provide a satisfactory SIJ DWI image.2. In the control group, the periarticularly bone marrow in the SIJ showed a higher or lower signal in the DWI image, hypointense signal in the ADC image and hyperintense signal in the EADC image. The periarticularly bone marrow oedema showed a hyperintense signal in the DWI and ADC images while hopyintense signal in the EADC image.3. In SIJ 1H-MRS spectrograph, lipid peak may be several different sites (0.9, 1.3, 1.6, 2.0, 5.3), While the water peak site was 4.7 ppm. WLR was obviously high in the active inflammatory group.4. The ADC values and the EADC values at b values of 300s/mm~2, and WLR are as standard for diagnosis axial SpA active sacroiliitis. They can discriminate acute lesions in sacroiliitis as well as the STIR sequeces can.