Application of Magnetic Resonance Diffusion Weighted Imaging in Early Ankylosing Spondylitis
|School||Huazhong University of Science and Technology|
|Course||Medical Imaging and Nuclear Medicine|
|Keywords||magnetic resonance imaging diffusion weighted imaging ankylosing spondylitis apparent diffusion coefficient|
Objective To estimate the evaluation of Magnetic Resonance Diffusion Weighted Imaging technique in detection of the abnormalities in sacroiliac joint of early Ankylosing Spondylitis patients. Using whole body DWI to investigate the characteristic manifestation and availability in evaluation of Ankylosing Spondylitis patients.Subjects and Methods 34 chronic low back pain patients who performed magnetic resonance diffusion weighted imaging of sacroiliac joint were included in this project, in which 16 patients were diagnosed as early Ankylosing Spondylitis (AS) and 18 patients as simple low back pain (LBP). To compare the difference of the apparent diffusion coefficient (ADC) value in subchondral bone marrow of AS versus LBP patients, GE special post-processing workstation was employed to analyse diffusion weighted images of sacroiliac joints, measuring ADC value of subchondral bone marrow in bilateral iliac bone and sacrum along sacroiliac joints. An independent sample t-test (SPSS16.0,SPSS, Chicago, Ill) was used to statistically analyse the difference of ADC value between AS and LBP patients, with P<0.05 as the level of significant statistical different. The mean ADC value of lesions presented in AS patients were measured. Whole body diffusion weighted imaging were performed in 8 clinical medical imaging confirmed AS patients, analysed by MIP, MPR techniques with post-processing workstation, compared with conventional MRI images to evaluate the availability of whole body diffusion weighted imaging techniques.Results Subchondral bone marrow ADC values of bilateral sacroiliac joint of 16 AS patients were measured, which mean value (mean±SD) of ADC were (0.506±0.190)×10-3 mm2/s in left sacrum and (0.485±0.136)×10-3 mm2/s in the left iliac bone versus (0.482±0.149)×10-3 mm2/s in the right sacrum and (0.542±0.116)×10-3 mm2/s in the right iliac bone. The mean values of ADC were measured in 18 LBP patients which were (0.317±0.007)×10-3 mm2/s in left sacrum and (0.301±0.053)×10-3 mm2/s in the left iliac bone versus (0.294±0.039)×10-3 mm2/s in the right sacrum and (0.344±0.075)×10-3 mm2/s in the right iliac bone. The mean value of ADC in bilateral sacrum and iliac bone of AS patients were higher than that of the LBP patients and significant statistical difference was exist between two groups (P<0.05). The mean ADC value of lesions of early AS patients is (0.932±0.299)×10-3 mm2/s。8 clinical confirmed AS patients were tested with whole body diffusion weighted imaging techniques. By suppressing the systemic background signal, abnormal changes - bone marrow edema were detected in bilateral sacroiliac joints and extra-sacroiliac joint lesions of which locations were corresponding with clinical symptom were also detected in 4 AS patients. The mean ADC value of lesions in sacrum is (1.311±0.384)×10-3mm2/s and (1.176±0.271)×10-3mm2/s in iliac bone.Conclusion Magnetic resonance diffusion weighted imaging techniques was extremely sensitive to bone marrow edema of early ankylosing spondylitis patients, by which early abnormal pathologic changes could be detect. Moreover, DWI sequence has a high speed in scanning and could accomplish an examination in a very short time. To a certain extent, by measuring the ADC value in subchondral bone marrow of sacroiliac joint, quantitative evaluation could be achieved in early AS patients to differentiate with LBP patients. In terms of the advantage of whole body diffusion weighted imaging in AS evaluation, combined with post-processing techniques such as MIP, MPR etc, a comprehensive evaluation of lesions distribution of AS patients can be achieved to accurately estimate AS patients’ condition, which would be great helpful in following treatment and prognosis evaluation. Compared with mean ADC value of lesions of AS patients, suspicious lesions can be qualitatively identified.