Guo R-M, Lin W-S, Liu W-M, Zhou W-Y, Cao S-E, Wang J, Li Q-L
Department of Radiology, The Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
Department of Laboratory, The Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
Clin Radiol. 2018 Mar;73(3):231-236. doi: 10.1016/j.crad.2017.10.015. Epub 2017 Nov 20.
To quantitatively assess fat infiltration in the sacroiliac joints (SIJs) of patients with ankylosing spondylitis (AS) by measuring the fat/water signal ratios of periarticular bone marrow with iterative decomposition of water and fat with echo asymmetry and least square estimation (IDEAL).
Routine SIJ magnetic resonance imaging (MRI) and IDEAL were performed on 40 patients with AS and 30 healthy subjects. The fat infiltration regions (FIRs) and normal-appearing regions (NARs) of patients were measured based on the fat/water signal intensity on IDEAL.
AS patients had higher fat/water signal ratios on FIRs and NARs (65.4-85.4%, p<0.05, and 44.1-70.7%, p<0.05, respectively) compared to healthy controls (38.3-43.3%). After treatment, the fat/water signal ratios of FIRs and NARs decreased (42.1-53.7% and 41.5-50.3%, respectively), but they remained higher than in the healthy controls (p<0.05). The fat infiltration was detected more effectively with a fat fraction map of the IDEAL sequence (95%) than other sequences, including the T1-weighted sequence (65%), and the fat/water signal ratios of the sacrum and ilium between the left and right sides of SIJs were approximately the same.
The findings of this study suggest that IDEAL may be useful as a quantitative and objective method for evaluating the fat infiltration in the periarticular bone marrow of SIJs with AS; additionally, the sensitivity of IDEAL is better than that of routine sequences in detecting micro-fat infiltration of SIJs, and IDEAL can be used to quantitatively measure the adipose content and monitor patient follow-up after AS treatment.
通过采用迭代分解水和脂肪的回波不对称最小二乘估计法（IDEAL）测量关节周围骨髓的脂肪/水信号比，定量评估强直性脊柱炎（AS）患者骶髂关节（SIJ）的脂肪浸润情况。
对40例AS患者和30名健康受试者进行SIJ常规磁共振成像（MRI）及IDEAL检查。基于IDEAL上的脂肪/水信号强度测量患者的脂肪浸润区域（FIR）和正常表现区域（NAR）。
与健康对照（38.3 - 43.3%）相比，AS患者FIR和NAR的脂肪/水信号比更高（分别为65.4 - 85.4%，p<0.05；44.1 - 70.7%，p<0.05）。治疗后，FIR和NAR的脂肪/水信号比下降（分别为42.1 - 53.7%和41.5 - 50.3%），但仍高于健康对照（p<0.05）。与其他序列（包括T1加权序列，65%）相比，IDEAL序列的脂肪分数图能更有效地检测到脂肪浸润（95%），且SIJ左右两侧骶骨和髂骨的脂肪/水信号比大致相同。
本研究结果表明，IDEAL可能是一种用于评估AS患者SIJ关节周围骨髓脂肪浸润的定量和客观方法；此外，IDEAL在检测SIJ微脂肪浸润方面的敏感性优于常规序列，并且可用于定量测量脂肪含量及监测AS治疗后患者的随访情况。
