mDixon Quant脂肪定量技术对强直性脊柱炎骶髂关节炎的应用研究

Evaluation of sacroiliitis with MR mDixon Quant fat quantification in patients with ankylosing spondylitis

目的探讨在MR mDixon Quant上根据脂肪分数评价强直性脊柱炎骶髂关节炎脂肪沉积的应用价值。方法收集2015年5月—2016年4月明确诊断的强直性脊柱炎病人63例作为病例组,其中男53例,女10例,平均年龄(25.2±3.8)岁;同时纳入年龄、性别构成匹配的20名健康志愿者,其中男17例,女3例,平均年龄(24.7±4.1)岁。所有受试者均行双侧骶髂关节常规MR扫描、MR mDixon Quant检查。依据研究组病人的影像表现、BASDAI评分、实验室指标将其分为早期活动组(20例)、慢性活动组(25例)、非活动组(18例)3组。在m Dixon Quant序列脂肪分数映射图中测量3组骨髓水肿区、脂肪沉积区的脂肪分数,测量所有病人及健康志愿者第1骶孔间骨髓的脂肪分数作为参考脂肪分数。采用独立样本t检验比较早期活动组、慢性活动组骨髓水肿病灶,以及慢性活动组、非活动组的脂肪沉积病灶脂肪分数的差异。采用单因素方差分析比较3个病变组和对照组的参考脂肪分数差异。结果慢性活动组骨髓水肿病灶的参考脂肪分数高于早期活动组[(30.6±10.6)%∶(20.3±10.2)%],非活动组脂肪沉积病灶的脂肪分数高于慢性活动组[(89.4±1.1)%∶(81.6±1.7)%](均P<0.05)。3个病变组的病变外区骨髓和对照组相应区域骨髓的脂肪分数差异无统计学意义(P>0.05)。结论 MR mDixon Quant技术通过测量脂肪分数,可以量化骶髂关节炎骨髓水肿区、脂肪沉积区的脂肪含量,在判断病情变化中具有价值。

Objective To investigate the value of MR m Dixon Quant technique by using fat fraction（FF） to evaluate the fat deposition of sacroiliitis in patients with ankylosing spondylitis（AS）. Methods A total of 63 patients（53 males, 10 females; 25.2±3.8 years） who had clinically confirmed AS were prospectively collected from May 2015 to April 2016 as the patient group, and twenty age-and gender-matched healthy volunteers（17 males, 3 females; 24.7±4.1 years） were enrolled into the control group. The routine sacroiliac joints MR scan and transverse MR m Dixon Quant scan were performed. All patients were divided into early active group（n=20）, chronic active group（n=25）, and non-active group（n=18） depending on their imaging findings, BASDAI scores, and laboratory parameters. The FF of bone marrow edema area and fat deposition area was calculated on quantitative fat fraction map of the m Dixon Quant sequence in all the patients. The FF of the first sacral interforaminal bone marrow was calculated as reference FF in both patients and healthy volunteers. Independent sample t test was used to compare the FF of edema area between early active group and chronic active group. Independent sample t test was also used to compare the FF of fat deposition area between chronic active group and non-active group. One-way ANOVA was used to compare the reference FF among patient and control groups. Results The FF of edema area of the chronic active group was significantly higher than that of the early active group [（30.6±10.6）% vs.（20.3±10.2）%,P〈0.05]. The FF of fat deposition area of non-active group was significantly higher than that of chronic active group [（89.4±1.1）% vs.（81.6±1.7）%,P〈0.05]. The reference FF in both patient groups and control group had no significant difference（P〉0.05）. Conclusions MRmDixon Quant technique by using FF can effectively quantify the relative content of fat in both bone marrow edema area and fat deposition area. MR mDixon Quant fat fraction technique could be used for assessing the activity of the disease.