急性骨质疏松性椎体压缩性骨折患者早期骨髓水肿磁共振形态特征与经皮椎体成形术后骨水泥分布的关系

Relationship between MRI features of early bone marrow edema and the bone cement distribution after percutaneous vertebroplasty in patients with acute osteoporotic vertebral compression fracture

目的观察急性骨质疏松性椎体压缩性骨折(osteoporosis vertebral compression fracture, OVCF)患者早期骨髓水肿磁共振形态特征,探讨其与经皮椎体成形术后骨水泥分布的关系。方法 OVCF患者88例,共发生110个急性OVCF椎体,均行经皮椎体成形术治疗,术前行磁共振T_(1)WI、T_(1)WI序列扫描,根据骨折椎体骨髓水肿T_(1)WI低信号形态特点将110个急性OVCF椎体分为Ⅰ型组24个(弥漫型),Ⅱ型组49个(半球或不均匀型),Ⅲ型组37个(横行条带型)。术后采用CT检查骨水泥分布情况,根据骨水泥弥散特征评估骨折椎体内骨水泥中心平面超过椎体中线及骨水泥入口侧达上下终板发生情况;根据骨水泥形状特征分为不均质型(骨水泥在压缩骨折椎体内分布不均匀、呈不规则团块状)、均质型(骨水泥在压缩骨折椎体内分布比较均匀、呈蜂窝状)、密实型(骨水泥在压缩骨折椎体内呈高密度、边缘锐利的团块状影),比较3组骨水泥形状特征、弥散及渗漏情况。结果Ⅰ型组术后骨水泥形状特征密实型比率(54.2%)高于不均质型(25.0%)、均质型(20.8%)(χ^(2)=4.269,P=0.039;χ^(2)=5.689,P=0.017),不均质型与均质型比较差异无统计学意义(χ^(2)=0.118,P=0.731);Ⅱ型组术后骨水泥形状特征密实型比率(14.3%)低于不均质型(44.9%)、均质型(40.8%)(χ^(2)=11.019,P=0.001;χ^(2)=8.640,P=0.003),不均质型与均质型比较差异无统计学意义(χ^(2)=2.003,P=0.157);Ⅲ型组术后骨水泥形状特征不均质型比率(64.9%)高于均质型(18.9%)、密实型(16.2%)(χ^(2)=16.044,P<0.001;χ^(2)=18.164,P<0.001),均质型与密实型比较差异无统计学意义(χ^(2)=0.093,P=0.760)。Ⅰ型组骨水泥入口侧达到上下终板发生率(75.0%)低于Ⅱ型组(95.9%)(χ^(2)=7.224,P=0.017),Ⅰ型组与Ⅲ型组(89.2%)、Ⅱ型组与Ⅲ型组比较差异均无统计学意义(χ^(2)=2.138,P=0.144;χ^(2)=1.471,P=0.225)。3组术后骨水泥超过椎体正中矢状面发生率、骨水泥渗漏发生率比较差异均无统计学意义(P>0.05)。结论急性OVCF患者早期骨髓水肿磁共振T_(1)WI低信号表现呈弥漫型时,经皮椎体成形术术后骨水泥形态CT影像多为高密度、边缘锐利的团块状影,提示其扩散范围和弥散受限。

Objective To observe the MRI features of bone marrow edema in early stage in patients with acute osteoporotic vertebral compression fracture(OVCF), and investigate its relationship with the distribution of bone cement after percutaneous vertebroplasty(PVP). Methods Eighty-eight patients with 110 acute OVCF vertebraes underwent PVP. T_(1)/T_(2) weighted imaging sequences for spine MRI were performed before surgery. Totally 110 acute OVCF vertebraes were divided into 24 vertebraes in diffuse type(type Ⅰ), 49 vertebraes in hemisphere or heterogeneous type(type Ⅱ), and 37 vertebraes in transverse band type(type Ⅲ) according to the low signal morphological features of bone edema on T_(1)WI. CT scan was done to observe the bone cement distribution after surgery. The bone cement diffusion feature was assessed by whether the central plane of bone cement in fractured vertebrae exceeded the midline of the vertebrae, and whether the bone cement on entrance side reached the upper and lower endplates. The bone cement shape was divided into heterogeneous type(with the bone cement unevenly distributing in the compressed fracture vertebrae,showing irregular masses),homogeneous type(with the bone cement evenly distributing in the compressed fracture vertebrae,in a honeycomb shape)and compact type(with the bone cement presenting a high density in the compressed fracture vertebrae,in the form of a sharp-edged mass).The shape diffusion and leakage of the bone cement were compared among three groups.Results In typeⅠ group,the percentage of postoperative bone cement shape was higher in compact type(54.2%)than that in heterogeneous type(25.0%)and homogeneous type(20.8%)(χ^(2)=4.269,P=0.039;χ^(2)=5.689,P=0.017),and showed no significant difference between heterogeneous type and homogeneous type(χ^(2)=0.118,P=0.731).In typeⅡgroup,the percentage of postoperative bone cement shape was lower in compact type(14.3%)than that in heterogeneous type(44.9%)and homogeneous type(40.8%)(χ^(2)=11.019,P=0.001;χ^(2)=8.640,P=0.003),and showed no significant difference between heterogeneous type and homogeneous type(χ^(2)=2.003,P=0.157).In type Ⅲ group,the percentage of postoperative bone cement shape was higher in heterogeneous type(64.9%)than that in homogeneous type(18.9%)and compact type(16.2%)(χ^(2)=16.044,P<0.001;χ^(2)=18.164,P<0.001),and showed no significant difference between homogeneous type and compact type(χ^(2)=0.093,P=0.760).The incidence of bone cement reaching the upper and lower endplates on the entrance side was lower in type Ⅰ group(75.0%)than that in typeⅡ group(95.9%)(χ^(2)=7.224,P=0.017),and showed no significant difference between typeⅠ group and typeⅢ group(89.2%)or between typeⅡ group and typeⅢ group(χ^(2)=2.138,P=0.144;χ^(2)=1.471,P=0.225).There were no significant differences in the incidence of bone cement exceeding the mid-sagittal plane of the vertebrae and the incidence of bone cement leakage after PVP among three groups(P>0.05).Conclusion When the early bone marrow edema in patients with acute OVCF shows diffuse low signal on T_(1)WI,the shape of bone cement after PVP is mostly high-density and sharp-edged masses on CT images,suggesting its spread and diffusion limit.