压缩性骨折椎体真空征的病理与影像表现对照研究

目的 研究压缩性骨折椎体真空征(intravertebral vacuum phenomenon,IVP)的影像表现.方法 对209例椎体压缩性骨折行经皮椎体成形术(percutaneous vertebroplasty,PVP)与经皮椎体后凸成形术(percutaneous kyphoplasty,PKP)患者常规实施椎体组织活检.所有患者术前行常规X线、CT、MR检查,评价IVP与病理学结果的一致性及IVP诊断压缩性骨折椎体骨坏死的阳性预测值、阴性预测值、特异度、敏感度及Youden指数,对IVP与骨坏死一致性行Fisher确切概率法检验.结果 病理学检查,209例椎体压缩性骨折中单纯骨质疏松146例(69.9%),骨质疏松合并骨坏死10例(4.8%),恶性肿瘤53例(25.4%).术前影像检查发现10例IVP,常规X线检查显示椎体线性透亮区,CT能更好显示椎体内积气,MR T_1WI均表现为低信号,随患者仰卧时间不同,T_2WI信号可有多种变化,其中9例病理学检查发现骨坏死;病理学检查10例骨坏死中9例有IVP,1例影像仅表现为骨质疏松征,IVP与病理学诊断有明显相关性(P<0.01).IVP诊断骨坏死的阳性预测值为90.0%(9/10),阴性预测值为99.5%(198/199),敏感度为90.0%(9/10),特异度为99.5%(198/199),Youden指数为0.9.结论 压缩性骨折椎体中出现IVP,提示椎体局部骨出现坏死.

Imaging and pathologic study of intravertebral vacuum phenomenon in vertebral compression fracture

Objective To investigate the features of intravertebral vacuum phenomenon (IVP)in vertebral compression fractures (VCFs). Methods Two hundred and nine patients with VCFs underwent percutaneous vertebroplasty (PVP) and percutaneous kyphoplasty (PKP). The biopsies and the images of X-ray, CT, MRI of VCFs were obtained. The consistency between IVP and osteonecrosis on histology and the positive predictive value (PPV), negative predictive value (NPV), sensitivity, specificity and Youden index of IVP for diagnosing local osteonecrosis in VCFs were analyzed. Fisher exact probability test was used to analyze the coherence between IVP and osteonecrosis. Results Histological examination revealed 146(69.9%) osteoporoses, 10 (4.8%) osteonecroses with osteoporoses, 53 (25.4%) neoplasms. Prior to surgery,10 cases of IVP were found. Plain radiograph showed horizontally oriented lucent cleft in the vertebral body;CT further confirmed the location of gas;T_1-weighted MR image appeared hypointensity,while the signal intensity of T_2-weighted MR image differed, depending on the duration of recumbency. Nine of 10 patients with IVP showed osteonecrosis on histology, while 9 of 10 patients with osteonecrosis contained IVP. The association of osteonecrosis on histology and the IVP was statistically significant(P <0.01). The PPV, NPV, sensitivity, specificity, and Youden index for diagnosing local osteonecrosis was 90% (9/10), 99.5% (198/199), 90.0% (9/10), 99.5% (198/199), and 0.9, respectively. Conclusion The IVP is stongly suggestive of local osteonecrosis in vertebral compression fracture.