神经根沉降征磁共振成像定量分析及其意义研究

Nerve root sedimentation sign MRI quantitative analysis and its significance

目的分析神经根沉降征(nerve root sedimentation sign,NRSS)与硬膜囊形态大小的关系及其意义。材料与方法回顾分析85例腰椎退变患者3.0 T磁共振成像资料,依T2WI轴位像马尾神经位于关节突连线背侧为NRSS阴性(-)、腹侧为阳性(+);硬膜囊形态大致分萎缩型和饱满型两类。测量硬膜囊面积(dural sac cross-section area,DSCA)及关节突连线腹侧(ventral)、背侧(dorsal)部分面积(v DSCA、d DSCA)并计算两者比值d/v值。DCSA分无腰椎管狭窄(lumbar spinal stenosis,LSS)(≥100 mm2)、相对LSS(76~100 mm2)和绝对LSS(≤75 mm2)3个等级。观察测量由两位高年资医师独立完成,结果行Kappa一致性检验;NRSS-和NRSS+层面DSCA、d/v值大小差异及DSCA不同级别对应层面d/v值比较采用t检验;DSCA不同级别间d/v值比较采用方差分析;NRSS与硬膜囊形态关系采用χ2检验。结果 85例腰2~5三节段NRSS-层面DCSA依次为(138.5±38.9)mm2、(124.8±33.5)mm2、(117.5±29.6)mm2,NRSS+层面依次为(118.5±31.7)mm2(P=0.032)、(95.5±27.9)mm2(P=0.029)、(80.2±25.4)mm2(P=0.027);萎缩型和饱满型硬膜囊占有比NRSS-层面为0.16、NRSS+层面为6.3(P=0.012);d/v值NRSS-层面为0.64±0.29,NRSS+层面为0.38±0.22(P=0.035),其中腰3~4、腰4~5层面间差异有统计学意义(P<0.05);DSCA三级d/v值依次为0.61±0.23、0.42±0.18和0.32±0.11,两两比较差异有统计学意义(F=18.46,P=0.025),腰2~5三节段对应层面d/v值差异有统计学意义(P<0.05)。结论 NRSS与硬膜囊形态、DCSA及d/v值大小相关,明析这些关系有助于诠释NRSS+形成机制。

Objective： To analyze the relations between nerve root sedimentation sign （NRSS） with the shape and size of dural sac and its signifcance. Materials and Methods： 3.0 T MRI data of 85 patients with lumbar degenerative were analyzed retrospectively, based on T2WI axis, NRSS negative （-） defined as horsetail nerve dorsal to the line connected between joints, and positive （＋） as it ventral to the line connected between joints. The form of dural sac was divided roughly into two types of atrophy and full. The dural sac cross-section area （DSCA） and its ventral part （vDSCA） and dorsal part （dDCSA） to the line connected between joints were measured, and both ratio d/v value was calculated. DCSA was divided into three levels： no LSS （≥100 mm2）, relative LSS （76-100 mm） and absolute LSS （≤75 mm2）. Observed by two high qualifcation doctor independently, result was checked by Kappa consistency; the comparison of differences of DSCA, d/v value and d/v value of the corresponding level in different level DSCA between NRSS- and ＋ was tseted by t test; the comparisons of d/v value between different DSCA levels using analysis of variance （ANOVA）; the relationship between NRSS with dural sac form was tseted by χ2 test. Results： In 85 cases, the DCSA of lumbar 2-5 three planes was （138.5±38.9） mm2, （124.8±33.5） mm2,（117.5±29.6） mm2 in NRSS- respectively and （118.5±31.7） mm2 （P=0.032）, （95.5±27.9） mm2 （P=0.029） and （80.2±25.4） mm2 （P=0.027） in NRSS＋respectively; the occupation ratio of atrophy and full dural sac was 0.16 in NRSS- and 6.3 in NRSS＋（P=0.012）; the d/v value was 0.64±0.29 in NRSS- and 0.38±0.22 in NRSS＋（P=0.035）; of DSCA≤75 mm2, 76-100 mm2 and ≥100 mm2, the d/v value was 0.61±0.23, 0.42±0.18 and 0.32±0.11 respectively, two more signifcant difference （F=18.46, P=18.46） and the signifcant difference was found in the corresponding level from lumbar 2-5 three section （P〈0.05）. Conclusions： NRSS was related to the morphology of dural sac and the size of DCSA and d/v value, understanding these relationships will help interpretation of formation mechanism of NRSS＋.