新生儿分娩性臂丛神经麻痹的MR扫描方案优化研究

Study on Optimization of MR Scanning Scheme in Neonatal Obstetrical Brachial Plexus Palsy

目的前瞻性对9例临床诊断一侧臂丛神经损伤的新生儿进行磁共振常规检查序列、3D-FIESTA、冠状位及轴位T_(2)-STIR序列成像,旨在评价各序列对新生儿臂丛神经损伤的诊断价值,进一步优化新生儿臂丛神经损伤的MR扫描方案。方法纳入分娩后即出现单侧上肢运动障碍且临床诊断分娩性臂丛神经损伤的新生儿,剔除分娩后双上肢运动障碍的患儿、颅脑损伤及颈部畸形的患儿,所有患儿均行轴位T_(1)WI,轴位T_(2)WI,轴位及冠状位T_(2)-STIR以及3D-FIESTA序列扫描。对5个序列显示臂丛神经的节前、节后段损伤效果的评价,并进行统计学分析。结果共纳入9例,其中男4例,女5例,中位年龄9天。1例为臂丛神经节前、节后段均损伤,共计累及4条臂丛神经,余8例均为节后神经根损伤,共累及23条臂丛神经。5例为右侧臂丛神经损伤,4例为左侧臂丛神经损伤。节前神经根损伤MR表现为神经根消失或纤细、神经根袖扩张和、或创伤性脊膜囊肿的形成,节后神经根损伤MR表现为神经根、干肿胀增粗、走行僵直,神经干的粘连肿胀变形,并伴周围结构损伤。在5个MR序列图像上,对27条损伤的臂丛神经显像进行主观评分,影像诊断平均评分分别为轴位T_(1)WI序列(1.04±0.19)分,轴位T_(2)WI序列(1.11±0.32)分,轴位T_(2)-STIR序列(1.74±0.76)分,冠状位T_(2)-STIR序列(3.81±0.40)分,3D-FIESTA序列(3.78±0.42)分;对1例4条节前段损伤的臂丛神经进行评分分别为轴位T_(1)WI序列1.00分,常规轴位T_(2)WI序列1.5分,轴位T_(2)-STIR序列2.5分,冠状位T_(2)-STIR序列2.5分,3D-FIESTA序列4分。在3D-FIESTA序列,冠状位T_(2)-STIR序列进行损伤神经灰阶值与健侧同水平脊神经走行区灰阶值比值对比分析,T_(2)-STIR序列约1.57±0.28,3D-FIESTA灰阶比值约1.33±0.15,配对t检验,t值约4.78,P<0.05,差异显著。结论冠状位T_(2)-STIR序列对节后段臂丛神经损伤诊断价值高于3D-FIESTA,3D-FIESTA序列对于节前神经段损伤的诊断优势高于冠状位T_(2)-STIR序列。

Objective The routine MRI sequence,3 D-FIESTA,coronal and axial T_(2)-STIR sequence imaging were performed prospectively in nine neonates clinically diagnosed with unilateral brachial plexus injury,in order to evaluate the diagnostic value of each sequence for neonatal brachial plexus injury and further optimize the MR scanning scheme for neonatal brachial plexus injury.Methods The neonates with unilateral upper limb dyskinesia and obstetrical brachial plexus injury diagnosed clinically after delivery were included.The neonates with bilateral upper limb dyskinesia,brain injury and neck deformity after delivery were excluded.All the neonates underwent axial T_(1)WI,axial T_(2)WI,axial and coronal T_(2)-STIR and 3 D-FIESTA sequence scanning.Evaluation and statistical analysis of the effects in five sequences showed the preganglionic and postganglionic segments of brachial plexus.Results A total of nine cases were included,including four boys and five girls,with a median age of 9 days.One case had preganglionic and postganglionic injuries of brachial plexus,involving four brachial plexus nerves,and the other eight cases had postganglionic nerve root injuries,involving 23 brachial plexus nerves in total.Five patients had right brachial plexus injury and four patients had left brachial plexus injury.The preganglionic nerve root injury on MR showed that the nerve root disappeared or was thin,the nerve root sleeve expanded,or the formation of traumatic spinal meningeal.The MR manifestations of postganglionic nerve root injury were swelling and thickening of nerve root and trunk,rigidity of shape,adhesion,swelling and deformation of nerve trunk,and damage of surrounding structures.On five MR sequence images,27 injured brachial plexus images were scored subjectively.The average imaging diagnostic scores were:axial T_(1)WI sequence(1.04±0.19)points,T_(2)WI sequence(1.11±0.32)points,axial T_(2)-STIR sequence(1.74±0.76)points,coronal T_(2)-STIR sequence(3.81±0.40)points,3 D-FIESTA sequence(3.78±0.42)points.A case of brachial plexus injury in 4 preganglionic nerve roots was scored as T_(1)WI sequence 1.00 points,conventional axial T_(2)WI sequence 1.5 points,axial T_(2)-STIR sequence 2.5 points,coronal T_(2)-STIR sequence 2.5 points and 3 D-FIESTA sequence 4 points.We measured the gray scale ratio of coronal T_(2)-STIR sequence and 3 D-FIESTA sequence compared them.T_(2)-STIR sequence was about 1.57±0.28,and 3 D-FIESTA gray scale ratio was about 1.33±0.15.Paired t test showed that t value was about 4.78,P<0.05,with significant difference.Conclusion The diagnostic value of coronal T_(2)-STIR sequence for postganglionic brachial plexus injury is higher than that of 3 D-FIESTA sequence,and the diagnostic advantage of 3 D-FIESTA sequence for preganglionic nerve injury is higher than that of coronal T_(2)-STIR sequence.