Applied Anatomy Study Of Lumbosacral Plexus Nerve By 3.0T Magnetic Resonance Neurography

BackgroundLumbar disc herniation often occurs in L4/5,L5/S1 disc,accounting for more than 90%,often resulting in lower back and leg pain.Operation is a common surgical method in the treatment.Minimally invasive surgery has the advantages of less injury and faster recovery,which makes it an important alternative to disc herniation surgery.However,the limited visual field of minimally invasive surgery is easier to cause nerve root injury and other complications,so identifing the herniated disc and the responsible nerve root before surgery is necessary.PurposesTo explore the anatomic relationship between the locations of L4,L5 nerve roots originating from the dural sac and the superior endplates of L5,S1 vertebrae respectively using 3D-T2W-FFE sequence before percutaneous endoscopic interlaminar discectomy and to investigete the effect of 3D-T2W-FFE,3D-STIR-TSE and DWIBS sequences on display,3D reconstruction of lumbosacral plexus.Methods1.Spine surgery patients with giant lumbar disc herniation and lumbar tumor were excluded,whose DICOM data of conventional lumbar MRI and 3D-T2W-FFE sequence were collected.Measurement indicators included:(1)The disc height of L3/4,L4/5 and L5/S1 on the mid-sagittal plane(Height,H);(2)The take-off angle of the L5、S1 nerve root on the coronal plane(Nerve Root Angle,NRA);(3)The distance between the origin of the nerve roots and the corresponding vertebrae upper endplate(Distance,D)2.Volunteers with giant lumbar disc herniation and lumbar tumor were excluded,whose DICOM data of conventional lumbar MRI and two or three sequences of lumbosacral plexus neurography was obtained.The contrast to noise ratio of nerve root and muscle(CNR N/M),the nerve root diameter and ganglion volume of the right sacral 1 nerve of the three sequences were calculated respectively The display effect and reconstruction effect on anatomy details of lumbosacral plexus of the three sequences were evaluated with different 4 grade score respectivelyResults1.A total of 79 patients(41 males and 38 females,mean age 54.3±13.5 years)were included,in which 68 patients’ L5 nerve roots(68/80,86.1%)originated from the upper part of the L5 superior endplate(L5-up group),the DL5R and DL5L were(5.7 ±4.5)mm and(5.6 ±4.4)mm,respectively;The rest 11 patients’L5 nerve roots(11/80.13.9%)originated from the lower part of the L5 superior endplate(15-down group),the DL5R and DL5L were(1.8 ± 1.5)mm and(3.3±3.3)mm,respectively There was no statistical difference in age,H3/4,H4/5 and H5/1 between L5-up group and L5-down group(P>0.05).All of the S1 nerves originated above the S1 upper endplate,the distance of DS1R and DS1L were(15.3±5.4)mm and(14.5±5.3)mm.2.A total of 49 volunteers(25 males and 24 females,mean age 54.3± 13.5 years)were included,including 3D-T2W-FFE,3D-STIR-TSE and DWIBS sequence in 48 cases,47 cases and 43 cases respectively.The CNR N/M of the three sequences were not identical,among which the 3D-T2W-FFE sequence was significantly different with the 3D-STIR-TSE and DWIBS sequences,P<0.05.There was no significant difference in ganglion volume among the three sequences,P>0.050.The diameters of the nerve roots of the three sequences were not identical,among which the 3D-STIR-TSE sequence was significantly different with the DWIBS sequence,P<0.05;but there was no significant difference between 3D-T2W-FFE sequence and 3D-STIR-TSE sequence,3D-T2W-FFE sequence and DWIBS sequence(P>0.05)The neural display score of the three sequences were not identical(P<0.001),among which DWIBS sequence was significant different from the 3D-T2W-FFE sequence and 3D-STIR-TSE sequence respectively(P<0.05).There were no statistical differences among the three sequences in neural 3D reconstruction score(P>0.05)Conclusions1.Most of the L5 nerve roots and all S1 nerve roots perforated from the dural sac were higher than the superior endplate of the L5 S1 vertebrae respectivel,which was not completely consistent with the results of anatomical studies on cadaver.Comprehensive understanding of the characteristics might help decrease neurologic complications in PEID2.The ability of displaying,3D reconstructing and measuring anatomical details of lumbosacral plexus of the three sequences are not identical,so the appropriate sequence should be selected according to specific requirements in practical application.