MR Imaging Of Brachial Plexopathies

Part 1: MR imaging of normal brachial plexus and thescan protocolObjective: To investigate the value of different MRI sequences inmanifesting the structure of normal brachial plexus, and determine the best MRI scanprotocol of brachial plexus. Materials and Methods: A total of 40 brachial plexus (20healthy volunteers) were examined with routine and new MR sequences. The routineMR sequences contain: axial SE T1WI,FSE T2WI,STIR, coronal SE T1WI and FSET2WI,sagittal FSE T2WI.And the new MR sequences contain:3D-FIESTA-c,coronalcontiguous thin slice STIR and 3D-FSPGR.The manifesting of normal brachial plexusin these sequences were observed. Nerve soft tissue contrast-to-noise-ratios (CNRs)and the display scores of brachial plexus were calculated and compared amongcoronal SE T1WI,FSE T2WI and STIR sequences. The comprehensive MRI scanprotocol to illustrate the preganglionic and postganglionic bundles of brachial plexusas well as the surrounding structures was designed. Results: On axial images, thenerve roots of cervical cord from C5 to T1 appeared as linear structure exiting fromthe intervertebral foramen and passing between the anterior and middle scalenemuscles in the sections of intervertebral foramen; in the sections of clavicle, underclavicle and axillary fossa, the divisions, cords and branches surrounded flow void ofthe subclavian artery. On coronal images, the roots appeared as linear structuresexiting from C5-T1 intervertebral foramen and collecting to infraclavicula andaxillary fission sagittal images, it appeared as oven or round structure wrapped by fattissue, in the intervertebral foramina and then surrounding the subclavian and axillaryartery. The brachial plexus was isointense on T1WI and T2WI, hyperintense on STIRimages compared with the signal intensity of normal muscle. CNRs of coronal SET1WI,FSE T2WI and STIR sequences was 2.04±0.97,2.11±1.01,23.68±5.93,respectively. CNRs of STIR was significantly higher than the other two sequences (P=0.000). The display scores of C5,C6 roots and the upper trunk on coronal STIRsequences were significantly higher than the other two sequences. The C7 root,middle and lower trunks,retroclavicular and infraclavicular segments can be continuously displayed on all the three squences..The 3D Fiesta-c images showedhigh contrast among cerebrospinal fluid, nerve roots and bone tissue; the nerve rootsappeared smoothly with low signal intensity and delineated well within the highsignal CSF. The anatomical details could be distinguished well in 3D FSPGR images,although the nerves were not so eye-catching. Conclusions: The brachial plexus MRIscan protocol, containing axial T1WI,T2WI,STIR, sagittal T2WI, 3D-FIESTA-c,coronal contiguous thin slice STIR and 3D-FSPGR,can illustrate well thepreganglionic and postganglionic bundles as well as the surrounding structures. Thiscomprehensive bpMRI protocol can be used as the routine scan modal to brachialplexus plexopathies.Part 2:MR imaging of brachial plexus injury【Abstract】Objective: To evaluate MRI in diagnosing brachial plexus injury.Materials and Methods:70 cases with brachial plexus injury underwent bpMRscanning before operation.MR imaging was obtained by GE Signa EXCITE 1.5 Tscanner.59 patients had carried out exploration of the supraclavicular plexus andelectrophysiology exam. 11 patients who had not surgery were followed-up. The MRIappearances and subtypes of brachial plexus injury were discussed. Results: Amongthe 196 pairs of injured roots,MR imaging detected 176 pairs. The accuracy,sensitivity and specificity of MRI in diagnosing preganglionic brachial plexus injurywere 89.1%,89.8%,84.8%, respectively...The direct signs of brachial plexuspreganglionic injury include:(1)lack or mutilation of nerve root, 161pairs(82.1%),(2)coarsening, bending,coursering stiff and can not be traced to theintervertebral foramen continuously,20 pairs(10.2 %);the indirect signsinclude:(1)cystoid cerebrospinal fluid concentrating in the vertebral canal,posttraumatic spinal meningocele,96 pairs(49.0 %),(2) abnormal shape of nervesleeve, 54 pairs(27.6%),(3)displacement and deformity of spinal cord, 79segments(40.3 %),(4)fibrae scar in intervertebral foramen region,11pairs(5.6 %)(5)abnormal signal in spinal cord,5 patients(10.6%)(6)abnormal signal ofparaspinal muscles,42 patients(89.4%).The signs of brachial plexus postganglionicinjury include: (1)natural courser of the nerve and the same structure and signalintensity with normal side,2 cases,(2)thickening of the nerve ,with continuity and natural courser, and high intensity on STIR, 17 cases(3) thickening of the nerve ,withcontinuity and stiff courser, and little lower signal intensity than the normal nerve onSTIR,19 cases,(4)losing of continuity completely, with isolated broken ends, 2cases(5)traumatic nerofibroma,appeared as isointensity on T1WI,mixture ofiso-and-hyperintensity on STIR,2 cases.(6)little thickening of the nerve ,withcontinuity, and pseudoaneurysm in the beginning of axillary artery compressed thebrachial plexus,1 ease. The MRI appearances of brachial plexus injury contained 6types: normal appearance(A),neural degeneration and oedema(B),neural scarificationand fibrosis(C),neurotmesis(D),root avulsion(E) and mixed type(F). Conclusion:MRI can distinctly manifest the nerves within and out of the vertebral canal, thus,help making a correct diagnosis in brachial plexus injuries, and making references forearly diagnosis.Part 3.MRI appearance and semi-quantitative researchof complete denervated muscle after brachial plexusinjury【Abstract】Objective: To approach MRI appearance,ADC value,and hypotrophydegree of complete denervated muscle after brachial plexus injury in different times.Materials and Methods:31 patients with complete denervated infraspinous muscleafter brachial plexus injury underwent MRI scan before EMG and operation all thepatients, had taken the routine scan sequences, containing axial T1WI,T2WI andSTIR. The axial EPI-DWI sequence were added to 8 acute/subacute patients. The areaof bilateral infraspinous muscle were measured, and the area ratio between denervatedand normal side were calculated. The ADC values of the muscle were measured bythe Functool software, and the ADC ratio between denervated and normal side werecalculated. The relationship between injury time and area ratio,injury time and ADCratio, and the differences of ADC values between two sides of infraspinatus werestatistical analyzed. Results: The MRI appearance of complete denervatedinfraspinous muscle after brachial plexus injury was: in acute and subacute stage,appearing hyperintensity on STIR, normal or patchy of hyperintensity shadow onT2WI and normal on T1WI;in chronic stage, appearing hyperintensity on T1WI with decreased volume. It was observed that the area ratio between denervated and normalside decayed over time and correlated negatively with time. The area ratio decreasedquickly within two months. There were significant differences in ADC value of themuscle between denervated and normal side (P=0.000). The ADC value of denervatedmuscle were higher than that of normal muscle. The ADC ratio between denervatedand normal side correlated positively with time. Conclusion: The MRI appearance ofcomplete denervated infraspinous muscle after brachial plexus injury have itscharacteristics. In acute and subacute stage, the denervated muscle had elevated ADCvalues. And MRI can be used as a tool of monitoring hypotrophy degree ofdenervated muscle.Part 4: MR imaging of common non-traumatic brachialplexopathies【Abstract】Objective: To establish MRI findings and diagnosis values in commonnon-traumatic brachial plexopathies. Materials and Methods:30 patients withnon-traumatic brachial plexopathies were retrospectively analysised.The patientsgroup contained 2 patients of neurofibromatosis involving brachial plexus,10 patientsof schwannoma,3 patients of metastases involving brachial plexus,3 patients ofradiation plexopathy,1 patient of multifocal motor neuropathy involving brachialplexus, and 11 patients of typical thoracic outlet syndrome.24 cases were proved bypathology after operation.2 cases underwent biopsy.1 case of metastases,2 cases ofneurofibromatosis and 1 cases of multifocal motor neuropathy were proved by clinicalinformations.All the patients had brachial plexus MRI plain scan,8 patients hadenhanced MR scan, and 1 patient also had CT plain scan. Thee MR characteristics ofthe lesions and relationship between them and brachial plexus were focusedobservations. Results: In 2 patients of neurofibromatosis, the tumors appeared asfusiform,bead-like mass, along the courser of brachial plexus, and iso-to littlehypointensity on T1WI,inhomogeneous hyperintensity on T2WI andinhomogeneously enhanced. Also the rootlets in vertebral canal were involved.Among 10 cases of schwannoma,2 cases located in intervertebral foramen region,2cases growed through vertebral canal ,6 cases located outside the spinal canal from the postganglionic part of brachial plexus. The schwannoma displayed as fusiformmass, eccentric to the original never with sharply defined edge, and hypointensity orinhomogeneous hyperintensity on T1WI,inhomogeneous hyperintensity on T2WIwith cystic necrosis in 3 cases, and inhomogeneously enhanced. Two of the 3 cases ofmetastases manifested as multiple masses besides brachial plexus, the other oneappeared as widespread lesion infiltrated brachial plexus and surrounding structures.The 3 cases of radiation plexopathy displayed as diffused thickened nerves, withincreased signal intensity,clear structure surrounding the plexus and no mass can befound. One cases of MMN showed thickened nerves with increased signal intensity. 11cases of typical thoracic outlet syndrome manifested as archformly raised C8,T1 andinferior trumk, with thickened nerves and increased signal intensity, meanwhile 8cases with raised subclavian artery. And one patient of TOS,MRI and CT imagesrevealed a mass in the end of cervical rib and compressed the local brachial plexus.Conclusion: MRI is an excellent tool in the evaluation of non-traumatic brachialplexus pathologies. Imaging helps in the accurate localization,involving scope of theabnormality, and picture the relationship among lesion and the surroundingstructures.bpMRI supplies reliable information for accurate diagnosing and treatingbrachial plexopathies.