Roles Of MR Imaging In Brachial Plexopathies

Part Ⅰ:MR imaging of normal brachial plexus[Abstract] Objective To investigate the value of different MRI sequences in manifesting the structure of normal brachial plexus and the feasibility of DTI in brachial plexus examination. Materials and Methods A total of20healthy volunteers underwent routine MR sequences, MR neurography and functional MRI exam. Conventional scanning included axial SE T1WI, FSE T2WI, and TIRM. MR neurography:coronal SPACE, TIRM and T1FLASH. Functional MRI:axial DTI. The normal appearance of brachial plexus in these sequences were observed. The displaying capability of SPACE in nerve roots was calculated, and coronal TIRM and T1FLASH for displaying postganglionic nerve were compared with scoring. DTI sequence of displaying the postganglionic part was compared with scoring4weeks apart. Results Axial images displayed brachial plexus roots piercing intervertebral foramen and the interscalene space, and then coursed with subclavian artery and axillary artery. Coronal images displayed the preganglionic segments as fine filaments from spinal cord to intervertebral foramen, and postganglionic segments was showed as trabs from bilateral C5-T1intervertebral foramen. Brachial plexus was showed isointensity on T1WI and T2WI, hyperintensity on TIRM. The display ability of nerve roots on coronal SPACE was100%. Coronal TIRM sequence was significantly better than T1FLASH in displaying postganglionic parts. The repeatability of DTI and FT in showing postganglionic segment was high, and the FA, λ1, λ2and λ3value of normal volunteers’ brachial plexus were measured on parameter maps. Conclusion T1WI, T2WI, and TIRM sequences were conventional MR scan for brachial plexus and coronal SPACE and TIRM could display the preganglionic and postganglionic segments. DTI could provide the fiber information for the diagnosis. Part Ⅱ:Roles of MRI in brachial plexus injury[Abstract] Objective To investigate the value of MR in diagnosing brachial plexus injury. Materials and Methods85cases with brachial plexus injury underwent MR scanning before operation. Surgical exploration, intraoperative EMG and preoperative MRI results were compared in order to investigate the diagnostic value of MRI, especially in early injury patients. Results Among the264pairs of injured roots, MR imaging detected226pairs of them. The sensitivity, specificity and accuracy of MRI in diagnosing preganglionic brachial plexus injury were85.6%,80.4%,84.8%, respectively. The accuracy for diagnosing patients of injury less than one month was84.1%, and for injury less than three months was84.4%. The direct signs of brachial plexus preganglionic injury include:complete avulsion (1) discontinuity or disappearance of nerve root,120pairs;(2) thickening, stiffness, tortuous of nerve root and could not be traced to intervertebral foramen continuously,27pairs; partial avulsion (1) the ventral or dorsal root disappeared,11pairs;(2) coronal image showed the number of nerve root were significantly reduced compared with contralateral,77pairs. Indirect signs include:(1) cystoid cerebrospinal fluid concentrating n vertebral canal, posttraumatic spinal meningocele (pseudo-meningocele),93pairs.(2) abnormal shape of nerve sleeve, bilateral asymmetry,22pairs;(3) displacement and deformity of spinal cord,4pairs;(4) spinal cord injury,1case. The sensitivity, specificity and accuracy of MRI in diagnosing postganglionic injury were89.7%,81.5%,87.1%, respectively. The diagnostic accuracy for injury patients less than one month was85.9%, and for injury less than three months was87.1%. The signs of brachial plexus postganglionic injury include:(1) nerve discontinuity, with broken ends separated,43roots.(2) traumatic nerofibroma, appeared as iso-and-hypointensity on T1WI, slightly hyperintensity on TIRM,4cases.(3) thickening of nerve, with continuity and stiff courser,31cases.(4) thickening of nerve, with continuity and natural courser, and hyperintensity on TIRM,52cases.(5) continuous nerve, natural courser and the same structure and signal intensity with normal side,2cases. FA, λ1, λ2, λ3value were measured on both sides of C5-C8nerve roots from37cases of postganglionic injury, and the differences between ipsilateral and contralateral were statistically significant (P<0.001). Only the differences of FA and λ3value were statistically significant (P<0.001, P=0.006) for injury less than one month, and the differences of FA, λ1, λ2,λ3value were statistically significant (P<0.001, P=0.001, P<0.001, P<0.001) for injury less than three months. Conclusion MRI could be helpful in making a correct diagnosis in patients with brachial plexus injury, especially for early injury cases. DTI could support the judgment of different damage, and was helpful for making a clinical surgery program and the prediction of patients’ outcome. Part Ⅲ:Roles of MRI diagnosis in brachial plexus neoplastic lesions[Abstract] Objective To analyze the MRI features of neoplastic lesions of brachial plexus, and its value in diagnosis and differential diagnosis. Materials and Methods In this study, we made an analysis of the MRI findings of17patients with neoplastic lesions and2cases with tumor-like lesions, which were proved pathologically, including11cases of schwannoma,2cases of neurofibroma,1case of invasive fibrous tumor,2cases of MPSNT and1case of synovial sarcoma. All patients underwent conventional MR scan and MR neurography exam, and11cases of which underwent DTI scanning. Results11cases of schwannoma were all involved the postganglionic segment, oval, sharply demarcated, enveloped, coursed with brachial plexus direction, one side growth, isointensity on T1WI, heterointensity on T2WI,2cases with cystic degeneration; coronal TIRM images showed the relationship between mass and parent nerve clearly.2cases of neurofibroma were grown along with brachial plexus, T1WI iso-and-low signal, T2WI and T1RM high signal.1case of invasive fibrous tumor showed a huge mass involved right brachial nerve roots, the T1WI slightly higher signal, T2WI high signal, T1RM heterogeneous signal.2cases of MPSNT involves the right brachial plexus branches, T1WI slightly lower signal, T2WI and TIRM showed iso-and-hyper intensity, enhanced significantly.1case of synovial sarcoma was located at left subclavian distriction, with brachial plexus mildly swelling, T1WI low signal, T2WI and TIRM showed high signal.11cases underwent DTI scan, and FT for8cases of schwannoma showed fiber displacement. Conclusion MRI could clearly show accurate localization and the relationship with adjacent structures of the tumor lesions involving brachial plexus, which indicated that MRI could provide reliable information for accurate diagnosis of tumor lesions. Part Ⅳ:MRI diagnosis in brachial plexus neuritis and peripheral neuropathies [Abstract] Objective To investigate the diagnositc value of MRI in brachial plexus neuritis and peripheral neuropathies. Materials and Methods In this part, we made an analysis of38cases involving brachial plexus for inflammation and peripheral neuropathies, including12cases of axonal neuropathy,10cases of mononeuritis multiplex,2cases of acute inflammatory demyelinating polyradiculoneuropathy (AIDP),7cases of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP),1case of herpes zoster infection,6cases of radiationinduced brachial plexopathy. The diagnosis was based on comprehensive clinical, EMG and laboratory examination. All patients underwent MRI in order to observe MRI features of different lesions. Results’MRN showed4cases as increased heterogeneous signal intensity in postganglionic segment of brachial plexus among12cases of axonal neuropathy. Four cases of mononeuritis multiplex showed asymmetric hyperintensity of both sides with nerve mildly swelling. Six cases of CIDP showed symmetry increased signal of bilateral nerves. Case of herpes zoster infection showed one side of the brachial plexus mildly swelling associated with increased signal. Five cases of radiation induced brachial plexopathy showed unilateral brachial plexus swelling associated with heterogeneous increased signal intensity. Grouped by diseases, FA values of axonal neuropathies, AIDP and CIDP group, mononeuritis multiplex were declined compared with normal controls, and the difference was statistically significant. Grouped by axonal and demyelination, FA values of axonal group and demyelination group were decreased, while λ2and λ3were decreased in axonal group and increased in demyelination group, and the difference was statistically significant. Conclusion MRI could clearly diaplay brachial plexus neuritis and peripheral neuropathies, and DTI could especially provide more information for diagnosis and differential diagnosis of them.