Roles Of Functional MRI In Brachial Plexopathies

Part I Roles of the conventional MRI and magnetic resonance neurography in brachial plexus injuryObjective To evaluate the performance and to investigate the diagnostic value of MRI in brachial plexus injury. Material and methods A total of 43 patients enrolled with brachial plexus injury underwent routine MRI and MR neurography at 3.0T before surgery. Conventional scanning includes axial SE T1WI, FSE T2WI, and TIRM. MR neurography includes:coronal SPACE, TIRM and T1 FLASH. Intraoperative findings and intraoperative EMG were used as the reference standard. MRI findings, sensitivity, specificity with 95% confidence intervals and accuracy were compared for investigating the diagnostic value of MRI in brachial plexus injury at early stage. Results 105 of 215 pairs of nerve roots were injured,98 of which were detected in MRI. The sensibility,specificity and accuracy of MRI in diagnosing preganglionic brachial plexus injury is 76.2%(80/105),83.6%(92/110),80.0% (172/215), respectively. The accuracy of MRI for diagnosing patients of injury less than 1 month is 79.1% and of injury between 1-3 months is 80%. There’s no significant difference between the two groups (P> 0.05). The direct signs of preganglionic brachial plexus injury include:Complete avulsions:(1) disappearance and discontinuity of the nerve roots,68 pairs. (2) thickening, stiffness and tortuous of nerve roots or failed to be traced to the intervertebral foramen continueously,8 pairs. Partially avulsions:(1) disappearance and discontinuity of ventral or dorsal nerve root,10 pairs. (2) significantly decreased number of radicular filaments compared with contralateral showed in coronal image,12 pairs. Indirect signs include:(1) cystoid cerebrospinal fluid concentrating in vertebral canal or post-traumatic spinal meningocele (pseudomeningocele),44 pairs. (2) abnormal shape and asymmetry of nerve root sleeve,9 pairs. (3) displacement and deformity of spinal cord,1 pairs. (4) spinal cord injury,1 case. The sensitivity, specificity and accuracy of MRI in diagnosing postganglionic injury were 74.8%,88.1%,79.2%, respectively. The diagnostic accuracy for patients injured less than one month was 81.4%, and for patients injured between 1-3 months was 85.7%. The MRI performance of brachial plexus postganglionic injury include:(1) nerve discontinuity with ends separated,12 roots. (2) thickening of nerve, with continuity and stiff courser,20 cases. (3) slightly thickening of nerve, with continuity and hyperintensity on TIRM,18 cases. (4) continuous nerve with natural courser, and same structure and signal intensity with normal side,3 cases. Conclusion MRI can provide accurate diagnosis of the location and nature of brachial plexus injuries, especially for early injury cases.Part Ⅱ:Roles of functional MRI in brachial plexus injuryObjective To investigate the diagnostic value of functional MRI in brachial plexus injury. Materials and Methods 42 patients with brachial plexus injury underwent functional MRI exam using diffusion tensor imaging at 3.0T before surgery. Intraoperative findings and intraoperative EMG were used as the reference standard. The parameter of DTI includes apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were obtained and analyzed to investigate the diagnostic value of functional MRI in brachial plexus injury at early stage. Results The ADC and FA values measured from C5-C8 nerve root on both sides were as follows:1.483±0.153 and 0.434±0.063(×10-3mm2/s) on the injured side, 1.380±0.163 and 0.482±0.070(×10-3mm2/s) on the normal side. The differences of ADC and FA values were statistically significant (P= 0.001, P= 0.001). Only the differences of FA values were statistically significant in patients of injury less than 1 month (P< 0.05). and for patients of injury between 1-3 months the differences of ADC and FA values were both statistically significant (P< 0.001, P< 0.001). Conclusion DTI could support the judgment of damage at early stage, help to make a clinical strategy and predict the patients’ outcome.Part Ⅲ:Roles of MRI diagnosis in neoplastic plexopathyObjective To analyze the features of MRI in neoplastic lesions of brachial plexus, and discuss its value in diagnosis and differential diagnosis. Materials and Methods In this study, we made an analysis of the MRI findings of 14 patients with neoplastic lesions,13 cases of which were proved pathologically, including 8 cases of schwannoma,l case of plexiform schwannoma,1 case of neurofibroma,1 case of aggressive fibromatosis and 1 case of synovial sarcoma.1 case of metastatic tumor was confirmed by biopsy of lymphnodes. All patients underwent conventional MR scan and MR neurography exam, and 13 cases of which underwent DTI scanning. Results 9 cases of schwannoma all involved the postganglionic segment, and were oval, sharply margined, encapsuled, coursed with BP fibers, one of which dumbbell-like growed through the intervertebral foramina,2 of which with cystic degeneration.1 case of plexiform schwannoma displayed the mass-like enlargement of right root and trunk of BP, which was sharply margined and isointensity on T1WI, hyperintensity on T2WI and TIRM. The coronal TIRM images showed the relationship between mass and parent nerve clearly.1 case of neurofibroma growed along with brachial plexus, showed oval mass with iso to hypo intensity on T1WI and hyperintensity on T2WI and TIRM.1 case of aggressive fibromatosis showed a huge mass involved right brachial nerve roots, with slightly lower signal on T1WI, isointensity on T2WI, hyperintensity mixed heterogeneous hypointensity on TIRM.1 case of synovial sarcoma was located at left subclavian district, with brachial plexus mildly swelling, hypointensity on T1WI, hyperintensity on T2WI and TIRM.1 case of metastatic tumor showed a fusiform mass involved left brachial plexus divisions with slightly hypointensity on T1WI, slightly hyperintensity on T2WI, and mixed hyper and hypo intensity on TIRM.13 cases underwent DTI scan, and DTT for 8 cases of schwannoma showed fiber displacement.1 case of aggressive fibromatosis showed focal compression and intimate relationship of the tumor and BP. Conclusion MRI could delineate accurate localization and the relationship of the neoplastic lesions and adjacent structures involving brachial plexus, which indicated that MRI could provide reliable information for diagnosis and treatment of neoplastic plexopathy.