Application of enhanced MR (3.0T) scanning with 3D-SPACE-STIR sequence for postganglionic neurogenic tumors of the brachial plexus

Objective To evaluate the feasibility of visualizing postganglionic neurogenic tumors of the brachial plexus (PNT-BP) with enhanced scanning with MR (3.0T) using the 3D-SPACE-STIR sequence. Methods From June 2012 to December 2014, 12 patients with suspected PNT-BP were subjected to MRI (3.0T) routine-sequence examination, 3D-SPACE-STIR sequence plain and enhanced scanning. The original images obtained in 3D-SPACE-STIR sequence plain and enhanced scanning then underwent MIP reconstruction, respectively, to maximally display the structures of the nerve root, trunk, division and cord of the brachial plexus. The location, size, shape, signal intensity and the edge morphology of the tumor as well as its relationship to the proximal and distal portions of the brachial plexus, and signs of nerve compression were observed. All the patients underwent surgical removal of the tumors and histopathological examination of the tumor tissue. Plain and enhanced MRI with routine-sequence and with 3D-SPACE-STIR sequence were repeated 6 months after the surgery. Results Enhanced MR (3.0T) scanning with 3D-SPACE-STIR sequence clearly visualized PNT-BP in all 12 cases. PNT-BP involved the upper trunk in 5 cases, the middle trunk in 2 cases, the lower trunk in 1 case, the lateral cord in 3 cases, and the posterior cord in 1 case. The maximum tumor volume was 5.4 cm×4.2 cm×4.3 cm, while the smallest was 2.4 cm×1.2 cm×1.3 cm. Histology confirmed Schwannoma in 10 cases and neurofibroma in 2 cases. Schwannomas presented as round or oval structures of high signal intensity (slightly higher than that of nerve fascicles). Tumor signals were in continuity with nerve fascicle signals. Neurofibromas presented as fusiform or spindle-like structures with slightly higher signal intensity or mixed high signal intensity. Reconstruction of enhanced 3D-SPACE-STIR scans obtained 6 months postoperatively of the postganglionic brachial plexus showed slightly uneven high signal and continuity of the nerve fascicles. Conclusion Enhanced MR (3.0T) 3D-SPACE-STIR sequence could clearly visualize tumor lesions in nerve root, trunk, division and cord levels of the brachial plexus. The reconstructed images showed high or slightly higher signal intensity, which could provide imaging evidences for the localization and diagnosis of PNT-BP. Key words: Brachial plexus; Neoplasms; Magnetic resonance imaging; 3D-SPACE-STIR