Abstract： Objective To evaluate the contrast-enhanced 3D sampling perfection with application-optimized contrasts by using different flip angle evolutions-short TI inversion recovery sequence (SPACE-STIR) for the imaging of the post-ganglionic segments of the brachial plexus.Methods Forty-three patients with suspected brachial plexus lesions were examined with 3D SPACE-STIR and contrast-enhanced 3D SPACE-STIR prospectively.Signal-to-noise ratios (SNR),contrast-to-noise ratios (CNR),and the conspicuousness of roots,trunks,divisions and cords of the brachial plexus of the two 3D sequences were retrospectively compared.Statistical analysis was performed by using student t-test and Wilcoxon rank sum test.Results Compared with 3D SPACE-STIR,contrast-enhanced 3D SPACE-STIR provided the similar SNRs (left,37.41 ±7.34 vs 36.27 ±7.66,t =1.574,P =0.123,right,43.85 ±9.56 vs 42.34 ±9.74,t =1.937,P =0.073),but significantly higher nerve-to-muscle CNRs (left,24.01 ± 6.31 vs 26.39 ± 6.95,right,29.31 ± 7.84 vs 31.77 ± 8.85,t =-3.278,-3.278,both P ＜ 0.01) and nerve-to-lymph gland CNRs(left,-0.84 ± 10.51 vs 15.35 ±8.02,right,-8.47 ± 10.85 vs 19.30 ± 10.35,t =-15.984,-15.651,both P ＜0.01).The conspicuousness of roots and trunks on contrast-enhanced 3D SPACE-STIR was significantly better than that on 3D SPACE-STIR (Z =-3.606,-4.472,P ＜ 0.01),while the conspicuousness of divisions and cords was similar(Z =-1.732,-1.414,P =0.083,0.157).The signal intensity of neoplastic lesions on contrast-enhanced 3D SPACE-STIR tended to decrease rapidly,thus the lesion conspicuousness was worse than that on 3D SPACE-STIR.Conclusions Contrast-enhanced 3D SPACE-STIR has obvious advantages in displaying normal brachial plexus and revealing non-neoplastic lesions of the brachial plexus,but may be insufficient for the diagnosis of neoplastic lesions of the brachial plexus.