Objective:To explore the clinical application value of each sequence by analyzing the characteristics of labyrinthine signal on MRI in patients with unilateral sudden deafness.Methods:Totally 52 patients of unilateral sudden deafness with inner ear MRI were analyzed retrospectively at Beijing Tongren Hospital, Capital Medical University from January 2016 to July 2019, all of which could find abnormalities in the labyrinth, including 17 cases of plain scan and 35 cases of enhanced scan, with sequences including plain T 1WI, enhanced T 1WI, plain and enhanced delayed 3D fluid attenuation inversion recovery (3D-FLAIR). The affected labyrinthine signal characteristics of each sequence were analyzed and the involvement sites were judged. The ability of each sequence to show labyrinthine abnormal signal was evaluated and scored. The Friedman test and Wilcoxon signed rank sum test were used to compare the subjective scores of the ability to show labyrinthine high signal in different sequences in plain and enhanced patients, respectively. Fisher′s exact probability method was used to analyze the relationship between the affected sites and the recovery of hearing, tinnitus and vertigo symptoms. Results:Fifty-two patients (100%, 52/52) showed labyrinthine high signal on T 1WI, 8 (15.4%, 8/52) showed higher signal and 3 (5.8%, 3/52) showed low signal on T 2WI. Thirty-five (100%, 35/35) showed high signal on enhanced T 1WI, among which 27 had enhancement (77.1%, 27/35). Fifty-two (100%, 52/52) showed significant high signal of the affected labyrinth on 3D-FLAIR (17 plain scan, 35 enhanced scan). The scores were 2 (2, 2), 3 (2, 3), 3 (3, 4) and 4 (4, 4) of T 1WI, enhanced T 1WI, plain and enhanced 3D-FLAIR respectively. The overall difference in subjective scores of plain T 1WI, enhanced T 1WI and enhanced 3D-FLAIR in enhanced patients was statistically significant (χ2=64.528, P<0.001), and the comparison between the two was statistically different (all corrected P<0.05). The plain 3D-FLAIR score was higher than the plain T 1WI in patients with a statistically significant difference ( Z=-3.729, P<0.001). Twenty-seven cases (51.9%, 27/52) exhibited high signal at the ampulla of semicircular canals, with a statistically significant difference in the distribution of hearing recovery or not ( P=0.001). Conclusions:Both T 1WI and 3D-FLAIR sequences can effectively identify the labyrinthine high signal, but the latter was better than the former of its ability to display, especially delayed enhanced 3D-FLAIR. The high signal at the ampulla of semicircular canals was a characteristic predictor of non-recovery of hearing.