Contrast-Enhanced Three-Dimensional Fluid-Attenuated Inversion Recovery Imaging with an Optimal Scan Interval and Angulation to Visualize Endolymphatic Hydrops

Background: There is no gold standard diagnostic test for endolymphatic hydrops (EH). Three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) imaging has been reported to depict EH with administration of gadolinium-based contrast media (GBCM). However, the optimal scan interval and angulation remain unknown in 3D-FLAIR labyrinthine imaging following double-dose injections of a gadolinium-based contrast agent in patients with vertigo and sensorineural hearing loss. Objectives: This study aimed to determine the optimal parameters of 3D-FLAIR labyrinthine imaging, including the optimal scan angulation and scan interval, for patients with sensorineural hearing loss and vertigo. Patients and Methods: In this cross-sectional clinical study, following the double-dose administration of a gadolinium contrast agent, 3D-FLAIR labyrinthine images were acquired from 22 patients with unilateral vertigo and sensorineural hearing loss at different intervals after injection. The corresponding contrast-to-noise ratios (CNRs) and signal-intensity ratios (SIRs) of these images, acquired at different intervals, were measured. Moreover, separate visualization of endolymphatic and perilymphatic spaces was scored, and angulation of the anterior skull base scan was investigated in the sagittal position. Results: The 3D-FLAIR images showed the strongest image contrast in the cochlea with a double-dose gadolinium-based contrast injection at six hours post-injection. Significantly higher SIR and CNR values were reported at six hours post-injection in both unaffected and affected ears compared to other intervals (4 h vs. 6 h in the affected side, SIR: 1.65 ± 0.24 vs. 2.09 ± 0.47, CNR: 13.88 ± 5.54 vs. 19.17 ± 6.81; in the unaffected side, SIR: 1.58 ± 0.27 vs. 1.82 ± 0.34, CNR: 12.20 ± 3.88 vs. 15.42 ± 4.58, P < 0.001 for all; 6 h vs. 8 h in the affected side: SIR: 2.09 ± 0.47 vs. 1.72 ± 0.43, CNR: 19.17 ± 6.81 vs. 12.22 ± 4.96; in the unaffected side, SIR: 1.82 ± 0.34 vs. 1.57 ± 0.30, CNR: 15.42 ± 4.58 vs. 10.61 ± 3.87, P < 0.001 for all). Visualization of the endo- and perilymphatic spaces for both the cochlea and vestibule was significantly better at six hours post-injection compared to four hours post-injection in both affected sides (P < 0.05 for both). The optimal angulation ranged from 6.20° to 13.6° (P < 0.001). Conclusion: By using an optimal scan interval, together with an optimal scan angulation, 3D-FLAIR imaging can reliably visualize the endolymphatic space and sensitively indicate cochlear blood-labyrinth barrier disruptions without requiring extra image reconstruction.