In Reference to Visualization of Endolymphatic Hydrops in Patients With Meniere???s Disease:

Diluted gadoteridol (ProHance®) causes mild ototoxicity in cochlear outer hair cells

CONCLUSION

Administration of diluted solutions of gadoteridol might cause considerably less toxic effects on cochlear outer hair cells (OHCs).

OBJECTIVES

Visualization of endolymphatic hydrops is done by intratympanic injection of gadolinium-based contrast agents (GBCAs) and three-dimensional fluid-attenuated inversion recovery (3-D FLAIR) magnetic resonance imaging. Here, we investigated the physiological and morphological responses of guinea pig cochlear cells to gadoteridol.

METHODS

Distortion product otoacoustic emission (DPOAE) levels were measured before and 1, 2, and 4 weeks after intratympanic injection of 1/8 or 1/16 dilution of gadoteridol in guinea pigs. Morphological changes in isolated cochlear OHCs were observed after application of gadoteridol and GdCl3.

RESULTS

At the highest frequency (F2 = 12 000 Hz), DPOAE level was significantly (p < 0.05) lower in the 1/8 diluted gadoteridol group than in the control group. Cell shape changes were observed in 24% (6/25) and 3% (1/33) of OHCs after application of 1/8 and 1/16 diluted gadoteridol, respectively. The occurrence of morphological damage was significantly lower after application of saline compared with 1/8 diluted gadoteridol. Morphological damage was significantly lower after application of 1/16 diluted gadoteridol compared with 1/8 diluted gadoteridol (p < 0.05). Morphological damage was observed at a high rate (8/10 cells, 80%) after application of GdCl3.

Visualization of endolymphatic hydrops after administration of a standard dose of an intravenous gadolinium-based contrast agent

CONCLUSION

Even after the administration of a standard dose of an intravenous gadolinium-based contrast agent (GBCA), visualization of endolymphatic hydrops (ELH) became possible in patients with Meniere's disease. The next step would be to consistently visualize ELH in the upper part of the cochlea.

OBJECTIVE

To visualize ELH after routine administration of an intravenous GBCA.

METHODS

An intravenous GBCA (gadodiamide; 0.2 ml/kg) was administered to three patients with unilateral Meniere's disease and two healthy volunteers. Three-dimensional fluid attenuated inversion recovery (3D-FLAIR) magnetic resonance imaging (MRI) was performed with a 3 T MRI scanner 4 h later.

RESULTS

In all three patients, ELH was observed in the affected vestibules. In contrast, the endolymphatic space of both vestibules was the same size in healthy volunteers. ELH of the cochlea was not observed in any of the subjects. Gadolinium enhancement was insufficient in the upper turns of both cochleae in patients 1 and 3.

Clinical significance of endolymphatic imaging after intratympanic gadolinium injection

CONCLUSION

Using three-dimensional real inversion recovery (3D-real IR) and three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) magnetic resonance imaging (MRI), various degrees of endolymphatic hydrops were observed in the basal and upper turns of the cochlea and in the vestibular apparatus after intratympanic gadolinium (Gd) injection. MRI may contribute to our understanding of inner ear diseases and may be a useful addition to intratympanic drug therapy in the management of inner ear diseases.

OBJECTIVE

To evaluate 3D-real IR MRI and 3D-FLAIR MRI with clinical symptoms and signs in patients with inner ear disease.

PATIENTS AND METHODS

Gd was diluted in saline and injected intratympanically in 73 patients with inner ear disease. The endolymphatic space was evaluated with 3-Tesla MRI at 1 day after the intratympanic Gd injection.

RESULTS

3D-real IR MRI was generally better than 3D-FLAIR MRI in discriminating between the perilymphatic space and endolymphatic space in the cochlear turns and in the vestibular apparatus. However, when Gd concentration was insufficient in the perilymph, it was more difficult to visualize the Gd with 3D-real IR MRI than with 3D-FLAIR MRI. Endolymphatic hydrops was observed using MRI in patients with 'probable' Meniere's disease based on the criteria.