[Endolymphatic hydrops detected with inner ear gd contrast-enhanced MRI; comparison between administration routes or...

Gadolinium (Gd) contrast-enhanced MRI has recently been introduced to clinical practice to detect endolymphatic hydrops. However, since the image depends on the hardware, pulse sequence or the way of Gd administration, the protocol and the evaluating criteria for hydrops on MRI have not yet been standardized. In this study, we assessed the usefulness of the hydrops detection by MRI following the intratympanic or intravenous Gd administration methods, and compared these findings with the electrocochleography and glycerol test.

MRI was taken in 27 patients with Meniere's disease or delayed endolymphatic hydrops. All patients had frequent episodes of vertigo attacks which were clinically considered as of unilateral ear origin. Two types of Gd administration were used; injection into the tympanic cavity in 17 patients or intravenous injection in 10 patients. Axial 2D-FLAIR images were obtained with a 3.0T MRI unit, 24 and 4 h after intratympanic or intravenous administration, respectively. The endolymphatic space was detected as a low signal intensity area, while the surrounding perilymphatic space showed high intensity with Gd contrast. Those cases in which low signal areas corresponding to the cochlear duct could be clearly noticed, were classified as cochlear hydrops. When the greater part of the vestibule was occupied by a low signal area in more than half of the images, it was classified as vestibular hydrops.

Endolymphatic hydrops was detected in 88% (15/17 cases) by the intratympanic Gd administration method, and 90% (9/10) by the intravenous method. In the contralateral ears, 20% (2/10) showed hydrops, detected by the intravenous method. ECochG and the glycerol test were difficult when the hearing of the patient was severely impaired. Positive results of EcochG and the glycerol test were obtained only in 15 and 6 cases, respectively. However, as far as the waves could be obtained, ECochG showed a high detection rate of 88% (15/17) in the affected ear. In those cases in which both MRI and EcochG could be obtained, including both ears, the results were matched in 78% (21/27ears).

For the qualitative detection of hydrops, intratympanic and intravenous Gd administration methods were equivalent. Inner ear Gd contrast-enhanced MRI had higher efficacy in the detection of hydrops than the conventional tests.