Observation of contrast enhancement in the cochlear fluid space of healthy subjects using a 3D-FLAIR sequence at 3 Tesla

Abstract

In animals, the enhancement of perilymph in the cochlea has been reported using 1.25 mmol/kg of Gd-DTPA, allowing the separate visualisation of perilymph and endolymph for the diagnosis of Meniere's disease. The purpose of this study was three-fold: (1) to determine the optimal timing for detecting cochlear fluid enhancement using 3D-FLAIR (fluid-attenuated inversion recovery) after intravenous administration of 0.1 mmol/kg of Gd-DTPA in healthy human subjects; (2) to examine the reliability of enhancement in multiple healthy subjects; and (3) to investigate whether endolymph and perilymph space can be visually discriminated. In two healthy subjects, 3D-FLAIR images were obtained before, immediately after and 2 h, 4 h and 6 h after the injection. Three more healthy subjects were scanned before and 4 h after the injection. In all four ears of the initial two subjects, cochlear fluid was found to be most intensely enhanced 4 h after the injection. In all of the additional three subjects, the cochlear fluid signal had increased after 4 h from injection. However, visual differentiation of endolymph and perilymph fluid could not be achieved. Using 3D-FLAIR and Gd-DTPA, cochlear fluid enhancement can be observed in healthy human ears, even with a single dose of contrast-medium injection.

Comparison of Contrast Effect on the Cochlear Perilymph after Intratympanic and Intravenous Gadolinium Injection

“…Furthermore, another previous study revealed the cochlear fluid enhancement 4 hours after singledose IV gadolinium injection on 3D-FLAIR in healthy subjects. 22 Therefore, the cochlear enhancement should be observed 4 hours after double-dose IV gadolinium injection in healthy people, though further investigation is required to clarify this matter because the number of controls in the present study was too small for statistical analysis.…”

“…28 The reports describing intratympanic gadolinium injection in human subjects have been published from several institutions, including ours, [11][12][13][14][15][23][24][25][29][30][31] and no marked side effects in the inner ear relating to intratympanic gadolinium injection have been reported on clinical application at present, to the best of our knowledge. In addition, intravenously administered gadolinium has been reported to infiltrate inner ear perilymph, 16,17,22,23 and no marked side effects in the inner ear relating to IV gadolinium injection have been reported in the clinical application at present. Therefore, gadolinium agent use in the clinical setting appears safe for inner ear imaging, but future study requires continued vigilance regarding the small possibility of side effects.…”

“…11 Intravenously administered gadolinium agent also distributes into the perilymph space of the scala tympani through the blood-perilymph barrier, and elevation of the cochlear basal turn signal intensity is most easily observed 4 hours after IV gadolinium injection on 3D-FLAIR in human subjects. 16,22,23 The region of interest of the medulla oblongata was set on the center of the medulla oblongata at the identical section of the basal turn of the cochlea. The region of interest of the medulla oblongata did not include the signal intensity of CSF or vessels.…”

Imaging of Endolymphatic and Perilymphatic Fluid at 3T After Intratympanic Administration of Gadolinium-Diethylene-Triamine Pentaacetic Acid

“…Four hours after intravenous administration of Gd-DTPA in healthy human volunteers, a slight increase in signal intensity was noted in the labyrinth. 8 However, probably because of a gadolinium concentration that was too low in the perilymphatic space, differentiation between the endolymphatic and perilymphatic space was not achieved. Intratympanic injection of Gd-DTPA and the application of 3D-FLAIR at 3T made the visualization of endolymphatic hydrops possible in vivo.…”

State of the Art: 3T Imaging of the Membranous Labyrinth

“…This can be done with triple-dose intravenous injection with delayed scanning (optimal at 4-8 hours), allowing contrast to diffuse from the CSF to the perilymph 11 or by introduction of dilute gadolinium into the middle ear with diffusion of contrast into the perilymph across the round window membrane. 12 Both these techniques would be difficult to introduce into clinical practice for obvious reasons.…”