Communication between the Perilymphatic Scalae and Spiral Ligament Visualized by in vivo MRI

We evaluated the transport of Gadolinium-diethylenetriaminepentaacetate-bismethylamide (Gd-DTPA-BMA) through the round window (RW) membrane into the perilymphatic space with 4.7-T MRI in an animal study and 1.5-T MRI in humans. After administration of Gd-DTPA-BMA onto the intact RW membrane of guinea pig, Gd-DTPA-BMA uptake was observed in the basal turn and part of the second turn within 40 min. The scala tympani, scala vestibuli, the fibrous part of the spiral ligament and semicircular canal all showed uptake of Gd-DTPA-BMA. All turns of the cochlea were filled with Gd within 10 min in the perforated RW membrane administration group and within 30 min in the intravenous administration group. In patients who accepted middle ear injection of Gd-DTPA-BMA, uptake was observed within 2 h in the basal turn and semicircular canal. After 12 h the apex did still not show any uptake. Gd-DTPA-BMA is transported from the RW to the semicircular canal, the scala tympani and scala vestibuli without passing the helicotrema.