Magnetic resonance imaging of the cochlea, spiral ganglia and eighth nerveof the guinea pig

THE membranous labyrinth of the guinea pig cochlea and retrocochlear neural structures were investigated by magnetic resonance imaging (MRI) using an experimental system with a field strength of 4.7T and a single turn surface coil 25 mm in diameter, or standard resonators of 34 or 70 mm in diameter and gradient field strengths of 950 mTm and 200 mTm. High-resolution 2-D an d 3-D images of 0.3-1.0 mm slice thickness were acquired by a rapid acquisi tion with relaxation enhancement (RARE) sequence and a standard multiecho t echnique. Structural and dimensional aspects of the cochlea were resolved i n vitro and in vivo down to < 50 mu m, showing the scala vestibule, scala m edia, scala tympani, spiral ganglia and the cochlear (eighth) nerve. In viv o perfusions with the gadolinium (GdDTPA-BMA) chelate-bound paramagnetic ga dolinium ion resulted in dynamic temporal enhancement of the scala vestibul e and scala tympani, but did not penetrate the scala media. (C) 1999 Lippin cott Williams & Wilkins.