MRI Evidence of Endolymphatic Impermeability to the Gadolinium Molecule in the In Vivo Mouse Inner Ear at 9.4 Tesla
S. Allen Counter1, *, Sahar Nikkhou2, Stefan Brené2, Peter Damberg2, Adam Sierakowiak2, Tomas Klason3, Cecilia Engmér Berglin4 , Göran Laurell5
1 Neurology Department, Harvard University Biological Laboratories, Cambridge, MA 02138,USA
2 Karolinska Experimental Research Imaging Center, Karolinska universitetssjukhuset Solna
3 Konsultfirman tekn. dr. Tomas Klason, Freyvägen 5A, SE 133 38 Saltsjöbaden, Sweden
4 Department of CLINTEC Karolinska Institutet, 171 76 Stockholm, Sweden
5 Department of Surgical Sciences Uppsala University, Uppsala, Sweden
Previous in vivo experimental magnetic resonance imaging (MRI) investigations of the mammalian inner ear at 4.7 Tesla have indicated that intravenously injected gadolinium (Gd) penetrates the perilymphatic labyrinth, but not the endolymphatic membranous labyrinth. In the present study, high field MRI at 9.4T was used to visualize the in vivo mouse vestibulo-cochlea system, and to determine whether the endolymphatic system is permeable to a Gd complex.
A 9.4 T Varian magnet equipped with a 12 cm inner diameter gradient system with maximum gradient strength of 600 mT/m, a millipede coil (Varian design) and a Gd contrast agent were used for image acquisition in the normal C57 BL-6 mouse.
High-resolution 2D and 3D images of the mouse cochlea were acquired within 80 minutes following intravenous injection of Gd. Gd initially permeated the perilymphatic scala tympani and scala vestibuli, and permitted visualization of both cochlear turns from base to apex. The superior, inferior and lateral semicircular canals were subsequently visualized in 3 planes. The membranous endolymphatic labyrinth was impermeable to intravenously injected Gd, and thus showed no apparent uptake of Gd at 9.4T.
The 9.4T field strength MRI permitted acquisition of high resolution images of anatomical and physiological features of the normal, wild type mouse perilymphatic inner ear in vivo, and provided further evidence that the endolymphatic system is impermeable to intravenously injected Gd.
Keywords: Magnetic resonance imaging, cochlea, vestibular, semicircular canals, Tesla.
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* Address correspondence to this author at Neurology Department, Harvard University Biological Laboratories, 16 Divinity Avenue, Cambridge, MA 02138,USA; Tel: +1 617.495-1527?; Fax: +1 617.496-1443; E-mail: firstname.lastname@example.org