MRIによる内リンパ水腫の画像診断

概要

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The first visualization of endolymphatic hydrops in patients with Ménières disease was performed using three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) imaging with a 3 Tesla MRI unit after gadolinium contrast agent (Gd) was injected intratympanically. The 3D-FLAIR MRI could differentiate the endolymphatic space from the perilymphatic space, but not from the surrounding bone. By optimizing the inversion time, the endolymphatic space, perilymphatic space and surrounding bone could be separately visualized on a single image using three-dimensional real inversion recovery (3D-real IR) MRI. Using 3D-FLAIR and 3D-real IR MRI, various degrees of endolymphatic hydrops were observed in the basal and upper turns of the cochlea and in the vestibular apparatus after intratympanic Gd injection. Recently, visualization of endolymphatic hydrops became possible 4 h after intravenous Gd injection in patients with Ménières disease. We applied a heavily T(2)—weighted 3D-FLAIR technique to detect Gd more sensitively for evaluation of endolymphatic hydrops after an ordinary amount of Gd was administered intravenously. Thus, newly developed MRI techniques have contributed significantly to the evaluation of endolymphatic hydrops. The intravenous administration of an ordinary amount of Gd is routinely done clinically. The relationship between endolymphatic hydrops and clinical symptoms will be investigated widely using new techniques.