Intratympanic iodine contrast injection diffuses across the round window membrane allowing for perilymphatic CT volume acquisition imaging

Nicholas B. Abt, Mohamed Lehar, Carolina Trevino Guajardo, Richard T. Penninger, Bryan K. Ward, Monica S. Pearl, John P. Carey

Research output: Contribution to journalArticlepeer-review

Abstract

Hypothesis: Whether the round window membrane (RWM) is permeable to iodine-based contrast agents (IBCA) is unknown; therefore, our goal was to determine if IBCAs could diffuse through the RWM using CT volume acquisition imaging. Introduction: Imaging of hydrops in the living human ear has attracted recent interest. Intratympanic (IT) injection has shown gadolinium's ability to diffuse through the RWM, enhancing the perilymphatic space. Methods: Four unfixed human cadaver temporal bones underwent intratympanic IBCA injection using three sequentially studied methods. The first method was direct IT injection. The second method used direct RWM visualization via tympanomeatal flap for IBCA-soaked absorbable gelatin pledget placement. In the third method, the middle ear was filled with contrast after flap elevation. Volume acquisition CT images were obtained immediately postexposure, and at 1-, 6-, and 24-hour intervals. Postprocessing was accomplished using color ramping and subtraction imaging. Results: After the third method, positive RWM and perilymphatic enhancement were observed with endolymph sparing. Gray scale and color ramp multiplanar reconstructions displayed increased signal within the cochlea compared with precontrast imaging. The cochlea was measured for attenuation differences compared with pure water, revealing a preinjection average of-1,103 HU and a postinjection average of 338 HU. Subtraction imaging shows enhancement remaining within the cochlear space, Eustachian tube, middle ear epithelial lining, and mastoid. Conclusion: Iohexol iodine contrast is able to diffuse across the RWM. Volume acquisition CT imaging was able to detect perilymphatic enhancement at 0.5-mm slice thickness. The clinical application of IBCA IT injection seems promising but requires further safety studies.

Original languageEnglish (US)
Pages (from-to)403-407
Number of pages5
JournalOtology and Neurotology
Volume37
Issue number4
DOIs
StatePublished - Mar 23 2016

Keywords

  • CT
  • Computed tomography
  • Contrast
  • Endolymph
  • Intratympanic
  • Iodine
  • Perilymph
  • Round window
  • Round window membrane.

ASJC Scopus subject areas

  • Otorhinolaryngology
  • Sensory Systems
  • Clinical Neurology

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