title: High- and ultrahigh-field magnetic resonance imaging of naïve, injured and scarred vocal fold mucosae in rats.
abstract: Subepithelial changes to the vocal fold mucosa, such as fibrosis, are difficult to identify using visual assessment of the tissue surface. Moreover, without suspicion of neoplasm, mucosal biopsy is not a viable clinical option, as it carries its own risk of iatrogenic injury and scar formation. Given these challenges, we assessed the ability of high- (4.7 T) and ultrahigh-field (9.4 T) magnetic resonance imaging to resolve key vocal fold subepithelial tissue structures in the rat, an important and widely used preclinical model in vocal fold biology. We conducted serial in vivo and ex vivo imaging, evaluated an array of acquisition sequences and contrast agents, and successfully resolved key anatomic features of naïve, acutely injured, and chronically scarred vocal fold mucosae on the ex vivo scans. Naïve lamina propria was hyperintense on T1-weighted imaging with gadobenate dimeglumine contrast enhancement, whereas chronic scar was characterized by reduced lamina propria T1 signal intensity and mucosal volume. Acutely injured mucosa was hypointense on T2-weighted imaging; lesion volume steadily increased, peaked at 5 days post-injury, and then decreased - consistent with the physiology of acute, followed by subacute, hemorrhage and associated changes in the magnetic state of hemoglobin and its degradation products. Intravenous administration of superparamagnetic iron oxide conferred no T2 contrast enhancement during the acute injury period. These findings confirm that magnetic resonance imaging can resolve anatomic substructures within naïve vocal fold mucosa, qualitative and quantitative features of acute injury, and the presence of chronic scar.
authors.affiliation: Department of Surgery, Division of Otolaryngology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA.
authors.forename: Ayami Ohno
authors.initials: AO
authors.lastname: Kishimoto
authors.affiliation: Department of Surgery, Division of Otolaryngology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA.
authors.forename: Yo
authors.initials: Y
authors.lastname: Kishimoto
authors.affiliation: Department of Surgery, Division of Otolaryngology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA.
authors.forename: David L
authors.initials: DL
authors.lastname: Young
authors.affiliation: Department of Radiology and Center for Magnetic Resonance Research, University of Minnesota-Twin Cities, Minneapolis, MN 55455, USA.
authors.forename: Jinjin
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Entomology, University of Wisconsin-Madison, Madison, WI 53706, USA irowland@wisc.edu welham@surgery.wisc.edu.
authors.forename: Ian J
authors.identifier: 0000-0003-2282-7765
authors.initials: IJ
authors.lastname: Rowland
authors.affiliation: Department of Surgery, Division of Otolaryngology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA irowland@wisc.edu welham@surgery.wisc.edu.
authors.forename: Nathan V
authors.identifier: 0000-0003-3484-3455
authors.initials: NV
authors.lastname: Welham
mesh_terms: D000818:Animals; D002921:Cicatrix / Q000000981:diagnostic imaging* / Q000473:pathology*; D007275:Injections, Intravenous; D007830:Larynx / Q000000981:diagnostic imaging / Q000473:pathology; D008279:Magnetic Resonance Imaging; D058185:Magnetite Nanoparticles / Q000737:chemistry; D008297:Male; D009092:Mucous Membrane / Q000000981:diagnostic imaging* / Q000473:pathology*; D011916:Rats, Inbred F344; D013997:Time Factors; D014827:Vocal Cords / Q000000981:diagnostic imaging* / Q000473:pathology*
chemical_list: D058185:Magnetite Nanoparticles
keywords: Fibrosis; Hemorrhage; Larynx; MRI; Tissue repair; Voice; Wound healing