11.7 Tesla magnetic resonance microimaging of laryngeal tissue architecture.
OBJECTIVE
High-resolution imaging of vocal folds that distinguishes vocal fold (VF) layered microstructure and VF implants would provide a key experimental tool for translational research investigating biomaterial-based interventions to treat vocal fold scar. To establish proof of concept, we studied whether 11.7 Tesla (T) magnetic resonance (MR) microimaging provides the needed resolution to resolve vocal fold tissue architecture.


METHODS
We performed ex vivo MR microimaging of fixed ferret and canine larynges to determine whether changes in the layered architecture can be detected in the presence of scar and subsequent to biomaterial injections into the vocal folds. Serial section histological analyses were done to corroborate MR microimaging findings.


METHODS
Multiple axial and transverse/coronal 300-microm slices were obtained using an 11.7 T MR spectrometer/500 MHz for proton with gradient-recalled echo and rapid acquisition with relaxation enhancement imaging sequences.


RESULTS
High-resolution (39 microm/pixel) MR microimages distinguished VF epithelium, lamina propria, muscle, and cartilage in ferret and canine larynges. In ferret scarred VFs (n = 25), collagen-rich dense scar tissue was distinguishable from contralateral nonscarred VFs and from normal ferret VFs (n = 25), as confirmed on histology. MR microimaging accurately detected injected autologous fat, hyaluronic acid-based and polyethylene glycol (PEG)-based implants injected into both ferret and canine VFs. Importantly, MRI accurately showed resorption of PEG implants in ferrets and canines, as confirmed on histology. Additionally, ex vivo MR spectroscopy distinguished fat from PEG-based implants.


CONCLUSIONS
Ex vivo 11.7 T MR microimaging provided high-resolution images of ferret and canine laryngeal tissue microstructure, although the superficial lamina propria could not be distinguished. Histology confirmed MR microimaging findings, indicating utility of MR microimaging of modeled scar, implant residence time, and tissue responses, thus providing integrative insight relevant to translational research.
Herrera
Victoria L M
VL
Department of Medicine, Boston University School of Medicine Boston, Massachusetts 02118, USA. vherrera@bu.edu
Viereck
Jason C
JC
Lopez-Guerra
Gerardo
G
Kumai
Yoshihiko
Y
Kobler
James
J
Karajanagi
Sandeep
S
Park
Hyoungshin
H
Hillman
Robert
R
Zeitels
Steven M
SM
D000818:Animals; D004285:Dogs; D005289:Ferrets; D007830:Larynx / Q000033:anatomy & histology* / Q000601:surgery; D008279:Magnetic Resonance Imaging / Q000379:methods*