BME PhD Dissertation Defense - Whan Wook Chang

12:00 pm on Thursday, December 13, 2012
2:00 pm on Thursday, December 13, 2012
44 Cummington St, Room 203
Seok Hyun Yun (Research advisor, Wellman Center for Photomedicine, HMS)
Jerome Mertz (Academic advisor, BME, BU)
Steve Colburn (Chair, BME, BU)
David Mountain (BME. BU)
James Kobler (MGH Voice Center, HMS)
John Rosowski (MEEI, HMS)


Cross-sectional imaging of rapidly vibrating tissues or biomaterials under rapid periodic motion is useful for medical diagnosis and tissue engineering. Optical coherence tomography (OCT) is a powerful technique, but its relatively low frame rates limited its use in such applications. Here, we present a novel method that enables capturing 4-dimensional (4D) images of samples in motu at oscillation frequencies of up to 10 kHz and potentially far beyond. Employing continuous axial-line acquisition, motion-triggered beam scanning, and subsequent space-time registration, phase-aligned snapshots of tissue oscillation over the entire vibratory cycle can be obtained. This technique is applied to structural and functional imaging of major systems of speech and hearing: aerodynamically driven vibrations of the vocal fold in an ex vivo calf larynx and acoustically driven vibrations of the middle ear in an ex vivo chinchilla and human cadaveric temporal bones. Oscillations of the surface and interior structure of the both organs can be viewed and analyzed with high three-dimensional resolution of 10-15 μm, temporal resolution of 50 μs. For functional middle ear imaging, we employed phase sensitive OCT to achieve sub-nanometer scale vibration sensitivity to differentiate simulated pathologies. The results suggest that the dynamic 4D OCT technique has the potential to become a powerful tool in clinical and research applications for assessing health and mechanical properties of vocal folds and middle ear in the field of otolaryngology.