Journal List > Clin Exp Otorhinolaryngol > v.13(2) > 1157831

Cho and Jang: Future Directions of Optical Coherence Tomography in Otology: A Morphological and Functional Approach
Optical coherence tomography (OCT) is a real-time optical imaging modality that enables tomographic imaging at the submicron scale. Basic research into applications of OCT systems in the field of otology has been conducted. For instance, Oh et al. [1] recently reported that OCT provided noninvasive, nondestructive two-dimensional cross-sectional and three-dimensional volumetric images of middle-ear and inner ear structures in rodents. Anatomical depth-resolved imaging has shown promising potential for morphological measurements of the middle and inner ear in chinchillas [2] and mice with blast trauma [3]. Moreover, OCT has demonstrated its capability as a functional analytical tool by characterizing the vibration of middle and inner ear structures using the Doppler principle without contrast labeling to identify fluid, cellular structures, and bone [4]. Interestingly, Eustachian tube status and stent position were evaluated noninvasively using an intraluminal three-dimensional OCT catheter in sheep cadaver heads [5].
Recently, various studies have attempted to apply OCT to the clinical field. Structural changes of the middle ear in otitis media were investigated using a hand-held OCT otoscope probe [6]. General trends in the thickness distribution of the human tympanic membrane (TM) were suggested based on in vivo thickness mapping by a mosaicking approach [7]. Additionally, a surgical microscope integrated with OCT was developed and its usefulness for surgical decision-making during tympanomastoidectomy was verified [8]. Furthermore, in vivo middle ear vibrations were measured using a combined microscope at the picometer scale in an outpatient clinic [9]. A major obstacle for OCT in clinical applications is its shallow penetration depth and field of view smaller than human middle ear structures such as the TM and ossicles. To overcome this hurdle, long-range wide-field swept-source OCT vibrometry was developed and validated for real-time imaging of normal middle ear structures and stapes fixation in living patients [10].
Morphological changes of the cochlea can be visualized by micro-OCT technology in addition to histological slide/labeling methods, such as confocal and two-photon microscopy. Since these techniques are used for post-mortem analyses, the structural properties of the cochlea may be changed and distorted by the embedding chemical solutions. Furthermore, specimen preparation and the imaging process could be time-consuming. MicroOCT technology requires no contrast agent and can be used to image entire structures within its detection field near-instantaneously. Micro-OCT images of guinea pig intracochlear anatomy in situ were generated to resolve the microanatomy at a cellular level [11].
OCT is already a useful imaging technique in basic research in otology. Although OCT is known to be difficult to apply in clinical otology due to several drawbacks, it has many advantages that may even surpass its limitations. It is important to pioneer this niche with original ideas such as an intraluminal OCT catheter for Eustachian tube evaluation, a functional hand-held OCT otoscope with vibrometry, a surgical microscope integrated with OCT, and micro-OCT for in vivo imaging. Ultimately, the development of a unique and accessible OCT device helpful for the accurate diagnosis and treatment of diseases could be a survival strategy of itself in otologic field.

Notes

No potential conflict of interest relevant to this article was reported.

REFERENCES

1. Oh SJ, Lee IW, Wang SG, Kong SK, Kim HK, Goh EK. Extratympanic observation of middle and inner ear structures in rodents using optical coherence tomography. Clin Exp Otorhinolaryngol. 2020; 13(2):106–12.
crossref
2. Ramier A, Cheng JT, Ravicz ME, Rosowski JJ, Yun SH. Mapping the phase and amplitude of ossicular chain motion using sound-synchronous optical coherence vibrography. Biomed Opt Express. 2018; Oct. 9(11):5489–502.
crossref
3. Kim J, Xia A, Grillet N, Applegate BE, Oghalai JS. Osmotic stabilization prevents cochlear synaptopathy after blast trauma. Proc Natl Acad Sci U S A. 2018; May. 115(21):E4853–60.
crossref
4. Cooper NP, Vavakou A, van der Heijden M. Vibration hotspots reveal longitudinal funneling of sound-evoked motion in the mammalian cochlea. Nat Commun. 2018; Aug. 9(1):3054.
crossref
5. Schuon R, Mrevlje B, Vollmar B, Lenarz T, Paasche G. Intraluminal three-dimensional optical coherence tomography: a tool for imaging of the Eustachian tube. J Laryngol Otol. 2019; Feb. 133(2):87–94.
6. Won J, Monroy GL, Huang PC, Hill MC, Novak MA, Porter RG, et al. Assessing the effect of middle ear effusions on wideband acoustic immittance using optical coherence tomography. Ear Hear. 2019; Oct. 18. [Epub]. https://doi.org/10.1097/AUD.0000000000000796.
crossref
7. Pande P, Shelton RL, Monroy GL, Nolan RM, Boppart SA. A Mosaicking approach for in vivo thickness mapping of the human tympanic membrane using low coherence interferometry. J Assoc Res Otolaryngol. 2016; Oct. 17(5):403–16.
crossref
8. Lee J, Wijesinghe RE, Jeon D, Kim P, Choung YH, Jang JH, et al. Clinical utility of intraoperative tympanomastoidectomy assessment using a surgical microscope integrated with an optical coherence tomography. Sci Rep. 2018; Nov. 8(1):17432.
crossref
9. Kim W, Kim S, Huang S, Oghalai JS, Applegate BE. Picometer scale vibrometry in the human middle ear using a surgical microscope based optical coherence tomography and vibrometry system. Biomed Opt Express. 2019; Aug. 10(9):4395–410.
crossref
10. Iyer JS, Batts SA, Chu KK, Sahin MI, Leung HM, Tearney GJ, et al. Micro-optical coherence tomography of the mammalian cochlea. Sci Rep. 2016; Sep. 6:33288.
crossref
11. MacDougall D, Morrison L, Morrison C, Morris DP, Bance M, Adamson RB. Optical coherence tomography doppler vibrometry measurement of stapes vibration in patients with stapes fixation and normal controls. Otol Neurotol. 2019; 40(4):e349–55.
crossref
TOOLS
Similar articles