Abstract

Increasing penetration remains one of the most important issues in optical coherence tomography (OCT) research, which we achieved with a parallel ultrasound beam. In addition to qualitative improvements of tissue imaging, quantitative improvements in resolution of up to 28%±2% was noted. At lower frequencies and energies the improvement occurred primarily by altering the detection of multiply scattered light (photon–phonon interaction), which was substantially greater in solids than in liquids (even though the liquid had the higher scattering coefficient). In conclusion, the use of an ultrasound beam with OCT appears the most effective means to date for increasing imaging penetration.

© 2008 Optical Society of America

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References

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2007 (1)

B. Liu and M. E. Brezinski, “Theoretical and practical considerations on detection performance of time domain, Fourier domain, and swept source optical coherence tomography,” J. Biomed. Opt. 12, 044007 (2007).
[CrossRef] [PubMed]

2003 (1)

A. F. Fercher, W. Drexler, C. K. Hitzenberger, and T. Lasser, “Optical coherence tomography,” Rep. Prog. Phys. 66, 239-303 (2003).
[CrossRef]

2002 (1)

J. O. Schenk and M. E. Brezinski, “Ultrasound induced improvement in optical coherence tomography (OCT) resolution,” Proc. Natl. Acad. Sci. U.S.A. 99, 9761-9764 (2002).
[CrossRef] [PubMed]

2001 (4)

I. K. Jang, J. G. Tearney, and B. E. Bouma, “Visualization of tissue prolapse between coronary stent struts by optical coherence tomography,” Circulation 104, 2754-2759 (2001).
[CrossRef] [PubMed]

L. V. Wang, “Mechanisms of ultrasonic modulation of multiply scattered coherent light: an analytic model,” Phys. Rev. Lett. 87, 043903-043906 (2001).
[CrossRef] [PubMed]

L. W. Wang, “Mechanisms of ultrasound modulation of multiply scattered coherent light: a Monte Carlo model,” Opt. Lett. 26, 1191-1993 (2001).
[CrossRef]

P. A. Edney and J. T. Walsh, “Acoustical modulation and photon-phonon scattering in optical coherence tomography,” Appl. Opt. 40, 6381-6388 (2001).
[CrossRef]

2000 (1)

1999 (5)

A. M. Rollins and J. A. Izatt, “Optimal interferometer designs for optical coherence tomography,” Opt. Lett. 24, 1484-1486 (1999).
[CrossRef]

M. E. Brezinski and J. G. Fujimoto, “Optical coherence tomography: high-resolution imaging in nontransparent tissue,” IEEE J. Sel. Top. Quantum Electron. 5, 1185-1192 (1999).
[CrossRef]

G. Yao and L. V. Wang, “Monte Carlo simulation of an optical coherence tomography signal in homogeneous turbid media,” Phys. Med. Biol. 44, 2307-2320 (1999).
[CrossRef] [PubMed]

J. M. Herrmann, C. Pitris, B. E. Bouma, S. A. Boppart, C. A. Jesser, D. L. Stamper, J. G. Fujimoto, and M. E. Brezinski, “High resolution imaging of normal and osteoarthritic cartilage with optical coherence tomography,” J. Rheumatol. 26 (3), 627-635 (1999).
[PubMed]

C. Pitris, A. Goodman, S. A. Boppart, J. J. Libus, J. G. Fujimoto, and M. E. Brezinski, “High-resolution imaging of gynecologic neoplasms using optical coherence tomography,” Obstet. Gynecol. 93, 135-139 (1999).
[PubMed]

1998 (1)

D. J. Smithies, T. Lindmo, C. Zhongping, J. S. Nelson, and T. E. Milner, “Signal attenuation and localization in optical coherence tomography studied by Monte Carlo simulation,” Phys. Med. Biol. 43, 2044-3025 (1998).
[CrossRef]

1997 (5)

M. E. Brezinski, G. J. Tearney, S. A. Boppart, E. A. Swanson, J. F. Southern, and J. G. Fujimoto, “Optical biopsy with optical coherencetomography: feasibility for surgical diagnostics,” J. Surg. Res. 71, 32-40 (1997).
[CrossRef] [PubMed]

G. J. Tearney, M. E. Brezinski, J. F. Southern, B. E. Bouma, S. A. Boppart, and J. G. Fujimoto, “Optical biopsy in human gastrointestinal tissue using optical coherence tomography,” Am. J. Gastroenterol. 92, 1800-1804 (1997).
[PubMed]

G. J. Tearney, M. E. Brezinski, B. E. Bouma, S. A Boppart, C. Pitris, J. F. Southern, and J. G. Fujimoto, “In vivo endoscopic optical biopsy withoptical coherence tomography,” Science 276, 2037-2039 (1997).
[CrossRef] [PubMed]

S. R. Chinn, E. A. Swanson, and J. G. Fujimoto, “Optical coherencetomography using a frequency-tunable optical source,” Opt. Lett. 22, 340-342 (1997).
[CrossRef] [PubMed]

G. J. Tearney, B. E. Bouma, and J. G. Fujimoto, “High-speed phase-and group-delay scanning with grating-based phase control delay line,” Opt. Lett. 22, 1811-1813 (1997).
[CrossRef]

1996 (1)

M. E. Brezinski, G. J. Tearney, B. E. Bouma, J. A. Izatt, M. R. Hee, E. A. Swanson, J. F. Southern, and J. G. Fujimoto, “Optical coherence tomography for optical biopsy: properties and demonstration of vascular pathology,” Circulation 93, 1206-1213 (1996).
[PubMed]

1995 (1)

W. Leutz and G. Maret, “Ultrasound modulation of multiply scatteredlight,” Physica B 204, 14-19 (1995).
[CrossRef]

1993 (1)

1991 (2)

D. F. Nelson, “Momentum, pseudomentum, and wave momentum: toward resolving the Minkowski-Abraham controversy,” Phys. Rev. A 44, 3985-3996 (1991).
[CrossRef] [PubMed]

D. Huang, E. A. Swanson, C. P. Lin, J. S. Schuman, W. G. Stinson, W. Chang, M. R. Hee, T. Flotte, K. Gregory, C. A. Puliafito, and J. G. Fujimoto, “Optical coherence tomography,” Science 254, 1178-1181 (1991).
[CrossRef] [PubMed]

1990 (2)

V. R. Singh, “Instrumentation techniques for acousto-optic studies incomplex materials,” Appl. Acoust. 29, 289-304 (1990).
[CrossRef]

W. Cheong, S. A. Prahl, and A. J. Welch, “A review of the opticalproperties of biological tissue,” IEEE J. Quantum Electron. 26, 2166-2185 (1990).
[CrossRef]

1989 (1)

1974 (1)

V. A. Del Grosso, “New equation for the speed of sound in natural waters with comparisons to other equations,” J. Acoust. Soc. Am. 56, 1084-1091 (1974).
[CrossRef]

1967 (1)

W. R. Klein and B. D. Cook, “Unified approach to ultrasonic light diffraction,” IEEE Trans. Sonics Ultrason. 14, 123-134 (1967).

1935 (1)

C. V. Raman and N. S. Nath, “Diffraction of light by high frequencysound waves,” Proc. Indian Acad. Sci., Sect. A 2, 406-412 (1935).

1932 (1)

W. H. Bragg and W. L. Bragg, “The reflection of x-rays by crystals,” Proc. R. Soc., London 20, 3271-3273 (1932).

Am. J. Gastroenterol. (1)

G. J. Tearney, M. E. Brezinski, J. F. Southern, B. E. Bouma, S. A. Boppart, and J. G. Fujimoto, “Optical biopsy in human gastrointestinal tissue using optical coherence tomography,” Am. J. Gastroenterol. 92, 1800-1804 (1997).
[PubMed]

Appl. Acoust. (1)

V. R. Singh, “Instrumentation techniques for acousto-optic studies incomplex materials,” Appl. Acoust. 29, 289-304 (1990).
[CrossRef]

Appl. Opt. (3)

Circulation (2)

I. K. Jang, J. G. Tearney, and B. E. Bouma, “Visualization of tissue prolapse between coronary stent struts by optical coherence tomography,” Circulation 104, 2754-2759 (2001).
[CrossRef] [PubMed]

M. E. Brezinski, G. J. Tearney, B. E. Bouma, J. A. Izatt, M. R. Hee, E. A. Swanson, J. F. Southern, and J. G. Fujimoto, “Optical coherence tomography for optical biopsy: properties and demonstration of vascular pathology,” Circulation 93, 1206-1213 (1996).
[PubMed]

IEEE J. Quantum Electron. (1)

W. Cheong, S. A. Prahl, and A. J. Welch, “A review of the opticalproperties of biological tissue,” IEEE J. Quantum Electron. 26, 2166-2185 (1990).
[CrossRef]

IEEE J. Sel. Top. Quantum Electron. (1)

M. E. Brezinski and J. G. Fujimoto, “Optical coherence tomography: high-resolution imaging in nontransparent tissue,” IEEE J. Sel. Top. Quantum Electron. 5, 1185-1192 (1999).
[CrossRef]

IEEE Trans. Sonics Ultrason. (1)

W. R. Klein and B. D. Cook, “Unified approach to ultrasonic light diffraction,” IEEE Trans. Sonics Ultrason. 14, 123-134 (1967).

J. Acoust. Soc. Am. (1)

V. A. Del Grosso, “New equation for the speed of sound in natural waters with comparisons to other equations,” J. Acoust. Soc. Am. 56, 1084-1091 (1974).
[CrossRef]

J. Biomed. Opt. (1)

B. Liu and M. E. Brezinski, “Theoretical and practical considerations on detection performance of time domain, Fourier domain, and swept source optical coherence tomography,” J. Biomed. Opt. 12, 044007 (2007).
[CrossRef] [PubMed]

J. Opt. Soc. Am. A (1)

J. Rheumatol. (1)

J. M. Herrmann, C. Pitris, B. E. Bouma, S. A. Boppart, C. A. Jesser, D. L. Stamper, J. G. Fujimoto, and M. E. Brezinski, “High resolution imaging of normal and osteoarthritic cartilage with optical coherence tomography,” J. Rheumatol. 26 (3), 627-635 (1999).
[PubMed]

J. Surg. Res. (1)

M. E. Brezinski, G. J. Tearney, S. A. Boppart, E. A. Swanson, J. F. Southern, and J. G. Fujimoto, “Optical biopsy with optical coherencetomography: feasibility for surgical diagnostics,” J. Surg. Res. 71, 32-40 (1997).
[CrossRef] [PubMed]

Obstet. Gynecol. (1)

C. Pitris, A. Goodman, S. A. Boppart, J. J. Libus, J. G. Fujimoto, and M. E. Brezinski, “High-resolution imaging of gynecologic neoplasms using optical coherence tomography,” Obstet. Gynecol. 93, 135-139 (1999).
[PubMed]

Opt. Lett. (4)

Phys. Med. Biol. (2)

D. J. Smithies, T. Lindmo, C. Zhongping, J. S. Nelson, and T. E. Milner, “Signal attenuation and localization in optical coherence tomography studied by Monte Carlo simulation,” Phys. Med. Biol. 43, 2044-3025 (1998).
[CrossRef]

G. Yao and L. V. Wang, “Monte Carlo simulation of an optical coherence tomography signal in homogeneous turbid media,” Phys. Med. Biol. 44, 2307-2320 (1999).
[CrossRef] [PubMed]

Phys. Rev. A (1)

D. F. Nelson, “Momentum, pseudomentum, and wave momentum: toward resolving the Minkowski-Abraham controversy,” Phys. Rev. A 44, 3985-3996 (1991).
[CrossRef] [PubMed]

Phys. Rev. Lett. (1)

L. V. Wang, “Mechanisms of ultrasonic modulation of multiply scattered coherent light: an analytic model,” Phys. Rev. Lett. 87, 043903-043906 (2001).
[CrossRef] [PubMed]

Physica B (1)

W. Leutz and G. Maret, “Ultrasound modulation of multiply scatteredlight,” Physica B 204, 14-19 (1995).
[CrossRef]

Proc. Indian Acad. Sci., Sect. A (1)

C. V. Raman and N. S. Nath, “Diffraction of light by high frequencysound waves,” Proc. Indian Acad. Sci., Sect. A 2, 406-412 (1935).

Proc. Natl. Acad. Sci. U.S.A. (1)

J. O. Schenk and M. E. Brezinski, “Ultrasound induced improvement in optical coherence tomography (OCT) resolution,” Proc. Natl. Acad. Sci. U.S.A. 99, 9761-9764 (2002).
[CrossRef] [PubMed]

Proc. R. Soc., London (1)

W. H. Bragg and W. L. Bragg, “The reflection of x-rays by crystals,” Proc. R. Soc., London 20, 3271-3273 (1932).

Rep. Prog. Phys. (1)

A. F. Fercher, W. Drexler, C. K. Hitzenberger, and T. Lasser, “Optical coherence tomography,” Rep. Prog. Phys. 66, 239-303 (2003).
[CrossRef]

Science (2)

D. Huang, E. A. Swanson, C. P. Lin, J. S. Schuman, W. G. Stinson, W. Chang, M. R. Hee, T. Flotte, K. Gregory, C. A. Puliafito, and J. G. Fujimoto, “Optical coherence tomography,” Science 254, 1178-1181 (1991).
[CrossRef] [PubMed]

G. J. Tearney, M. E. Brezinski, B. E. Bouma, S. A Boppart, C. Pitris, J. F. Southern, and J. G. Fujimoto, “In vivo endoscopic optical biopsy withoptical coherence tomography,” Science 276, 2037-2039 (1997).
[CrossRef] [PubMed]

Other (12)

E. Hecht, Hecht Optics (Addison-Wesley, 1998).

A. Korpel, Acousto-Optics (Marcel Dekker, 1998).

M. E. Brezinski Optical Coherence Tomography, Principle and Practice (Academic, 2006).

J. S. Schuman, C. A. Puliafito, and J. G. Fujimoto, Optical Coherence Tomography of Ocular Diseases, 2nd ed. (Slack, 2004).

R. L. Liboff, Introductory Quantum Mechanics 3rd ed. (Addison-Wesley, 1998).

P. W. Anderson, Basic Notions of Condensed Matter Physics (Addison-Wesley, 1997).

A. M. Zagoskin, Quantum Theory of Many Body Systems: Techniques and Applications (Springer, 1998).
[CrossRef]

R. F. Feynman, Statistical Mechanics (Addison-Wesley, 1998).

A. Korpel, “Acousto-optics--a review of fundamentals,” in Proceedings of the IEEE (IEEE, 1981) pp. 48-53.
[CrossRef]

M. Teich and B. Saleh, Fundamentals of Photonics (Wiley, 1991).

F. Schwabl, Advanced Quantum Mechanics (Springer, 1997).

M. Le Bellac, Quantum Physics (Cambridge U. Press, 2006).

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Figures (7)

Fig. 1
Fig. 1

OCT System. Schematics of the real-time OCT system with a near-parallel ultrasound beam. The system consists of a bandpass and a low-pass filter, which are critical for improving penetration with ultrasound. Ultrasound frequency varies from 0 to 9 MHz , and the energy varies from 0 to 10 Vpp (peak to peak). A gel column ( 2 cm ) is used with the ultrasound transducer to keep the beam in the far field. SLD, Superluminiscent diode.

Fig. 2
Fig. 2

Two-dimensional OCT images showing sections of rabbit trachea, including cartilage imaged in the absence (top) and presence (bottom) of ultrasound. C is the cartilage, and the shorter arrow in the ultrasound image marks the back of the cartilage. The longer arrow in both images shows the area of multiple scattering, where it is greatly reduced in the bottom.

Fig. 3
Fig. 3

Decay curves in tissue. A-scans of chicken in the presence and absence of ultrasound are demonstrated. The x axis is distance, while the y axis is intensity. The use of 9 MHz ultrasound led to a statistically significant increase in backreflected OCT signal ( p < 0.005 ) .

Fig. 4
Fig. 4

Representative OCT PSF at varying energies and frequencies. (a) Example PSF at varying energies. Shown are representative PSFs with ultrasound exposure at 7.5 MHz and at energies varying from 0 to 10 Vpp . Several points are noted from the image of a reflector 1 mm within chicken. First, increasing ultrasound energy results in a higher resolution or smaller FWHM in the PSF. Second, the reduction in width does not occur symmetrically, as photons to the left are predominately removed. Photons to the right are ballistic photons, while those to the left are late, representing multiply scattered light. This pattern is seen at lower energies, but as will be shown, slightly different patterns (more symmetric) are seen at higher frequencies for reasons discussed later. Third, the peak intensity of the PSF decreases as the energy is increased, consistent with a reduction in multiply scattering photons. (b) Example PSF at varying frequencies. Shown are representative PSFs with energies of 10 Vpp and frequencies of 0 9 MHz . Several points are noted from the image of a reflector 1 mm within chicken. First, there is an improvement in resolution with increasing frequency. Second, improvements become less apparent above 5 MHz . Third, improvements above 5 MHz are associated with less shift to the right then from 0 to 5 MHz [or in (a)]. Fourth, a point that is discussed in the text, the intensity increases from 7.5 to 9 MHz . (c) The same data used in (b) are used here, except the fast Fourier transforms (FFTs) are plotted. In addition, data are normalized to a constant intensity [see Figs. 4b, 5a for intensity variations] to make differences in FWHM more clear. The FWHM clearly improves with ultrasound bandwidth, with a larger Gaussian FWHM corresponding to a smaller PSF.

Fig. 5
Fig. 5

(a) Plot of ultrasound frequency versus modification in the PSF for chicken. This figure shows a plot of improvement in the PSF as a function of frequency in solid tissue (chicken). PSF increases significantly with frequency. However, a sharp jump occurs at 9 MHz (shaded area) that it will be argued is due to an effect of the ultrasound beam on single-scattered rather than multiply scattered light. This is the same reason as for the intensity increase in the previous figures from 7.5 to 9 MHz . (b) Plot of ultrasound frequency versus modification in the PSF for Intralipid. The effect in Intralipid is minimal except at the highest frequencies and energies (shadow area as in Fig. 4). This is in spite of a high scattering coefficient for the Intralipid.

Fig. 6
Fig. 6

(a) Plot of energy versus modification in the PSF for chicken. This figure shows a plot of improvement in the PSF as a function of energy in solid tissue (chicken). PSF increases significantly and almost linearly with energy. The rate almost doubles between 6 and 10 V , consistent with this linear dependence. (b) Plot of energy versus modification in the PSF for Intralipid. This figure shows a plot of improvement in the PSF as a function of energy in a liquid (Intralipid). It can be seen that up to 8 MHz , the increases are linear but substantially less than those in solid. A sharp increase occurs in the shaded area for the reason described in the text.

Fig. 7
Fig. 7

Plot of frequency versus peak intensity for chicken. In this figure it can be seen that, other than in the shaded zone, intensity decreases with both frequency and energy. However, in the shaded zone, the pattern is reversed both in terms of frequency and power. This again illustrates that at least two distinct mechanisms are occurring. We are 95% confident that the mean intensity at 9 MHz and 10 Vpp is between 0.112 and 0.118, and at 9 MHz and 8 Vpp is between 0.112 and 0.116. The deviation from the expected values at 9 MHz is consistent with the second mechanism inducing an improved PSF. The dotted line represents the best fit comparison used for analysis.

Equations (4)

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Q = 2 π λ L L n o Λ 2 ,
H = k s = 1 3 ω k , s ( a k , s a k , s + 1 2 ) .
h ν = E n E n = ω 0 ( n + 1 2 ) ω 0 ( n + 1 2 ) = ω 0 ( n + n ) = ω 0 s .
S coh ( k , ω ) = d t 2 π e i ω t V N ρ k ( t ) ρ k ( 0 ) ,

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