Intravascular Megahertz Doppler Optical Coherence Tomography - - PowerPoint PPT Presentation

Intravascular Megahertz Doppler Optical Coherence Tomography

Tianshi Wang

FFT a + bi Phase signal

Coherence fringes

Phase-sensitive Optical coherence tomography

Sensitive to motion along the laser beam (moving away or moving close) Nanometer to sub-micrometer scale Absolute signal

OCT image of coronary artery

Velocity = d /△t

Catheter based intravascular Doppler OCT

Victor Yang, FRCSC MASc MD PhD PEng Doppler phase shift Unwrapped Doppler phase shift

Limited by the speed of system

• 20 frames/s
• Phase wrap
• C. Sun et al,. "In vivo feasibility of endovascular Doppler optical coherence tomography,"
• Biomed. Opt. Express 3, 2600-2610 (2012)

1.2 mm outer diameter 1.7 mm length 5600 frames/s for Heartbeat OCT < 600 frames/s for Doppler imaging > 2600 A-lines per frame

Motorized catheter and 1.5 MHz OCT

catheter

80o Velocity sin (10o) Velocity

DAQ computer catheter 50/50 90% 10% reference arm mirror BPD PC FDML laser λ0 = 1310 nm Δλ = 90 nm Calibration mirror 95% 5%

Phase-shift between two neighboring A-scans (600 ns)

Intensity Phase

A-line (n) A-line (n+1) PVA Phantom and Diluted intralipid

600 frames/s

1.0 mm

• pi

pi

Phase signal processing

Non-Uniform Rotational Distortion (NURD)

1.0 mm

• 1

1

* * *

2 ml/s infusion rate

Using the catheter tube to correct the phase error

1.0 mm

• 1

1

* * *

• 1

1 1.0 mm

Phase error correction

* * *

Before compensation

* * *

After compensation

Phase-shift

Root Mean Square Error 0.19 à 0.08 rad (0.95 cm/s error)

1.0 mm

Intralipid flowing in a tube with 0.75 mm inner diameter

Velocity measurement validation

catheter

Velocity sin (10o)

• 37.5 to 37.5 cm/s speed range

(along the beam)

• 220 to 220 cm/s speed range

(along the tube)

0.1 ml/s 0.2 ml/s 0.3 ml/s 0.4 ml/s 1.0 mm

Intralipid flowing in a tube with 0.75 mm inner diameter

Velocity measurement validation

• pi

pi

Infusion rate (ml/s) Theoretical mean velocity(cm/s) Measured mean velocity(cm/s) 0.1 22.6 23.8 ± 7.5 0.2 45.3 47.2 ± 9.7 0.3 67.9 68.9 ± 9.1 0.4 90.5 88.3 ± 4.5

Measured speed profile

Imaging of flow in a swine coronary artery

• 37.5 cm/s

37.5 cm/s

Imaging of flow in a swine coronary artery

37.5 cm/s 0 cm/s

• 37.5 cm/s

1.0 mm

Doppler imaging pullback in vitro swine artery

• 37.5 cm/s

37.5 cm/s

• 600 frames/s
• 4 cm/s pullback (~0.68 cm/s in beam) ~26 mRad shift induced
• 1.3 ml/s infusion rate

~0.7 s

3D reconstruction

37.5 (cm/s)

• 37.5

32 mm

Longitudinal image

32 mm length

37.5 (cm/s)

• 37.5

Longitudinal video

32 mm 37.5 (cm/s)

• 37.5

Conclusion

High speed morphological imaging

• 600 frames/s
• 4 cm/s pullback

High speed Doppler imaging

• -37.5 cm/s to 37.5 cm/s speed range
• flow visualization of the entire artery
• flow pattern near bifurcation

Future work

Quantitative study Optimization for in vivo imaging Combine with commercial catheters

Acknowledgements

Tom Pfeiffer Robert Huber Lubeck University

Gijs van Soest A.F.W. van der Steen Geert Springeling Frits Mastik Heleen van Beusekom Sophinese Iskander-Rizk Brett E. Bouma Robert Beurskens Mathijs Stam Frank Gijsen Leonado Cecchetti

Erasmus MC Walfgang Wieser Thomas Klein Optores Gmbh

Thank you!