Intravascular Megahertz Doppler Optical Coherence Tomography - PowerPoint PPT Presentation

Intravascular Megahertz Doppler Optical Coherence Tomography Tianshi Wang

Phase-sensitive Optical coherence tomography FFT Absolute signal a + bi Coherence fringes Phase signal OCT image of coronary artery Velocity = d / △ t Sensitive to motion along the laser beam (moving away or moving close) Nanometer to sub-micrometer scale

Catheter based intravascular Doppler OCT Doppler phase shift Unwrapped Doppler phase shift Victor Yang, FRCSC MASc MD PhD PEng 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)

Motorized catheter and 1.5 MHz OCT Velocity sin (10 o ) Velocity 80 o catheter catheter λ 0 = 1310 nm 95% Δλ = 90 nm 1.2 mm outer diameter 5% 1.7 mm length Calibration mirror 5600 frames/s for Heartbeat OCT FDML laser 90% 50/50 < 600 frames/s for Doppler imaging DAQ > 2600 A-lines per frame 10% BPD PC computer reference arm mirror

Phase signal processing Phase-shift between two neighboring A-scans (600 ns) PVA Phantom and Diluted intralipid pi A-line (n) A-line (n+1) 0 1.0 mm -pi Intensity Phase 600 frames/s

Non-Uniform Rotational Distortion (NURD) 1 * 0 * * -1 1.0 mm 2 ml/s infusion rate

Using the catheter tube to correct the phase error 1 * 0 * * -1 1.0 mm

Phase error correction Phase-shift 1 * * * * 0 * * -1 1.0 mm After compensation Before compensation Root Mean Square Error 0.19 à 0.08 rad (0.95 cm/s error)

Velocity measurement validation Velocity sin (10 o ) catheter -37.5 to 37.5 cm/s speed range (along the beam) -220 to 220 cm/s speed range 1.0 mm (along the tube) Intralipid flowing in a tube with 0.75 mm inner diameter

Velocity measurement validation 0.1 ml/s 0.2 ml/s pi 0 0.3 ml/s 0.4 ml/s -pi 1.0 mm Intralipid flowing in a tube with 0.75 mm inner diameter

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

Imaging of flow in a swine coronary artery 37.5 cm/s 0 -37.5 cm/s

Imaging of flow in a swine coronary artery 1.0 mm 37.5 cm/s 0 cm/s - 37.5 cm/s

Doppler imaging pullback in vitro swine artery 37.5 cm/s 0 -37.5 cm/s ~0.7 s - 600 frames/s - 4 cm/s pullback (~0.68 cm/s in beam) ~26 mRad shift induced - 1.3 ml/s infusion rate

3D reconstruction 32 mm - 37.5 0 37.5 (cm/s)

Longitudinal image 32 mm length - 37.5 0 37.5 (cm/s)

Longitudinal video 32 mm - 37.5 0 37.5 (cm/s)

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 Erasmus MC 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 Lubeck University Optores Gmbh Tom Pfeiffer Walfgang Wieser Robert Huber Thomas Klein

Thank you!