Optically Guided Surgery John Black 4/6/10 Outline Overview I. - - PDF document

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Optically Guided Surgery John Black 4/6/10 Outline Overview I. - - PDF document

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Optically Guided Surgery John Black 4/6/10 Outline Overview I. How I came to love the laser I. Diagnostics what can we do / what should we do? II. Case Study Opportunities in Atrial Fibrillation II. Case Study Peripheral and

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John Black 4/6/10

Optically Guided Surgery

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Outline

I.

Overview

I.

How I came to love the laser

II.

Diagnostics – what can we do / what should we do?

II.

Case Study – Opportunities in Atrial Fibrillation

III.

Case Study – Peripheral and Coronary Artery Disease

IV.

Conclusions

2

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Acknowledgements

  • Professor Jennifer Barton, PhD
  • Tissue Optics Lab – The University of Arizona, Tucson
  • Roger Gammon, MD and Frank Zidar, MD.
  • Austin Heart, Austin TX
  • Horst Sievert, MD
  • Sankt Katharinen Krankenhaus Frankfurt
  • John B Simpson, MD, PhD
  • And the staff at Avinger

3

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Background

4

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2010 – 50th anniversary of the laser

  • (CLEO (San Jose – May))
  • Introduced as a surgical therapeutic in the 1960’s
  • Ophthalmology
  • Surgery
  • Prostate reduction in BPH
  • OB/GYN
  • Dermatology

5

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Ophthalmology

  • Healthy retina

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Ophthalmology

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Optic Nerve Head Macula http://en.wikipedia.org/wiki/Retina Drexler – Radial view of a porcine retina. http://www.iovs.org/cgi/content/full/48/12/5340

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Diseases of the Retina

  • Macular edema, Age-related Macular Degeneration
  • Diabetic retinopathy, Retinopathy of prematurity …
  • All conspire to rob you of vision at some rate.

8

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Treatment

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http://www.optimedica.com/PASCAL-Method/fundus_images.aspx

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Surgery

  • Benign Prostatic Hyperplasia
  • Chances you get this over 50 y/o = your age
  • Trans-urethral resection – HoLEP, PVP
  • Holmium laser, Green Laser

10

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Dermatology – Skin Anatomy

Stratum Corneum Epidermis Rete Ridges Papillary Dermis Reticular Dermis Pilo-sebaceous Unit Sebaceous Gland Hair Follicle Sweat Gland Feeder vessel / Vascular Plexus Muscle / Fat

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Port Wine Stain

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  • Treatment
  • 532 nm laser
  • Strong absorption in hemoglobin
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  • One treatment 6 week follow-up.
  • Improvement rated as “Good 50 – 89% Clearance”
  • Mark M. Hamilton, MD.
  • Perkins-Hamilton Facial Plastic Surgery P.C., Indianapolis, IN
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Optical Diagnostic Overview

  • What do we need to “see” to guide a procedure
  • Aside from the visual surgical field
  • http://www.ted.com/talks/catherine_mohr_surgery_s_past_pre

sent_and_robotic_future.html

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Why Optical Sensing?

  • Bandwidth – GBs
  • Immunity
  • Fiber optic signals are insensitive to EM interference
  • Physical / Mechanical Impact
  • Small

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2 mm OD Catheter 100 micron OD Fiber

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Pick up on “non-visual” surgical cues

  • Atrial Fibrillation
  • Contraction of heart chambers becomes unsynchronized
  • Especially left atrium
  • Serious condition

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http://en.wikipedia.org/wiki/Heart

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Treatment – Pre-Catheter

  • Surgical Maze Procedure
  • Series of incisions to block impulse conduction pathways
  • Full sternotomy

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http://www.stopafib.org/surgical-ablation.cfm

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Treatment – RF / Microwave Catheter

  • Femoral access, inferior vena cava to RA
  • Trans-septal puncture to LA
  • Full wall thickness coagulation around pulmonary vein.
  • Interrupt nerve conduction pathways

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Clinical Procedure

  • X-ray fluoroscopy
  • Problems
  • X-ray dose
  • Surgeon and Patient
  • Contrast agent
  • Iodinated compound
  • Nephrotoxin
  • Limits procedure time
  • Especially in renally compromised patients

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http://www.healthcare.philips.com/de_de/products/interventional_xray/Solutions/Cli nicalSpecialties/xper_swing/index.wpd

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Loss of Dimensionality

  • 3-D structure is flattened to 2D

plane when image is captured

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Horst Sievert, MD Sankt Katharinen Krankenhaus Frankfurt

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What would you like to know / see?

  • CLINICAL RELEVANCE
  • Anything that can improve the outcome for the patient
  • Shorten procedure time
  • Improve long-term efficacy
  • Reduce X-ray or contrast burden
  • …
  • Is the catheter in contact with the heart wall?
  • Am I applying too much force?
  • What is the temperature of the coagulation zone?
  • Have I made a full-thickness lesion?

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Am I in contact with my target?

  • Apposition
  • Not just a question of pushing and feeling resistance
  • Catheter length can contribute to sensed resistance
  • No contact – no wall coagulation

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Am I in contact with my target?

  • Rotate catheter in the vessel
  • Sub-mm resolution (wall approach and contact)

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Poor Apposition (Blood in Field) Wall Reflection

Roger Gammon (Austin Heart) – New Horizons 2007

Well Apposed Up Down

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Am I applying too much force?

  • Tearing of trans-septal puncture area
  • Danger of perforation

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Fiber Bragg Gratings (FBG)

  • Periodic refractive index step functions in fiber core

21 microns 5 microns

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Bragg Gratings

  • Reflect or eject very specific wavelengths
  • Performance is very sensitive to stress on FBG
  • Stress imparted by bending, torsion or tension
  • Submarine hulls, bridges, buildings, oil wells use FGBs
  • Hansen Medical
  • Distributed force sensing on catheter.
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Am I applying too much force on the tip?

  • Honeywell O-RIMS Technology
  • Silicon microstructure on the end of a fiber

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What is the temperature of the target?

  • Clinical end point – Coagulation
  • Under-treat

– potentially a sub-optimal outcome

  • Over-treat

– charring

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Stuart J. Loui, Honors Thesis, Electrical Engineering Department, U. Of Arizona 2002

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Optical Temperature Measurement

  • Based on Refraction
  • Happens when light goes from one medium to another

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Archer Fish

  • Nature solved refraction
  • A long time ago!
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Archer Fish

  • Learned (not inherited trait)
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Refraction

  • Critical Angle
  • Where light is no-longer refracted, but is reflected at

the interface.

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Temperature Measurement

  • Refractive index can be sensitive to temperature.
  • Very!
  • Strength of the beam at point C

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( )

( ) ( )

θ θ θ θ

θ

2 2 1 2 2 1 2 2 2 2 1 2 2 1 2 2 2

sin cos sin ,

cos

n n n n n n n n n r − + − − =

n1 n2 IEEE JSTQE, 7, p 936 – 943 (2001).

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Simple Experiment

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IEEE JSTQE, 7, p 936 – 943 (2001).

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Results

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IEEE JSTQE, 7, p 936 – 943 (2001).

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Results

  • Non-perturbative, real time interface T measurement
  • Can be insensitive to the heating method
  • RF interferes with thermocouples
  • No fitting parameters
  • Know refractive index behavior wrt T – know temperature
  • Can be measured off-line
  • Bandwidth determined by detector and probe laser power
  • Select AOI and polarization to set sensitivity
  • On-off at a critical temperature
  • Feedback loop to heater power
  • Usefulness?
  • Confirm FEM model of heating

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Comparison to Finite Element Model

  • Use the measurement to refine the model

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http://www.ece.arizona.edu/~bmeoptics/publications.html

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Have I made a full-thickness burn?

  • Depth-resolved Measurement
  • Optical Coherence Tomography

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IVUS OCT Xray

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Depth / Resolution trade-offs with optical methods

Resolution Depth of Penetration

1 cm 1 mm 100 µm 10 µm 1 µm 0.1 µm 10 µm 100 µm 1 mm 1 cm 10 cm Optical Diffuse Tomography Confocal Microscopy Micro- scopy Optical Coherence Tomography Photo- Acoustic Tomography Laser- Induced Fluorescence MRI CT Ultrasound

http://www.ece.arizona.edu/~bmeoptics/publications.html

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Which one should I use?

  • What are your resolution needs?
  • Cellular level?
  • Are you potentially limited by penetration depth?
  • Progressively harder to implement as resolution ▲
  • Need a good excuse to do OCT, confocal microscopy!
  • Retinal imaging, cancer (cervical, lung), arterial disease
  • OCT, confocal can be implemented fiber-optically
  • Endoscope / catheter compatible
  • DOT and microscopy mainly “free-space” techniques

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  • Optical analog of

ultrasound

  • Minimal crossing profile

impact

  • COTS telecom

components

  • Image quality allows for

intuitive pattern recognition

  • Optical bandwidths
  • 10x better resolution

1 – 1.5 mm penetration

  • Preferable for therapeutic

device incorporation

  • Straightforward fiber optic

implementation

  • Reduced training

requirements and time-of- procedure

  • Microsecond time resolution

Optical Coherence Tomography

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Experimental Geometry

Pump Laser Beam Blood Sample (200 microns) OCT Probe Beam Heated Blood Volume Cuvette “Hot” Mirror

http://www.ece.arizona.edu/~bmeoptics/publications.html

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OCT Data

  • M-Mode OCT Data
  • Depth vs Time image
  • 1.25 ms time steps, 15 micron axial resolution.

Time Sample Depth 200 um

Cuvette Wall Cuvette Wall

Coagulum formation

http://www.ece.arizona.edu/~bmeoptics/publications.html

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OCT comparison to FEM

  • FEM
  • Shows peak temperature is just inside cuvette wall
  • Shows lower part of cuvette does not get irradiated
  • Good agreement between OCT and FEM

Cuvette Wall

http://www.ece.arizona.edu/~bmeoptics/publications.html

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Intra-operative parameters

  • Apposition
  • Force
  • Temperature
  • Function and Structure
  • See beneath the surface
  • Tissue organization
  • Molecular content

(Endogenous contrast)

  • Clinical Need
  • Retinal function / structure
  • Cancer
  • ARTERIAL DISEASE

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Healthy Artery

  • Distinctive Layer Structure

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http://www.siumed.edu/~dking2/crr/CR023b.htm 250 Microns

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OCT Healthy Coronary Artery

  • Intuitive pattern recognition

Intima Media Adventitia

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360 Capability

Intima Media Pericardium Adventitia Catheter

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  • Impact on distal tip.
  • Only adds 0.010”
  • Minimal proximal clutter

Advantages of fiber-based catheter OCT

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6F compatible catheter 100 micron OD Fiber

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Arterial Disease Progression

  • Inflammatory reaction
  • Smoking, diet, other disease (diabetes), insult, genetics …

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PAD

  • If you have PAD, you probably have CAD
  • Coronary artery disease.

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Prevalence: 8-12 million in US

Source: American Heart Association

Endovascular: >400K procedures

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CAD > 2/3 of MI’s occur at non-critical stenoses

Circulation (1988) 78, 1157

78 d prior to MI: 47% stenosis 13 d after to MI: 100% stenosis

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%Stenosis does not predict time to MI

Circulation (1988) 78, 1157

  • Cannot use angiography as a truly predictive technique
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Clinical need for functional and structural information

  • Vulnerable plaque hypothesis
  • Lipid rich necrotic cores
  • Thin fibrous caps
  • TCFAs – Thin Cap Fibro-Atheroma
  • Lipid core is highly thrombogenic
  • Rupture triggers a thrombus to form – acute MI
  • Balloon and stents can trigger a rupture if they land incorrectly
  • First look for lipids?
  • InfraRedX – Molecular Spectroscopy
  • OCT companies – lipid-rich OCT signatures?

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Anatomy of a coronary artery lesion

http://www.siumed.edu/~dking2/crr/CR023b.htm 250 Microns

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Anatomy of a coronary artery lesion

http://www.siumed.edu/~dking2/crr/CR023b.htm 250 Microns 2 x 1.25 mm lumen

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Anatomy of a coronary artery lesion

Atheroma Calcium Nodule

  • Asymptomatic lesion (!)

Adventitia

  • 88y/o
  • COD – CVA
  • Bilateral CAD
  • 140 pack/yr
  • Hypertensive
  • Multiple Strokes
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OCT: Histology Correlation

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Optical Coherence Tomography

Adventitia Calcium Nodule Catheter Atheroma

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Optical Coherence Tomography

Catheter Possible lipid pocket

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  • 88y/o
  • COD – CVA
  • Bilateral CAD
  • 140 pack/yr
  • Hypertensive
  • Multiple Strokes

Adventitia Complex Atheroma 2 mm Catheter Intimal Thickening Bright Sclerotic Media

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Catheter Atheroma Adventitia Possible lipid rich pocket – shadowing below bright cap RCA Adventitia Adventitia Atheroma

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OCT: Histology Correlation

  • Symmetric In-stent Restenosis
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OCT: Histology Correlation

  • Asymmetric In-stent Restenosis
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Barotrauma

  • Balloon or Stent Overstretch
  • Disease grows asymmetrically but is treated symmetrically

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Endothelium and internal elastic lamina Adventitia Plaque Media Weakened Adventitia

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OCT: Histology Correlation

  • Dissection
  • Bad long term prognosis
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Remember the disease progression?

  • Early stage
  • Separation of endothelium and IEL

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Stage 1 – Separation of IEL and endothelium

  • Caught in the act
  • Separation of endothelium and IEL
  • Development of plaque between laminae

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Disease develops 250 µm Endothelium IEL

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Case Study (Horst Sievert, MD)

  • Guided cut around ostium of anterior tibial artery

Angiogram Cut Positioning

Cut Plane Image Plane

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Post-Tx Fluoro

  • 4 cutting passes produced 5 fragments
  • 5 of 5 – Various disease states in histology
  • 4 of 5 – Medial components included
  • 2 of 5 – Lipid and inflammatory cell infiltration included
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Can you show too much detail?

  • Angiographically – a good result?
  • OCT still shows mm of disease!

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Roger Gammon (Austin Heart) – New Horizons 2007

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Conclusions

  • Possible to measure key surgical parameters optically
  • Non-perturbatively
  • Rapidly
  • With minimal size impact to the surgical tool
  • (with moderate COGS burden)
  • Structural and functional information can be derived
  • In real time
  • With relevant surgical precision

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Thank You !