This document summarizes research on using optical coherence tomography (OCT) to characterize coronary plaques. OCT uses near-infrared light to generate high-resolution cross-sectional images of tissue microstructure. Researchers studied 357 arterial segments ex vivo using OCT and validated plaque types (fibrous, calcific, lipid-rich) against histology with high accuracy. A pilot clinical study of 10 patients found OCT feasible and safe for in vivo coronary imaging before and after percutaneous coronary intervention, identifying a variety of plaque types and stent appositions. While blood obstruction and motion artifacts posed challenges, the results support further evaluation of OCT as a potential "optical biopsy" tool.

1. Optical Coherence
Tomography: Optical Biopsy
with a Short Photonic
Needle?
I.K. Jang, MD
Massachusetts General Hospital
Harvard Medical School
The 3rd
Vulnerable Plaque Symposium
Atlanta, March 16, 2002

2. Optical Coherence
Tomography
• Optical analog of ultrasound
• Cross-sectional imaging
• 10 µm resolution
• 2 mm penetration depth
Low signal High signal

3. MGH OCT
System Technical
Data
Optical wavelength :
Image acquisition rate :
Catheter:
Axial Resolution :
Transverse Resolution :
Data storage :
1300 nm
4-8 images / sec
3.0 F
10 µm
25 µm
Digital

4. Ex Vivo Study
Aim
Establish OCT criteria for plaque
characterization
Materials and Methods
• 357 arterial segments from 90 cadavers
– 78 Coronary; 86 Carotid; 143 Aorta
• training set, n=50
validation set, n = 307
• Specimen registration
• OCT imaging
• Histology processing
• Correlation of OCT with histology

5. Ex Vivo Study
Type Number
Fibrous 11 (22%)
Calcific 27 (54%)
Lipid pool 12 (24%)
Type Number
Fibrous 67 (22%)
Calcific 167 (54%)
Lipid pool 73 (24%)
Validation Set (n = 307)Training Set (n = 50)
Histologic Diagnoses

6. OCT Characteristics
lp
lp
Homogeneous,
Signal-rich
Fibrous Lipid
Echolucent,
Diffuse Borders
Echolucent,
Sharp Borders
Calcific
500 µm

7. Intimal Hyperplasia
Low signal High signal

8. Fibrous Plaque
F
I
M
A
F
EEL
IEL

9. lp
n
lp
Lipid-Rich Plaque
(with neovascularization)

10. Calcific Plaque
C
C

11. Ex Vivo Study Results
SENS .87 PPV .88
SPEC .97 NPV .96
SENS .95 PPV 1.0
SPEC 1.0 NPV .95
SENS .92 PPV .81
SPEC .94 NPV .97
Accuracy Statistics
Fibrous
Calcific
Lipid pool
Interobserver κ = 0.88, Intraobserver κ = 0.91

12. Clinical Study 1
Feasibility and Safety:
Pre and Post PCI

13. Pilot Human Study
Aim: Test feasibility and safety of OCT in
patients
Methods
• 10 patients (average age 59, 8M/2F)
• Coronary angiogrpahy
• IVUS + OCT imaging (3.2 F catheter)
• PCI
• Repeat IVUS + OCT Imaging

14. Fibrous Plaque

15. Fibrous Plaque

16. Lipid-rich Plaque

17. Lipid Rich Plaque
g
lplp
f
g
2x
m
a
i
iel eel
f
OCT IVUS

18. Fibrous Plaque with Calcium

19. Fibrous Plaque with Calcium

20. Post balloon Dissection

21. Cutting balloon

22. Stent

23. Stent

24. Stent

25. Pilot Human Study Results
 No OCT related complications
 Variety of pathology imaged and
compared with IVUS
• 10 patients with 28 plaque segments
• 8 dissections
• 13 stent locations
 Problems
• Obstruction by blood
• Motion artifacts

26. Acknowledgements
Massachusetts General Hospital
Cardiology Division
H. Yabushita, B. MacNeill, H. Lowe, M. Hayashi, S. Clarke, E. Pomerantsev,
D. DeJoseph, I.K. Jang
Wellman Laboratories of Photomedicine
B.E. Bouma, M. Shishkov, C. Kauffman, N. Iftima, G.J. Tearney
Dept. of Pathology
S. Houser, H.T. Aretz
CIMIT
J. Muller, T. Brady, J. Rosen
Guidant Corporation
D. Kilpatrick, J. Ellis, R. Jones, T. Linnemeier