Author + information
- Received July 6, 2017
- Revision received September 19, 2017
- Accepted September 21, 2017
- Published online November 5, 2018.
- Martin Villiger, PhDa,∗ (, )
- Kenichiro Otsuka, MD, PhDa,
- Antonios Karanasos, MD, PhDb,
- Pallavi Doradla, PhDa,
- Jian Ren, PhDa,
- Norman Lippok, PhDa,
- Milen Shishkov, PhDa,
- Joost Daemen, MDb,
- Roberto Diletti, MDb,
- Robert-Jan van Geuns, MD, PhDb,
- Felix Zijlstra, MD, PhDb,
- Gijs van Soest, PhDb,
- Peter Libby, MDc,
- Evelyn Regar, MD, PhDb,
- Seemantini K. Nadkarni, PhDa and
- Brett E. Bouma, PhDa,d
- aWellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
- bDepartment of Interventional Cardiology, Thoraxcenter, Erasmus Medical Center, Rotterdam, the Netherlands
- cDivision of Cardiovascular Medicine, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
- dInstitute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, Massachusetts
- ↵∗Address for correspondence:
Dr. Martin Villiger, Wellman Center for Photomedicine, Massachusetts General Hospital, 50 Blossom Street, Boston, Massachusetts 02114.
Objectives This study aimed to evaluate whether polarimetry, performed using a modified optical frequency domain imaging (OFDI) system, can improve the assessment of histological features relevant to characterizing human coronary atherosclerosis.
Background The microscopic structure and organization of the arterial wall influence the polarization of the infrared light used by OFDI. Modification of the OFDI apparatus, along with recently developed image reconstruction methods, permits polarimetric measurements simultaneously with conventional OFDI cross-sectional imaging through standard intravascular imaging catheters.
Methods The main coronary arteries of 5 cadaveric human hearts were imaged with an OFDI system capable of providing polarimetric assessment. Cross-sectional views of tissue birefringence, measured in refractive index units, and depolarization, expressed as the ratio of depolarized signal to total intensity, were reconstructed, together with conventional OFDI images. Following imaging, the vessels underwent histological evaluation to enable interpretation of the observed polarization features of individual tissue components.
Results Birefringence in fibrous tissue was significantly higher than in intimal tissue with minimal abnormality (0.44 × 10−3 vs. 0.33 × 10−3; p < 0.0001). Birefringence was highest in the tunica media (p < 0.0001), consistent with its high smooth muscle cell content, cells known to associate with birefringence. In fibrous areas, birefringence showed fine spatial features and close correspondence with the histological appearance of collagen. In contrast, necrotic cores and regions rich in lipid elicited significant depolarization (p < 0.0001). Depolarization was also evident in locations of cholesterol crystals and macrophages.
Conclusions Intravascular measurements of birefringence and depolarization can be obtained using conventional OFDI catheters in conjunction with a modified console and signal processing algorithms. Polarimetric measurements enhance conventional OFDI by providing additional information related to the tissue composition and offer quantitative metrics enabling characterization of plaque features.
- cholesterol crystals
- optical coherence tomography
- optical frequency domain imaging
- polarized light
This work was supported by the National Institutes of Health (grants P41EB-015903 and R01HL-119065) and by Terumo Corporation. Massachusetts General Hospital and the Erasmus Medical Center have patent licensing arrangements with Terumo Corporation. Dr. Villiger has the right to receive royalties as part of the patent licensing arrangements with Terumo Corporation; and was partially supported by a fellowship from the Swiss National Science Foundation. Dr. Otsuka has received support from the Japan Heart Foundation and the Bayer Yakuhin Research Grant Abroad. Dr. Daemen has been a consultant for Pythagoras Medical; and has received institutional research support from Medtronic, Acist Medical, St. Jude Medical, AstraZeneca, and Boston Scientific. Drs. van Soest and Bouma have the right to receive royalties as part of the patent licensing arrangements with Terumo Corporation. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Received July 6, 2017.
- Revision received September 19, 2017.
- Accepted September 21, 2017.
- 2018 The Authors