Fiber-optic catheter-based polarization-sensitive OCT for radio-frequency ablation monitoring

Abstract

An all-fiber optic catheter-based polarization-sensitive optical coherence tomography system is demonstrated. A novel multiplexing method was used to illuminate the sample, splitting the light from a 58.5kHz Fourier-domain mode-locked laser such that two different polarization states, alternated in time, are generated by two semiconductor optical amplifiers. A 2.3mm forward-view cone-scanning catheter probe was designed, fabricated, and used to acquire sample scattering intensity and phase retardation images. The system was first verified with a quarter-wave plate and then by obtaining intensity and phase retardation images of high-birefringence plastic, human skin in vivo, and untreated and thermally ablated porcine myocardium ex vivo. The system can potentially in vivo image of the cardiac wall to aid radio-frequency ablation therapy for cardiac arrhythmias.

Laser thermal therapy monitoring using complex differential variance in optical coherence tomography

“…By overlaying this information directly on intensity OCT images, the active treatment zone was visualized simultaneously with the underlying tissue architecture, which enables lesions to be targeted more precisely. Compared to previous work based on PS‐OCT or polarimetry‐based techniques , the current method is not limited to biological tissues with high birefringence at baseline (e.g, skin, muscle, and tendon) and has broader implications in a number of clinical applications.…”

“…PS‐OCT was also shown to be useful for burn assessment in patients and for studying the remodeling of hypertrophic scars longitudinally in vivo . In addition, catheter‐based PS‐OCT was demonstrated for radiofrequency ablation monitoring in porcine myocardium ex vivo , following earlier observation of changes in birefringence bands between untreated and ablated myocardial tissue with intensity‐based OCT . Recently, depolarization (in addition to linear retardance) was investigated to visualize radiofrequency‐ablated myocardial tissue ex vivo using Mueller matrix polarimetry in a backscattered geometry .…”

Polarization sensitive optical coherence tomography – a review [Invited]

“…In both approaches, the polarization incident on the sample changes due to the rotation mechanism, and these changes need to be taken into account to properly calculate the tissue birefringence [70,136,137]. In cardiovascular OCT, polarization sensitivity has found application in the assessment of collagen in the fibrous cap of atherosclerotic plaques [138], the determination of collagen and smooth muscle cell content in atherosclerotic plaques [139,140], RF ablation monitoring of the endocardium [141], and the in human in vivo assessment of plaque rupture [142]. Figure 10 shows a PS-OCT example of ex-vivo human coronary artery.…”

Multimodal Imaging Spectroscopy of Tissue

“…However, as clinically relevant lesions are often inaccessible for microscopes, progress toward an incorporation of the different imaging modalities in endoscopes is required. For single optical modalities, applicability in endoscopy has already been shown (135)(136)(137). However, signal quality and acquisition speed as well as the option for large-area imaging have to meet the diagnostic requirements.…”