Constant linear velocity spiral scanning for near video rate 4D OCT ophthalmic and surgical imaging with isotropic transverse sampling

Abstract

Ultrahigh speed optical coherence tomography (OCT) systems with >100 kHz Ascan rates can generate volumes rapidly with minimal motion artifacts and are well suited for 4D imaging (volumes through time) applications such as intra-operative imaging. In such systems, high OCT data acquisition efficiency (defined as the fraction of usable A-scans generated during the total acquisition time) is desired to maximize the volumetric frame rate and sampling pitch. However, current methods for beam scanning using non-resonant and resonant mirror scanners can result in severe scan distortion and transverse oversampling as well as require acquisition dead times, which limit the acquisition efficiency and performance of ultrahigh speed 4D OCT. We introduce constant linear velocity spiral scanning (CLV-SC) as a novel beam scanning method to maximize the data acquisition efficiency of ultrahigh speed 4D OCT systems. We demonstrate that CLV-SC does not require acquisition dead times and achieves more uniform transverse sampling compared to raster scanning. To assess its clinical utility, we implement CLV-SC with a 400 kHz OCT system and image the anterior eye and retina of healthy adults at up to 10 volumes per second with isotropic transverse sampling, allowing B-scans with equal sampling pitch to be extracted from arbitrary locations within a single volume. The feasibility of CLV-SC for intra-operative imaging is also demonstrated using a 800 kHz OCT system to image simulated retinal surgery at 15 volumes per second with isotropic transverse sampling, resulting in high quality volume renders that enable clear visualization of surgical instruments and manipulation of tissue.

Depth-Based, Motion-Stabilized Colorization of Microscope-Integrated Optical Coherence Tomography Volumes for Microscope-Independent Microsurgery

“…Therefore, higher line rate laser sources, faster scanning speeds and improved computational processing separate from colorization subsequently will increase the refresh rate of colorization. 26 New approaches to mapping and applying the color gradients also will help improve colorization efficacy in specific surgical scenarios.…”

High dynamic range optical coherence tomography angiography (HDR-OCTA)

“…Many scanning patterns have been developed to eliminate fly-back and increase scanning speed and efficiency. Examples include Lissajous scanning [21], constant linear velocity spiral scanning [29], and constant angular velocity spiral scanning [30]. However, these methods all require an additional step to resample the image into Cartesian coordinates, which increases the complexity of image post-processing.…”

Nonresonant Raman spectroscopy of isolated human retina samples complying with laser safety regulations for in vivo measurements

“…OCT angiography is a functional extension of OCT, which improves the diagnostic results, since not only the typical structural features in an OCT image are recorded but also blood vessels and blood perfusion can be visualized. 4 , 5 Recently, advances have been made to speed up in vivo volumetric OCT imaging for ophthalmic surgery 6 and to minimize aberration effects by applying adaptive optics during OCT measurements. 7 …”