Abstract
Purpose :
Optical coherence tomographic angiography (OCT-A) has been broadly adopted in recent years for the diagnosis of ophthalmic vascular diseases. However, motion-artifacts are common and result from patient motion. In handheld applications, patient motion is further compounded by motion in the imaging probe. Here, we demonstrate handheld spectrally encoded coherence tomography and reflectometry (HH-SECTR), which provides concurrent en face reflectance and volumetric OCT imaging that enables bulk-motion compensation of structural and angiography data. HH-SECTR overcomes limitations of current-generation OCT-A and will enable non-invasive ophthalmic diagnostic imaging of pediatric and bedridden patients.
Methods :
SECTR imaging optics were optimized and used to design and rapid-prototype a compact handheld optomechanical enclosure (Fig. 1(a)). Imaging was performed using a custom 400 kHz 1060 nm swept-source OCT engine. Concurrently acquired spectrally encoded reflectometry (SER) and OCT data were sampled at 2560 x 500 pix. (spectral x lateral) with 500 frames-per-volume and 4 repeated frames. Lateral and axial motion were measured from corresponding SER frames and OCT B-scans using sub-pixel registration and applied to motion-correct the respective OCT volume. Intensity-based deformable registration was performed on overlapping motion-compensated OCT-A projections for widefield mosaicking of retinal vasculature.
Results :
In vivo OCT-A mosaicking of retinal vasculature was performed in a healthy volunteer using HH-SECTR. SER (Fig. 1(b)) and OCT (Fig 1(c), (d)) registration was performed using structural and vascular fiducials and then processed using OCT-A algorithms. Vessels in the optic nerve head to the foveal avascular zone are clearly visualized on the OCT-A mosaic (Fig. 1(e)).
Conclusions :
We demonstrated motion-compensated SECTR for handheld retinal OCT and OCT-A imaging. Complementary en face SER and cross-sectional OCT data enable volumetric registration and overcomes motion-artifact limitations of OCT-A. Clinical translation of our portable HH-SECTR probe may benefit ophthalmic diagnostic imaging in pediatric and bedridden patients.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.