Abstract
Purpose: :
Doppler optical coherence tomography enables non-invasive vasculature imaging of the human posterior eye. However, its low flow sensitivity limits the imaging quality and speed. Fast and high quality vasculature imaging is demonstrated with high-speed, high-sensitive Doppler optical coherence tomography.
Methods: :
Newly developed spectral-domain OCT with double probing beams is used. Doppler frequency shift is obtained from the phase shift between two OCT signals acquired from each probing beam at the same location, but the different time position. These two probing beams are horizontally separated on the retina, and scan the same position sequentially with a time difference. The time difference is proportional to flow sensitivity and can be long without sacrificing the scanning speed, hence high-speed, high-sensitive Doppler flow imaging is achieved. This system is operated at 27,000 axial scans per second. Three-dimensional blood flow imaging has been applied for a healthy volunteer. The scanning range was 7.7 x 7.7 mm and the acquisition time was 5 s. Wide range, high-sensitive three-dimensional blood flow imaging is realized since this method does not require high density of axial scans and is over 11 times more sensitive to flow than previous phase-resolved Doppler OCTs. We call this method as high-sensitive Doppler optical coherence angiography (HS-D-OCT).
Results: :
The projection of flow images for the retina is shown as Fig. 1A. In addition to the major retinal vessels, fine retinal vessel branches are observed. The projection at inner part of the choroid with the thickness of ~ 62 µm (Fig. 1B) visualizes fine choroidal vasculature. This might exhibits choriocapillaris and some arterioles and venules.
Conclusions: :
HS-D-OCA enables wide-range three-dimensional vasculature imaging of the posterior eye with high-sensitivity within comparable acquisition time to commercial SD-OCTs. This method will leads to non-invasive monitoring of the retinal and choroidal vasculatures.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • blood supply • retina