Intraoperative microscope integrated optical coherence tomography angiography

Abstract

Purpose : We have previously reported on a custom 4D microscope integrated OCT (MIOCT) system capable of intraoperative imaging. OCT angiography (OCTA) is an emerging functional extension of OCT that has allowed for insights into the clinical evaluation of retinal diseases. The combination of these two technologies has not been used in the operating suite. MIOCT angiography (MIOCTA) could provide insight into changes to retinal vasculature that occur during surgery and allow for imaging of traditionally non-compliant patients such as young children.

Methods : Microscope integrated OCTA was performed using a custom microscope attachment and a 100 kHz 1060nm swept source OCT engine. OCTA images were acquired during exams under anesthesia using a BIOM lens. OCTA images were taken at 300 A-scans/B-scan with 150 lateral locations sampled. OCTA images were generated using speckle variance and segmentation was used to create en face projections of the retinal vasculature. Fluorescein angiography (FA) was performed as clinically indicated during exam under anesthesia. All human subject research was performed under a research protocol approved by the Duke University Health System institutional research board.

Results : A comparison of fluorescein angiograms and MIOCTA images from a 7 month-old infant girl with familial exudative vitreoretinopathy (FEVR) and an 8 year-old boy with Coats’ disease is shown in figure 1. In the FEVR case MIOCTA showed abnormalities in the fine perifoveal vasculature that is not visible on FA. In the Coats’ case MIOCTA provides superior visualization of the mid-peripheral retinal vasculature. MIOCTA also appears to show deeper vascular malformation that was not evident on FA. However, it is unclear if the MIOCTA signal comes from some vascular flow in this region or is an artifact caused by the structural abnormalities visible on the B-scan. In both cases MIOCTA provided superior vascular visualization when compared to FA.

Conclusions : We have demonstrated 4D MIOCTA imaging in young children. MIOCTA provides improved visualization of the retinal vasculature and to the best of our knowledge these are the first OCTA images taken of an infant.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

 

Figure 1: Top: FA (left), magnified FA (center), and MIOCTA (right) from an infant with FEVR. The red square denotes the location of the magnified images. Bottom: FA (left), MIOCTA (center), and B-scans with and without flow (right) from a child with Coats’ disease.