A Registration Approach to Endoscopic Laser Speckle Contrast Imaging for Intrauterine Visualisation of Placental Vessels
Intrauterine interventions such as twin-to-twin transfusion syndrome procedure require accurate mapping of the fetal placental vasculature to ensure complete photocoagulation of vascular anastomoses. However, surgeons are currently limited to fetoscopy an
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Translational Imaging Group, CMIC, University College London, NW1 2HE, UK Dept. Med. Phys. and Biomed. Eng., University College London, WC1E 6BT, UK 3 Institute for Women’s Health, University College London, WC1E 6HX, UK 4 Dept. of Obstetrics, University Hospitals KU Leuven, Belgium
Abstract. Intrauterine interventions such as twin-to-twin transfusion syndrome procedure require accurate mapping of the fetal placental vasculature to ensure complete photocoagulation of vascular anastomoses. However, surgeons are currently limited to fetoscopy and external ultrasound imaging, which are unable to accurately identify all vessels especially those that are narrow and at the periphery. Laser speckle contrast imaging (LSCI) is an optical method for imaging blood flow that is emerging as an intraoperative tool for neurosurgery. Here we explore the application of LSCI to minimally invasive fetal surgery, with an endoscopic LSCI system based on a 2.7-mm-diameter fetoscope. We establish using an optical phantom that it can image flow in 1-mm-diameter vessels as far as 4 mm below the surface. We demonstrate that a spatiotemporal algorithm produces the clearest images of vessels within 200 ms, and that speckle contrast images can be accurately registered using groupwise registration to correct for significant motion of target or probe. When tested on a perfused term ex vivo human placenta, our endoscopic LSCI system revealed small capillaries not evident in the fetoscopic images.
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Introduction
An augmented view of vasculature and blood flow is required for surgical procedures that rely on accurate identification of the vessels. Laser speckle contrast imaging (LSCI) is emerging as an intraoperative tool for monitoring tissue perfusion and blood flow, particularly in neurosurgery where its clinical potential has been recently demonstrated [1]. Despite its potential for imaging perfusion and blood flow in minimally invasive procedures, relatively few applications of LSCI for endoscopic surgery have been described [2]. The present study proposes a novel application for endoscopic LSCI for intrauterine fetal surgery. In twin-to-twin transfusion syndrome (TTTS) therapy, the surgeon aims to photocoagulate anastomosing placental vessels that cause a net transfusion of c Springer International Publishing Switzerland 2015 N. Navab et al. (Eds.): MICCAI 2015, Part I, LNCS 9349, pp. 455–462, 2015. DOI: 10.1007/978-3-319-24553-9_56
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blood between identical twins sharing a placenta [3]. Success depends on the degree of remaining anastomoses, since perinatal morbidity and mortality is highest in cases where anastomoses are not identified or completely photocoagulated [4]. Narrow vessels (
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