Intraoperative use of OCT in Robotic Assisted Thyroidectomy

Abstract

CONCLUSION: This is the first study to systematically use OCT invivo to differentiate thyroid and parathyroid glands during robotic assisted thyroidectomy. OCT can be used to evaluate these structures, which can be then confirmed with histopathologic evaluation via frozen or permanent sections. In the future, OCT has potential for use as an intraoperative method to more efficiently differentiate parathyroid glands, and thus not only decrease the operating time, but potentially obviate the need for frozen section confirmation, which decreasing the risk of damaging the parathyroid during dissection. DISCUSSION: This study represents the first reported use of OCT during robot assisted surgery, adding to the collective knowledge of optical coherence tomography, while simultaneously evaluating trans-axillary robotic assisted surgery. Particular attention was paid to the feasibility of instrumentation during the procedure. As mentioned, an OCT catheter handle was created to direct the probe to its target tissue in addition to protecting the fiber from harm (Figure 3). Manual manipulation was found to be tedious and ineffective in positioning the probe in light contact with the tissue of interest. Utilization of the catheter allowed the consol surgeon to manipulate the probe with the bipolar graspers, providing control, while protecting the delicate technology from inadvertent destruction by the attenuated tactile sensation provided by the robot arms (Figure 4). In Figure 5, an OCT image of normal parathyroid tissue is illustrated, where the stromal fat can be observed (arrows) and clear differences can be observed when compared to fat tissue (Figure 6). METHODS: An OCT imaging system (Niris, Imalux, Cleveland, OH) was used to image parathyroid and thyroid in ten patients during robotic assisted thyroidectomy. Images were obtained by raster scanning, a single mode fiber across the interior of the probe. The imaging probe was sterilized and inserted through the incision and placed in light contact with the tissue of interest. Images were acquired at a frame rate of 1Hz and resolution of ~10 mm with a 1 mm depth penetration. Robotic assisted surgery was performed via the SI da Vinci Robot (Intuitive Surgical, Sunnyvale, CA). Due to the direction of the operative field and the depth of dissection from the axilla during robotic thyroid resection (Figure 1), novel instrumentation was created for this procedure, including the OCT probe handle, as seen in Figure 2. INTRODUCTION: Optical coherence tomography is a high resolution optical imaging modality that generates a cross-sectional image within turbid media such as living tissue with resolution approaching that of light microscopy. OCT relies upon intrinsic differences in tissue optical properties for image contrast and has been shown to accurately differentiate tissue types. Trans-axillary robotic surgery is a relatively new approach to thyroid lobectomy, parathyroidectomy, and total thyroidectomy. This technique preserves the anterior neck from potentially deforming scar, while maintaining a wide surgical access, which at times is sacrificed during minimally invasive techniques that attempt to reduced the visibility of the incision. Recent domestic and international literature and personal experience suggest its safety and efficacy in the surgical removal of the thyroid and parathyroid glands. Figure 1. Patient positioning and field of dissection.