Development of an Intraoperative Imaging Tool for Thyroid and Parathyroid Surgical Guidance
Loss of parathyroid function (hypoparathyroidism) is an unintended consequence of endocrine neck surgeries. This leads to an inability of the patient to maintain healthy levels of blood calcium, as the parathyroid glands are the primary regulators of calcium. Consequently, debilitating effects like muscle spasms, cardiac arrhythmias and seizures ensue in the absence of regular therapy. With therapy, there is still reduced quality of life, added financial burden, and the potential for long-term side effects. Reducing the incidence of hypoparathyroidism after surgery is therefore of great importance. Two challenges faced in preserving parathyroid function during surgery are identification of the glands, and accurate assessment of their vascularity. Recent work has established near-infrared autofluorescence (NIRAF) detection as a reliable technique for intraoperative identification of parathyroid glands. However, studies show that identification alone does not reduce the rates of post-surgical hypoparathyroidism. It is equally important to accurately evaluate blood flow to parathyroid glands in order to make appropriate intraoperative decisions. However, there are currently no objective methods to do this. This dissertation reports the first use of laser speckle contrast imaging (LSCI) for real-time label-free assessment of parathyroid vascularity. The technique was shown to be 91.5% accurate in detecting differences in parathyroid vascularity. Additionally, intraoperative assessments of parathyroid glands made with an LSCI device were strongly related to the postoperative outcomes of total thyroidectomy patients. Furthermore, it was determined that a minimum of one vascularized parathyroid gland, determined by LSCI, is needed for healthy postoperative parathyroid function. These findings show great promise for the use of LSCI in label-free surgical guidance to help reduce post-surgical hypoparathyroidism. Finally, a device combining LSCI with NIRAF imaging is presented. This provides, for the first time, a single tool for complete label-free surgical guidance involving the parathyroid gland, i.e. identification and vascularity assessment.