BACKGROUND: Postoperative hypoparathyroidism due to damage to the parathyroid glands during a thyroidectomy is a well-known surgical complication. The current gold standard intraoperative method for identifying parathyroid glands is surgical judgment; other methods are limited in both their sensitivity and convenience. There is a clear need for an objective diagnostic tool that is effective in its identification of the parathyroid glands and of their viability. We hypothesized that an intraoperative tool using Elastic Scattering Spectroscopy (ESS) has the potential to differentiate optical signatures of the parathyroid gland from surrounding tissues in real-time. METHODS: ESS optical signatures were collected intraoperatively from perfused parathyroid, thyroid, fat, muscle, and nerve tissue during thyroidectomy. The ESS data was collected using a portable, handheld, noninvasive, "cold" fiber optic probe able to detect spectra in a non-ionizing, broadband spectrum of light (320 to 920 nm). Five measurements were collected at each tissue site over a total of 1.2 seconds. Visual analysis of tissue was analyzed and compared to pathology, and spectral measurements attained with ESS. RESULTS: No complications resulted from the use of the ESS probe. Of the 10 parathyroid glands evaluated to be at risk in the study, the optical probe utilizing ESS was able to detect unique spectral features associated with the parathyroid gland. All 10 parathyroid glands are optically differentiable from surrounding tissues with ESS. CONCLUSIONS: Utilizing spectroscopy in the form of a hand-held probe is feasible for intraoperative differentiation between tissue types. Preliminary results of this spectral technique warrant further investigation. If successful, implementation of a portable ESS probe to identify the parathyroid tissue during endocrine surgical procedures could reduce surgical complications and improve patient safety.

Thesis (M.A.)--Boston University, 2011. / OBJECTIVE: Thyroid cancer is the most common endocrine malignancy and patients presenting with thyroid nodules often undergo surgery solely for diagnostic purposes. The goal of our study was to examine the accuracy of Elastic Scattering Spectroscopy (ESS) in distinguishing between benign and malignant thyroid nodules in fresh ex vivo specimens and to design an in vivo ESS probe and device, manufacture it and conduct a clinical trial. METHODS: Patients already undergoing thyroidectomy surgery were consented for the ex vivo study. ESS data was obtained from ex vivo specimens by recording 5 readings per nodule with five repetitive readings per each site. Final pathology reports were used to confirm the diagnosis. The spectra were analyzed using principal component analysis, linear discriminant analysis and leave one out technique. The in vivo ESS study was conceptually designed and IRB approval from Boston Medical Campus was obtained. RESULTS: The ex vivo study showed that ESS could predict the difference between benign and malignant tumors with a sensitivity of 74%, specificity of 90%, positive predictive value of 82% and negative predictive value of 85%. 193 spectra were analyzed from 64 patients, 120 spectra were from benign nodules and 73 from malignant nodules. Subanalysis examined only indeterminate nodules showed sensitivity of 65%, specificity of 79%, PPV 77% and NPV 67%. The in vivo ESS probe was designed and 12 identical instruments were manufactured. Initial experimental readings were taken and parameters were adjusted for the in vivo tissue environment. The clinical trial is underway. CONCLUSIONS: ESS is a practical tool that can accurately identify malignancy in ex vivo thyroid specimens with high specificity and sensitivity. Initial in vivo experimental trials have been conducted and show promise for similar results.