Assessing Intraoperative Laser Speckle Contrast Imaging of Parathyroid Glands in Relation to Total Thyroidectomy Patient Outcomes

Abstract

Background: Accurate assessment of parathyroid gland vascularity is important during thyroidectomy to preserve the function of parathyroid glands and to prevent postoperative hypocalcemia. Laser speckle contrast imaging (LSCI) has been shown to be accurate in detecting differences in parathyroid vascularity. In this surgeon-blinded prognostic study, we evaluate the relationship between intraoperative LSCI measurements and postoperative outcomes of total thyroidectomy patients. Methods: Seventy-two thyroidectomy patients were included in this study. After thyroid resection, an LSCI device was used to image all parathyroid glands identified, and a speckle contrast value was calculated for each. An average value was calculated for each patient, and the data were grouped according to whether the patient had normal (16-77 pg/mL) or low levels of parathyroid hormone (PTH) measured on postoperative day 1 (POD1). The aim of this study was to establish a speckle contrast threshold for classifying a parathyroid gland as adequately perfused and to determine how many such glands are required for normal postoperative parathyroid function. Results: A speckle contrast limit of 0.186 separated the normoparathyroid and hypoparathyroid groups with 87.5% sensitivity and 84.4% specificity: 7 of 8 patients with low PTH on POD1 had an average parathyroid speckle contrast above this limit, while 54 of 64 patients with normal postoperative PTH had an average parathyroid speckle contrast below this limit. Taking this value as the threshold for adequate parathyroid perfusion, it was determined that only one vascularized gland was needed for normal postoperative parathyroid function: 64 of 69 patients (92.8%) with at least one vascularized gland (determined by LSCI) had normal postoperative PTH, while all 3 patients (100%) with no vascularized glands had low postoperative PTH. Overall, the rates of temporary and permanent hypoparathyroidism in this study were 8.3% and 1.4%, respectively. Conclusions: LSCI is a promising technique for assessing parathyroid gland vascularity. It has the potential to help reduce the incidence of hypocalcemia after thyroidectomy by providing surgeons with additional information during surgery to aid in the preservation of parathyroid function.

Heterogeneity in Utilization of Optical Imaging Guided Surgery for Identifying or Preserving the Parathyroid Glands—A Meta-Narrative Review

“…The first study by Mannoh et al (2017) was a feasibility study using a sample size of seven participants undergoing either a parathyroidectomy or a thyroidectomy [ 75 ]. The second study was an in-depth study of the first feasibility study containing a larger study population ( n = 72) of patients undergoing a thyroidectomy (total or complementary) ( Table 3 ) [ 76 ].…”

“…Overhead light did not have any influence on the results. In the second study, the methods are mentioned briefly, and reference is made to the first article [ 76 ]. Both papers use the same LSCI device, although a slight change was made to the laser to reduce specular reflections in the images.…”

“…The first study by Mannoh et al (2017) was a feasibility study using a sample size of seven participants undergoing either a parathyroidectomy or a thyroidectomy [75]. The second study was an in-depth study of the first feasibility study containing a larger study population (n = 72) of patients undergoing a thyroidectomy (total or complementary) (Table 3) [76]. Both reported studies were prospective cohort studies, with the first study from 2017 mainly focusing on demonstrating the technique (n = 7), while the second study (2021) correlated the postoperative outcomes with the intraoperative LCSI measurements (n = 72).…”

Thyroidectomy for Cancer: The Surgeon and the Parathyroid Glands Sparing

“…Looking at the group of instruments based on optical technology such as DOCI (dynamic optical contrast imaging), FLIm (fluorescence lifetime imaging), LSCI (laser speckle contrast imaging), NIMI (near infrared molecular imaging), LIBS (laser induced breakdown spectroscopy), it is immediately evident that, despite the advantage of not using any contrast medium and not being influenced by ambient light, these are still experimental applications and reserved for research centres with strong financial backing, certainly not within the reach of most thyroid surgery centres [22][23][24][25][26]33]. They demonstrate a high level of accuracy in identifying and assessing glandular perfusion, but cannot prevent any iatrogenic damage produced during retrieval, which in any case precedes the test.…”

“…(a) Vital dye such as methylene bleu [19][20][21]. (b) Optical devices without contrast media and unaffected by ambient light [22][23][24][25][26]. (c) Autofluorescence of parathyroids detected by infrared light or laser stimulation [27][28][29][30][31][32][33].…”