Near-Infrared Autofluorescence Imaging May Reduce Temporary Hypoparathyroidism in Patients Undergoing Total Thyroidectomy and Central Neck Dissection

The use of artificial intelligence to detect parathyroid tissue on ex vivo specimens during thyroidectomy and parathyroidectomy procedures using near-infrared autofluorescence signals

BACKGROUND

In thyroidectomy and parathyroidectomy procedures, diagnostic dilemmas related to whether an index tissue is of parathyroid or nonparathyroid origin frequently arise. Current options of frozen section and parathyroid aspiration are time-consuming. Parathyroid glands appear brighter than surrounding tissues on near-infrared autofluorescence imaging. The aim of this study was to develop an artificial intelligence model differentiating parathyroid tissue on surgical specimens based on near-infrared autofluorescence.

METHODS

With institutional review board approval, an image library of ex vivo specimens obtained in thyroidectomy and parathyroidectomy procedures was created between November 2019 and April 2023 at a single academic center. Ex vivo autofluorescence images of surgically removed parathyroid glands, thyroid glands, lymph nodes, and thymic tissue were uploaded into an artificial intelligence platform. Two different models were trained, with the first model using autofluorescence images from all specimens, including thyroid, and the second model excluding thyroid, to prevent the effect of specimen size on the results. Deep-learning models were trained to detect autofluorescence signals specific to parathyroid glands. Randomly chosen 80% of data were used for training, 10% for validation, and 10% for testing. Recall, precision, and area under the curve of models were calculated.

RESULTS

Surgical procedures included 377 parathyroidectomies, 239 total thyroidectomies, 97 thyroid lobectomies, and 32 central neck dissections. For the development of the model, 1151 images from a total of 678 procedures were used. The dataset comprised 648 parathyroid, 379 thyroid, 104 lymph node, and 20 thymic tissue images. The overall precision, recall, and area under the curve of the model to detect parathyroid tissue were 96.5%, 96.5%, and 0.985, respectively. False negatives were related to dark and large parathyroid glands.

CONCLUSION

The visual deep-learning model developed to identify parathyroid tissue in ex vivo specimens during thyroidectomy and parathyroidectomy demonstrated a high sensitivity and positive predictive value. This suggests potential utility of near-infrared autofluorescence imaging to improve intraoperative efficiency by reducing the need for frozen sections and parathyroid hormone aspirations to confirm parathyroid tissue.

Intraoperative Adjuncts in Thyroid Surgery

Thyroidectomy is relatively safe and often can be done as a minimally invasive procedure. Although they may be associated with a learning curve, thoughtful use of intraoperative adjuncts such as energy devices, recurrent laryngeal nerve monitoring, and parathyroid autofluorescence have the potential to make incremental improvements in the safety and efficiency of thyroid surgery. Perhaps many of these adjuncts may be of greatest benefit when used routinely by less experienced surgeons or selectively in higher-risk operations, although their adoption in practice continues to increase overall.

Current and Future of Robotic Surgery in Thyroid Cancer Treatment

Thyroid cancer is among the most common endocrine malignancies, necessitating effective surgical interventions. Traditional open cervicotomy has long been the standard approach for thyroidectomy. However, the advent of robotic surgery has introduced new possibilities for minimally invasive procedures with benefits in terms of cosmetic outcomes, enhanced precision, comparable complication rates, and reduced recovery time. This study mainly reviewed the most widely used and well-known robotic thyroidectomy approaches: the transaxillary approach, the bilateral axillo-breast approach, and the transoral approach. This review examines the current status and future potential of robotic surgery in thyroid cancer treatment, comparing its efficacy, safety, and outcomes with those of conventional open cervicotomy. Challenges such as a longer operative time and higher costs exist. Future directions include technological advancements, tele-surgery, single-port surgery, and the integration of artificial intelligence. Robotic surgery holds promise in optimizing patient outcomes in thyroid cancer treatment.

Impact of autofluorescence-guided surgery of parathyroid glands during total thyroidectomy in experienced surgeons: A randomized clinical trial

INTRODUCTION

Post-surgical hypoparathyroidism often occurs after total thyroidectomy (TT). The aim of this study is to investigate whether the use of near-infrared autofluorescence (NIRAF) of parathyroid glands (PGs) can aid experienced surgeons in identifying more PGs during surgery, potentially reducing unintended resection, and assessing its impact on post-surgical hypoparathyroidism.

MATERIALS AND METHODS

All patients undergoing at least a TT by two experienced surgeons, between 2020 and 2021, were enrolled and randomized into two cohorts: NIRAF group (NG) and CONTROL group (CG). Transient hypoparathyroidism was defined by serum concentration of PTH<12 ng/mL at the 1st post-operative day and permanent by the need of calcium-active vitamin D treatment >6 months from the surgery with still undetectable PTH or <12 ng/m.

RESULTS

Among 236 patients (111 in NG, 125 in CG), the number of PGs identified was higher in NG (93.9%, 417/444) compared to CG (81.4%, 407/500) (p < 0.001), with a mean of 3.76 ± 0.44 PGs per patient in NG and 3.25 ± 0.79 in CG. The number of unintendedly resected PGs was 14 in NG and 42 in CG (p < 0.0001). Transient hypoparathyroidism was observed in 18 patients (16.2%) in NG and 40 patients (32.0%) in CG (p = 0.004). Permanent hypoparathyroidism affected 1 patient in NG and 7 patients in CG (p = 0.06). The mean operative time was longer in NG (104.3 ± 32.08 min) compared to CG (85.5 ± 40.62 min) (p < 0.001).

CONCLUSIONS

NIRAF enhances the identification of PGs, preventing their inadvertent resection and reducing the overall incidence of post-surgical hypoparathyroidism.

Intraoperative strategies in identification and functional protection of parathyroid glands for patients with thyroidectomy: a systematic review and network meta-analysis

BACKGROUND

This study aimed to assess the benefits and limitations of four intraoperative visualization of parathyroid gland (IVPG) strategies in the identification and functional protection of parathyroid glands (PGs).

METHODS

We searched PubMed, the Cochrane Central Register of Controlled Trials, CNKI, EMBASE, Web of Science and Google Scholar databases until 30 June 2023. Four IVPG strategies were composed of the naked eyes (NE) and three imaging strategies: autofluorescence (AF), indocyanine green fluorescence (ICGF), and carbon nanoparticles (CN). We performed a pairwise meta-analysis (PMA) for direct comparisons and a Bayesian network meta-analysis (NMA) for indirect comparisons.

RESULTS

A total of 29 eligible studies were included. According to NMA and PMA, AF had significantly lower rates of postoperative hypocalcemia and hypoparathyroidism, PG inadvertent resection, and PG auto-transplantation compared to NE, while had significantly higher rate of PG identification. CN showed significantly lower rates of postoperative hypocalcemia and hypoparathyroidism, and PG inadvertent resection compared to NE in PMA and NMA. ICGF showed a significantly higher rate of PG auto-transplantation compared to NE in PMA and AF in NMA. According to SUCRA values, AF showed the best advantage in reducing the rate of postoperative hypocalcemia (0.85) and PG inadvertent resection (0.89), and increasing the rate of PG identification (0.80). CN had the greatest advantage in reducing the rate of postoperative hypoparathyroidism (0.95). ICGF ranked the highest in the rate of PG auto-transplantation (0.98).

CONCLUSIONS

Three imaging strategies demonstrate significant superiority over NE in the intraoperative PG identification and functional protection. AF is the best strategy in reducing the incidence of postoperative hypocalcemia, increasing the rate of PG identification, and reducing the rate of PG inadvertent resection and auto-transplantation. ICGF has great value in assessing PG viability, leading to the trend towards PG auto-transplantation. CN is the best strategy in reducing the incidence of postoperative hypoparathyroidism.

Management of Postthyroidectomy Hypoparathyroidism and Its Effect on Hypocalcemia-Related Complications: A Meta-Analysis

OBJECTIVE

The aim of this Meta-analysis is to evaluate the impact of different treatment strategies for early postoperative hypoparathyroidism on hypocalcemia-related complications and long-term hypoparathyroidism.

DATA SOURCES

Embase.com, MEDLINE, Web of Science Core Collection, Cochrane Central Register of Controlled Trials, and the top 100 references of Google Scholar were searched to September 20, 2022.

REVIEW METHODS

Articles reporting on adult patients who underwent total thyroidectomy which specified a treatment strategy for postthyroidectomy hypoparathyroidism were included. Random effect models were applied to obtain pooled proportions and 95% confidence intervals. Primary outcome was the occurrence of major hypocalcemia-related complications. Secondary outcome was long-term hypoparathyroidism.

RESULTS

Sixty-six studies comprising 67 treatment protocols and 51,096 patients were included in this Meta-analysis. In 8 protocols (3806 patients), routine calcium and/or active vitamin D medication was given to all patients directly after thyroidectomy. In 49 protocols (44,012 patients), calcium and/or active vitamin D medication was only given to patients with biochemically proven postthyroidectomy hypoparathyroidism. In 10 protocols (3278 patients), calcium and/or active vitamin D supplementation was only initiated in case of clinical symptoms of hypocalcemia. No patient had a major complication due to postoperative hypocalcemia. The pooled proportion of long-term hypoparathyroidism was 2.4% (95% confidence interval, 1.9-3.0). There was no significant difference in the incidence of long-term hypoparathyroidism between the 3 supplementation groups.

CONCLUSIONS

All treatment strategies for postoperative hypocalcemia prevent major complications of hypocalcemia. The early postoperative treatment protocol for postthyroidectomy hypoparathyroidism does not seem to influence recovery of parathyroid function in the long term.

Intraoperative Parathyroid Gland Identification Using Autofluorescence Imaging in Thyroid Cancer Surgery with Central Neck Dissection: Impact on Post-Operative Hypocalcemia

Hypoparathyroidism is the most frequent complication in thyroid surgery. The aim of this study was to evaluate the impact of intraoperative parathyroid gland identification, using autofluorescence imaging, on the rate of post-operative (PO) hypoparathyroidism in thyroid cancer surgery. Patients undergoing total thyroidectomy with central neck dissection from 2018 to 2022 were included. A prospective cohort of 77 patients operated on using near-infrared autofluorescence (NIRAF+) with the Fluobeam® (Fluoptics, Grenoble, France) system was compared to a retrospective cohort of 94 patients (NIR-). The main outcomes were the rate of PO hypocalcemia, with three cutoffs: corrected calcium (Cac) < 2.10 mmol/L, <2.00 mmol/L and <1.875 mmol/L, and the rate of permanent hypoparathyroidism, at 12 months. The rate of PO Cac < 2.10 mmol/L was statistically lower in the NIRAF+ group, compared to the control group (36% and 60%, p = 0.003, respectively). No statistically significant difference was observed for the other two thresholds. There was a lower rate of permanent hypoparathyroidism in the NIRAF+ group (5% vs. 14% in the control group), although not statistically significant (p = 0.07). NIRAF is a surgically non-invasive adjunct, and can improve patients' outcomes for thyroid cancer surgery by reducing post-operative temporary hypoparathyroidism. Larger prospective studies are warranted to validate our findings.

The magic mirror: a novel intraoperative monitoring method for parathyroid glands

The accurate detection of parathyroid glands (PGs) during surgery is of great significance in thyroidectomy and parathyroidectomy, which protects the function of normal PGs to prevent postoperative hypoparathyroidism and the thorough removal of parathyroid lesions. Existing conventional imaging techniques have certain limitations in the real-time exploration of PGs. In recent years, a new, real-time, and non-invasive imaging system known as the near-infrared autofluorescence (NIRAF) imaging system has been developed to detect PGs. Several studies have confirmed that this system has a high parathyroid recognition rate and can reduce the occurrence of transient hypoparathyroidism after surgery. The NIRAF imaging system, like a magic mirror, can monitor the PGs during surgery in real time, thus providing great support for surgeries. In addition, the NIRAF imaging system can evaluate the blood supply of PGs by utilizing indocyanine green (ICG) to guide surgical strategies. The NIRAF imaging system and ICG complement each other to protect normal parathyroid function and reduce postoperative complications. This article reviews the effectiveness of the NIRAF imaging system in thyroidectomies and parathyroidectomies and briefly discusses some existing problems and prospects for the future.

Central node dissection in papillary thyroid carcinoma in the era of near-infrared fluorescence

The most common site of lymph node metastases in papillary thyroid carcinoma is the central compartment of the neck (level VI). In many patients, nodal metastases in this area are not clinically apparent, neither on preoperative imaging nor during surgery. Prophylactic surgical clearance of the level VI in the absence of clinically suspicious lymph nodes (cN0) is still under debate. It has been suggested to reduce local recurrence and improve disease-specific survival. Moreover, it helps to accurately diagnose the lymph node involvement and provides important staging information useful for tailoring of the radioactive iodine regimen and estimating the risk of recurrence. Yet, many studies have shown no benefit to the long-term outcome. Arguments against the prophylactic central lymph node dissection (CLND) cite minimal oncologic benefit and concomitant higher operative morbidity, with hypoparathyroidism being the most common complication. Recently, near-infrared fluorescence imaging has emerged as a novel tool to identify and preserve parathyroid glands during thyroid surgery. We provide an overview of the current scientific landscape of fluorescence imaging in thyroid surgery, of the controversies around the prophylactic CLND, and of fluorescence imaging applications in CLND. To date, only three studies evaluated fluorescence imaging in patients undergoing thyroidectomy and prophylactic or therapeutic CLND for thyroid cancer. The results suggest that fluorescence imaging has the potential to minimise the risk of hypoparathyroidism associated with CLND, while allowing to exploit all its potential benefits. With further development, fluorescence imaging techniques might shift the paradigm to recommend more frequently prophylactic CLND.

The Utility of Near-Infrared Autofluorescence for Parathyroid Gland Identification During Thyroid Surgery: A Single-Center Experience

Parathyroid gland injury during thyroid surgery is common and can lead to postoperative hypocalcemia. This study aims to determine the utility of near-infrared autofluorescence (NIRAF) technology for parathyroid gland identification in thyroid surgery. A prospective case series of patients who underwent thyroid surgery between March and June 2021 were examined. Following intra-operative visualisation, parathyroid glands and surrounding tissues were exposed to near-infrared light with a wavelength of approximately 800 nm using the Storz® Near-Infrared Range/Indocyanine Green (NIR/ICG) endoscopic system. Parathyroid glands were expected to show autofluorescence following exposure. Twenty patients who underwent thyroid surgery were included. Eighteen patients (90%) were female, with a median age of 50.0 (IQR 41.0 - 62.5). Surgeries performed include hemithyroidectomy (9 patients; 45.0%), total thyroidectomy (8 patients; 40.0%), completion thyroidectomy (2 patients; 10.0%) and right inferior parathyroidectomy (1 patient; 5.0%). Attempts were made to identify 56 parathyroid glands in this case series. There were 46/56 (82.1%) surgeon-identified parathyroid glands through direct visualisation. Using NIRAF technology, 39/46 (84.8%) were identified as parathyroid glands. There was no inadvertent resection of parathyroid glands or post-operative hypocalcaemia. NIRAF technology has the potential to be a useful tool in confirming the presence of parathyroid glands following direct visualisation intra-operatively.

Effect of near infrared autofluorescence guided total thyroidectomy on postoperative hypoparathyroidism: a randomized clinical trial

PURPOSE

The purpose of this single-blinded, 2-centre, randomized controlled trial was to test if near-infrared (NIR) autofluorescence image guidance for parathyroid gland (PG) detection during total thyroidectomy can reduce the incidence of hypoparathyroidism in both malignant and benign cases.

METHOD

Patients admitted for primary or completion total thyroidectomy were randomized to either the NIR intervention group or the standard care NONIR (no near infrared) group. The primary endpoint was the rate of hypoparathyroidism at the 3-month follow-up, defined as hypocalcemia and inappropriately low parathyroid hormone levels and/or continuous treatment with active vitamin D. The secondary endpoint was the PG identification rate.

RESULTS

A total of 147 patients were included of whom 73 were allocated to NIR. Primary or completion thyroidectomy was conducted in 84 and 63 cases, respectively. A total of 130 completed 3 months follow-up. Postoperative hypoparathyroidism in the NIR group at 12 h, 1 month and 3 months was, respectively, 31.8, 14.1, 6.5% compared with 35.9, 18.9, 11.8% in the NONIR group (all p > 0.46). In the NIR group, the identification rate of PGs was 69.5% (146 of 210 PGs), and 9% (19 of 210 PGs) were identified only due to additional use of NIR. For 15 out of 69 patients (21.7%) additionally PGs was found.

CONCLUSION

Hypoparathyroidism was nominally less frequent in the NIR group, although not statistically significant. Further studies are needed to confirm if NIR may be a supportive PG identification tool to minimize the number of PG which would have been otherwise missed, especially during more complicated thyroid procedures.

TRIAL REGISTRY

ClinicalTrials.gov: NCT04193332. Registration date: 16.08.2019.

The impact of near-infrared autofluorescence on postoperative hypoparathyroidism during total thyroidectomy: a case-control study

PURPOSE

Near-infrared autofluorescence is a new technology in thyroid surgery to better localize and preserve parathyroid glands. The purpose of this study is to assess if the adoption of NIR-AF can improve in short-, medium-, and long-term post-operative calcium and PTH levels compared to conventional "naked eye" surgery in patients undergoing TT for benign or malignant conditions.

METHODS

134 patients undergone total thyroidectomy between January 2020 and June 2022; 67 were treated with conventional thyroidectomy, the other 67 underwent surgery adopting an autofluorescence detecting device.

RESULTS

Significant differences were found between the two groups in percentage of patients with short-term hypocalcemia (p = 0.04) and short-term hypoparathyroidism (p = 0.011). Median short-term (p = 0.01) and medium-term (p = 0.03) PTH levels were significantly higher in autofluorescence group, while, short- (p = 0.001), medium- (p < 0.001) and long-term (p = 0.019) percentage variation of PTH levels from baseline were significantly higher in the standard-care group. Finally, the prescription of oral calcium (p < 0.01) after surgery were significantly lower in the autofluorescence group.

CONCLUSION

The adoption of near-infrared autofluorescence during total thyroidectomy is related to lower short-term hypocalcemia and hypoparathyroidism rates, decreased variation of post-operative PTH levels in short- and medium- and long-term, reducing the necessity of supplementation therapy with oral calcium compared to conventional surgery.

Intraoperative Autofluorescence Imaging for Parathyroid Gland Identification during Total Laryngectomy with Thyroidectomy

OBJECTIVE

Hypoparathyroidism is a known complication of total laryngectomy, although parathyroid preservation and/or reimplantation are not routine. Autofluorescence is a new technique for identifying parathyroid glands intraoperatively. The aim of this study was to evaluate the feasibility of autofluorescence in this context.

MATERIALS AND METHODS

A retrospective study of patients undergoing total laryngectomy/pharyngectomy with concomitant thyroidectomy using the Fluobeam^® (Fluoptics, Grenoble, France) and frozen section of a parathyroid fragment in case of reimplantation. The rates of identification using autofluorescence, reimplantation, and hypoparathyroidism were evaluated.

RESULTS

Eighteen patients (16 males, median age 67) underwent total laryngectomy/pharyngectomy with total thyroidectomy (n = 12) or hemithyroidectomy (n = 6). A median of 2 parathyroid glands were identified per patient. Ninety-two percent were identified by autofluorescence before visualisation. All parathyroids were reimplanted due to devascularization. Temporary hypoparathyroidism occurred in nine patients, and was permanent in one patient. After 34 months of median follow-up (range 1-49), no tumor recurrence was observed in the reimplantation sites.

CONCLUSIONS

To our knowledge, this is the largest study to evaluate autofluorescence during total laryngectomy with thyroidectomy. No tumor recurrence occurred in the sites of parathyroid reimplantation.

Detectable depth of unexposed parathyroid glands using near-infrared autofluorescence imaging in thyroid surgery

Background

Near-infrared light can penetrate the fat or connective tissues overlying the parathyroid gland (PG), enabling early localization of the PG by near-infrared autofluorescence (NIRAF) imaging. However, the depth at which the PG can be detected has not been reported. In this study, we investigated the detectable depth of unexposed PGs using NIRAF during thyroidectomy.

Materials and methods

Fifty-one unexposed PGs from 30 consecutive thyroidectomy patients, mapped by an experienced surgeon (K.D. Lee) with the use of NIRAF imaging, were included. For NIRAF detection of PGs, a lab-built camera imaging system was used. Detectable depths of the unexposed PGs were measured using a Vernier caliper. The NIRAF images were classified as faint or bright depending on whether a novice could successfully interpret the image as showing the PG. Data on variables that may affect detectable depth and NIRAF intensity were collected.

Results

Detectable depth ranged between 0.35 and 3.05 mm, with a mean of 1.23 ± 0.73 mm. The average NIRAF intensity of unexposed PGs was 3.13 au. After dissection of the overlying tissue, the intensity of the exposed PG increased to 4.88 au (p < 0.001). No difference in NIRAF intensity between fat-covered (3.27 ± 0.90 au) and connective tissue-covered PGs (3.00 ± 1.23 au) was observed (p = 0.369). PGs covered by fat tissue (depth: 1.77 ± 0.67 mm) were found at deeper locations than those covered by connective tissue (depth: 0.70 ± 0.21 mm) (p < 0.001). The brightness of images of the faint group (2.14 ± 0.48 au) was on average 1.24 au lower than that of the bright group (3.38 ± 1.04 au) (p = 0.001). A novice successfully localized 80.4% of the unexposed PGs. Other variables did not significantly affect detectable depth.

Conclusion

Unexposed PGs could be mapped using NIRAF imaging at a maximum depth of 3.05 mm and an average depth of 1.23 mm. A novice was able to localize the PGs before they were visible to the naked eye at a high rate. These results can be used as reference data for localization of unexposed PGs in thyroid surgery.

Advances in Endocrine Surgery

Recent changes in the landscape of endocrine surgery include a shift from total thyroidectomy for almost all patients with papillary thyroid cancer to the incorporation of thyroid lobectomy for well-selected patients with low-risk disease; minimally invasive parathyroidectomy with, and potentially without, intraoperative parathyroid hormone monitoring for patients with well-localized primary hyperparathyroidism; improvement in the management of parathyroid cancer with the incorporation of immune checkpoint blockade and/or targeted therapies; and the incorporation of minimally invasive techniques in the management of patients with benign tumors and selected secondary malignancies of the adrenal gland.

Optical diagnostic imaging and therapy for thyroid cancer

Thyroid cancer, as one of the most common endocrine cancers, has seen a surge in incidence in recent years. This is most likely due to the lack of specificity and accuracy of its traditional diagnostic modalities, leading to the overdiagnosis of thyroid nodules. Although there are several treatment options available, they are limited to surgery and 131I radiation therapy that come with significant side effects and hence cannot meet the treatment needs of anaplastic thyroid carcinoma with very high malignancy. Optical imaging that utilizes optical absorption, refraction and scattering properties, not only observes the structure and function of cells, tissues, organs, or even the whole organism to assist in diagnosis, but can also be used to perform optical therapy to achieve targeted non-invasive and precise treatment of thyroid cancer. These applications of screening, diagnosis, and treatment, lend to optical imaging's promising potential within the realm of thyroid cancer surgical navigation. Over the past decade, research on optical imaging in the diagnosis and treatment of thyroid cancer has been growing year by year, but no comprehensive review on this topic has been published. Here, we review key advances in the application of optical imaging in the diagnosis and treatment of thyroid cancer and discuss the challenges and potential for clinical translation of this technology.

Autofluoreszenz der Nebenschilddrüsen in der Schilddrüsenchirurgie

Eine Unterfunktion der Nebenschilddrüsen (postoperativer Hypoparathyreoidismus) ist die häufigste Komplikation in der Schilddrüsenchirurgie. Obwohl sie zumeist nur vorübergehend besteht, kann sie zu einer starken Einschränkung der Lebensqualität führen. Um die Rate an temporärem und permanentem Hypoparathyreoidismus zu vermindern, kann zur intraoperativen Erkennung der Nebenschilddrüsen die Nahinfrarot-Autofluoreszenz(NIRAF)-Bildgebung verwendet werden. Die Overlay-Ansicht stellt hierbei eine Weiterentwicklung der bisherigen NIRAF-Bildgebung dar, die durch die Überlappung von Nahinfrarot und Weißlicht entsteht und sich somit von der klassischen Schwarz-weiß-Ansicht unterscheidet.

Hypoparathyroidism Risk After Total Endoscopic Thyroidectomy for Papillary Thyroid Cancer: A Comparison of the Transoral Vestibular and Breast Approaches

Background

This study aimed to compare the risk of hypoparathyroidism between the transoral vestibular approach (TOVA) and the breast approach (BA) in patients undergoing total endoscopic thyroidectomy (TET) for papillary thyroid carcinoma (PTC).

Methods

The medical records of 121 PTC patients (all women) who underwent total TET from January 2015 to January 2021 were retrospectively analyzed. Patients were grouped according to surgical approach (BA or TOVA). Clinical status and concentrations of parathyroid hormone (PTH) and calcium were monitored in the perioperative period and 1, 6, and 12 months after surgery.

Results

The BA and TOVA groups comprised 101 and 20 patients, respectively. Clinicopathologic and characteristics and surgical data were comparable between the groups. Incidence of transient hypoparathyroidism was significantly lower in the TOVA group than the BA group (10% vs 63.4%; p <0.01). Incidence of permanent hypoparathyroidism was comparable (5% vs 6.9%). Two days after TET, mean PTH concentration was significantly higher and incidence of abnormal PTH was significantly lower in the TOVA group. The incidence of abnormal calcium concentration 2 days after surgery was significantly lower in the TOVA group. One month after surgery, the mean calcium concentration was significantly higher in the TOVA group. Univariate and multivariate Cox regression analysis suggested that patients who underwent TOVA had a lower risk of transient hypoparathyroidism (hazard ratio 0.05, 95% confidence interval, 0.01–0.23; p<0.01). No clinicopathological factors examined were significantly associated with permanent hypoparathyroidism.

Conclusion

In patients undergoing TET for PTC, the incidence of transient hypoparathyroidism may be lower with the TOVA than the BA. Surgeons should be aware of the relatively high risk of transient hypoparathyroidism when performing the BA.

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

Background: Postoperative hypoparathyroidism is the most common complication after total thyroidectomy. Over the past years, optical imaging techniques, such as parathyroid autofluorescence, indocyanine green (ICG) angiography, and laser speckle contrast imaging (LSCI) have been employed to save parathyroid glands during thyroid surgery. This study provides an overview of the utilized methods of the optical imaging techniques during total thyroidectomy for parathyroid gland identification and preservation. Methods: PUBMED, EMBASE and Web of Science were searched for studies written in the English language utilizing parathyroid autofluorescence, ICG-angiography, or LSCI during total thyroidectomy to support parathyroid gland identification or preservation. Case reports, reviews, meta-analyses, animal studies, and post-mortem studies were excluded after the title and abstract screening. The data of the studies were analyzed qualitatively, with a focus on the methodologies employed. Results: In total, 59 articles were included with a total of 6190 patients. Overall, 38 studies reported using parathyroid autofluorescence, 24 using ICG-angiography, and 2 using LSCI. The heterogeneity between the utilized methodology in the studies was large, and in particular, regarding study protocols, imaging techniques, and the standardization of the imaging protocol. Conclusion: The diverse application of optical imaging techniques and a lack of standardization and quantification leads to heterogeneous conclusions regarding their clinical value. Worldwide consensus on imaging protocols is needed to establish the clinical utility of these techniques for parathyroid gland identification and preservation.

Thyroidectomy for Cancer: The Surgeon and the Parathyroid Glands Sparing

BACKGROUND

The diagnosis of thyroid cancer is continuously increasing and consequently the amount of thyroidectomy. Notwithstanding the actual surgical skill, postoperative hypoparathyroidism still represents its most frequent complication. The aims of the present study are to analyze the rate of postoperative hypoparathyroidism after thyroidectomy, performed for cancer by a single first operator, without any technological aid, and to compare the data to those obtained adopting the most recent technological adjuncts developed to reduce the postoperative hypoparathyroidism.

METHODS

During the period 1997-2020 at the Endocrine Surgery Unit of the Department of Clinical and Experimental Medicine of the University of Florence, 1648 consecutive extracapsular thyroidectomies for cancer (401 with central compartment node dissection) were performed. The percentage of hypoparathyroidism, temporary or permanent, was recorded both in the first period (Group A) and in the second, most recent period (Group B). Total thyroidectomies were compared either with those with central compartment dissection and lobectomies. Minimally invasive procedures (MIT, MIVAT, some transoral) were also compared with conventional. Fisher's exact and Chi-square tests were used for comparison of categorical variables. p < 0.01 was considered statistically significant. Furthermore, a literature research from PubMed® has been performed, considering the most available tools to better identify parathyroid glands during thyroidectomy, in order to reduce the postoperative hypoparathyroidism. We grouped and analyzed them by technological affinity.

RESULTS

On the 1648 thyroidectomies enrolled for the study, the histotype was differentiated in 93.93 % of cases, medullary in 4% and poorly differentiated in the remaining 2.06%. Total extracapsular thyroidectomy and lobectomy were performed respectively in 95.45% and 4.55%. We recorded a total of 318 (19.29%) cases of hypocalcemia, with permanent hypoparathyroidism in 11 (0.66%). In regard to the literature, four categories of tools to facilitate the identification of the parathyroids were identified: (a) vital dye; (b) optical devices; (c) autofluorescence of parathyroids; and (d) autofluorescence enhanced by contrast media. Postoperative hypoparathyroidism had a variable range in the different groups.

CONCLUSIONS

Our data confirm that the incidence of post-surgical hypoparathyroidism is extremely low in the high volume centers. Its potential reduction adopting technological adjuncts is difficult to estimate, and their cost, together with complexity of application, do not allow immediate routine use. The trend towards increasingly unilateral surgery in thyroid carcinoma, as confirmed by our results in case of lobectomy, is expected to really contribute to a further reduction of postsurgical hypoparathyroidism.

Fluorescence Image-Guided Surgery for Thyroid Cancer: Utility for Preventing Hypoparathyroidism

Background: Hypoparathyroidism is one of the most frequent complications of thyroid surgery, especially when associated with lymph node dissection in cases of thyroid cancer. Fluorescence-guided surgery is an emerging tool that appears to help reduce the rate of this complication. The present review aims to highlight the utility of fluorescence imaging in preserving parathyroid glands during thyroid cancer surgery. Methods: We performed a systematic review of the literature according to PRISMA guidelines to identify published studies on fluorescence-guided thyroid surgery with a particular focus on thyroid cancer. Articles were selected and analyzed per indication and type of surgery, autofluorescence or exogenous dye usage, and outcomes. The Methodological Index for Non-Randomized Studies (MINORS) was used to assess the methodological quality of the included articles. Results: Twenty-five studies met the inclusion criteria, with three studies exclusively assessing patients with thyroid cancer. The remaining studies assessed mixed cohorts with thyroid cancer and other thyroid or parathyroid diseases. The majority of the papers support the potential benefit of fluorescence imaging in preserving parathyroid glands in thyroid surgery. Conclusions: Fluorescence-guided surgery is useful in the prevention of post-thyroidectomy hypoparathyroidism via enhanced early identification, visualization, and preservation of the parathyroid glands. These aspects are notably beneficial in cases of associated lymphadenectomy for thyroid cancer.