Indocyanine green as a near-infrared fluorescent agent for identifying parathyroid glands during thyroid surgery in dogs

Radical Resection of Differentiated Thyroid Cancer in Elderly Patients: Evaluation of the Efficacy of the Immunocolloidal Gold Strip Method Combined with Nanocarbon Negative Imaging Tracing Technology for Parathyroid Gland Imaging

OBJECTIVE

Extant imaging methods used for the proper identification of the parathyroid glands to prevent post-operative hypothyroidism associated with the resection of differentiated thyroid cancer (DTC) are limited by factors such as low specificity, high cost, and technical complexity. This study, therefore, sought to investigate the efficacy of the immunocolloidal gold strip method combined with nanocarbon negative imaging tracing technology for parathyroid gland imaging during radical resection of DTC in elderly patients.

METHODS

A total of 100 elderly patients with DTC were enrolled and randomly divided into two groups: the control group and the observation group. The control group underwent conventional radical thyroidectomy with bilateral cervical lymph node dissection, while the observation group received the immunocolloidal gold strip method combined with nanocarbon negative imaging tracing technology for parathyroid gland imaging during the surgery. The baseline characteristics, intraoperative findings, postoperative parathyroid hormone (PTH), and serum calcium levels, as well as postoperative complications, were compared between the two groups.

RESULTS

There were no significant differences in age, gender, body mass index, comorbidities, or smoking history between the two groups. The observation group had a significantly higher number of parathyroid glands identified during surgery compared with the control group. The postoperative PTH and serum calcium levels at postoperative days 1 and 3 and at 6 months were significantly higher in the observation group than those in the control group. The incidence of postoperative hypoparathyroidism was significantly lower in the observation group.

CONCLUSION

The immunocolloidal gold strip method combined with nanocarbon negative imaging tracing technology is effective in identifying and preserving parathyroid glands during radical resection of DTC in elderly patients.

Meta-Analysis of Image-Based Versus Probe-Based Parathyroid Near-Infrared Autofluorescence

Proper identification of parathyroid tissue is a critical component in surgery involving the thyroid and parathyroid gland (PG). In recent years, near infrared autofluorescence (NIRAF) has been investigated as a non-invasive strategy to detect PG in parathyroidectomy and in PG preservation in thyroidectomy. There are currently two FDA approved NIRAF modalities, image-based and probe-based. The aim of this meta-analysis is to evaluate the efficacy of these two NIRAF modalities. PubMed, Scopus, and MEDLINE were utilized, with 238 studies analyzed via independent, blinded review. Studies from January 2000 to February 2023, Boolean phrase "parathyroid autofluorescence", written in English, and included results found within the body of the article were the inclusion criteria used. Conference abstracts, reviews, case reports, commentary, discussion and letter, non-English, animal studies, in vitro studies, contrast enhanced fluorescence, and NIRAF with use of indocyanine green, were the exclusion criteria used. Five studies were enrolled based on inclusion and exclusion criteria. The estimated overall accuracy of image-based methods is 0.96 (95% CI of (0.87, 0.99)), while the estimated overall accuracy of probe-based methods is 0.93 (95% CI of (0.92, 0.94)). With p=0.36, there is insufficient evidence to indicate a significant difference in overall accuracy, sensitivity and specificity between image-based methods and probe-based methods. Both imaging and probe-based detection modalities offer effective, noninvasive means for identifying parathyroid glands intraoperatively. Further studies comparing the efficacy of these two modalities are needed to further differentiate their clinical performance.

Guideline From the Brazilian Society of Surgical Oncology and Brazilian College of Surgeons in Preventing and Managing Acute Hypoparathyroidism After Thyroid Surgery

The risk of hypoparathyroidism and hypocalcemia is a critical concern in thyroid surgery. Preserving parathyroid gland vascularization during surgery is essential for effective prevention. Preoperative and postoperative management, including calcium and Vitamin D supplementation, is paramount. Measurement of parathyroid hormone levels after surgery is the best predictor of hypoparathyroidism. This guideline offers recommendations for the prevention, diagnosis, and treatment of acute hypoparathyroidism and hypocalcemia after thyroid surgery.

Intraoperative indocyanine green angiography in preventing hypoparathyroidism after thyroid cancer surgery

BACKGROUND

The aim of this study was to determine whether the use of indocyanine green angiography to identify devascularized parathyroids during thyroidectomy for thyroid cancer would decrease the rates of postoperative hypoparathyroidism.

METHODS

Retrospective study of patients who had undergone total thyroidectomy for treatment of thyroid cancer between March 2021 and March 2023. The indocyanine group included patients with all four parathyroids identified and evaluated by indocyanine green angiography at the end of the procedure. Those with parathyroid glands classified with no vascularization had the glands autotransplanted. A group without indocyanine angiography was used to compare results.

RESULTS

The analysis included 100 patients in each group. Indocyanine angiography identified 14.75% of devascularized parathyroids at surgery. The number of parathyroids with a score of 2 (i.e., good vascularization) was not a safe predictor of normal parathyroid hormone levels after surgery. Indeed, 29.2% of the patients with three parathyroids with a score of 2 developed transient hypoparathyroidism. Permanent hypoparathyroidism occurred in 7% of the patients without indocyanine group and in none of the patients in the indocyanine group (p = 0.014).

CONCLUSION

Intraoperative angiography with indocyanine green could contribute to reduce the occurrence of permanent hypoparathyroidism in patients undergoing surgical treatment for thyroid cancer.

Comparison of indocyanine green angiography vs intraoperative parathyroid hormone in early prediction of risk of post-thyroidectomy hypocalcemia: a prospective cohort study

Introduction

Indocyanine green (ICG) angiography is the 'real-time intraoperative imaging' technique used to reduce the chances of hypoparathyroidism in post-thyroidectomy patients. In our study, the authors predicted the risk of early post-thyroidectomy hypocalcemia by intraoperative evaluation of parathyroid gland perfusion by ICG angiography.

Materials and methods

In patients who underwent total thyroidectomy, ICG angiography was done using the SPY PHI imaging system (Stryker). Post-thyroid specimen removal, scoring of parathyroids was done in spy contrast mode. All 4 or <4 visualized parathyroids were scored for vascularity with the highest score of 8. Serum ionized calcium was done 6 h postsurgery and on the morning and evening of postoperative days 1 and 2. Calcium supplements were given to only those who developed clinical or severe biochemical hypocalcemia.

Results

Out of 60, postoperative hypocalcemia was noted in 41 patients. Total ICG score ≤5 was seen in 34 patients, out of which 28 developed postoperative hypocalcemia showing PPV 82.3% and diagnostic accuracy of 68.3% while iPTH (4.28 pmol/l) showed PPV 76.7 and diagnostic accuracy 70 %. In eight patients, none of the glands was scored as 2 (White) and all these patients developed hypocalcemia requiring calcium infusion.

Conclusion

The absence of visualization of at least 1 well-perfused (score 2) gland on ICG angiography is highly predictive of hypocalcemia and the majority of patients with total ICG score ≤5 developed hypocalcemia in the immediate postoperative period. ICG is a good predictor of the absence of hypoparathyroidism after thyroidectomy and is comparable to iPTH in the prediction of post-thyroidectomy hypocalcemia.

Intraoperative indocyanine green angiography for predicting postoperative hypoparathyroidism

BACKGROUND

Postoperative hypocalcemia is a common complication of thyroidectomy. This problem is most often associated with accidental devascularization or excision of the parathyroid glands (PG).

AIM

Aim was to study near-infrared (NIR) fluorescent imaging with intraoperative PG indocyanine green (ICG) angiography to help identify and preserve PG during total thyroidectomy in order to avoid postoperative hypocalcemia.

MATERIAL AND METHODS

From 2017 to 2022, a total of 92 patients underwent total thyroidectomy at Odessa Regional Hospital. Indications for surgery were multinodular goiter (n = 42), thyroid cancer (n = 43), and Graves' disease (n = 7). By randomization all patients were divided into two groups: in the control group, 48 patients underwent standard total thyroidectomy, and in the main group, 44 patients underwent NIR-assisted total thyroidectomy with ICG angiography. Serum calcium and parathyroid hormone levels were compared between the two groups of patients in 1, 7-15 days after surgery and then 3, 6 months later.

RESULTS

In the control group, based on a visual assessment of the PG, autotransplantation of the PG was conducted in only five cases. In the second group, autotransplantation was performed in 16 patients. The transient postoperative hypocalcemia was observed in 8 patients of the control group (16, 70%) and in the 2 patients of ICG group (4, 50%) on 5-10 postoperative days. In the first group, 2 patients at 3 months after surgery had permanent hypocalcaemia.

CONCLUSION

NIR fluorescent imaging with intraoperative PG ICG angiography is a safe and an easily repeatable method. This technique provides improved detecting and assessment of the perfusion of the PG. The need for autotransplantation of the PG can be determined more objectively using ICG imaging than simple visualization.

Intraoperative prevention of postoperative hypoparathyroidism

Objective

More than 30,000 thyroid surgeries are performed annually in the Russian Federation. The surgeries are relatively safe because of the prevention methods for postoperative complications. Currently, there is no single effective method of postoperative hypoparathyroidism prevention. This complication is frequently reported and may be health and life-threatening.

Aim

We aimed to estimate the effectiveness of the intraoperative ICG-angiography and intrathyroid injection of Brilliant Green for the prevention of postoperative hypoparathyroidism.

Material and methods

One hundred and forty-three thyroidectomies were performed. Patients were divided into three groups: intraoperative angiography was used in 24 cases; Brilliant Green was injected in 58 cases to identify parathyroid glands; the visual estimation of the parathyroid preservation was used in 61 cases. Calcium level was measured in all patients before and after surgery.

Results

Calcium level in the serum before and after surgery was 2.37±0.14 and 2.27±0.17 in Group 1, 2.38±0.16 and 2.21±0.16 in Group 2, and 2.39±0.17 and 2.18±0.19 in Group 3. Postoperative hypocalcemia was more prominent in the group with the visually estimated PTG than in the two other groups. The differences in postoperative calcium levels in Groups 1 and 3 were statistically different. Pre- and postoperative Parathormone levels were 6.2±0.4 in Group 1, 5.6±0.57 in Group 2, and 3.5±0.32 in Group 3. Postoperative levels significantly differed in Groups 1 and 3 (p<0.01) and in Groups 2 and 3 (p<0.05).

Conclusions

ICG-angiography and intrathyroid injection of the Brilliant Green are safe methods of identification and sparing of the parathyroid glands. The severity of hypocalcemia and hypoparathormonemia in Group 3 shows the necessity of finding new methods in endocrine surgery to improve patient outcomes.

Robot-Assisted Parathyroidectomy Using Indocyanine Green (ICG) Fluorescence in Primary Hyperparathyroidism

Background and Objectives: Surgical treatment for primary hyperparathyroidism (PHPT) has evolved from bilateral exploration through a long transcervical incision to focused parathyroidectomy with a minimal incision above the pathologic gland. Recently, endoscopic or robot-assisted parathyroid surgery without direct neck incision has been introduced. The aim of this study was to investigate the effectiveness of indocyanine green (ICG) fluorescence as a new method for the visual identification of abnormal hyperfunctioning parathyroid glands in robot-assisted parathyroidectomy using FireflyTM technology. We also aimed to conduct a comparative analysis between robot-assisted parathyroidectomy and conventional focused parathyroidectomy in order to identify clinical differences between the two surgical approaches. Materials and Methods: A total of 37 patients with PHPT underwent parathyroidectomy at a single university hospital between September 2018 and December 2022. Thirty-one patients underwent open focused parathyroidectomy (open group), and six patients underwent robot-assisted parathyroidectomy (robot group). Pre-operative localization via parathyroid SPECT-CT and an intraoperative parathyroid hormone (IOPTH) assay were used to successfully remove the pathologic parathyroid in both groups. ICG was administered only in the robot group. Results: Pathologic parathyroid showed a persistent fluorescence pattern under near-infrared vision. After the removal of the fluorescent parathyroid gland, IOPTH was normalized in all six patients in the robot group. However, the open group showed shorter hospital stays (1.8 ± 1.2 vs. 3.0 ± 0.0 days, p < 0.001) and shorter operation times (91.1 ± 69.1 vs. 152.5 ± 23.6 min, p = 0.001) than the robot group. After 6 months of surgery, PTH, calcium, and ionized calcium levels were all normalized without significant differences between the groups. Conclusions: Robot-assisted parathyroidectomy using ICG is helpful for the visual identification of the pathologic parathyroid gland. The advantage of robot parathyroidectomy is a better cosmetic outcome. However, it still does not show better clinical outcomes than conventional open focused parathyroidectomy.

Preservation of parathyroid glands during thyroid and neck surgery

The parathyroid glands are situated in close proximity to the thyroid gland. They have an important endocrine function maintaining calcium and phosphate homeostasis in the body by the secretion of parathormone (PTH), which is responsible for this function. The parathyroid glands are commonly damaged during thyroid surgeries. This could lead to transient or permanent hypoparathyroidism in 30% of cases. Preservation of the parathyroid glands, is an important and integral part of thyroidectomy and other surgical interventions in the neck. The main principle underlying this is a thorough understanding of parathyroid anatomy in relation to the thyroid gland and other important structures in the area. There can also be significant variation in the anatomical location of the glands. Various techniques and methods have been described for parathyroid preservation. They include intraoperative identification utilizing indocyanine green (ICG) fluorescence, carbon nanoparticles, loupes, and microscopes. The techniques of surgery (meticulous capsular dissection), expertise, central compartment neck dissection, preoperative vitamin D deficiency, extent and type of thyroidectomy are the risk factors associated with damaged thyroids, inadvertent parathyroidectomy and subsequent hypoparathyroidism. Parathyroid Autotransplantation is a treatment option for inadvertent parathyroidectomy. Ultimately, the best way to assure normal parathyroid function is to preserve them in situ intraoperatively undamaged.

Impact of near-infrared fluorescence imaging with indocyanine green on the surgical treatment of pulmonary masses in dogs

Objectives

To investigate the intraoperative identification and complete resection of pulmonary masses, and to evaluate lymph node metastasis of pulmonary malignant tumors in dogs using indocyanine green (ICG) fluorescence imaging.

Methods

Forty dogs with pulmonary masses were included, all of which underwent surgical treatment. ICG fluorescence imaging was performed on pulmonary masses before lobectomy and the resection margins after lobectomy. In addition, ICG fluorescence of the excised masses and lymph nodes was evaluated in the shaded box. The fluorescence findings were compared with the histopathological diagnosis.

Results

Of 44 nodules resected from 40 dogs, 32 nodules were histopathologically diagnosed as lung adenocarcinoma, five were histiocytic sarcoma, three were undifferentiated sarcoma, two were malignant epithelial tumor metastases, one was carcinosarcoma, and one was a non-neoplastic lesion. Fluorescence was observed in all nodules. In addition to the main lesion, other fluorescent nodules were found in four dogs. Regarding the diagnostic accuracy of complete resection based on ICG fluorescence, the sensitivity was 67.7% and the specificity was 60.0%. The sensitivity and specificity of ICG fluorescence for the diagnosis of lymph node metastasis were 100 and 75.0%, respectively.

Conclusions

ICG fluorescence imaging might be a useful intraoperative diagnostic method to identify the location of tumors and lymph node metastasis, but not to evaluate complete tumor resection, in dogs with pulmonary malignant tumors.

Safe thyroid surgery: comparison effectiveness of ICG angiography and intrathyroidal brilliant green injection for the prevention of postoperative hypoparathyroidism

BACKGROUND: More than 30,000 surgical interventions on the thyroid gland are performed annually in the Russian Federation. Surgeons are developing methods for the prevention of various postoperative complications, and therefore operations on this organ are considered relatively safe. Currently, there is no unequivocal effective method to prevent postoperative hypoparathyroidism. This complication is often recorded and can threaten the life and health of the patient, which is contrary to the concept of safe surgery.

AIM: To evaluate the effectiveness of intraoperative ICG angiography and intrathyroidal injection of brilliant green for the prevention of postoperative hypoparathyroidism.

MATERIALS AND METHODS: 143 thyroidectomies were performed. The patients were divided into 3 groups: intraoperative angiography was used in 24 cases, brilliant green was injected to identify the parathyroid glands in 58 cases, visual assessment of the preservation of the parathyroid glands was used in 61 case. Calcium levels were measured in all patients included in the study before and after surgery.

RESULTS: Serum calcium levels in the pre- and postoperative period: 2.37±0.14 and 2.27±0.17 in group 1, and 2.38±0.16 and 2.21±0.16 in group 2, 2.39±0.17 and 2.18±0.19 in group 3. Hypocalcemia in the postoperative period was significantly higher in the group with a visual assessment of the parathyroid glands relative to the first two groups. Differences between calcium levels in the postoperative period in groups 2 and 3 were significant with a probability of more than 99% (p<0.01). Significant differences (≥95%) in calcium levels in the postoperative period between groups 1 and 2 (p < 0.05) were obtained. Serum PTH levels in the postoperative period: 6,2±0,4 in group 1, 5,6±0,57 in group 2, 3,5±0,32 in group 3. Differences between PTH levels in the postoperative period in groups 1 and 3 were significant with a probability of more than 99% (p<0.01). Significant differences (≥95%) in PTH levels in the postoperative period between groups 2 and 3 (p < 0.05) were obtained.

CONCLUSION: ICG angiography and brilliant green intrathyroidal injection are safe methods for identifying and preserving the parathyroid glands. The high level of hypocalcemia in group 3 indicates the need to search for new techniques in endocrine surgery in order to improve the safety of patients undergoing surgical treatment of thyroid pathology.

Clinical impact of near-infrared fluorescence imaging with indocyanine green on surgical treatment for hepatic masses in dogs

BACKGROUND

Near-infrared fluorescence imaging using indocyanine green (ICG) is clinically applied to intraoperatively identify hepatic masses in humans. In addition, it is reported to be effective for assessing complete resection in human hepatocellular carcinoma (HCC). However, there is limited information on ICG fluorescence imaging for canine HCC, and its clinical usefulness is still unclear. Therefore, the purpose of this study was to evaluate the intraoperative identification and status of surgical margin for canine hepatic masses using near-infrared ICG fluorescence imaging. This clinical study included 104 dogs with hepatic masses. Between 12 and 24 h prior to surgery, ICG solution was injected intravenously at a dose of 0.5 mg/kg. The fluorescence intensity and pattern of each hepatic mass was investigated using an infrared camera before resection. After resection, the fluorescence intensity of the resection margin was also investigated. The resected masses were histopathologically diagnosed and compared using ICG fluorescence imaging.

RESULTS

One hundred and twenty-two masses obtained from 104 dogs included 76 HCCs, 16 hepatocellular adenomas, 12 focal nodular hyperplasias, and 18 other lesions. Of the 122 masses, 106 (94 partial, 9 whole, and 3 ring fluorescence patterns), 7, and 9 masses showed increased, the same, or decreased fluorescence compared to the normal liver tissue, respectively. The fluorescence intensity and pattern were not significantly related to the histopathological diagnosis. The sensitivity and specificity of the margin evaluation in the 47 dogs were 100% and 77.3%, respectively. The median survival times in cases of HCC with complete and incomplete resection were 914 and 254 days, respectively. The median survival time of patients with a complete resection was significantly longer than that of patients with a incomplete resection (p = 0.043).

CONCLUSION

ICG fluorescence imaging has potential clinical value for the identification and margin evaluation of canine hepatic masses. Although it is difficult to use fluorescence imaging for the differential diagnosis of liver tumours, it may be useful for assessing complete resection in cases of hepatic masses demonstrating increased fluorescence in dogs, and complete resection of HCC could have a survival benefit.

Intraoperative quantitative assessment of parathyroid blood flow during total thyroidectomy using indocyanine green fluorescence imaging - surgical strategies for preserving the function of parathyroid glands

Objective

We investigated the factors affecting postoperative parathyroid gland (PTG) function and devised an objective index to predict the postoperative PTG function during total thyroidectomy.

Method

This was a retrospective clinical review of 21 consecutive patients who were diagnosed with papillary thyroid carcinoma and underwent total thyroidectomy. The maximum intensity ratio (MIR) was determined as the maximum fluorescence intensity after ICG injection divided by the intensity before ICG injection.

Results

Postoperative hypoparathyroidism is significantly associated with simultaneous central neck dissection (CND) and lateral neck dissection (LND) (p = .032). The Spearman correlation test showed a moderate correlation between the MIR and iPTH levels (p = .0047). The optimal MIR cutoff value for predicting postoperative hypoparathyroidism was 2.14 with area under the curve = 0.904 (sensitivity: 0.769 and specificity: 1.00).

Conclusion

CND + LND was significantly associated with postoperative hypoparathyroidism. MIR was found useful in predicting the postoperative PTG function.

Level of Evidence 3b

A pilot feasibility study to assess vascularity and perfusion of parathyroid glands using a portable hand-held imager

OBJECTIVES

Intraoperative localization and preservation of parathyroid glands (PGs) are challenging during thyroid surgery. A new noninvasive technique of combined near-infrared PG autofluorescence detection and dye-free imaging angiography that allows intraoperative feedback has recently been introduced. The objective of this study was to evaluate this technique in real-time.

MATERIALS AND METHODS

A pilot feasibility study of a portable imaging device in four patients who underwent either thyroid lobectomy or total thyroidectomy is presented. PG autofluorescence and vascularity/tissue perfusion were monitored using a real-time screen display during the surgical procedure.

RESULTS

Three lobectomies and one total thyroidectomy were performed. Among the nine PGs identified by the operating surgeon, eight PGs were confirmed using the autofluorescence device. Each PG was successfully determined to be either well-perfused or devascularized, and devascularized PGs were autotransplanted.

CONCLUSIONS

The preliminary results suggest that the combination of PG autofluorescence detection and dye-free angiography can potentially be used to assess PG function. With further validation studies, the effectiveness of this technique in clinical practice can be further delineated.

Development of a non-invasive, dual-sensor handheld imager for intraoperative preservation of parathyroid glands

Intraoperative localization and preservation of parathyroid glands (PTGs) are challenging during thyroid surgery. Using a technique of combined near-infrared PTG autofluorescence detection and dye-free imaging angiography, this study developed a portable device for localization of PTGs and assessment of viability by confirming tissue perfusion. The imager's performance was evaluated through a pilot clinical study (N=10).

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

Background: Near-infrared autofluorescence (NIRAF) imaging is known to reduce the incidence of post-thyroidectomy hypocalcemia. However, there are no studies on how much NIRAF imaging affects the serum parathyroid hormone (PTH) level after surgery. We investigated the changes of the serum PTH level and ionized calcium (iCa.) in patients undergoing total thyroidectomy with central neck dissection (CND). Materials and Methods: This retrospective study with historical control enrolled 542 patients who underwent total thyroidectomy with CND. Patients were divided into two groups: the NIRAF group (261 patients) and the control group (281 patients). PTH and iCa. levels were measured at the hospital stay, 1, 3, and 6 months after surgery. In addition, the number of identified parathyroid glands (PGs), autotransplanted PGs, and the inadvertent resection rate of PGs was evaluated. Results: The incidence of postoperative hypoparathyroidism (PTH <15 pg/mL) was significantly lower in the NIRAF group during the hospitalization (88 patients: 33.7% vs. 131 patients: 46.6%; p = 0.002) and at 1 month postoperatively (23 patients: 8.8% vs. 53 patients: 18.9%; p = 0.001). There was no difference in the permanent hypoparathyroidism rate (6 months after surgery) between the NIRAF group and the control group (4.2% vs. 4.6%; p = 0.816). There was no difference in the incidence of hypocalcemia (iCa. <1.09 mmol/L) (during hospitalization: 6.5% vs. 10.0%; 1 month: 2.3% vs. 2.5%; 3 months: 0.8% vs. 0.7%; 6 months after surgery: 1.1% vs. 1.1%) between the two groups. The number of inadvertently resected PGs was significantly lower in the NIRAF group (18:6.9% vs. 36:12.8%; p = 0.021). Conclusions: These results suggest that NIRAF imaging may reduce temporary hypoparathyroidism and the risk of inadvertent resection of PGs in patients undergoing total thyroidectomy with CND.

Artificial intelligence-augmented, label-free molecular imaging method for tissue identification, cancer diagnosis, and cancer margin detection

Label-free high-resolution molecular and cellular imaging strategies for intraoperative use are much needed, but not yet available. To fill this void, we developed an artificial intelligence-augmented molecular vibrational imaging method that integrates label-free and subcellular-resolution coherent anti-stokes Raman scattering (CARS) imaging with real-time quantitative image analysis via deep learning (artificial intelligence-augmented CARS or iCARS). The aim of this study was to evaluate the capability of the iCARS system to identify and differentiate the parathyroid gland and recurrent laryngeal nerve (RLN) from surrounding tissues and detect cancer margins. This goal was successfully met.

Feasibility of Autofluorescence for Parathyroid Glands During Thyroid Surgery and the Risk of Hypocalcemia: First Results in Belgium and Review of the Literature

Background. Post-operative hypocalcemia remains the most frequent complication after total thyroidectomy. Recently, autofluorescence imaging was introduced to detect parathyroid glands early during dissection. Aim. We aimed to check the feasibility of autofluorescence regarding the number of parathyroid glands visualised and the risk of post-operative hypocalcemia. Methods. In a prospectively gathered cohort of patients undergoing thyroid surgery, we describe the risk of hypocalcemia in relation to the number of parathyroid glands visualised during surgery (and the risk reported in the scientific literature) and the feasibility to obtain an autofluorescence of the parathyroid glands. Results. From 2010 to 2019, 1083 patients were referred for total thyroidectomy in our tertiary referral centre for endocrine surgery, of which, 40 consecutive cases were operated using autofluorescence. Among the autofluorescence group, 14 (35.0%) had all 4 parathyroid glands visualised, compared to 147 (14.1%) in the other patients, without differences in the number of parathyroid glands reimplanted. No permanent hypocalcemia occurred in the autofluorescence group and 17.5% temporary hypoparathyroidism, compared to 3.1% and 31.9% among the other patients, and 4% (95% confidence interval [CI] 3-5%) and 19% (95% CI 15-24%) in the literature. Conclusion. Autofluorescence imaging provides reliable real-time visualisation at any point during thyroid surgery and helps to identify the parathyroid glands before detection with the naked eye. To date, it cannot be used as a standard technique and does not replace meticulous dissection. To become a useful adjunct in peroperative parathyroid management, large multicentre studies need to establish a potential clinical benefit of this novel technique.

Novel techniques for intraoperative parathyroid gland identification: a comprehensive review

INTRODUCTION

The parathyroid glands (PGs) are critical for calcium regulation and homeostasis. The preservation of PGs during neck surgery is crucial to avoid postoperative hypoparathyroidism. There are no existing guidelines for intraoperative PG identification, and the current approach relies heavily on the experience of the operating surgeon. A technique that accurately and rapidly identifies PGs would represent a useful intraoperative adjunct.

AREAS COVERED

This review aims to assess common dye and fluorescence-based PG imaging techniques and examine their utility for intraoperative PG identification. A literature search of published data on methylene blue (MB), indocyanine green (ICG) angiography, near-infrared autofluorescence (NIRAF), and the PGs between 1971 and 2020 was conducted on PubMed.

EXPERT OPINION

NIRAF and near-infrared (NIR) parathyroid angiography have emerged as promising and reliable techniques for intraoperative PG identification. NIRAF may aid with real-time identification of both normal and diseased PGs and reduce the risk of postoperative complications such as hypocalcemia. Further large prospective multicenter studies should be conducted in thyroid and parathyroid surgical patient populations to confirm the clinical efficacy of these intraoperative NIR-based PG detection techniques.

Use of Indocyanine Green and Fluorescence Angiography in Parathyroid Surgery: A Feasibility Study

Background. Indocyanine green (ICG) with near-infrared (NIR) fluorescence is an established method for assessing vascularity in various clinical settings. We hypothesized that parathyroid adenomas, with increased capillary networks, may demonstrate a fluorescence which could aid intraoperative identification and confirmation of the abnormal parathyroid tissue. Methods. This prospective case-control study compared patients with primary hyperparathyroidism undergoing parathyroidectomy (cases) to normal parathyroid in thyroidectomy patients (controls). After exposing the parathyroid gland, ICG was injected and the fluorescence of parathyroid and thyroid was recorded and graded in comparison to the surrounding tissue and vasculature (0 = nonfluorescent and 5 = vasculature). Results. The intensity of parathyroid fluorescence was more in cases (4 ± 2) than controls (2 ± 1) when graded intraoperatively (P = .001). Thyroid fluorescence did not differ (3 vs 3, P = .072); however, parathyroid fluorescence was more intense than thyroid in cases (parathyroid = 4 ± 2 and thyroid = 3 ± 1, P = .018). Conclusions. ICG fluorescence in diseased parathyroid was more intense than normal parathyroid and thyroid, suggesting the ICG/NIR technology may be a useful intraoperative tool for identification of abnormal parathyroid.

A comparison of the quantitative evaluation of in situ parathyroid gland perfusion by indocyanine green fluorescence angiography and by visual examination in thyroid surgery

Objective The most vital complications of thyroidectomy are recurrent nerve damage and hypocalcaemia. We aimed to compare the tissue perfusion scores (PS) of IG fluorescence angiography (IGFA) and visual examination by the surgeon after total thyroidectomy. Subjects and methods Forty-three patients were accepted into the study. Localisation of the parathyroid gland (PG) was determined by the naked eye and scored in terms of tissue perfusion. The averages of fluorescent light intensities for each IGFA were calculated, the perfusions were scored and compared with the PS given by the surgeon. Biochemical parameters were noted. Results 37.2% of patients had autotransplanted PGs, according to their visual scores. The means of IGFA-PS for PGs scored as 0, 1 or 2 on visual inspection were 48.58 ± 4.49 [30-70], 89.65 ± 8.93 [36-144] and 158.76 ± 8.93 [70-253], respectively, which correlated with the visual PSs in a statistically significant manner (P < 0.0001). The predictive cut-off value for IGFA-PS was determined to be 70, given a visual PS of 0 (95% CI [0.72-0.85]), and this was interpreted to be a candidate cut-off point for the autotransplantation of PGs. Conclusion IGFA scoring may be considered as an operative predictor, providing objective criteria to evaluate the tissue and blood perfusion of PGs after thyroidectomy. IGFA scoring may be considered to have value in minimising postoperative permanent hypoparathyroidism in patients.

Intraoperative Indocyanine Green (ICG) Angiography for the Identification of the Parathyroid Glands: Current Evidence and Future Perspectives

BACKGROUND/AIM

Recently, indocyanine green (ICG) fluorescence imaging has been used for the identification of the parathyroid glands (PG) during thyroid and parathyroid surgery. However, an overall consensus on the optimal technique, the dosage, the timing of the ICG administration and finally its interpretation and clinical usefulness is still lacking evidence. The aim of this review is to investigate the use of ICG angiography during thyroidectomy and/or parathyroidectomy for identification as well as for the perfusion integrity of the parathyroid glands.

MATERIALS AND METHODS

The PubMed database was systematically searched for publications regarding intraoperative ICG imaging in patients that undergo thyroidectomy or parathyroidectomy.

RESULTS

Eighteen publications reporting on 612 patients, namely 71 parathyroidectomy and 541 thyroidectomy patients met the inclusion criteria. Eleven publications reported the use of ICG angiography for the identification of the parathyroid glands during thyroidectomy and seven during parathyroidectomy for primary and secondary hyperparathyroidism.

CONCLUSION

ICG fluorescence imaging is a simple, fast and reproducible method capable of intraoperatively visualizing and assessing the function of parathyroid glands, and can, therefore, assist surgeons in their decision-making. Despite all this, ICG fluorescence imaging technique for PG detection still lacks standardization and further studies are needed to establish its clinical utility.

Preoperative and Intraoperative Methods of Parathyroid Gland Localization and the Diagnosis of Parathyroid Adenomas

Accurate pre-operative determination of parathyroid glands localization is critical in the selection of minimally invasive parathyroidectomy as a surgical treatment approach in patients with primary hyperparathyroidism (PHPT). Its importance cannot be overemphasized as it helps to minimize the harmful side effects associated with damage to the parathyroid glands such as in hypocalcemia, severe hemorrhage or recurrent laryngeal nerve dysfunction. Preoperative and intraoperative methods decrease the incidence of mistakenly injuring the parathyroid glands and allow for the timely diagnosis of various abnormalities, including parathyroid adenomas. This article reviews 139 studies conducted between 1970 and 2020 (49 years). Studies that were reviewed focused on several techniques including application of carbon nanoparticles, carbon nanoparticles with technetium sestamibi (99m Tc-MIBI), Raman spectroscopy, near-infrared autofluorescence, dynamic optical contrast imaging, laser speckle contrast imaging, shear wave elastography, and indocyanine green to test their potential in providing proper parathyroid glands' localization. Apart from reviewing the aforementioned techniques, this study focused on the applications that helped in the detection of parathyroid adenomas. Results suggest that applying all the reviewed techniques significantly improves the possibility of providing proper localization of parathyroid glands, and the application of indocyanine green has proven to be the 'ideal' approach for the diagnosis of parathyroid adenomas.

Fine-needle aspiration with rapid parathyroid hormone assay to identify parathyroid gland in thyroidectomy

To determine the levels of parathyroid hormone (PTH) in the fluids of various tissues for identification of parathyroid glands during thyroidectomy.Our study comprised 31 patients with thyroid cancer who underwent lobectomy with central compartment dissection at our hospital from October 2014 to February 2015. A total of 186 tissue samples, including 28 from parathyroid glands and 158 from non-parathyroid tissues, were obtained during the operations. Tissue fluids were collected via fine-needle aspiration to measure PTH levels; the tissue was punctured 3 times with a 26-gauge syringe needle and washed with 0.5 mL normal saline. Tissues were also prepared for pathological examination.PTH concentrations were significantly higher in parathyroid tissues than non-parathyroid tissues. None of the patients had irremediable parathyroid dysfunction after surgical resection.Use of fine-needle aspiration for quantification of PTH levels in tissue fluids rapidly, safely, and effectively identifies the parathyroid glands during thyroidectomy.

Postoperative Hypoparathyroidism: Prognosis, Prevention, and Treatment (Review)

This review summarizes the results of studies concerning the problem of post-surgical hypoparathyroidism, a common complication of thyroid gland surgery, decreasing the quality of life in patients and, in some cases, leading to disability. A search for publications was carried out in electronic databases Web of Science, Scopus, Academic Search Complete (EBSCO), eLIBRARY, using keywords. The search depth was 7-10 years. Prevalence of post-surgical hypoparathyroidism was evaluated, the pathogenetic causes of the disease development, its clinical forms, methods of diagnosis and treatment were studied. It has been found that there is no single algorithm for analyzing the prognostic factors for the development of this pathological condition. It is emphasized that drug therapy of post-surgical hypoparathyroidism has a number of adverse effects. Therefore, the issues of prevention and surgical correction are of particular relevance. However, controversial opinions of contemporary authors about their clinical effectiveness determine the scientific and practical significance of further research on these issues.

Evaluation of Parathyroid Glands with Indocyanine Green Fluorescence Angiography After Thyroidectomy

BACKGROUND

Indocyanine green fluorescence angiography (ICGA) is a new adjunct that has been used in surgical procedures to assess blood flow. This study evaluated the utility of ICGA compared to visual inspection to predict parathyroid function, guide autotransplantation and potentially decrease permanent hypoparathyroidism.

METHODS

This was a retrospective study of patients who underwent total or near-total thyroidectomy (T-NT) between January 2015 and March 2018. Patients with preoperative hyperparathyroidism and those undergoing reoperation were excluded. Patients who had ICGA were compared to T-NT patients without ICGA. Data were analyzed to assess the frequency of autotransplantation and incidence of hypoparathyroidism between groups.

RESULTS

In total, 210 patients underwent T-NT: 86 with ICGA and 124 without. Autotransplantation was more common in the ICGA group at 36% compared to 12% in the control (p = 0.0001). There was no correlation with at least one normal parathyroid gland on ICGA and postoperative PTH levels (p = 0.75). There was a difference in having normal postoperative PTH when there were at least two normal parathyroid glands (n = 50) compared to patients with less than two normal ICGA glands (n = 36, p = 0.044). Visual assessment and ICGA assessment of vascularity were in agreement, 245/281 (87%). There were 19 glands (6.8%) that would have undergone autotransplant based on visual inspection that had adequate blood supply on ICGA. Transient hypoparathyroidism was present in 45 out of 124 controls (36%) and 32 out of 86 (37%) in the ICG group.

CONCLUSIONS

ICGA is a novel technique that may improve the assessment of parathyroid gland blood supply compared to visual inspection. ICGA can guide more appropriate autotransplantation without compromising postoperative parathyroid function. At least two vascularized glands on ICGA may predict postoperative parathyroid gland function.

New Advances of ICG Angiography in Parathyroid Identification

Objective:

For surgeons, locating parathyroid in thyroidectomy and parathyroidectomy is critical since parathyroid plays an important role in calcium balance. The fluorescence of parathyroid has already been found by researchers and the angiography equipment detecting the fluorescence of parathyroid with indocyanine green has been widely applied. Using the indocyanine green angiography and looking at the actual fluorescence of in vivo and in vitro tissues, it was possible to identify thyroid, parathyroid, lymph nodes and fat tissues during the surgical procedure. This mini-review aims to present the application of indocyanine green angiography in parathyroid detection and discusses the safety of this method.

Methods:

The relevant data were searched by using the keywords “Indocyanine green,” “Parathyroid,” and “Identification” and “Protection” in “Pubmed,” “Web of Science” and “China Knowledge Resource Integrated databases”, and a manual search was done to acquire peer-reviewed articles and reports about indocyanine green.

Results:

Indocyanine green dye along with the intraoperative fluorescence imaging system is safe in detecting parathyroid and predicting postoperative hypoparathyroidism.

Conclusion:

The conclusion suggests that indocyanine green angiography is a safe, effective and easy way to detect parathyroid glands. The conclusion will be of interest to surgeons regarding thyroidectomy and parathyroidectomy.

Indocyanine Green Fluorescence Angiography Can Guide Intraoperative Localization During Parathyroid Surgery

BACKGROUND AND AIMS

Intraoperative localization of pathologic parathyroid glands is of major importance for the hyperparathyroidism treatment. Based on the small size and the anatomic variability, the localization can be very challenging. The current practice is to compare preoperative ultrasonography with Technetium-99m sestamibi scintigraphy (MIBI) and plan the resection accordingly. In this study, we implemented indocyanine green angiography for the intraoperative localization of parathyroid glands.

MATERIALS AND METHODS

This is a retrospective analysis of 37 patients with primary, secondary, or tertiary hyperparathyroidism who were operated using indocyanine green angiography for the intraoperative localization of pathological parathyroid glands. An indocyanine green solution of 2.5 mg was were intravenously administered for parathyroid gland visualization. Different fluorescence scores were correlated with changes in postoperative parathyroid hormone levels.

RESULTS

Patients were divided into two groups depending on the presence of uniglandular or multiglandular disease. Sixty-four lesions were resected, and the final histopathologic analysis confirmed the parathyroid origin in 62 of them (96.8%). None of the patients with uniglandular disease developed postoperative hypoparathyroidism, whereas three patients in the multiglandular group developed temporary hypoparathyroidism symptoms. Indocyanine green imaging had higher sensitivity for the intraoperative detection of parathyroid glands compared with ultrasonography and MIBI (p < 0.001).

CONCLUSION

Indocyanine green angiography indicated high sensitivity for the intraoperative identification of pathologic parathyroid glands leading to a resection rate of 95.16%. The modality was useful, especially in cases of revisional surgery or ectopic parathyroid glands. Randomized trials have already proven the value of indocyanine green imaging in predicting postoperative hypocalcemia. Our results support the regular use of this method during parathyroid surgery.

Impact of fluorescence and autofluorescence on surgical strategy in benign and malignant neck endocrine diseases

Fluorescence and autofluorescence have been shown by several recent studies to be valuable adjuncts in identifying parathyroid glands during thyroidectomy and parathyroidectomy. The aim of this chapter is to review the impact of this new technology on surgical strategy concerning identification and preservation of parathyroid glands during thyroidectomy, identification of parathyroid glands in hyperparathyroidism, and the potential role in thyroid cancer surgery.

Application of indocyanine green in the parathyroid detection and protection: Report of 3 cases

BACKGROUND

It was thought that identifying the parathyroid gland during surgery was difficult for surgeons. It may be critical to locate the parathyroid for surgeons during thyroidectomy or parathyroidectomy due to the significant function of the parathyroid in calcium balance. According to recent reports, intrinsic fluorescence of the parathyroid has been found. There is some evidence to suggest that new equipment can detect the intrinsic fluorescence via imaging technology. In this case reports, a newly-invented intraoperative fluorescence imaging system and indocyanine green dye were applied to detect the parathyroid gland and evaluate the vascularization of parathyroid.

CASE PRESENTATION

From July 1st to August 8st, 2018, 3 patients underwent total thyroidectomy in Zhuhai People's Hospital. The 3 subjects were recruited into our research. Indocyanine green angiography was performed on all the three participants. By ICG angiography, parathyroid glands were identified and protected. In the 3 patients, postoperative PTH levels were in the normal range. No one of them developed transient hypoparathyroidism.

CONCLUSIONS

This study has identified that the fluorescence imaging system applied with indocyanine green is a safe, easy and effective method to protect the parathyroid and predict postoperative parathyroidism.

The use of Indocyanine green in endocrine surgery of the neck: A systematic review

BACKGROUND

The insufficient reliability of preoperative imaging technology and limited convenience of intraoperative visualizing techniques have been associated with difficulty in surgical navigation in neck endocrine surgery. Indocyanine green (ICG) fluorescence imaging has stood out as the real-time intraoperative guide amidst research for novel modalities, with an emerging use in endocrine surgery.

METHODS

We performed a systematic review of the PubMed, Scopus and Embase databases, to identify published studies on parathyroid and thyroid operations employing ICG. Well-described articles were selected according to 7 criteria and analyzed per operation type and organ structure.

RESULTS

Twenty-one articles matched our selection criteria. Dosage, equipment, and techniques are well-described in literature. ICG was found to significantly enhance the surgical experience and outcomes. Occasional discrepancy among studies was attributed to the lack of standard quantification of values and divergence of study designs.

CONCLUSION

The most successful applications of ICG are:Future research is needed for standard quantification of fluorescence intensity and objective comparisons.

Feasibility of indocyanine green fluorescence imaging for intraoperative identification of parathyroid glands during thyroid surgery

Background

This study assessed the feasibility of near‐infrared fluorescence imaging with indocyanine green (ICG) to identify the parathyroid glands (PGs) intraoperatively and to assess their perfusion after thyroid resection.

Methods

Patients undergoing elective thyroidectomy were enrolled in this prospective study. An intravenous bolus of 7.5 mg ICG was administered twice: the first bolus to identify the PGs before resection of the thyroid and the second to assess vascularization of the PGs after resection.

Results

A total of 30 operations in 26 patients were included. In 17 surgeries (56.7%), fluorescence imaging was of added value, especially to confirm the presence of a suspected PG. No intraoperative or postoperative complications occurred because of the use of ICG.

Conclusion

Near‐infrared fluorescence imaging with the use of ICG for intraoperative identification of the PGs and the assessment of its vascularization is feasible and safe and can provide more certainty about the location of the PGs.

Indocyanine green fluorescence-guided parathyroidectomy for primary hyperparathyroidism

BACKGROUND

Our aim was to evaluate the ease and utility of using indocyanine green fluorescence angiography for intraoperative localization of the parathyroid glands.

METHODS

Indocyanine green fluorescence angiography was performed during 60 parathyroidectomies for primary hyperparathyroidism during a 22-month period. Indocyanine green was administered intravenously to guide operative navigation using a commercially available fluorescence imaging system. Video files were graded by 3 independent surgeons for strength of enhancement using an adapted numeric scoring system.

RESULTS

There were 46 (77%) female patients and 14 (23%) male patients whose ages ranged from 17 to 87 (average 60) years old. Of the 60 patients, 43 (71.6%) showed strong enhancement, 13 (21.7%) demonstrated mild to moderate vascular enhancement, and 4 (6.7%) exhibited little or no vascular enhancement. Of the 54 patients who had a preoperative sestamibi scan, a parathyroid adenoma was identified in 36, while 18 failed to localize. Of the 18 patients who failed to localize, all 18 patients (100%) had an adenoma that fluoresced on indocyanine green imaging. The operations were performed safely with minimal blood loss and short operative times.

CONCLUSION

Indocyanine green angiography has the potential to assist surgeons in identifying parathyroid glands rapidly with minimal risk.

A reappraisal of vascular anatomy of the parathyroid gland based on fluorescence techniques

Identification of the parathyroid glands (PGs) during thyroid surgery may prevent their inadvertent surgical removal and prevent postoperative hypoparathyroidism. However, identification of the PGs does not guarantee their function, and their vascular supply needs to be preserved as well. The recent introduction of intraoperative indocyanine green (ICG) fluorescent angiography of the PGs during thyroid surgery allows for the appraisal of the vascular anatomy and evaluation of PG function. The use of this tool could lead to a significant reduction in the rate of postoperative hypoparathyroidism, as it allows surgeons to adapt their surgical technique for the preservation of the PGs. ICG fluorescent angiography is currently the only available real-time tool to assess the vascular blood supply of each individual PG intraoperatively and can thus assist surgeons in their decision-making. Herein, we review the relevant literature.

Intraoperative Near-infrared Imaging for Parathyroid Gland Identification by Auto-fluorescence: A Feasibility Study

BACKGROUND

Parathyroid glands (PGs) can be particularly hard to distinguish from surrounding tissue and thus can be damaged or removed during thyroidectomy. Postoperative hypoparathyroidism is the most common complication after thyroidectomy. Very recently, it has been found that the parathyroid tissue shows near-infrared (NIR) auto-fluorescence which could be used for intraoperative detection, without any use of contrast agents. The work described here presents a histological validation ex vivo of the NIR imaging procedure and evaluates intraoperative PG detection by NIR auto-fluorescence using for the first time to our knowledge a commercially available clinical NIR imaging device.

METHODS

Ex vivo study on resected operative specimens combined with a prospective in vivo study of consecutive patients who underwent total or partial thyroid, or parathyroid surgery at a comprehensive cancer center. During surgery, any tissue suspected to be a potential PG by the surgeon was imaged with the Fluobeam 800 (®) system. NIR imaging was compared to conventional histology (ex vivo) and/or visual identification by the surgeon (in vivo).

RESULTS

We have validated NIR auto-fluorescence with an ex vivo study including 28 specimens. Sensitivity and specificity were 94.1 and 80 %, respectively. Intraoperative NIR imaging was performed in 35 patients and 81 parathyroids were identified. In 80/81 cases, the fluorescence signal was subjectively obvious on real-time visualization. We determined that PG fluorescence is 2.93 ± 1.59 times greater than thyroid fluorescence in vivo.

CONCLUSIONS

Real-time NIR imaging based on parathyroid auto-fluorescence is fast, safe, and non-invasive and shows very encouraging results, for intraoperative parathyroid identification.

Intraoperative real-time localization of parathyroid gland with near infrared fluorescence imaging

Surgeons have cited difficulties in identifying the parathyroid glands (PG) during thyroidectomy. To overcome the limitation of naked eye, many studies on near-infrared fluorescence imaging of PGs have been introduced and suggested that fluorescence imaging is useful for both localizing PGs and evaluating their function. This imaging technique has been reported in two ways: (I) imaging using a fluorescent material called indocyanine green (ICG); and (II) autofluorescence using intrinsic fluorophores. These innovative and novel techniques are expected to have a significant impact on performing thyroid or parathyroid surgery. In this article, current papers that describe ICG fluorescence and autofluorescence imaging of PG during thyroid and parathyroid surgery are reviewed.

Novel Cause of 'Black Thyroid': Intraoperative Use of Indocyanine Green

The antibiotic minocycline is virtually pathognomonic for brown-black discoloration of the thyroid gland referred to as 'black thyroid'. Black thyroid' is an incidental finding in patients taking the drug who undergo thyroid surgery for another indication and is not of known clinical significance. However, its recognition is important so as not to raise concern for a disease process. Here, we present the first case of 'black thyroid' attributable to the iodine-containing compound indocyanine green. Intraoperative indocyanine green was administered as part of a research protocol transoral robotic-assisted surgery for a base of tongue cancer in a 44-year-old man. Hemithyroidectomy was subsequently performed during the same operation for further evaluation of an indeterminate thyroid nodule. The resected thyroid lobe was dark, nearly black in color, and histologically showed extensive brown pigment deposition in the follicular epithelial cells and colloid, mimicking minocycline-induced 'black thyroid'. In this case, however, the patient was not taking minocycline; instead the 'black thyroid' was attributed to the iodine-containing compound indocyanine green. Indocyanine green is a hereto unreported cause of 'black thyroid' with histopathologic features that are remarkably similar to that induced by minocycline. Indocyanine green should be included the differential diagnosis of 'black thyroid'. Clinical history is important so as not to raise concern for a disease process.

Intraoperative Parathyroid Localization with Near-Infrared Fluorescence Imaging Using Indocyanine Green during Total Parathyroidectomy for Secondary Hyperparathyroidism

The detection of all glands during total parathyroidectomy (TPTX) in secondary hyperparathyroidism (SHPT) patients is often difficult due to their variability in number and location. The objective of this study was to evaluate the feasibility of near-infrared fluorescence (NIRF) imaging using indocyanine green (ICG) for intraoperative parathyroid gland (PTG) localization in SHPT patients. Twenty-nine patients with SHPT were divided into two groups with or without intraoperative NIRF imaging. ICG was administered in patients undergoing intraoperative imaging, and the fluorescence of PTGs was assessed. Clinical and histopathologic variables were analyzed to determine factors associated with ICG uptake. Comparisons between NIRF and preoperative imaging, as well as differences between groups with or without NIRF imaging, were carried out to evaluate the efficacy of this technique. Most PTGs could be clearly identified, including one ectopic gland. The sensitivity of NIRF imaging is 91.1% in contrast to 81.82% for ultrasonography (US), 62.34% for ^99mTc-MIBI and 85.71% for computed tomography (CT). In addition, intraoperative NIRF imaging can reduce the operation time and improve the complete resection rate compared with the group not using it. Intraoperative NIRF imaging using ICG during TPTX is technically feasible and reliable for assisting surgeons in detecting and confirming PTGs.

The use of near-infrared fluorescence imaging in endocrine surgical procedures

Near-infrared fluorescence imaging in endocrine surgery is a new, yet highly investigated area. It involves indocyanine green use as well as parathyroid autofluorescence. Several groups have described their technique and reported on the observed utility. However, there is no consensus on technical details. Furthermore, the correlation between intraoperative findings and postoperative outcomes is unclear. With this study, we aim to review the current literature on fluorescence imaging and share our insights on technical details.

Intraoperative Real-Time Localization of Normal Parathyroid Glands With Autofluorescence Imaging

CONTEXT

This biomedical investigation is valuable for identification and localization of parathyroid glands during thyroidectomy, which can provide an intraoperative real-time visual guidance.

OBJECTIVE

The objective of the study was to investigate the feasibility of real-time autofluorescence imaging of the parathyroid glands without exogenous contrast dye for their localization and demonstration of relation to the background tissues.

SETTING

This research was undertaken at Kosin University Gospel Hospital.

METHODS

Sixteen normal parathyroid glands from eight patients with papillary thyroid carcinoma were enrolled. Photo images of the surgical field including the parathyroid and background tissues were taken with a digital camera, 780 nm light-emitting diode to excite the parathyroid, and infrared illuminator to visualize the entire neck. The area-averaged autofluorescence intensity of parathyroid over the area-averaged fluorescence intensity of background tissues was measured.

MAIN OUTCOME MEASURE

The location of the parathyroid gland was verified with a single image.

RESULTS

The area-averaged autofluorescence intensity of parathyroid over the area-averaged fluorescence intensity of background tissues for all parathyroid glands was higher than 1, with a minimum of 1.95 and a maximum of 5.20 (average 2.76, SD 0.79). By our technique, all 16 parathyroid glands were detected (positive predictive value of 100%), and the entire surgical field including the parathyroid and background tissues was visualized as well. The parathyroid glands that were exposed or even covered by connective tissues or blood vessels could be detected with strong emission.

CONCLUSIONS

This method showed the precise localization of the parathyroid glands and demonstrated their relation to background tissue. We believe that this simple, nonexogenous dye technique of anatomical guidance can aid surgeons to preserve parathyroid glands during thyroidectomy.

Intraoperative localization of the parathyroid glands with indocyanine green and Firefly(R) technology during BABA robotic thyroidectomy

BACKGROUND

It is unclear whether near-infrared (NIR) light-induced indocyanine green (ICG) fluorescence can effectively identify, and thus permit the preservation of, parathyroid glands in bilateral axillo-breast approach (BABA) robotic thyroidectomy. This case-control study with a prospectively recruited consecutive series and a retrospectively selected control group assessed the usefulness of ICG with Firefly(R) technology to identify the parathyroid glands intraoperatively during BABA robotic thyroidectomy.

METHODS

All consecutive patients (N = 22) who were scheduled to undergo BABA robotic thyroidectomy for papillary thyroid carcinoma in December 2013-August 2015 and met the study eligibility criteria were recruited prospectively. ICG fluorescence was used with the Firefly system (NIR illuminator: 805 nm; filter: 825 nm) integrated in the da Vinci Si robot system to identify the lower parathyroid glands. Parathyroid hormone levels were recorded on postoperative days 0, 1, 2, and 14. Propensity score matching was used to identify an age-, gender-, tumor size-, and operation type-matched group of control patients who underwent BABA robotic thyroidectomy without the Firefly system. The two groups were compared in terms of parathyroid-related outcomes.

RESULTS

ICG fluorescence-mediated identification of the parathyroid and thyroid glands required on average (range) 203 ± 89 (125-331) and 207 ± 112 (130-356) s, respectively. The mean (range) fluorescence duration in these glands was 20.8 ± 6.0 (16.6-35.8) and 20.1 ± 7.3 (15.5-33.8) min, respectively. The ICG group had a significantly lower rate of incidental parathyroidectomy than the control group (0 vs. 15.9%, P = 0.048).

CONCLUSIONS

ICG with NIR light may feasibly and safely identify the parathyroid glands in BABA robotic thyroidectomy.

Indocyanine green fluorescence angiography for quantitative evaluation of in situ parathyroid gland perfusion and function after total thyroidectomy

BACKGROUND

Because the fluorescent light intensity on an indocyanine green fluorescence angiography reflects the blood perfusion within a focused area, the fluorescent light intensity in the remaining in situ parathyroid glands may predict postoperative hypocalcemia risk after total thyroidectomy.

METHODS

Seventy patients underwent intraoperative indocyanine green fluorescence angiography after total thyroidectomy. Any parathyroid glands with a vascular pedicle was left in situ while any parathyroid glands without pedicle or inadvertently removed was autotransplanted. After total thyroidectomy, an intravenous 2.5 mg indocyanine green fluorescence angiography was given and real-time fluorescent images of the thyroid bed were recorded using the SPY imaging system (Novadaq, Ontario, Canada). The fluorescent light intensity of each indocyanine green fluorescence angiography as well as the average and greatest fluorescent light intensity in each patient were calculated. Postoperative hypocalcemia was defined as adjusted calcium <2.00 mmol/L within 24 hours.

RESULTS

The fluorescent light intensity between discolored and normal-looking indocyanine green fluorescence angiographies was similar (P = .479). No patients with a greatest fluorescent light intensity >150% developed postoperative hypocalcemia while 9 (81.8%) patients with a greatest fluorescent light intensity ≤150% did. Similarly, no patients with an average fluorescent light intensity >109% developed PH while 9 (30%) with an average fluorescent light intensity ≤109% did. The greatest fluorescent light intensity was more predictive than day-0 postoperative hypocalcemia (P = .027) and % PTH drop day-0 to 1 (P < .001).

CONCLUSION

Indocyanine green fluorescence angiography is a promising operative adjunct in determining residual parathyroid glands function and predicting postoperative hypocalcemia risk after total thyroidectomy.

Advances in fluorescent-image guided surgery

Fluorescence imaging is increasingly gaining intraoperative applications. Here, we highlight a few recent advances in the surgical use of fluorescent probes.

Indocyanine green-enhanced fluorescence for assessing parathyroid perfusion during thyroidectomy

Identification of the parathyroid glands during thyroid surgery may prevent their inadvertent surgical removal and thus provide a better postoperative quality of life. Nevertheless, the most common "technique" for intraoperative evaluation of perfusion of parathyroid gland tissues during thyroid surgery is visual inspection of the physical condition of tissues, e.g., their color and bleeding edges. Another technique is measurement of intact parathyroid hormone. Recently, indocyanine green-enhanced fluorescence has been used in various surgical techniques, particularly laparoscopic surgery, to improve visualization and to provide detailed anatomical information. Fluorescent optical guidance helps surgeons to avoid inadvertent tissue injury while enhancing procedural efficiency. This technique has potential use for evaluating perfusion of the parathyroid gland in real-time intraoperative angiography.

Utility of Indocyanine Green Fluorescence Imaging for Intraoperative Localization in Reoperative Parathyroid Surgery

Background. Due to the variations in anatomic location, the identification of parathyroid glands may be challenging. Although there have been advances in preoperative imaging modalities, there is still a need for an accurate intraoperative guidance. Indocyanine green (ICG) is a new agent that has been used for intraoperative fluorescence imaging in a number of general surgical procedures. Its utility for parathyroid localization in humans has not been reported in the literature. Results. We report 3 patients who underwent reoperative neck surgery for primary hyperparathyroidism. Using a video-assisted technique with intraoperative ICG fluorescence imaging, the parathyroid glands were recognized and removed successfully in all cases. Surrounding soft tissue structures remained nonfluorescent, and could be distinguished from the parathyroid glands. Conclusions. This report suggests a potential utility of ICG imaging in intraoperative localization of parathyroid glands in reoperative neck surgery. Future work is necessary to assess its benefit for first-time parathyroid surgery.

Indocyanine green fluorescence-guided redo parathyroidectomy

Re-operative neck surgery for hyperparathyroidism is a technically difficult operation that requires adjunctive studies to assist with finding the parathyroid tissues. Intraoperative tests help minimise exploration of the neck and decrease injuries to the surrounding structures. Indocyanine green is a near-infrared fluorescent dye that in pre-clinical models was found to be useful in locating the parathyroid glands of dogs. No study has yet reported its use as a tool for parathyroid localisation in humans. We investigated the use of indocyanine green to assist with localisation of a recurrent parathyroid adenoma using a near-infrared imaging system. After exposure of the neck tissues, the parathyroid gland fluoresced brightly and directed our dissection. Exploration of the neck was minimal, and allowed for fast localisation and excision of the adenoma. Overall, use of indocyanine green is a simple and safe technique of intraoperative parathyroid localisation that warrants further investigation.