Do Near-Infrared Intra-Operative Findings Obtained Using Indocyanine Green Correlate with Post-Thyroidectomy Parathyroid Function? the Icgpredict Study

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.

Assessing Parathyroid Gland Viability and Predicting Postoperative Hypoparathyroidism in Thyroid Surgery: The Utility of Indocyanine Green Angiography

Objectives

Postoperative hypoparathyroidism is a common complication following thyroidectomy, with the potential for significant morbidity and cost. While various techniques have been proposed for intraoperative parathyroid gland (PG) identification and preservation, indocyanine green (ICG) angiography has emerged as a promising method. In this retrospective study, patients who underwent total thyroidectomy with or without central neck dissection were evaluated for the utility of ICG angiography in identifying PGs and the correlation of ICG scores with postoperative parathyroid function.

Methods

ICG angiography was performed using a standardized protocol, and the degree of PG vascularization was assessed visually. A scoring system was employed based on ICG uptake intensity in PGs, as described in the literature. Pearson's correlation test examined the relationship between the total ICG score and percentage parathyroid hormone (PTH) gradient, postoperative calcium, and PTH levels. In addition, patients with at least one well-vascularized PG were also evaluated.

Results

Twenty-two patients were included in the study. Significant positive correlations were found between the total ICG score and postoperative PTH levels (r=0.549, p=0.008), and a negative correlation with the percentage of PTH gradient (r=-0.504, p=0.01). However, six patients with well-vascularized PGs on ICG angiography still developed postoperative hypoparathyroidism.

Conclusion

ICG angiography offers a potential tool for evaluating PG vascularization during thyroidectomy and predicting the risk of postoperative hypoparathyroidism. However, its application should be used judiciously, and the technique should be improved for PG preservation. Further studies are warranted to better understand its benefits and limitations in thyroid surgery.

Update on the current management of persistent and recurrent primary hyperparathyroidism after parathyroidectomy

Primary hyperparathyroidism (pHPT) is the third most common endocrine disease. The surgical procedure aims for permanent cure, but recurrence has been reported in 4%-10% of pHPT patients. Preoperative localization imaging is highly valuable. It includes ultrasound, computed tomography (CT), single-photon-emission CT, sestamibi scintigraphy and magnetic resonance imaging. The operation has been defined as successful when postoperative continuous eucalcemia exists for more than the first six months. Ongoing hypercalcemia during this period is defined as persistence, and recurrence is defined as hypercalcemia after six months of normocalcemia. Vitamin D is a crucial factor for a good outcome. Intraoperative parathyroid hormone (PTH) monitoring can safely predict the outcomes and should be suggested. PTH ≤ 40 pg/mL or the traditional decrease ≥ 50% from baseline minimizes the likelihood of persistence. Risk factors for persistence are hyperplasia and normal parathyroid tissue on histopathology. Risk factors for recurrence are cardiac history, obesity, endoscopic approach and low-volume center (at least 31 cases/year). Cases with double adenomas or four-gland hyperplasia have a greater likelihood of persistence/ recurrence. A 6-mo calcium > 9.7 mg/dL and eucalcemic parathyroid hormone elevation at 6 mo may be associated with recurrence necessitating long-term follow-up. 18F-fluorocholine positron emission tomography and 4-dimensional CT in persistent and recurrent cases can be valuable before reoperation. With these novel advances in preoperative imaging and localization as well as intraoperative PTH measurement, the recurrence rate has dropped to 2.5%-5%. Six-month serum calcium ≥ 9.8 mg/dL and parathyroid hormone ≥ 80 pg/mL indicate a risk of recurrence. Negative sestamibi scintigraphy, diabetes and elevated osteocalcin levels are predictors of multiglandular disease, which brings an increased risk of persistence and recurrence. Bilateral neck exploration was considered the gold-standard diagnostic method. Minimally invasive parathyroidectomy and neck exploration are both effective surgical techniques. Multidisciplinary diagnostic and surgical management is required to prevent persistence and recurrence. Long-term follow-up, even up to 10 years, is necessary.

Emerging Imaging Technologies for Parathyroid Gland Identification and Vascular Assessment in Thyroid Surgery: A Review From the American Head and Neck Society Endocrine Surgery Section

Importance

Identification and preservation of parathyroid glands (PGs) remain challenging despite advances in surgical techniques. Considerable morbidity and even mortality result from hypoparathyroidism caused by devascularization or inadvertent removal of PGs. Emerging imaging technologies hold promise to improve identification and preservation of PGs during thyroid surgery.

Observation

This narrative review (1) comprehensively reviews PG identification and vascular assessment using near-infrared autofluorescence (NIRAF)-both label free and in combination with indocyanine green-based on a comprehensive literature review and (2) offers a manual for possible implementation these emerging technologies in thyroid surgery.

Conclusions and Relevance

Emerging technologies hold promise to improve PG identification and preservation during thyroidectomy. Future research should address variables affecting the degree of fluorescence in NIRAF, standardization of signal quantification, definitions and standardization of parameters of indocyanine green injection that correlate with postoperative PG function, the financial effect of these emerging technologies on near-term and longer-term costs, the adoption learning curve and effect on surgical training, and long-term outcomes of key quality metrics in adequately powered randomized clinical trials evaluating PG preservation.

Indocyanine green (ICG) fluorescence guide for the use and indications in general surgery: recommendations based on the descriptive review of the literature and the analysis of experience

Indocyanine Green is a fluorescent substance visible in near-infrared light. It is useful for the identification of anatomical structures (biliary tract, ureters, parathyroid, thoracic duct), the tissues vascularization (anastomosis in colorectal, esophageal, gastric, bariatric surgery, for plasties and flaps in abdominal wall surgery, liver resection, in strangulated hernias and in intestinal ischemia), for tumor identification (liver, pancreas, adrenal glands, implants of peritoneal carcinomatosis, retroperitoneal tumors and lymphomas) and sentinel node identification and lymphatic mapping in malignant tumors (stomach, breast, colon, rectum, esophagus and skin cancer). The evidence is very encouraging, although standardization of its use and randomized studies with higher number of patients are required to obtain definitive conclusions on its use in general surgery. The aim of this literature review is to provide a guide for the use of ICG fluorescence in general surgery procedures.

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.

Application of Indocyanine Green Angiography in Bilateral Axillo-Breast Approach Robotic Thyroidectomy for Papillary Thyroid Cancer

BACKGROUND

Indocyanine green angiography (ICGA) has been used to identify and preserve the parathyroid glands (PGs), and to evaluate PGs viability and function during thyroid surgery. However, evidence on the utilization of IGCA in thyroid cancer and robotic surgery is lacking. The efficacy of IGCA remains to be evaluated in PTC patients undergoing bilateral axillo-breast approach robotic thyroidectomy (BABA RT) and central neck dissection (CND).

METHODS

From March 2020 to August 2021, 81 papillary thyroid cancer (PTC) patients receiving total thyroidectomy and CND were enrolled in this retrospective analysis. An intravenous bolus of 7.5 mg ICG was administrated three times in the ICGA group (n=34). Medical records were reviewed and analyzed, including the baseline characteristics, surgical parameters, PGs-related parameters, and perioperative PTH and calcium levels.

RESULTS

The mean number of total identified PGs and preserved PGs were significantly more in the ICG group than in the control group (3.74 ± 0.45 vs. 3.15 ± 0.55, P<0.001; 3.12 ± 0.64 vs. 2.74 ± 0.57, P=0.007, respectively), as were PTH and calcium levels on POD 1 (23.16 ± 18.32 vs. 6.06 ± 7.74, P=0.039; 2.13 ± 0.11 vs. 2.08 ± 0.08, P=0.024, respectively). While there were no differences in PTH levels on POD 30. Additionally, patients with at least one well vascularized PG had higher ioPTH 3 and PTH on POD 1, which significantly suggested the absence of postoperative hypocalcemia. Although not statistically significant, ICGA seemed superior to relative ioPTH decline and ioPTH 3 in predicting postoperative hypocalcemia.

CONCLUSION

In PTC patients undergoing BABA RT and CND, ICGA is a simple, safe, effective, and cost-effective tool in better identification and preservation of PGs as well as evaluation of PGs viability and function, with the potential to preserve more PGs, guide more appropriate autotransplantation, and accurately predict postoperative hypocalcemia.

Indocyanine green fluorescence for parathyroid gland identification and function prediction: Systematic review and meta-analysis

BACKGROUND

To evaluate the diagnostic accuracies of indocyanine green (ICG) fluorescence for identifying parathyroid glands during surgery and predicting the postoperative function.

METHODS

From six databases, 21 studies were finally included in the study. True-positive, true-negative, false-positive, and false-negative data were extracted for the analysis. The quality of each study was analyzed using the QUADAS-2 tool.

RESULTS

The sensitivity of ICG-based parathyroid gland identification was 0.9380 (95% CI [0.9003, 0.9621]). The diagnostic odds ratio for ICG-based prediction of parathyroid gland function was 54.5652 [13.2059, 225.4570]. The area under the summary receiver operating characteristic curve was 0.909. Fluorescence intensity-based prediction presented higher diagnostic accuracy than that of score-based prediction. The incidence of postoperative hypoparathyroidism was higher in the group with a zero ICG score compared to the high scored group.

CONCLUSIONS

Identification of parathyroid gland and prediction of postoperative function using ICG are valuable to patients undergoing thyroidectomy or parathyroidectomy.

The effect of intraoperative autofluorescence monitoring on unintentional parathyroid gland excision rates and postoperative PTH concentrations-a single-blind randomized-controlled trial

PURPOSE

Intraoperative imaging of parathyroid glands (PGs) has been developed in order to reduce the risk of unintentional parathyroidectomy during total thyroidectomy. This novel modality is based on their intrinsic characteristic of autofluorescence (AF) after near-infrared light exposure. The aim of this study was to assess the effect of this method on the risk of unintentional PG excision (total or partial) during total thyroidectomy.

METHODS

This was a single-blind, randomized-controlled trial including adult patients who underwent scheduled total thyroidectomy between December 2019 and March 2020. These patients were randomly allocated to two groups: one in which near-infrared autofluorescence imaging (NIRAF) was applied (NIR group) and one without NIRAF (NONIR group). Hormonal and biochemical assessment was performed pre- and 24-h postoperatively. AF findings and the number of PGs autotransplanted were recorded.

RESULTS

One-hundred and eighty patients were eligible. Unintentional (total or partial) PG excision rates during total thyroidectomy in the NONIR (n = 90) and NIR (n = 90) groups were 28.9% [95% confidence interval (CI) 19.8-39.4%] and 14.4% (95% CI 7.7-22.1%), respectively (p = 0.02). Furthermore, NIR reduced the risk of parathyroid tissue presence in the specimen sent for pathology (relative risk 0.51, 95% CI 0.28-0.92; p = 0.02). However, the number of PGs identified by NIR could not predict the risk of postoperative hypoparthyroidism.

CONCLUSIONS

NIRAF imaging during total thyroidectomy led to a significant reduction in PG excision rates. However, this modality did not result in the reduction of postoperative hypoparathyroidism or hypocalcemia risk.

Preoperative Vitamin D Deficiency is a Risk Factor for Postthyroidectomy Hypoparathyroidism: A Systematic Review and Meta-Analysis of Observational Studies

CONTEXT

Whether preoperative vitamin D deficiency (VDD) contributes to postoperative hypoparathyroidism (hypoPT) risk is unknown.

OBJECTIVE

This work aimed to meta-analyze the best available evidence regarding the association between preoperative vitamin D status and hypoPT risk.

METHODS

A comprehensive literature search was conducted in PubMed, CENTRAL, and Scopus databases, up to October 31, 2020. Study selection included patients undergoing thyroidectomy with preoperative vitamin D status and postoperative hypoPT data. Two researchers independently extracted data from eligible studies. Data were expressed as risk ratio (RR) with 95% CI. The I2 index was employed for heterogeneity.

RESULTS

Thirty-nine studies were included in the quantitative analysis (61 915 cases with transient and 5712 with permanent hypoPT). Patients with VDD demonstrated a higher risk for transient hypoPT compared with those with preoperative vitamin D sufficiency (RR 1.92, 95% CI, 1.50-2.45, I2 = 85%). These results remained significant for patients with preoperative 25-hydroxyvitamin D concentrations less than or equal to 20 ng/mL (mild VDD; RR 1.46, 95% CI, 1.10-1.94, I2 = 88%) and less than or equal to 10 ng/mL (severe VDD; RR 1.98, 95% CI 1.42-2.76, I2 = 85%). The risk of permanent hypoPT was increased only in cases with severe VDD (RR 2.45, 95% CI, 1.30-4.63, I2 = 45%). No difference was evident in subgroup analysis according to study design or quality.

CONCLUSION

Patients with preoperative VDD are at increased risk of transient hypoPT following thyroidectomy. The risk for permanent hypoPT is increased only for those with severe VDD.

The Accuracy of Near Infrared Autofluorescence in Identifying Parathyroid Gland During Thyroid and Parathyroid Surgery: A Meta-Analysis

OBJECTIVE

We aim to assess the accuracy of near infrared autofluorescence in identifying parathyroid gland during thyroid and parathyroid surgery.

METHOD

A systematic literature search was conducted by using PubMed, Embase, and the Cochrane Library electronic databases for studies that were published up to February 2021. The reference lists of the retrieved articles were also reviewed. Two authors independently assessed the methodological quality and extracted the data. A random-effects model was used to calculate the combined variable. Publication bias in these studies was evaluated with the Deeks' funnel plots.

RESULT

A total of 24 studies involving 2,062 patients and 6,680 specimens were included for the meta-analysis. The overall combined sensitivity and specificity, and the area under curve of near infrared autofluorescence were 0.96, 0.96, and 0.99, respectively. Significant heterogeneities were presented (Sen: I² = 87.97%, Spe: I² = 65.38%). In the subgroup of thyroid surgery, the combined sensitivity and specificity, and the area under curve of near infrared autofluorescence was 0.98, 0.99, and 0.99, respectively, and the heterogeneities were moderate (Sen: I² = 59.71%, Spe: I² = 67.65%).

CONCLUSION

Near infrared autofluorescence is an excellent indicator for identifying parathyroid gland during thyroid and parathyroid surgery.

The Ability of Near-Infrared Autofluorescence to Protect Parathyroid Gland Function During Thyroid Surgery: A Meta-Analysis

OBJECTIVE

We conducted this meta-analysis to assess the ability of near-infrared autofluorescence to protect parathyroid gland function during thyroid surgery.

METHOD

A systematic literature search was conducted using PubMed, Embase, and the Cochrane Library electronic databases for studies published up to February 2021. The reference lists of the retrieved articles were also reviewed. Two authors independently assessed methodological quality and extracted the data. A random-effects model was used to calculate the overall pooled variable and the weighted mean deviation. Publication bias in these studies was evaluated using the Egger's and Begg's tests.

RESULT

Seven studies involving 1,480 patients were included in the analysis. Compared with patients in the naked eye group, the pooled relative risk of inadvertent parathyroid gland resection and parathyroid gland autotransplantation for the patients in the near-infrared autofluorescence group was 0.48 (95% CI, 0.26-0.9, p = 0.023) and 0.39 (95% CI, 0.09-1.68, p = 0.208), respectively. The pooled relative risk of hypocalcemia at 1 day postoperatively and at 6 months postoperatively for the patients in the near-infrared autofluorescence group was 0.49 (95% CI, 0.34-0.71, p < 0.001) and 0.34 (95% CI, 0.06-2.03, p = 0.238) compared with patients in the naked eye group.

CONCLUSION

Near-infrared autofluorescence is significantly associated with a reduced risk of inadvertent parathyroid gland resection and hypocalcemia at 1 day postoperatively.