Parathyroid gland management using optical technologies during thyroidectomy or parathyroidectomy: A systematic review

Autofluorescence-guided hemithyroidectomy in a low-volume thyroid institution with no experience in parathyroid surgery: randomized clinical trial

BACKGROUND

Recent studies suggest that low-volume surgeons with no experience in parathyroid surgery are at increased risk of causing parathyroid gland damage during thyroid surgery. The aim of this RCT was to evaluate the impact of using autofluorescence in hemithyroidectomy on parathyroid gland identification and preservation in a low-volume institution with no experience in parathyroid surgery.

METHODS

Patients referred for hemithyroidectomy were randomized 1 : 1 to either autofluorescence-guided hemithyroidectomy (the near-infrared autofluorescence group) or conventional hemithyroidectomy (the control group). The primary outcome was parathyroid gland identification rate. Secondary outcomes were the rate of parathyroid gland autotransplantation and the rate of inadvertent parathyroid gland excision.

RESULTS

A total of 170 patients were randomized to either autofluorescence-guided hemithyroidectomy (84 patients) or conventional hemithyroidectomy (86 patients). In the near-infrared autofluorescence group, 81.0% of parathyroid glands were identified, compared with 57.0% in the control group (P < 0.001). Autofluorescence enabled parathyroid gland visualization before the naked eye in 46.3% of cases. Surgeons had lower confidence in the parathyroid gland identification process in the control group than in the near-infrared autofluorescence group (59.1% versus 87.5% respectively; P < 0.001). In the near-infrared autofluorescence group, the parathyroid gland autotransplantation rate was initially high, but declined over time. There was no difference in the rate of inadvertent parathyroid gland excision.

CONCLUSION

Autofluorescence guidance significantly improved the parathyroid gland identification rate in hemithyroidectomy in a low-volume institution with no experience in parathyroid surgery and provided an increase in surgical confidence. The pattern of parathyroid gland autotransplantation in autofluorescence-guided surgery indicates the presence of a learning curve.

REGISTRATION NUMBER

NCT05044351 (http://www.clinicaltrials.gov).

Fluorescence imaging to visualize the recurrent laryngeal nerve during thyroidectomy procedures: analysis of 65 cases and 81 nerves

BACKGROUND

Recurrent laryngeal nerve (RLN) injury after thyroidectomy is relatively common. Locating the RLN prior to thyroid dissection is paramount to avoid injury. We developed a fluorescence imaging system that permits nerve autofluorescence. We aimed to determine the sensitivity and specificity of fluorescence imaging at detecting the RLN relative to thyroid and other background tissue and compared it to white light.

METHODS

In this prospective study, 65 patients underwent thyroidectomy from January to April 2022 (16 bilateral thyroid resections) using white and fluorescent light. Fluorescence intensity [relative fluorescence units (RFU)] was recorded for RLN, thyroid, and background. RFU mean, minimum, and maximum values were calculated using Image J software. Thirty randomly selected pairs of white and fluorescent light images were independently reviewed by two examiners to compare RLN detection rate, number of branches, and length and minimum width of nerves visualized. Parametric and nonparametric statistical analysis was performed.

RESULTS

All 81 RNLs observed were visualized more clearly under fluorescence (mean intensity, µ = 134.3 RFU) than either thyroid (µ = 33.7, p < 0.001) or background (µ = 14.4, p < 0.001). Forest plots revealed no overlap between RLN intensity and that of either other tissue. Sensitivity and specificity for RLN were 100%. All 30 RLNs and all 45 nerve branches were clearly visualized under fluorescence, versus 17 and 22, respectively, with white light (both p < 0.001). Visible nerve length was 2.5 × as great with fluorescence as with white light (µ = 1.90 vs. 0.76 cm, p < 0.001).

CONCLUSIONS

In 65 patients and 81 nerves, RLN detection was markedly and consistently enhanced with autofluorescence neuro-imaging during thyroidectomy, with 100% sensitivity and specificity.

Comparison of incidental parathyroid tissue detection rates on pathology after total thyroidectomy performed with or without near-infrared autofluorescence imaging

BACKGROUND

Near-infrared autofluorescence imaging is an adjunct to parathyroid identification. As it does not show perfusion, it is important to study its impact during thyroidectomy by measuring quantifiable data on parathyroid detection rather than function. The aim of this study was to compare incidental parathyroidectomy rates in patients undergoing total thyroidectomy with or without near-infrared autofluorescence.

METHODS

Retrospective study of patients who underwent total thyroidectomy between 2014 and 2022 at one center. Clinical parameters, including rates of incidental parathyroid tissue on pathology reports, were compared between near-infrared autofluorescence and non-near-infrared autofluorescence groups. Near-infrared autofluorescence was used to guide dissection (identification) and/or to confirm tissue as parathyroid (confirmation). Statistical analysis was done with Wilcoxon rank sum test and χ2 analysis.

RESULTS

There were 300 patients in the near-infrared autofluorescence and 750 patients in the non-near-infrared autofluorescence group. The rate of incidental parathyroid tissue detection on final pathology was 13.3% (n = 40) in the near-infrared autofluorescence and 23.2% (n = 174) in the non-near-infrared autofluorescence group (P < .001). The rate of incidental parathyroid tissue detected on pathology with near-infrared autofluorescence decreased when used for identification and confirmation of parathyroid tissue (30.0% to 13.4%, P < .001), but not when used for confirmation only (19.6% to 18.5%, P = .89). Impact of near-infra red autofluorescence in decreasing the rate of incidental parathyroid tissue was more profound for early (38.5% to 17.1%) versus mid-late career surgeons (20% to 13%).

CONCLUSION

Our results suggest that the use of near-infrared autofluorescence may help decrease the rate of incidental parathyroid tissue detected on final pathology if used for both identification and confirmation of parathyroid glands during thyroidectomy.

Identifying Parathyroids in Pediatric Thyroid/Parathyroid Surgery by Near Infrared Autofluorescence

OBJECTIVES

Compared to adult patients undergoing thyroid surgery, pediatric patients have higher rates of hypoparathyroidism often related to parathyroid gland (PG) inadvertent injury or devascularization. Previous studies have shown that near-infrared-autofluorescence (NIRAF) can be reliably used intraoperatively for label-free parathyroid identification, but all prior studies have been performed in adult patients. In this study, we assess the utility and accuracy of NIRAF with a fiber-optic probe-based system to identify PGs in pediatric patients undergoing thyroidectomy or parathyroidectomy.

METHODS

All pediatric patients (under 18 years of age) undergoing thyroidectomy or parathyroidectomy were enrolled in this IRB-approved study. The surgeon's visual assessment of tissues was first noted and the surgeon's confidence level in the tissue identified was recorded. A fiber-optic probe was then used to illuminate tissues-of-interest with a wavelength of 785 nm and resulting NIRAF intensities from these tissues were measured while the surgeon was blinded to results.

RESULTS

NIRAF intensities were measured intraoperatively in 19 pediatric patients. Normalized NIRAF intensities for PGs (3.63 ± 2.47) were significantly higher than that of thyroid (0.99 ± 0.36, p < 0.001) and other surrounding soft tissues (0.86 ± 0.40, p < 0.001). Based on the PG identification ratio threshold of 1.2, NIRAF yielded a detection rate of 95.8% (46/48 pediatric PGs).

CONCLUSION

Our findings indicate that NIRAF detection can potentially be a valuable and non-invasive technique to identify PGs during neck operations in the pediatric population. To our knowledge, this is the first study in children to assess the accuracy of probe-based NIRAF detection for intraoperative parathyroid identification.

LEVEL OF EVIDENCE

Level 4 Laryngoscope, 133:3208-3215, 2023.

Intraoperative Identification of Thyroid and Parathyroid Tissues During Human Endocrine Surgery Using the MasSpec Pen

Importance

Intraoperative identification of tissues through gross inspection during thyroid and parathyroid surgery is challenging yet essential for preserving healthy tissue and improving outcomes for patients.

Objective

To evaluate the performance and clinical applicability of the MasSpec Pen (MSPen) technology for discriminating thyroid, parathyroid, and lymph node tissues intraoperatively.

Design, Setting, and Participants

In this diagnostic/prognostic study, the MSPen was used to analyze 184 fresh-frozen thyroid, parathyroid, and lymph node tissues in the laboratory and translated to the operating room to enable in vivo and ex vivo tissue analysis by endocrine surgeons in 102 patients undergoing thyroidectomy and parathyroidectomy procedures. This diagnostic study was conducted between August 2017 and March 2020. Fresh-frozen tissues were analyzed in a laboratory. Clinical analyses occurred in an operating room at an academic medical center. Of the analyses performed on 184 fresh-frozen tissues, 131 were included based on sufficient signal and postanalysis pathologic diagnosis. From clinical tests, 102 patients undergoing surgery were included. A total of 1015 intraoperative analyses were performed, with 269 analyses subject to statistical classification. Statistical classifiers for discriminating thyroid, parathyroid, and lymph node tissues were generated using training sets comprising both laboratory and intraoperative data and evaluated on an independent test set of intraoperative data. Data were analyzed from July to December 2022.

Main Outcomes and Measures

Accuracy for each tissue type was measured for classification models discriminating thyroid, parathyroid, and lymph node tissues using MSPen data compared to gross analysis and final pathology results.

Results

Of the 102 patients in the intraoperative study, 80 were female (78%) and the median (IQR) age was 52 (42-66) years. For discriminating thyroid and parathyroid tissues, an overall accuracy, defined as agreement with pathology, of 92.4% (95% CI, 87.7-95.4) was achieved using MSPen data, with 82.6% (95% CI, 76.5-87.4) accuracy achieved for the independent test set. For distinguishing thyroid from lymph node and parathyroid from lymph node, overall training set accuracies of 97.5% (95% CI, 92.8-99.1) and 96.1% (95% CI, 91.2-98.3), respectively, were achieved.

Conclusions and Relevance

In this study, the MSPen showed high performance for discriminating thyroid, parathyroid, and lymph node tissues intraoperatively, suggesting this technology may be useful for providing near real-time feedback on tissue type to aid in surgical decision-making.

New Techniques for Intraoperative Parathyroid Localization

Accurate identification of abnormal parathyroid glands (PGs) during parathyroidectomy and thyroidectomy can be challenging even for experienced surgeons given PGs variable location, size, and similar appearance to surrounding tissue. Inadvertent removal or devascularization of healthy PGs can lead to transient or permanent hypoparathyroidism. Permanent hypoparathyroidism is associated with increased rates of renal insufficiency, seizures, skeletal abnormalities, increased costs, decreased quality of life, and increased mortality. Conversely, the inability to identify and remove hyperfunctioning PGs results in failed parathyroidectomy which can result in need for reoperations that are associated with increased technical difficulty, operative duration, rates of hypoparathyroidism and recurrent laryngeal nerve damage, and cost.

Modern Surgical Techniques of Thyroidectomy and Advances in the Prevention and Treatment of Perioperative Complications

Thyroid cancer is the most common cancer of the endocrine system, and, in recent years, there has been a phenomenon of overdiagnosis followed by subsequent overtreatment. This results in an increasing number of thyroidectomy complications being faced in clinical practice. In this paper, we present the current state of knowledge and the latest findings in the fields of modern surgical techniques, thermal ablation, the identification and assessment of parathyroid function, recurrent laryngeal nerve monitoring and treatment and perioperative bleeding. We reviewed 485 papers, from which we selected 125 papers that are the most relevant. The main merit of this article is its comprehensive view of the subject under discussion-both general, concerning the selection of the appropriate method of surgery, and particular, concerning the selection of the appropriate method of prevention or treatment of selected perioperative complications.

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.

Application of Indocyanine Green Fluorescence Imaging in Assisting Biopsy of Musculoskeletal Tumors

(1) Background: Biopsies are the gold standard for the diagnosis of musculoskeletal tumors. In this study, we aimed to explore whether indocyanine green near-infrared fluorescence imaging can assist in the biopsy of bone and soft tissue tumors and improve the success rate of biopsy. (2) Method: We recruited patients with clinically considered bone and soft tissue tumors and planned biopsies. In the test group, indocyanine green (0.3 mg/kg) was injected. After identifying the lesion, a near-infrared fluorescence camera system was used to verify the ex vivo specimens of the biopsy in real time. If the biopsy specimens were not developed, we assumed that we failed to acquire lesions, so the needle track and needle position were adjusted for the supplementary biopsy, and then real-time imaging was performed again. Finally, we conducted a pathological examination. In the control group, normal biopsy was performed. (3) Results: The total diagnosis rate of musculoskeletal tumors in the test group was 94.92% (56/59) and that in the control group was 82.36% (42/51). In the test group, 14 cases were not developed, as seen from real-time fluorescence in the core biopsy, and then underwent the supplementary biopsy after changing the puncture direction and the location of the needle channel immediately, of which 7 cases showed new fluorescence. (4) Conclusions: Using the near-infrared fluorescence real-time development technique to assist the biopsy of musculoskeletal tumors may improve the accuracy of core biopsy and help to avoid missed diagnoses, especially for some selected tumors.

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.

Educational Review: Intraoperative Parathyroid Fluorescence Detection Technology in Thyroid and Parathyroid Surgery

BACKGROUND

Accurate parathyroid gland (PG) identification is a critical yet challenging component of cervical endocrine procedures. PGs possess strong near-infrared autofluorescence (NIRAF) compared with other tissues in the neck. This property has been harnessed by image- and probe-based near-infrared fluorescence detection systems, which have gained increasing popularity in clinical use for their ability to accurately aid in PG identification in a rapid, noninvasive, and cost-effective manner. All NIRAF technologies, however, cannot differentiate viable from devascularized PGs without the use of contrast enhancement. Here, we aim to provide an overview of the rapid evolution of these technologies and update the surgery community on the most recent advancements in the field.

METHODS

A PubMed literature review was performed using the key terms "parathyroid," "near-infrared," and "fluorescence." Recommendations regarding the use of these technologies in clinical practice were developed on the basis of the reviewed literature and in conjunction with expert surgeons' opinions.

RESULTS

The use of near-infrared fluorescence detection can be broadly categorized as (1) using parathyroid NIRAF to identify both healthy and diseased PGs, and (2) using contrast-enhanced (i.e., indocyanine green) near-infrared fluorescence to evaluate PG perfusion and viability. Each of these approaches possess unique advantages and disadvantages, and clinical trials are ongoing to better define their utility.

CONCLUSIONS

Near-infrared fluorescence detection offers the opportunity to improve our collective ability to identify and preserve PGs intraoperatively. While additional work is needed to propel this technology further, we hope this review will be valuable to the practicing surgeon.

Near-infrared fluorescent imaging techniques for the detection and preservation of parathyroid glands during endocrine surgery

Objectives

In over 30% of all thyroid surgeries, complications arise from transient and definitive hypoparathyroidism, underscoring the need for real-time identification and preservation of parathyroid glands (PGs). Here, we evaluate the promising intraoperative optical technologies available for the identification, preservation, and functional assessment of PGs to enhance endocrine surgery.

Methods

We performed a review of the literature to identify published studies on fluorescence imaging in thyroid and parathyroid surgery.

Results

Fluorescence imaging is a well-demonstrated approach for both in vivo and in vitro localization of specific cells or tissues, and is gaining popularity as a technique to detect PGs during endocrine surgery. Autofluorescence (AF) imaging and indocyanine green (ICG) angiography are two emerging optical techniques to improve outcomes in thyroid and parathyroid surgeries. Near-infrared-guided technology has significantly contributed to the localization of PGs, through the detection of glandular AF. Perfusion through the PGs can be visualized with ICG, which can also reveal the blood supply after dissection.

Conclusions

Near infrared AF and ICG angiography, providing a valuable spatial and anatomical information, can decrease the incidence of complications in thyroid surgery.

A coaxial excitation, dual-red-green-blue/near-infrared paired imaging system toward computer-aided detection of parathyroid glands in situ and ex vivo

Early and precise detection of parathyroid glands (PGs) is a challenging problem in thyroidectomy due to their small size and similar appearance to surrounding tissues. Near-infrared autofluorescence (NIRAF) has stimulated interest as a method to localize PGs. However, high incidence of false positives for PGs has been reported with this technique. We introduce a prototype equipped with a coaxial excitation light (785 nm) and a dual-sensor to address the issue of false positives with the NIRAF technique. We test the clinical feasibility of our prototype in situ and ex vivo using sterile drapes on 10 human subjects. Video data (1287 images) of detected PGs were collected to train, validate and compare the performance for PG detection. We achieved a mean average precision of 94.7% and a 19.5-millisecond processing time/detection. This feasibility study supports the effectiveness of the optical design and may open new doors for a deep learning-based PG detection method.

Real-time intraoperative near-infrared autofluorescence imaging to locate the parathyroid glands: A preliminary report

Identification and localization of parathyroid glands (PGs) remains a challenge for surgeons. The aim of this study was to evaluate the efficiency of intraoperative near-infrared autofluorescence (NIRAF) imaging to detect PGs in thyroid and parathyroid diseases. Seventy-six patients undergoing surgery for thyroid or parathyroid diseases between July 9, 2020 and August 20, 2021 were retrospectively analyzed. Intraoperative carbon nanoparticle (CN) negative imaging and handheld NIRAF imaging were successively performed for each patient. Of 206 PGs that needed to be identified for surgery, 162 were identified by NIRAF imaging, with a theoretical rate of identification of 78.64%. This was higher than the rate of identification with CN negative imaging, which was 75.73%. The number of PGs identified by NIRAF imaging and CN negative imaging did not differ significantly in either total thyroidectomy or thyroid lobectomy. In addition, the autofluorescence (AF) intensity of secondary parathyroid adenoma was weaker than that of normal PGs. NIRAF imaging is potentially a more efficient tool for identification of PGs than CN negative imaging, with a shorter learning curve and lower risk. It may not be well-suited to secondary hyperthyroidism or adenoma, but it was more efficient at identifying excised specimens than visual identification by a surgeon.

Nerve autofluorescence under near-ultraviolet light: cutting-edge technology for intra-operative neural tissue visualization in 17 patients

BACKGROUND

Nerve visualization and the identification of other neural tissues during surgery is crucial for numerous reasons, including the prevention of iatrogenic nerve and neural structure injury and facilitation of nerve repair. However, current methods of intra-operative nerve detection are generally expensive, unproven, and/or technically challenging. Recently, we have documented, in both in vivo animal models and ex vivo human tissue, that nerves autofluorescence when viewed in near-ultraviolet light (NUV). In this paper, we describe our use of nerve autofluorescence to facilitate the visualization of nerves and other neural tissues intra-operatively in 17 patients undergoing a range of surgical procedures.

METHODS

Employing the same prototype axon imaging system previously documented to markedly enhance nerve visualization in both in vivo animal and ex vivo human models, surgical fields were observed in 17 patients under both white and NUV light during parotid tumor resection (n = 3), thyroid tumor resection (n = 7), and surgery for peripheral nerve and spinal tumors and injury (n = 7).

RESULTS

In all 17 patients, the intra-operative use of the imaging system both was feasible and markedly enhanced the localization of all neural tissues throughout their course within the surgical field. All 17 procedures were successful and devoid of any peri-operative complications or post-operative neurological deficits.

CONCLUSIONS

Intra-operatively visualizing auto-fluorescent peripheral nerves and other neural tissues under NUV light is feasible in human patients across a range of clinical scenarios and appears to appreciably enhance nerve and other neural tissue visualization. Controlled studies to explore this technology further are needed.

Detection of near-infrared autofluorescence from adrenal neoplasms: An initial experience

BACKGROUND AND OBJECTIVES

Fluorescence from adrenal tumors can be detected with near-infrared imaging after injection with indocyanine green. However, it is unknown if adrenal tumors exhibit autofluorescence. The aim of this study was to determine whether adrenal tumors emit near-infrared autofluorescence (NIRAF).

METHODS

This was a prospective study of patients who underwent minimally invasive adrenalectomy at a tertiary center. Intraoperative images were analyzed to detect NIRAF with a 750 nm camera. Descriptive and comparative statistical analyses were performed.

RESULTS

Twenty-five adrenalectomies were examined. Only 11 tumors (44%), that originated from the cortex exhibited autofluorescence. A contrast distinction between the tumor and retroperitoneum was observed in 23 patients, whereas a contrast distinction between the tumor and normal adrenocortical tissue was seen in 12 patients. The overall fluorescence intensity of adrenal tumors was found to be variable and ranging between 0.3 and 5.6 times that of the background tissue. Pheochromocytoma, malignancy and adrenal cyst did not demonstrate NIRAF.

CONCLUSION

This is the first study to show that adrenocortical tissue can demonstrate NIRAF. The pattern of fluorescence was similar to that observed after indocyanine green injection in our historical experience. NIRAF has a potential to be used as an intraoperative optical adjunct during adrenalectomy.

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.

Nerve autofluorescence in near-ultraviolet light markedly enhances nerve visualization in vivo

BACKGROUND

During surgery, surgeons must accurately localize nerves to avoid injuring them. Recently, we have discovered that nerves fluoresce in near-ultraviolet light (NUV) light. The aims of the current study were to determine the extent to which nerves fluoresce more brightly than background and vascular structures in NUV light, and identify the NUV intensity at which nerves are most distinguishable from other tissues.

METHODS

We exposed sciatic nerves within the posterior thigh in five 250-300 gm Wistar rats, then observed them at four different NUV intensity levels: 20%, 35%, 50%, and 100%. Brightness of fluorescence was measured by fluorescence spectroscopy, quantified as a fluorescence score using Image-J software, and statistically compared between nerves, background, and both an artery and vein by unpaired Student's t tests with Bonferroni adjustment to accommodate multiple comparisons. Sensitivity, specificity, and accuracy were calculated for each NUV intensity.

RESULTS

At 20, 35, 50, and 100% NUV intensity, fluorescence scores for nerves versus background tissues were 117.4 versus 40.0, 225.8 versus 88.0, 250.6 versus 121.4, and 252.8 versus 169.4, respectively (all p < 0.001). Fluorescence scores plateaued at 50% NUV intensity for nerves, but continued to rise for background. At 35%, 50%, and 100% NUV intensity, a fluorescence score of 200 was 100% sensitive, specific, and accurate identifying nerves. At 100 NUV intensity, artery and vein scores were 61.8 and 60.0, both dramatically lower than for nerves (p < 0.001).

CONCLUSIONS

At all NUV intensities ≥ 35%, a fluorescence score of 200 is 100% accurate distinguishing nerves from other anatomical structures in vivo.

Hypoparathyroidism after thyroidectomy: A 20-year experience at a children's hospital

INTRODUCTION

Hypoparathyroidism (HP) is the most common complication of total thyroidectomy and can be an emergency.

OBJECTIVES

To describe the prevalence of HP after total thyroidectomy in children under 14 years of age, the variables related to its appearance and its clinical expression.

PATIENTS AND METHODS

Retrospective study at a children's hospital in the last 20 years. HP was defined by the need to supplement calcium after the intervention and was considered permanent if it could not be suspended within 12 months. Fisher's statistical method of comparison of proportions.

RESULTS

Thirty-nine children and adolescents (26 females) with an age range of 3.67-14.00 years. In 25 patients, the intervention was prophylactic and in 14 it was therapeutic; 14 suffered accidental excision of some parathyroid gland, but none more than two of them; 12 presented HP, of which 3 were permanent; 5 presented clinical symptoms; 1 of them was an emergency. The frequency of HP was 4/4 when 2 parathyroids were dissected, 2/10 when one was dissected, and 6/25 when none were dissected (p = 0.02). In the prophylactic interventions, it was 6/25 compared to 6/14 in the therapeutic ones (p = 0.29). The three cases of permanent HP were in children under 6 years of age, and it did not occur in any older children (p = 0.09).

CONCLUSIONS

HP is a common and sometimes serious complication in children after total thyroidectomy. It can occur, and even be permanent, even if the intervention is prophylactic and parathyroid glands remain in situ. Younger age could be a risk factor.

The anatomical basis for preserving the blood supply to the parathyroids during thyroid surgery, and a review of current technologic advances

BACKGROUND

Devascularization of the parathyroid glands is generally accepted as the most common mechanism for iatrogenic hypocalcemia, a frequently seen complication of both total and completion thyroidectomy procedures. Much has been written about iatrogenic hypoparathyroidism, but few papers have precisely delineated the arterial supply of the parathyroid glands and the common anatomical variations that may impact parathyroid preservation during thyroid surgery.

METHODS

We offer an illustrated review and discussion of the only two anatomic studies published in the medical literature focusing on parathyroid vasculature. In addition, we examine current techniques of parathyroid identification, preservation, and classification.

FINDINGS

A surgical technique that preserves the parathyroid arteries is vital to preserving the viability of the parathyroid gland(s) during thyroid surgery. In 1907, Halsted and Evans described a technique of ligating the distal branches of the thyroid arteries beyond the origin of the parathyroid arteries, a technique termed ultra-ligation. In 1982, Flament et al.. reported three distinct anatomical variations of the parathyroid arteries which place the parathyroid blood supply at risk for devascularization during thyroid surgery. Our review also highlights novel techniques that aid surgeons in identification and assessment of the parathyroid glands.

CONCLUSIONS

Recognition of the variations of parathyroid anatomy and their potential to lead to devascularization aids thyroid surgeons in their pursuit of parathyroid preservation. An awareness of the variety of novel parathyroid identification and preservation techniques can assist surgeons to achieve this goal.

Combined Use of Autofluorescence and Indocyanine Green Fluorescence Imaging in the Identification and Evaluation of Parathyroid Glands During Total Thyroidectomy: A Randomized Controlled Trial

BACKGROUND AND OBJECTIVES

Accurate identification and evaluation of the parathyroid glands (PGs) intraoperatively is critical to reduce the incidence of postoperative hypoparathyroidism after total thyroidectomy. Near-infrared fluorescence imaging (NIFI), including the autofluorescence (AF) and indocyanine green fluorescence (ICGF) imaging, is a promising technique to protect PGs. This study aimed to assess whether the combined use of AF and ICGF could reduce the incidence of postoperative hypoparathyroidism and improve the identification and evaluation of PGs during total thyroidectomy.

METHODS

This randomized controlled trial enrolled 180 patients who were randomized into two groups and underwent total thyroidectomy with unilateral or bilateral central lymph node dissection. In the control group, the PGs were identified and evaluated by the naked eye. In the NIFI group, AF was used to identify the PGs and ICGF was applied to assess the blood perfusion of the PGs in situ. The primary outcome was the incidence of postoperative hypoparathyroidism. The secondary outcomes included the number of identified PGs, autotransplanted PGs, and known preserved PGs in situ.

RESULTS

The incidence of postoperative transient hypoparathyroidism was significantly lower in the NIFI group than in the control group (27.8% vs. 43.3%, P = 0.029). More PGs were identified in the NIFI group than in the control group (3.6 ± 0.5 vs. 3.2 ± 0.4, P < 0.001). No significant difference was observed in the number of autotransplanted PGs between the two groups (P = 0.134). Compared with the control group, a greater number of known PGs were preserved in situ in the NIFI group (1.3 ± 0.6 vs. 1.0 ± 0.5, P < 0.001). In the NIFI group, only 4.5% of the patients with at least one well-perfused PG (ICG score of 2) developed postoperative hypoparathyroidism, which was significantly lower than that of the control group (34.6%, P < 0.001).

CONCLUSION

Combined use of AF and ICGF during total thyroidectomy reduces the risk of transient postoperative hypoparathyroidism, enhances the ability to identify and preserve PGs, and improves the accuracy of evaluating the perfusion of PGs during surgery.

CLINICAL TRIAL REGISTRATION

Chinese Clinical Trial Register (www.chictr.org.cn), identifier ChiCTR2100045320. Registered on April 12, 2021.

Trastornos posoperatorios del metabolismo del calcio postiroidectomía

Introducción: revisión narrativa que revela como la tiroidectomía ha aumentado en los últimos años y con ella sus complicaciones: la hipocalcemia y el hipoparatiroidismo. Métodos: los motores de búsqueda utilizados fueron PubMed, Clinical Key, Embase, Cochrane y Lilacs, se incluyeron referencias en español e inglés, publicadas entre 2016 y 2020. Los artículos seleccionados se revisaron utilizando CONSORT, STROBE o PRISMA, según el caso. Resultados: fueron seleccionados 35 artículos que tenían relación directa con el tema, entre ellos: metanálisis, revisiones sistemáticas, estudios prospectivos y observacionales, revisiones narrativas y consensos de expertos, procedentes de los cinco continentes. La hipocalcemia y el hipotiroidismo en sus dos formas se relacionan con la afectación de la vascularización de las glándulas paratiroides o su exérecis accidental, existiendo factores predisponentes propios del paciente, derivados de la técnica quirúrgica o la característica patológica de la lesión en el tiroides. Como estrategias de prevención disponemos de herramientas ópticas para definir en el perioperatorio la disposición de las paratiroides; además existe la posibilidad de autotrasplantarlas al identificarlas en la pieza anatómica. El mejor marcador del estado metabólico del calcio es la PTHi. Conclusiones: la preservación de las paratiroides y de su irrigación es la mejor estrategia para prevenir los trastornos posoperatorios del calcio.

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.

Indocyanine Green Angiography for Parathyroid Gland Evaluation during Transoral Endoscopic Thyroidectomy

Indocyanine green (ICG) angiography, a real-time intraoperative imaging technique, is associated with better parathyroid identification and functional evaluation during open thyroidectomy. However, the benefits of ICG fluorescence imaging application in transoral endoscopic thyroidectomy are not well-documented. Consecutive patients who underwent transoral endoscopic thyroidectomy were retrospectively reviewed. Parathyroid glands were assessed with visual inspection followed by ICG angiography. The fluorescence intensity of all parathyroid glands was recorded. In total, 158 parathyroid glands from 60 patients (41 underwent lobectomy and 19 underwent total thyroidectomy) were eligible for evaluation. A total of 135 parathyroid glands (85.4%) were identified, including nine glands (5.7%) that were solely localized because of ICG angiography. Incidental parathyroidectomy occurred in 12 patients with predominant inferior gland (83.3%) and associated with central neck dissection (66.7%). Among patients receiving total thyroidectomy, patients who retained at least one well-perfused parathyroid gland had higher parathyroid hormone (PTH) level and were less likely to develop hypoparathyroidism on postoperative day one than those without any well-perfused ICG-enhanced parathyroid gland (p = 0.038). In addition, the duration of calcium supplementation to maintain normocalcemia was also shorter. ICG angiography is a feasible adjunct procedure for parathyroid identification and postoperative functional prediction in transoral endoscopic thyroidectomy.

Association between number of parathyroid glands identified during total thyroidectomy and functional parathyroid preservation

Purpose

Systematic identification of all 4 parathyroid glands has been recommended during total thyroidectomy (TT); however, it is unclear whether this strategy necessarily translates into optimized functional parathyroid preservation. We wished to investigate the association between number of parathyroids identified intraoperatively during TT, and incidence of incidental parathyroidectomy, and postoperative hypoparathyroidism.

Methods

Retrospective review of prospectively maintained database of 511 consecutive patients undergoing TT at an academic teaching hospital. The association between number of parathyroid glands identified intraoperatively and incidence of biochemical hypocalcaemia (defined as any calcium < 2 mmol/L n first 48 h after surgery), symptomatic hypocalcaemia; permanent hypoparathyroidism (defined as any hypocalcaemia or need for calcium or vitamin D > 6 months after surgery), and incidental parathyroidectomy, was investigated. The association between number of parathyroid glands visualized and postoperative parathyroid hormone (PTH) levels was investigated in a subset of 454 patients.

Results

Patients in whom a greater number of parathyroids had been identified had a significantly higher incidence of biochemical and symptomatic hypocalcaemia, and significantly lower postoperative PTH levels, than patients with fewer glands identified. There were no significant differences in incidence of permanent hypoparathyroidism or incidental parathyroidectomy. On multivariate analysis, malignancy, Graves disease, and identification of 3–4 parathyroids were independent predictors of biochemical hypocalcaemia. For symptomatic hypocalcaemia, identification of 2–4 parathyroids, and identification of 3–4 parathyroids, were significant.

Conclusions

Systematic identification of as many parathyroid glands as possible during TT is not necessary for functional parathyroid preservation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00423-021-02287-6.

Near-infrared autofluorescence-based parathyroid glands identification in the thyroidectomy or parathyroidectomy: a systematic review and meta-analysis

PURPOSE

To evaluate the diagnostic accuracy of near-infrared autofluorescence-based identification in the identification of parathyroid glands during thyroidectomy or parathyroidectomy.

METHODS

The clinical studies were retrieved from PubMed, the Cochrane Central Register of Controlled Trials, Embase, Web of Science, SCOPUS, and Google Scholar. The study protocol was registered on Open Science Framework ( https://osf.io/um8rj/ ). The search period ranged from the date of each database's inception to May 2021. Cohort studies dealing with patients of whom parathyroid glands were detected by near-infrared autofluorescence and confirmed clinically or pathologically during thyroidectomy or parathyroidectomy were included. Editorials, letters, "how-I-do-it" descriptions, other site head and neck tumors, and articles with lack of diagnostic identification data were excluded. True positive, true negative, false positive, and false negative were extracted. The QUDAS ver. 2 was used to evaluate the methodological quality.

RESULTS

Seventeen studies with 1198 participants were evaluated in this analysis. Near-infrared autofluorescence-based identification of parathyroid glands showed a diagnostic odds ratio of 228.8759 (95% confidence interval, 134.1099; 390.6063). The area under the summary receiver operating characteristic curve was 0.967. The sensitivity, specificity, negative predictive value, and positive predictive value were 0.9693 (0.9491; 0.9816), 0.9248 (0.8885; 0.9499), 0.9517 (0.8981; 0.9778), and 0.9488 (0.9167; 0.9689), respectively. Subgroup analyses were performed to compare two autofluorescence detection methods, because there was high heterogeneity in the outcomes. The diagnostic accuracy was higher in probe-based detection than in image-based detection.

CONCLUSIONS

Near-infrared autofluorescence-based identification is valuable for identifying the parathyroid glands of patients during thyroidectomy or parathyroidectomy.

Hypoparathyroidism after thyroidectomy: A 20-year experience at a children's hospital

INTRODUCTION

Hypoparathyroidism (HP) is the most common complication of total thyroidectomy and can be an emergency.

OBJECTIVES

To describe the prevalence of HP after total thyroidectomy in children under 14 years of age, the variables related to its appearance and its clinical expression.

PATIENTS AND METHODS

Retrospective study at a children's hospital in the last 20 years. HP was defined by the need to supplement calcium after the intervention and was considered permanent if it could not be suspended within 12 months. Fisher's statistical method of comparison of proportions.

RESULTS

Thirty-nine children and adolescents (26 females) with an age range of 3.67 to 14.00 years. In 25 patients, the intervention was prophylactic and in 14 it was therapeutic. Fourteen suffered accidental excision of some parathyroid gland, but none more than t2 of them. Twelve presented HP, of which 3 were permanent; 5 presented clinical symptoms; one of them was an emergency. The frequency of HP was 4/4 when 2 parathyroids were dissected, 2/10 when one was dissected, and 6/25 when none were dissected (P=.02). In the prophylactic interventions, it was 6/25 compared to 6/14 in the therapeutic ones (P=.29). The 3 cases of permanent HP were in children under 6 years of age, and it did not occur in any older children (P=.09).

CONCLUSIONS

HP is a common and sometimes serious complication in children after total thyroidectomy. It can occur, and even be permanent, even if the intervention is prophylactic and parathyroid glands remain in situ. Younger age could be a risk factor.

Can near-infrared autofluorescence imaging be used for intraoperative confirmation of parathyroid tissue?

BACKGROUND AND OBJECTIVES

Whether ex vivo autofluorescence (AF) imaging findings could be quantified to intraoperatively differentiate parathyroid tissue has not been reported. Our aim was to assess the ability of AF imaging to confirm parathyroid tissue during thyroidectomy and parathyroidectomy procedures.

METHODS

This was a retrospective Institutional Review Board-approved study. AF signals of specimens imaged ex vivo before submission to pathology during thyroidectomy and parathyroidectomy procedures were quantified. Using receiver operating characteristic (ROC) curves, optimal values for sensitivity/specificity to differentiate parathyroid tissue were calculated.

RESULTS

166 parathyroid and 217 non-parathyroid specimens were analyzed. With surgical drapes as background, the optimal normalized AF intensity threshold to predict parathyroid tissue on ROC curve analysis was 1.72 (86.1% sensitivity, 84.8% specificity, and area under the curve [AUC]: 0.919). The cutoff for 97% sensitivity was 1.31 and for 99.1% specificity was 3.16. With Telfa as background, the optimal threshold to predict parathyroid tissue was 1.46 (88.4% sensitivity, 76.8% specificity, and AUC: 0.896). The threshold for 96.8% sensitivity was 1.18 and for 98.8% specificity was 2.44. If thresholds for highest specificity were used, 40% of frozen sections to confirm parathyroid tissue could have been avoided.

CONCLUSION

Quantified brightness analysis of ex vivo AF signals may have utility in intraoperative differentiation of parathyroid tissue for 40% of surgical specimens.

Nerve autofluorescence in near-ultraviolet light markedly enhances nerve visualization in vivo

BACKGROUND

During surgery, surgeons must accurately localize nerves to avoid injuring them. Recently, we have discovered that nerves fluoresce in near-ultraviolet light (NUV) light. The aims of the current study were to determine the extent to which nerves fluoresce more brightly than background and vascular structures in NUV light, and identify the NUV intensity at which nerves are most distinguishable from other tissues.

METHODS

We exposed sciatic nerves within the posterior thigh in five 250-300 gm Wistar rats, then observed them at four different NUV intensity levels: 20%, 35%, 50%, and 100%. Brightness of fluorescence was measured by fluorescence spectroscopy, quantified as a fluorescence score using Image-J software, and statistically compared between nerves, background, and both an artery and vein by unpaired Student's t tests with Bonferroni adjustment to accommodate multiple comparisons. Sensitivity, specificity, and accuracy were calculated for each NUV intensity.

RESULTS

At 20, 35, 50, and 100% NUV intensity, fluorescence scores for nerves versus background tissues were 117.4 versus 40.0, 225.8 versus 88.0, 250.6 versus 121.4, and 252.8 versus 169.4, respectively (all p < 0.001). Fluorescence scores plateaued at 50% NUV intensity for nerves, but continued to rise for background. At 35%, 50%, and 100% NUV intensity, a fluorescence score of 200 was 100% sensitive, specific, and accurate identifying nerves. At 100 NUV intensity, artery and vein scores were 61.8 and 60.0, both dramatically lower than for nerves (p < 0.001).

CONCLUSIONS

At all NUV intensities ≥ 35%, a fluorescence score of 200 is 100% accurate distinguishing nerves from other anatomical structures in vivo.

Primary study of identification of parathyroid gland based on laser-induced breakdown spectroscopy

The identification and preservation of parathyroid glands (PGs) is a major issue in thyroidectomy. The PG is particularly difficult to distinguish from the surrounding tissues. Accidental damage or removal of the PG may result in temporary or permanent postoperative hypoparathyroidism and hypocalcemia. In this study, a novel method for identification of the PG was proposed based on laser-induced breakdown spectroscopy (LIBS) for the first time. LIBS spectra were collected from the smear samples of PG and non-parathyroid gland (NPG) tissues (thyroid and neck lymph node) of rabbits. The emission lines (related to K, Na, Ca, N, O, CN, C₂, etc.) observed in LIBS spectra were ranked and selected based on the important weight calculated by random forest (RF). Three machine learning algorithms were used as classifiers to distinguish PGs from NPGs. The artificial neural network classifier provided the best classification performance. The results demonstrated that LIBS can be adopted to discriminate between smear samples of PG and NPG, and it has a potential in intra-operative identification of PGs.

Narrative review of management of thyroid surgery complications

Currently, thyroid surgery is the most common and safe operation worldwide. However, thyroidectomy is still not free from the risks of complications and death due to the anatomical structure and physiological function particularity of the thyroid gland. Postoperative complications affect the life quality and life safety of patients after surgery. The common complications include hypoparathyroidism (HP), recurrent laryngeal nerve (RLN) injury, injury to the external branch of the superior laryngeal nerve (EBSLN), postoperative bleeding (PB), thoracic duct injury, laryngeal edema, tracheospasm, tracheal injury, and esophageal injury. A severe complication, such as dyspnea, asphyxia, or thyroid crisis, might cause the death of the patient. Therefore, every thyroid surgeon's responsibility is to remain alert and aware of the occurrence of various intraoperative and postoperative complications and exercise effective prevention and treatment. This is closely related to the advancement in thyroid disease research, the increase in local anatomy knowledge, the standardization of surgical approaches, the improvement in operating skills, the application of new technologies, and the emphasis on specialty training. In addition, many complications that effect patients are much better tolerated if the patient has appropriate expectations of what the complications are and how to treat them. Open communication between surgeon and patient optimizes the potential negative effects that complications may have on patients' quality of life. This paper discusses the prevention, recognition and therapy of intraoperative and postoperative complications in thyroid surgery.

Does near-infrared fluorescent cholangiography with indocyanine green reduce bile duct injuries and conversions to open surgery during laparoscopic or robotic cholecystectomy? - A meta-analysis

BACKGROUND

Bile duct injury and conversion-to-open-surgery rates remain unacceptably high during laparoscopic and robotic cholecystectomy. In a recently published randomized clinical trial, using near-infrared fluorescent cholangiography with indocyanine green intraoperatively markedly enhanced biliary-structure visualization. Our systematic literature review compares bile duct injury and conversion-to-open-surgery rates in patients undergoing laparoscopic or robotic cholecystectomy with versus without near-infrared fluorescent cholangiography.

METHODS

A thorough PubMed search was conducted to identify randomized clinical trials and nonrandomized clinical trials with ≥100 patients. Because all near-infrared fluorescent cholangiography studies were published since 2013, only studies without near-infrared fluorescent cholangiography published since 2013 were included for comparison. Incidence estimates, weighted and unweighted for study size, were adjusted for acute versus chronic cholecystitis, and for robotic versus laparoscopic cholecystectomy and are reported as events/10,000 patients. All studies were assessed for bias risk and high-risk studies excluded.

RESULTS

In total, 4,990 abstracts were reviewed, identifying 5 near-infrared fluorescent cholangiography studies (3 laparoscopic cholecystectomy/2 robotic cholecystectomy; n = 1,603) and 11 not near-infrared fluorescent cholangiography studies (5 laparoscopic cholecystectomy/4 robotic cholecystectomy/2 both; n = 5,070) for analysis. Overall weighted rates for bile duct injury and conversion were 6 and 16/10,000 in near-infrared fluorescent cholangiography patients versus 25 and 271/10,000 in patients without near-infrared fluorescent cholangiography. Among patients undergoing laparoscopic cholecystectomy, bile duct injuries, and conversion rates among near-infrared fluorescent cholangiography versus patients without near-infrared fluorescent cholangiography were 0 and 23/10,000 versus 32 and 255/10,000, respectively. Bile duct injury rates were low with robotic cholecystectomy with and without near-infrared fluorescent cholangiography (12 and 8/10,000), but there was a marked reduction in conversions with near-infrared fluorescent cholangiography (12 vs 322/10,000).

CONCLUSION

Although large comparative trials remain necessary, preliminary analysis suggests that using near-infrared fluorescent cholangiography with indocyanine green intraoperatively sizably decreases bile duct injury and conversion-to-open-surgery rates relative to cholecystectomy under white light alone.

Evaluation of Autofluorescence in Identifying Parathyroid Glands by Measuring Parathyroid Hormone in Fine-Needle Biopsy Washings

BACKGROUND

Near-infrared autofluorescence imaging has potentially great value for assisting endocrine surgeons in identifying parathyroid glands and may dramatically change the surgical strategy of endocrine surgeons in thyroid surgery. This study is designed to objectively evaluate the role of near-infrared autofluorescence imaging in identifying parathyroid glands during thyroid surgery by measuring intraoperative parathyroid hormone in fine-needle aspiration biopsy washings.

METHODS

This study was conducted at a tertiary referral teaching hospital in China from February 2020 to June 2020. Patients undergoing total thyroidectomy with or without neck lymph node dissection were consecutively included. The surgeon used near-infrared autofluorescence imaging to identify parathyroid glands during thyroid surgery and confirmed suspicious parathyroid tissues by measuring their intraoperative parathyroid hormone. Nanocarbon was injected into the thyroid gland if the thyroid autofluorescence intensity was too strong. The sensitivity and accuracy of near-infrared autofluorescence imaging and vision for identifying parathyroid glands, and the difference in autofluorescence intensity in various tissues were the main outcomes.

RESULTS

Overall, 238 patients completed the trial. Based on the pathological and aIOPTH results, the sensitivity of near-infrared autofluorescence imaging for detecting parathyroid glands (568 of 596 parathyroid glands; 95.30%)was significantly higher than that of vision (517 of 596 parathyroid glands; 86.74%, P<.001). The accuracy of near-infrared autofluorescence imaging (764 of 841 tissues; 90.84%) was significantly higher than that of vision (567 of 841 tissues; 67.42%, P<.001) when the evaluations of certain tissues were inconsistent. There was a significant difference between the autofluorescence intensity of the parathyroid glands and that of the lymph nodes (74.19 ± 17.82 vs 33.97 ± 10.64, P<.001).

CONCLUSION

The use of near-infrared autofluorescence imaging, along with intraoperative parathyroid hormone and nanocarbon for the identification of parathyroid glands in thyroid surgery may increase the number of confirmed parathyroid glands. Using near-infrared autofluorescence imaging can effectively distinguish lymph nodes and parathyroid glands during lymph node dissection.

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.

Intraoperative near-infrared imaging of parathyroid glands: A comparison of first- and second-generation technologies

BACKGROUND

Intraoperative near-infrared imaging (NIFI) of parathyroid glands (PG) by first-generation technology had limited image quality and depth penetration. Second-generation NIFI has recently been introduced. Our aim was to compare (1) capability to detect PG and (2) image quality between older and newer technologies.

METHODS

Accurately detecting PG, as well as, quality of autofluorescence (AF) was compared between an older charge-coupled device (CCD) camera and a newer complementary metal-oxide semiconductor (CMOS). χ² , t test, and analysis of variance were used for analysis.

RESULTS

There were 300 patients who underwent parathyroidectomy (PTX) and/or thyroidectomy (THY) with NIFI, 200 with CCD, and 100 with CMOS. Although both NIFI technologies detected >94% of PG, CMOS was superior to CCD. Comparing AF quality, mean pixel intensity of PG compared with the background was higher with CMOS compared with CCD. When comparing PG detected by NIFI before visual identification by a surgeon, both CCD and CMOS had similar results (25% vs. 22%; p = .3).

CONCLUSION

Both NIFI cameras were excellent at detecting PG. Second-generation NIFI (CMOS) displayed higher detection rates and AF intensity. Although surgeons identified majority of PG before NIFI detection, 25% of PG were identified with NIFI first, suggesting future advancements of this technology may expand its applications during parathyroid/thyroid operations.

Autofluorescence and Indocyanine Green in Thyroid Surgery: A Systematic Review and Meta-Analysis

OBJECTIVES/HYPOTHESIS

To estimate the impact of optical techniques on prevention of post-operative hypocalcemia and hypoparathyroidism after total thyroidectomy.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A literature search was conducted in Pubmed, EMBASE, SCOPUS, and Cochrane databases. The main inclusion criteria for eligible articles for meta-analysis were patients with benign or malignant thyroid pathologies who underwent total thyroidectomy, utilization of optical techniques to support PGs preservation, the availability of calcium and/or PTH levels. The primary outcome was to evaluate the variation of calcium and PTH levels when adopting optical technologies compared to standard naked-eye surgery.

RESULTS

In total, 13 papers with 1484 procedures were included. Pooled proportion for short- and medium-term hypocalcemia rates were 8% (95% CI, 5%:11%) and 1% (95% CI, 0%:4%) for optical techniques, while for naked-eye surgery were 15% (95% CI, 9%:23%) and 5% (95% CI, 2%:9%), respectively.

CONCLUSIONS

Optical technologies reduced short and medium term hypocalcemia compared to conventional surgery.

LEVEL OF EVIDENCE

NA Laryngoscope, 131:1683-1692, 2021.

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.

Current state of intraoperative use of near infrared fluorescence for parathyroid identification and preservation

BACKGROUND

Finding and preserving normal parathyroid glands or localizing and removing diseased parathyroid glands are crucial steps to successful thyroid and parathyroid operations. Using near-infrared fluorescence detection to identify parathyroid glands during thyroid and parathyroid operations has lately gained widespread recognition, with 2 Food and Drug Administration-cleared devices currently in the market. We aim to update the endocrine surgery community on how near-infrared fluorescence detection can be most optimally used for rapid intraoperative parathyroid gland identification or preservation.

METHODS

A literature review was performed using the key terms: "parathyroid," "near infrared," and "fluorescence" in relevant search engines. Based on the reviewed literature and expert surgeons' opinions, recommendations were formulated for applying near-infrared fluorescence detection to identify or preserve parathyroid glands during cervical endocrine surgery.

RESULTS

The scope of near-infrared fluorescence detection can be broadly categorized into (1) using near-infrared auto-fluorescence to identify or locate both healthy and diseased parathyroid glands, and (2) using contrast-enhanced near-infrared fluorescence to evaluate parathyroid gland perfusion. The benefits and pitfalls for both near-infrared-based approaches are described herein.

CONCLUSION

Near-infrared fluorescence detection appears helpful for identification and likely preservation of parathyroid glands. We hope these recommendations will be valuable to the practicing endocrine surgeon as they consider incorporating these intraoperative adjuncts in their surgical practice.

Ultrasound dye-assisted parathyroidectomy (USDAP): Experience of a tertiary center

BACKGROUND

Primary hyperparathyroidism is primarily caused by parathyroid adenoma, followed by hyperplasia and parathyroid carcinoma. In the era of minimally invasive, targeted parathyroidectomy, the main challenge remains that of distinguishing intraoperatively pathological parathyroid from normal glands and peri-thyroid fat tissue. The aim of this study is to evaluate the surgical outcomes of a novel minimally invasive technique called ultrasound-guided dye-assisted parathyroidectomy (USDAP).

METHODS

We perform a retrospective analysis of patients affected by parathyroid adenoma, treated with USDAP at our institution between 2014 and 2019. Data were collected on patient age and sex, tumor location and size, preoperative investigations, histopathology, perioperative complications and surgical outcomes.

RESULTS

Between January 2014 and June 2019, 43 patients underwent parathyroidectomy in our Institute. Each case was discussed by the Institutional Multidisciplinary Board. All patients undergoing thyroidectomy together with USDAP or patients undergoing USDAP under endoscopic control were excluded from the present study. The final cohort, the largest to our knowledge, consisted of 29 patients. All patients were successfully treated with USDAP and remained disease-free during follow up. In all cases, pathological parathyroid was correctly identified and removed. There was no postoperative allergic reaction, nor were there neurotoxicity complications. USDAP permitted a shortening of operative and hospitalization time.

CONCLUSIONS

USDAP is an effective and safe procedure both as first line treatment and as a re-operative procedure after previous surgical failures in selected cases.

Multi-Wavelength Fluorescence in Image-Guided Surgery, Clinical Feasibility and Future Perspectives

With the rise of fluorescence-guided surgery, it has become evident that different types of fluorescence signals can provide value in the surgical setting. Hereby a different range of targets have been pursued in a great variety of surgical indications. One of the future challenges lies in combining complementary fluorescent readouts during one and the same surgical procedure, so-called multi-wavelength fluorescence guidance. In this review we summarize the current clinical state-of-the-art in multi-wavelength fluorescence guidance, basic technical concepts, possible future extensions of existing clinical indications and impact that the technology can bring to clinical care.

Efficacy of Fluorescein Green Dye in Assessing Intra-Operative Parathyroid Gland Vascularity and Predicting Post-Thyroidectomy Hypocalcaemia- A Novel Prospective Cohort Study

BACKGROUND

Postoperative hypocalcaemia (POH) after total thyroidectomy (TT) is a common complication. Parathyroid hormone (PTH), an accurate predictor of POH cannot assess intra-operative viability of parathyroid glands (PGs). Different dyes including indocyanine green or carbon nanoparticles have been used, but they are expensive and not widely available. Fluorescein green dye (FD) has been used as a low-cost alternative to study viability of various organs, but seldom tried in visualizing PGs. This novel study aims to assess utility of FD in determining parathyroid viability and predicting POH.

MATERIAL AND METHOD

Total 72 out of 88 patients undergoing TT between January and December 2019 were included. Two ml of 25% FD was given intravenously before wound closure and attempts were made to visualize PGs under blue light. A numerical score was given according to the number of PGs visualized. Intact-PTH and corrected calcium were measured on postoperative day 1 and patients observed for POH.

RESULTS

No PGs were visualized in 6 patients, 1 in 13, 2 in 30, 3 in 16 & 4 in 7 patients. Mean PTH was 6, 16.9, 31.6, 33.2 and 48.5 respectively. Corrected-calcium was 7.08, 7.7, 7.9, 8.5 and 8.5 respectively. All patients with score 0 received supplementary IV calcium, while 53.8% (score-1), 30% (score-2), 0% (scores-3, 4) received the same. Sensitivity, specificity and ROC of PG score of ≥2 on FD in predicting POH were 100%, 44% and 0.83 respectively.

CONCLUSION

FD visualization of parathyroids post TT is feasible and can be used as low cost efficacious method to predict POH.

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.

Intraoperative Adjunct Methods for Localization in Primary Hyperparathyroidism

Primary hyperparathyroidism (pHPT) is a frequently seen endocrine disease, and its main treatment is surgery. In the majority of pHPT, the disease involves only a single gland, and the majority of the pathological glands can be determined by preoperative localization methods.In addition to preoperative localization studies in parathyroidectomy, the use of adjunct methods to improve intraoperative localization in order to increase success of surgery is becoming widespread. These methods include different approaches, mainly intraoperative parathyroid hormone (PTH) measurement, followed by intraoperative gamma probe application, intraoperative ultrasonography, parathyroid imaging with methylene blue, and frozen section examination. Recently, especially promising new imaging methods have been described in the literature with various optical technologies to increase the localization of the parathyroid glands and to evaluate their viability. These methods include parathyroid imaging with autofluorescence, indocyanine green imaging with autofluorescence, autofluorescence imaging with methylene blue, autofluorescence imaging with 5-aminolevulinic acid, optical coherence tomography, laser speckle contrast imaging, dynamic optical contrast imaging, and Raman spectroscopy. Currently, minimally invasive parathyroidectomy has become the standard treatment for selected pHPT patients with the aid of preoperative imaging and intraoperative auxiliary methods . The aim of the present study was to evaluate the routinely used new promising intraoperative adjunct methods in pHPT.

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.

Intraoperative Autofluorescence and Indocyanine Green Angiography for the Detection and Preservation of Parathyroid Glands

Fluorescence imaging is a well-known method for both the in vivo and in vitro identification of specific cells or tissues. This imaging tool is gaining importance in the intraoperative detection and preservation of parathyroid glands during endocrine surgery owing to the intrinsic properties of parathyroid tissue. The aim of this paper is to provide an overview of the basics of the technology, its history, and the recent surgical intraoperative applications of near-infrared imaging methods. Moreover, a literature review of the utilization of fluorescence devices in thyroid surgery suggests that the use of near-infrared imaging seems to be beneficial in reducing postoperative hypoparathyroidism, which is one of the most frequent complications of thyroid surgery.