Autofluorescence pattern of parathyroid adenomas

Correlation Between Near-Infrared Autofluorescence Properties and Sestamibi Uptakes of Parathyroid Glands in Primary Hyperparathyroidism

OBJECTIVE

Near-infrared autofluorescence (NIRAF) characteristics of parathyroid glands in primary hyperparathyroidism (pHPT) vary, with unclarity regarding the underlying mechanism. Similarly, 99mTc-sestamibi uptake in diseased parathyroid glands is variable. There is a suggestion that oxyphilic cell content may influence both imaging modalities. This study aims to analyze the relationship between NIRAF imaging characteristics, 99mTc-sestamibi uptake, and cellular composition in pHPT.

STUDY DESIGN

Retrospective analysis of an Institutional Review Board-monitored prospective database.

SETTING

Single tertiary referral center.

METHODS

NIRAF characteristics of parathyroid glands of patients with pHPT between 2019 and 2024 were compared with 99mTc-sestamibi scan findings from a prospective database. Using third-party software, brightness intensity and heterogeneity index (HI) of the glands were calculated. A subgroup of parathyroid glands obtained from consecutive patients with pHPT in 2020 to 2021 underwent histological analysis.

RESULTS

A total of 428 patients with 638 diseased parathyroid glands were analyzed. Forty-seven percent of the glands showed an uptake on 99mTc-sestamibi scans. The brightness intensity of the NIRAF signals from parathyroid glands that were seen versus not seen on sestamibi was 2.1 versus 2.3 (P = .002) and HI 0.18 versus 0.17 (P = .35), respectively. On multivariate analysis, low autofluorescence intensity, high gland volume, and single adenoma were associated with detectability on 99mTc-sestamibi scan (P < .0001). Intraglandular adipose tissue content was lower in diseased glands that were detected on 99mTc-sestamibi scans (0% vs 5%, P < .0001).

CONCLUSION

Our findings indicate an inverse relationship between autofluorescence intensity and detectability on 99mTc-sestamibi scans and a lack of correlation between different cell types and autofluorescence properties.

Near-infrared autofluorescence pattern in parathyroid gland adenoma

BACKGROUND

Parathyroid gland (PG) surgery is often challenging due to the small size and indistinct nature of these glands. The introduction of intraoperative near-infrared autofluorescence (NIRAF) has shown promise in localizing parathyroid tissue. However, the NIRAF features of parathyroid adenomas remain unclear. The aim of this study is to assess the NIRAF pattern of parathyroid adenomas.

METHODS

Patients who underwent surgery for primary hyperparathyroidism at the University Hospital of Pisa, Endocrine Surgery Unit, between December 2021 and February 2022 were enrolled in this study. Intraoperative NIRAF patterns of suspected parathyroid adenomas were evaluated, with particular attention given to the presence of a bright cap.

RESULTS

A retrospective study was conducted on 11 patients with primary hyperparathyroidism who underwent parathyroidectomy at our institution. Histopathological examination of the 15 resected specimens confirmed 14 parathyroid adenomas (12 chief cell parathyroid adenomas, 1 oxyphil cell parathyroid adenoma, and 1 mixed cell parathyroid adenoma) and one schwannoma. All adenomas exhibited a heterogeneous NIRAF pattern, distinct from the homogeneous pattern observed in the schwannoma. A bright cap was identified in 9 out of 14 (64.3%) parathyroid adenomas (all chief cell adenomas). On the contrary, all 9 macroscopically normal PGs identified during surgery presented an homogeneous pattern.

CONCLUSION

Our findings support the integration of NIRAF into parathyroid surgical procedures. The heterogeneous NIRAF pattern observed in parathyroid adenomas, often accompanied by a bright cap, offers a promising intraoperative diagnostic tool to differentiate hyperfunctioning from normal parathyroid tissue. Larger-scale randomized trials are warranted to further validate these findings.

Near-Infrared Autofluorescence Signatures of Single- vs Multigland Disease in Primary Hyperparathyroidism

Importance

The success of parathyroidectomy depends on accurate intraoperative localization and identification of all diseased glands in parathyroid exploration based on surgeon expertise to prevent persistent hyperparathyroidism. Near-infrared autofluorescence (NIRAF) imaging has recently emerged as a promising adjunctive intraoperative tool for localizing parathyroid glands; however, its potential utility in the assessment of parathyroid glands has yet to be established.

Objective

To analyze the differences in NIRAF signatures of parathyroid glands in single vs multiple glands in primary hyperparathyroidism (pHPT).

Design, Setting, and Participants

This prospective diagnostic study analyzed in vivo NIRAF images of parathyroid glands obtained during parathyroidectomies between November 18, 2019, and December 31, 2023, at a single tertiary referral center. Pixel intensities of the images were measured using third-party software. Patients who underwent parathyroidectomy for sporadic pHPT using a second-generation NIRAF imaging device were included. Patients with multiple endocrine neoplasm disorders were excluded. In vivo NIRAF images obtained during the procedures were analyzed.

Exposure

Near-infrared autofluorescence imaging during parathyroidectomy.

Main Outcomes and Measures

The primary outcomes were the autofluorescence intensity and heterogeneity of single adenomas and multigland disease (ie, double adenomas and 3- or 4-gland hyperplasia) in sporadic pHPT. Normalized autofluorescence intensity was calculated by dividing the mean pixel intensity of the parathyroid gland by the background tissue. A heterogeneity index was calculated by dividing the standard deviation by the mean pixel intensity of the gland. The secondary outcome was the visibility of each parathyroid gland on NIRAF imaging before it became apparent to the naked eye during exploration.

Results

A total of 1287 in vivo NIRAF images obtained from 377 patients (median [IQR] age, 66 [56-73] years; 299 female [79.3%]) were analyzed. Of all patients, 230 (61.0%) had a single adenoma, 91 (24.1%) had double adenomas, and 56 (14.9%) had 3- or 4-gland hyperplasia. A mean (SD) of 3.4 (1.1) parathyroid glands were identified in the procedures. A comparison of 581 diseased glands (45.1%) and 706 normal glands (54.9%) showed a lower median normalized autofluorescence intensity of 2.09 (95% CI, 1.07-4.01) vs 2.66 (95% CI, 1.43-4.20; effect size = 0.36) and higher heterogeneity index of 0.18 (95% CI, 0.07-0.41) vs 0.11 (95% CI, 0.01-0.27; effect size = 0.45), respectively. Of diseased glands, single adenomas (233 [40.1%]) vs double adenomas (187 [32.2%]) and 3- or 4-gland hyperplasia (161 [27.7%]) had a lower median autofluorescence intensity of 1.92 (95% CI, 1.02-4.44) vs 2.22 (95% CI, 1.10-3.97; effect size = 0.21), respectively. On receiver operating characteristic analysis, the optimal autofluorescence intensity threshold to differentiate between single adenomas vs multigland disease was 2.14, with a sensitivity of 64.4%, specificity of 58.1%, and area under the curve of 0.626.

Conclusions and Relevance

These findings suggest that parathyroid glands in single- vs multigland disease may exhibit different autofluorescence characteristics. Although the effect size was modest, the differences identified should be kept in mind when assessing the parathyroid glands during surgical exploration.

Silicon-Rhodamine Functionalized Evocalcet Probes Potently and Selectively Label Calcium Sensing Receptors In Vitro, In Vivo, and Ex Vivo

The calcium sensing receptor (CaSR) is a ubiquitously expressed G-protein coupled receptor (GPCR) that regulates extracellular calcium signals via the parathyroid glands. CaSR has recently also been implicated in noncalcitropic pathophysiologies like asthma, gut inflammation, and cancer. To date, molecular tools that enable the bioimaging of CaSR in tissues are lacking. Based on in silico analyses of available structure-activity relationship data on CaSR ligands, we designed and prepared silicon-rhodamine (SiR) conjugates of the clinically approved drug evocalcet. The new probes EvoSiR4 and EvoSiR6, with differing linker lengths at the evocalcet carboxyl end, both showed a 6-fold and 3-fold increase in potency toward CaSR (EC50 < 45 nM) compared to evocalcet and the evocalcet-linker conjugate, respectively, in an FLIPR-based cellular functional assay. The specificity of the EvoSiR probes toward CaSR binding and the impact of albumin was evaluated in live cell experiments. Both probes showed strong albumin binding, which facilitated the clearance of nonspecific binding interactions. Accordingly, in zebrafish embryos, EvoSiR4 specifically labeled the high CaSR expressing neuromasts of the lateral line in vivo. EvoSiR4 was also assessed in human parathyroid tissues ex vivo, showing a specific absolute CaSR-associated fluorescence compared to that of parathyroid autofluorescence. In summary, functionalization of evocalcet by SiR led to the preparation of potent and specific fluorescent CaSR probes. EvoSiR4 is a versatile small-molecular probe that can be employed in CaSR-related biomedical analyses where antibodies are not applicable.

Heterogeneous parathyroid near-infrared autofluorescence patterns are associated with single adenomas in primary hyperparathyroidism

BACKGROUND

Primary adenoma (PA) and multi-gland hyperplasia (MGH) account for 85% and 15% of primary hyperparathyroidism (PHPT) cases, respectively. Near-infrared autofluorescence (NIRAF) enhances intraoperative parathyroid identification. We hypothesized that PA would display a more heterogeneous NIRAF pattern compared to MGH.

METHODS

Patients undergoing surgery for sporadic PHPT were categorized based on the presence of PA or MGH. To quantify heterogeneity, we utilized ratios of (1) mean parathyroid gland (PG) NIRAF over background NIRAF (mean ratio), (2) minimum and (3) maximum PG NIRAF over mean PG NIRAF (minimum and maximum ratios). Additionally, a heterogeneity score was quantified using mean ratio (mean PG NIRAF over background NIRAF), and overall NIRAF (mean NIRAF of eight random 15 × 15 pixel areas). A point was assigned to ratios <0.8 or >1.2. Images were quantified by ImageJ software. Mann-Whitney test was performed for all comparisons.

RESULTS

Of 78 patients, 63 had a single PA and 15 had MGH, totaling 102 PGs. There was no difference between their mean ratios. PA had a lower minimum ratio compared to that of MGH (0.86 ± 0.01 vs. 0.93 ± 0.01, p = 0.001) and a brighter maximum ratio (1.21 ± 0.02 vs. 1.12 ± 0.01, p = 0.0008). PA also scored higher on their heterogeneity scores compared to MGH (1.27 ± 0.23 vs. 0.33 ± 0.15, p = 0.001).

CONCLUSION

Single parathyroid adenomas display a more heterogeneous autofluorescence pattern compared to that of multi-gland hyperplasia. Intraoperative characterization of PGs by real-time NIR imaging patterns may be a beneficial adjunct during parathyroid surgery.

Feasibility of Autofluorescence Using Overlay Imaging for the Detection of Parathyroid Glands: Defining Standards

BACKGROUND

The aim of this study is to define standards for the use of near-infrared autofluorescence (NIRAF)-based overlay imaging via EleVision IR (Medtronic, Dublin, Ireland) and to evaluate its clinical applicability.

PATIENTS AND METHODS

This prospective study included 189 patients who had undergone open thyroid and/or parathyroid surgery and in whom EleVision IR was applied to visualize at least one parathyroid gland (PG) between January 2021 and May 2022 in a tertiary referral care center. Whether the PGs were first localized by the surgeon or by overlay imaging was noted. Handling of the device, application time and duration, distance, infrared intensity (IR%), and the angle of each measurement were analyzed. In thyroidectomies, the specimens were subsequently scanned for further PGs. NIRAF patterns and intensities were described.

RESULTS

Overall, 543 PGs were analyzed in 158 (83.6%) surgeries of thyroid glands (TGs) and in 49 (25.9%) surgeries for hyperparathyroidism. In 111 (58.7%) patients, identical numbers of PGs were detected by the surgeon and by overlay imaging. While a larger number of PGs was identified by the surgeon in 48 (25.4%) patients, overlay imaging served to detect more PGs in 30 (15.9%) cases. In four (2.1%) patients, PGs were visualized post-thyroidectomy due to their autofluorescence on the specimen. NIRAF-based overlay imaging was applied to depict the PGs early on after exposure by the surgeon. The ideal distance for the measurement ranged between 8 and 12 cm with an angle of 90° and a mean IR% of 34.5% (± 17.6).

CONCLUSIONS

Considering the standard operating procedures, NIRAF-based overlay imaging can be used as an adjunct tool for intraoperative localization.

Future Directions in the Treatment of Thyroid and Parathyroid Disease

The surgical management of thyroid and parathyroid disease has evolved considerably since the era of Theodor Kocher. We review the current trends in thyroid and parathyroid surgery concerning robotic surgery for remote access, the use of parathyroid autofluorescence detection technology to aid in the prevention of hypocalcemia as well as the use of thermal ablation to target thyroid nodules in a minimally invasive way. We also discuss how artificial intelligence is being used to improve the workflow and diagnostics preoperatively as well as for intraoperative decision-making. We also discuss potential areas where future research may enhance outcomes.

An update on the use of near-infrared autofluorescence imaging in endocrine surgical procedures

Over the past decade, near-infrared autofluorescence (NIRAF) imaging has been a major breakthrough in endocrine surgery. Although initial focus was directed at the parathyroid glands, subsequent work has also shown that non-parathyroid neuroendocrine tumors also possess autofluorescence properties. The aim of this review is to present an update and synopsis about NIRAF applications in various endocrine surgical procedures. Methodology includes a review of the literature supplemented with expert opinion. Overall, our review reveals that the use of NIRAF may provide the surgeon with adjunctive critical information that has the potential to change the conduct of many various endocrine surgical procedures.

Why does diseased parathyroid appear weak or heterogenous intensity during intraoperative near-infrared autofluorescence?

Background

During intraoperative autofluorescence, the imaging intensity of diseased parathyroid glands is often lower than that of normal parathyroid glands, and some diseased glands especially those in secondary hyperparathyroidism (HPT) show heterogeneous intensities. This study aimed to investigate the reasons for these findings.

Methods

After formalin and paraffin fixation and bivalve cutting, 18 diseased glands from patients with primary HPT, 35 diseased parathyroid glands from patients with uremic HPT, and the surrounding thyroid and thymus tissues were measured using near-infrared autofluorescence with a Fluorobeam imaging system (Fluoptics, France). None of the tissues were stained with indocyanine green. Hematoxylin and eosin staining matched the intensity of the autofluorescence.

Results

Using the bright white intensity of the adult normal parathyroid gland as a reference (index score of 2), the chief cells and oxyphilic cell tissues of the diseased parathyroid had the same intensity score of 2 as that of the normal parathyroid gland, and the clear water parathyroid cell had a weaker intensity score (1-1.5). Their glandular architecture, including the trabecular, follicular, or solid arrangements, did not affect the level of intensity. The thymus, thyroid, fat, fibrosis, and necrosis had very low intensities (scores of 0). The red blood cell-hemorrhage appeared dark black (intensity score -1). The thickness of the fibrotic capsule varied in the diseased parathyroid glands; however, only a very thin capsule was observed in the normal parathyroid glands.

Conclusions

Various degrees of fibrotic capsules in the diseased parathyroid gland may be the main factor contributing to the lower intensity during autofluorescence, and different cell types, necrosis, fibrosis, and hemorrhage may explain the appearance of heterogeneous intensity in the diseased parathyroid glands.

Converting a probe-based fluorescence system into an easy-to-use adjunct for the detection of parathyroid glands accidentally resected intraoperatively

PURPOSE

The reported threshold of a near-infrared fluorescence detection probe (FDP) for judging parathyroid glands (PGs) is based on the autofluorescence intensity relative to other non-PG tissues, making it unreliable when not enough reference tissues are measured. We aim to convert FDP into a more convenient tool for identifying accidentally resected PGs by quantitative measurements of autofluorescence in resected tissues.

METHODS

It was a prospective study approved by the Institutional Review Board. The research was divided into two stages: (1) In order to calibrate the novel FDP system, autofluorescence intensity of different in / ex vivo tissues was measured and the optimal threshold was obtained using receiver operating characteristic (ROC) curve. (2) To further validate the effectiveness of the new system, detection rates of incidental resected PGs by pathology in the control group and by FDP in the experimental group were compared.

RESULTS

Autofluorescence of PGs was significantly higher than that of non-PG tissue (43 patients, Mann-Whitney U test, p < 0.0001). An optimal threshold of sensitivity / specificity (78.8% and 85.1%) for discriminating PGs was obtained. The detection rates of experimental group (20 patients) and control group (33 patients) are 5.0% and 6.1% respectively (one-tailed Fisher's exact test, p = 0.6837), indicating the novel FDP system can achieve a similar proportion of PG detection compared with pathological examinations.

CONCLUSIONS

The novel FDP system can be used as an easy-to-use adjunct for detecting PG accidentally resected intraoperatively before the tissues are sent for frozen sections during thyroidectomy surgeries.

TRIAL REGISTRATION

Registration number: ChiCTR2200057957.

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.

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.

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.

Preliminary experience with the EleVision IR system in detection of parathyroid glands autofluorescence and perfusion assessment with ICG

BACKGROUND

Postoperative hypoparathyroidism remains the most frequent complication of neck endocrine surgery. In order to reduce the incidence of this feared complication, several systems for imaging of near infrared autofluorescence (NIRAF) have been invented to help surgeons identify parathyroid glands (PTGs) and evaluate their vascularization. We evaluated the efficacy of the EleVision IR system in thyroid and parathyroid surgery.

METHODS

We used the EleVision IR system in 25 patients who underwent thyroid/parathyroid surgery or both at our institution between December 2020 and July 2021. At various stages of the surgery, the surgeon first looked for PTGs with the naked eye and then completed the visual inspection with NIRAF imaging. We then compared both the naked eye and NIRAF-supported PTGs detection rates. At the end of surgery, we performed indocyanine green angiography of PTGs in 17 patients.

RESULTS

In total, we identified 80% of PTGs: 65% with the naked eye only and additional 15% with the assistance of the EleVision IR system. 14 of 17 patients evaluated by ICG angiography had at least one well-vascularized PTG. Only one of these patients (a case of subtotal parathyroidectomy for tertiary hyperparathyroidism) developed symptomatic postoperative hypocalcemia despite a normal parathormone level. The three other patients had at least one remaining moderately-vascularized PTG and only one patient developed transient postoperative hypoparathyroidism.

CONCLUSION

We concluded that EleVision IR provides an efficient support for identification and evaluation of PTGs, and may be of great assistance in endocrine surgery. The images are easy to interpret even for less experienced surgeons thanks to the different types of color visualization and the possibility to measure the relative fluorescence intensity of PTGs and surrounding tissues.

Parathyroid Gland Autofluorescence Characteristics in Patients With Primary Hyperparathyroidism

OBJECTIVE

Near-infrared imaging for intraoperative parathyroid gland (PG) detection has recently commanded significant attention. The PTeye (Medtronic, Minneapolis, MN) is a probe-based system for near-infrared autofluorescent evaluation of PGs. This study was designed to evaluate the capabilities of the PTeye in the setting of surgery for primary hyperparathyroidism.

STUDY DESIGN

Prospective, Cohort study.

METHODS

This single-institution, prospective cohort study included all patients undergoing parathyroidectomy for primary hyperparathyroidism with presumed single gland disease from June 2020 to December 2020. Absolute intensity and intensity ratios, with the thyroid as the control tissue, were obtained for the adenoma, ipsilateral normal PG, and adjacent tissue. The ability of the PTeye to function when not in direct contact with tissue was measured.

RESULTS

Twenty-two patients were included. The median intensity ratio for the in situ adenomas was 4.38 (interquartile range [IQR]: 2.03-5.87), ipsilateral normal PGs 6.17 (IQR: 3.83-7.67), strap muscle 0.47 (IQR: 0.30-0.60), and fat 0.20 (IQR: 0.17-0.47). All normal PGs and 21/22 adenomas demonstrated autofluorescence above the detection threshold. The PTeye functioned at a maximum distance of separation of 10 mm through saline medium and 6 mm through clear solid medium.

CONCLUSION

This study confirms the PTeye's ability to recognize PGs with a high degree of precision. The device was found to function properly even with the probe not in direct contact with the tissue. Although adenomatous PGs appear to demonstrate altered autofluorescent properties from normal PGs, additional research is required to determine if these differences are clinically useful.

LEVEL OF EVIDENCE

3 Laryngoscope, 2021.

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.