Total thyroidectomy with intraoperative neural monitoring and near-infrared fluorescence imaging

Will the autofluorescence take over inadvertent parathyroidectomy? Results from a multicentre cohort study

BACKGROUND

Recently, several devices exploiting the near-infrared autofluorescence (NIR-AF) of parathyroid glands (PGs) have been developed. Nevertheless, their impact on both preserving PGs from inadvertent surgical dissection and on post-surgical hypoparathyroidism (hypoPTH) is controversial.

METHODS

A retrospective study of 845 patients undergoing thyroid surgery in 2 academic tertiary centres was conducted. In 291 patients, a NIR-AF device was used during surgery to identify PGs. The characteristics of the cohort were examined. The number of PGs identified during surgery, missed PGs, auto-transplants, inadvertent parathyroidectomies, as well as the occurrence of transient and permanent hypoPTH, were analysed.

RESULTS

The use of NIR-AF device resulted in a higher identification of PGs (92% versus 88%, p = 0.0008), and a significant reduction in the number of PGs inadvertently removed and detected on histopathological examination (4.7% versus 6.5%, p = 0.045). An increase in PG auto-transplantations was observed in the NIR-AF + group (10.4% versus 3.5%, p < 0.0001). The use of NIRAF did not significantly impact the occurrence of either transient or permanent hypoPTH.

CONCLUSION

Intraoperative NIR-AF detection is a promising technology to reduce incidental parathyroidectomies in thyroid surgery. The impact of this technology on the occurrence of post-surgical hypoPTH needs to be furtherly investigated.

Enamel microcrack inspection using near-infrared light transillumination with fluorescence staining

Enamel microcracks are often apparent in the teeth of elderly individuals. However, accurate clinical diagnosis of enamel microcracks is very difficult. The purpose of this study was to examine the utility of inspections for enamel microcracks using a near-infrared light transillumination device with fluorescence staining. Human upper incisors with typical enamel microcracks were selected. Grayscale pictures of each tooth specimen were then taken by digital camera under visible light as control. Every tooth specimen was stained using indocyanine green solutions, then examined, and photographed under visible light. All digital images were compared with the background enamel surface and measured using image analysis software. Inspection using near-infrared light transillumination with indocyanine green solution was effective for detecting the presence of enamel microcracks. This method offers a non-invasive method of chair-side diagnosis and appears effective for detecting the presence of enamel microcracks.

Near-Infrared Autofluorescence or Intraoperative Parathyroid Hormone Determination as a Surgical Support Tool in Primary Hyperparathyroidism: Too Close to Call?

Background: This study investigates the use of near-infrared fluorescence imaging (NIFI) as an alternative to intraoperative parathyroid hormone (ioPTH) measurement in patients with primary hyperparathyroidism (PHP) due to parathyroid adenoma (PA) with two preoperative imaging examinations in agreement on the position of the altered parathyroid gland. Methods: Fifty patients who underwent minimally invasive parathyroidectomy (MIP) from March 2021 to April 2024 were enrolled. MIPs utilised both NIFI and ioPTH, comparing the time to adenoma excision with NIFI against the total surgical time, including ioPTH measurement wait time. Results: Results showed successful MIPs in all patients, with a mean excision time of 44.7 min (SD ± 25.2) and a total procedure time of 85.5 min (SD ± 37.1). The median of the duration of the surgical procedure until adenoma excision was 35.0 min (IQR 38.8), while the median duration of the entire procedure was 74.5 min (IQR 40.5). This difference in medians is statistically significant using the Wilcoxon non-parametric test for paired samples (p < 0.001). The average wait for ioPTH results post-excision was 37 min (SD ± 12.2). Three fluorescence patterns were identified: "cap" (46%), heterogeneous (30%), and homogeneous (24%). Conclusions: If preoperative imaging confirms PA location, NIFI could replace ioPTH reducing surgical time without compromising success rates.

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.

The use of near-infrared autofluorescence during total laryngectomy with hemi- or total thyroidectomy

PURPOSE

The aim of this study is to describe the use of near-infrared autofluorescence (NIR-AF) to identify and preserve parathyroid glands (PGs) in a group of patients with advanced hypopharyngeal/laryngeal cancer undergone total (pharyngo)laryngectomy with hemi- or total thyroidectomy.

METHODS

At San Raffaele Hospital, Milan (Italy), from January 2021 to May 2021, 7 patients affected by cT4a laryngeal squamous cell carcinoma (SCC) underwent surgery using an autofluorescence detection system (Fluobeam-Fluoptics^®). For proper surgical planning, the demolition phase envisaged extension of the intervention to 4 hemithyroidectomies and 3 total thyroidectomies associated, respectively, with homolateral or bilateral CCND. Serum calcium, ionized calcium, and parathyroid hormone (PTH) levels at post-operative day (POD) 1 and 2 and at 2 weeks after surgery were monitored. Finally, we compared the data obtained with a cohort of patients who underwent surgery without the adoption of NIR-AF.

RESULTS

With the use of NIR-AF, 18/20 PGs were identified, of which 7/18 were preserved exclusively thanks to the use of autoflorescence. The technique also made it possible to identify and isolate three PGs from the surgical specimen, which were subsequently transplanted only after intraoperative histological confirmation. On POD-1, 3/7 patients (42.8%) were hypocalcemic; on POD-2 and after 2 weeks only 1/7 patient (14.2%) was hypocalcemic. Comparing the two groups, we highlighted that the utilization of NIR-AF was related to a significant decrease of median serum (p = 0.026) and ionized calcium levels (p = 0.017) 2 weeks after surgery. Using this new technology, in no case did definitive histological examination reveal the presence of PGs in the surgical specimen, reaching an accuracy of 100%.

CONCLUSIONS

In our cohort of patients who underwent total (pharyngo)laryngectomy with hemi- or total thyroidectomy, the use of near-infrared autofluorescence improved medium term postoperative hypocalcemia rates. This new technology helps to achieve a better calcemic outcome compared to the standard naked eye approach, since it helps the surgeon to identify and preserve parathyroid glandular tissue with a lower incidence of post-operative hypocalcemia.

Use of fluorescence imaging and indocyanine green during thyroid and parathyroid surgery: Results of an intercontinental, multidisciplinary Delphi survey

BACKGROUND

In recent years, fluorescence imaging-relying both on parathyroid gland autofluorescence under near-infrared light and angiography using the fluorescent dye indocyanine green-has been used to reduce risk of iatrogenic parathyroid injury during thyroid and parathyroid resections, but no published guidelines exist regarding its use. In this study, orchestrated by the International Society for Fluorescence Guided Surgery, areas of consensus and nonconsensus were examined among international experts to facilitate future drafting of such guidelines.

METHODS

A 2-round, online Delphi survey was conducted of 10 international experts in fluorescence imaging use during endocrine surgery, asking them to vote on 75 statements divided into 5 modules: 1 = patient preparation and contraindications to fluorescence imaging (n = 11 statements); 2 = technical logistics (n = 16); 3 = indications (n = 21); 4 = potential advantages and disadvantages of fluorescence imaging (n = 20); and 5 = training and research (n = 7). Several methodological steps were taken to minimize voter bias.

RESULTS

Overall, parathyroid autofluorescence was considered better than indocyanine green angiography for localizing parathyroid glands, whereas indocyanine green angiography was deemed superior assessing parathyroid perfusion. Additional surgical scenarios where indocyanine green angiography was thought to facilitate surgery are (1) when >1 parathyroid gland requires resection; (2) during redo surgeries, (3) facilitating parathyroid autoimplantation; and (4) for the predissection visualization of abnormal glands. Both parathyroid autofluorescence and indocyanine green angiography can be used during the same procedure and employing the same imaging equipment. However, further research is needed to optimize the dose and timing of indocyanine green administration.

CONCLUSION

Though further research remains necessary, using fluorescence imaging appears to have uses during thyroid and parathyroid surgery.

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

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