Current practice in the surgical management of parathyroid disorders: a United Kingdom survey

Utility of Intraoperative Intrinsic Near-Infrared Imaging for Primary Hyperparathyroidism in Multiple Endocrine Neoplasia Type 1

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder caused by mutations in the tumor suppressor gene MEN1 and is characterized by parathyroid, pancreatic islet, and anterior pituitary tumors. Primary hyperparathyroidism is the most characteristic finding in MEN1, and intraoperative identification and accurate removal of the diseased parathyroid glands are vital since incomplete excision results in recurrence. This case report describes a 59-year-old woman who had pancreatic islet cell tumors and pituitary tumors and underwent selective transsphenoidal adenomectomy. Based on her medical history and examination, the diagnosis of primary hyperparathyroidism in MEN1 was made, and she underwent total parathyroidectomy with autotransplantation with SPY-Elite®️ Fluorescence Imaging (Stryker Corp., Kalamazoo, MI). Intraoperative identification of the parathyroid glands using autofluorescence with real-time intrinsic near-infrared (NIR) imaging made it easier to detect all of the parathyroid hyperplasia. After the surgery, she had hypoparathyroidism and continued with her oral calcium and vitamin D supplementation to maintain normal calcium levels during follow-up. Herein, we would like to advocate that the use of parathyroid gland autofluorescence with real-time intrinsic NIR imaging may be useful for identifying parathyroid tumors in patients with primary hyperparathyroidism in MEN1.

Near-infrared fluorescent imaging for parathyroid identification and/or preservation in surgery for primary hyperparathyroidism

Introduction

Near infrared autofluorescence (NIRAF) is a novel intraoperative technology that has shown promising results in the localisation of parathyroid glands (PGs) over the last decade. This study aimed to assess the potential utility of NIRAF in first time surgery for primary hyperparathyroidism (PHPT).

Methods

An observational study over a period of 3 years in patients who underwent surgery for PHPT was designed. Data on the use of NIRAF and fluorescent patterns in different organs (thyroid and parathyroid) and parathyroid pathology (single versus multi-gland disease) were explored. In addition, cure rates and operating times were compared between the NIRAF and no-NIRAF groups to determine the potential value of NIRAF in this cohort.

Results

In 230 patients undergoing first time surgery for PHPT, NIRAF was used in 50 patients. Of these 50 patients, NIRAF was considered to aid parathyroid identification in 9 patients (18%). The overall cure rate at 6 months of follow-up was 96.5% (98% in NIRAF and 96.1% without NIRAF; p=1.0). The median (interquartile range) operating time was longer in the NIRAF arm at 102 minutes (74-120 minutes) compared to the no-NIRAF arm at 75 minutes (75-109 minutes); however, this difference was not statistically significant (p=0.542). Although the median parathyroid to thyroid (P/T) auto-fluorescence (AF) ratio was similar between single gland and multi gland disease (2.5 vs to 2.76; p=1.0), the P/T AF ratio correlated negatively with increasing gland weight (p=0.038).

Conclusion

The use of NIRAF resulted in some potential "surgeon-perceived" benefit but did not lead to improvements in cure rates. The negative correlation between fluorescent intensity and gland weight suggests loss of fluorescence with pathology, which needs further investigation. Further studies on larger cohorts of patients, in depth analysis of fluorescence patterns between normal, adenomatous, and hyperplastic glands and evaluation of user experience are needed. Primary hyperparathyroidism, hyperparathyroidism, autofluorescence, near-infrared fluorescence, parathyroid glands, endocrine, surgery.

Stepwise Approach for Parathyroid Localisation in Primary Hyperparathyroidism

INTRODUCTION

Primary hyperparathyroidism (PHPT) is a relatively common condition in surgical practice. Availability of localisation studies has shifted the treatment from bilateral neck exploration to selective parathyroidectomy. Several imaging modalities, each with varying sensitivities, are available to detect abnormal parathyroid glands. Ultrasound is almost universally accepted as the first line radiological investigation however its sensitivity is particularly heterogeneous and operator-dependent.

MATERIAL AND METHODS

We studied 250 consecutive patients with PHPT who underwent parathyroidectomy in our hospital over a period of 33 months. Pre-operative neck ultrasound, 99mTc-sestamibi and single-photon emission computed tomography (SPECT CT) were performed in 249, 237 and 198 patients respectively. Unilateral and bilateral neck exploration was performed in 190 and 60 patients, respectively. Sensitivity, positive predictive value (PPV) and accuracy were calculated comparing the results with surgical and pathology findings.

RESULTS

Mean pre and postoperative PTH and adjusted calcium were, 11 ± 10.6 pmol/L, 1.9 ± 3.6, 2.81 ± 0.2 and 2.45 ± 0.2 mmol/L. There were 71 (29.95%) discordant results between US, compared to sestamibi and SPECT CT. An average of 1.9 parathyroid glands were removed with a mean weight of 0.92 g. Overall success rate based on postoperative PTH levels was 94.8%. Overall sensitivity, PPV and accuracy for US were 80.80%, 92.35%, and 75.73% respectively; for sestamibi were 71.82%, 94.61%, 69.00% and for SPECT CT were; 70.21%, 97.78%, 69.11% respectively.

CONCLUSION

Ultrasound performed by an experienced specialist sonographer is highly sensitive in localising abnormal parathyroid glands. It can be used as a main and sole investigation in the majority of patients. Sestamibi, SPECT CT and other investigations should be performed in a step-wise manner and reserved for patients with negative US, failed primary procedure and recurrences.

Intraoperative Probe-Based Confocal Endomicroscopy to Histologically Differentiate Thyroid From Parathyroid Tissue Before Resection

BACKGROUND

Frozen section is the standard method to histologically distinguish parathyroid tissue from thyroid tissue during endocrine neck surgery. Frozen section can be time-consuming and costly. Its drawback is that it is to be performed only after the removal of a suspected pathological tissue. This study demonstrates the use of probe-based confocal laser endomicroscopy (pCLE) to confirm histology prior to tissue resection.

DESIGN

A prospective, single-institution, nonrandomized study was conducted. No sample size calculation was performed for this observational trial. The primary objective was the description of histological rendering of normal and pathological tissues through pCLE. Real-time in vivo fluorescence microscopy imaging was performed with the CystoFlex UHD probe after intravenous injection of 2.5 mL of 10% fluorescein sodium.

RESULTS

Eleven patients with hyperparathyroidism and thyroid conditions were included. A total of 104 videos showing thyroid, parathyroid, adipose tissue, muscle, laryngeal nerve, and lymph nodes were recorded. Videos were compared with visual information and pathological samples (when sampling was indicated). Thyroid tissue could be identified based on the presence of colloid follicles (intensely fluorescent area surrounded by a small ridge of low-fluorescence epithelial cells) including the pathognomonic aspect of resorption vacuole. Parathyroid tissue could be identified based on a regular, "diamond-shaped" capillary network encompassing parathyroid chief cells. Blinded reinterpretation of pCLE videos demonstrated an 89.3% sensitivity and a 90% specificity as compared with histology in tissue recognition.

CONCLUSION

This pilot study describes representative renderings of intraoperative pCLE to nontraumatically differentiate thyroid, parathyroid, and lymph nodes before surgical removal.

Preoperative Localization Studies in Primary Hyperparathyroidism

Primary hyperparathyroidism (pHPT) is the third most frequently seen endocrine disease and it is the most common cause of hypercalcemia seen in ambulatory patients. PHPT is most often (80%-85%) caused by a single parathyroid adenoma, followed by double adenoma (4%-5%), multiple gland hyperplasia (10%-15%), and parathyroid carcinoma (<1%). The diagnosis of pHPT is biochemically established and the only curative treatment is surgery. Since the cause of pHPT is typically single-gland disease, it is possible to determine the majority of pathological glands with preoperative localization methods and use the minimally invasive parathyroidectomy (MIP) approach. MIP has become the standard treatment for pHPT in selected patients. There are both noninvasive and invasive preoperative localization methods. Noninvasive methods currently used include ultrasonography (US), parathyroid scintigraphy, 4-dimensional computed tomography (CT), magnetic resonance imaging, and positron emission tomography-CT with 18F-fluoroquinolone and 11C-methionine. Preoperative invasive localization methods include parathyroid hormone (PTH) measurement with fine-needle aspiration biopsy, lateralization with PTH measurement via bilateral jugular vein sampling, selective venous sampling, and parathyroid arteriography. The aim of this study was to evaluate preoperative localization studies used in cases of pHPT.