The efficacy of technetium-99m-MIBI scan and intraoperative methylene blue staining for the localization of abnormal parathyroid glands

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.

The utility of indocyanine green near infrared fluorescent imaging in the identification of parathyroid glands during surgery for primary hyperparathyroidism

BACKGROUND AND OBJECTIVES

Intraoperative adjuncts for the localization of parathyroid glands in parathyroid surgery are limited. The aim of this study is to assess the usefulness of indocyanine green (ICG) near-infrared (NIR) fluorescent imaging in patients undergoing surgery for primary hyperparathyroidism (PHPT).

METHODS

ICG imaging was performed in 33 patients undergoing parathyroidectomy (PTX). Thyroid and parathyroid ICG uptake were assessed and independently verified on a grading scale. Clinical variables were recorded and analyzed for factors associated with ICG uptake.

RESULTS

Of 112 glands identified by naked eye, 104 (92.9%) demonstrated ICG uptake. Concomitant ICG fluorescence was identified in the thyroid in all patients. There was a trend toward increased ICG fluorescence in patients <60 years of age (P = 0.05). A higher degree of fluorescence was seen in patients presenting with pre-operative calcium values >11 mg/dl (P = 0.04) and in those parathyroids larger than 10 mm (P < 0.01). All patients had biochemically proven cure. No patients who underwent subtotal PTX (n = 6) developed postoperative hypoparathyroidism.

CONCLUSION

ICG can reliably localize parathyroid glands during PTX and additionally allow for assessment of parathyroid perfusion in patients undergoing subtotal resection. Concomitant fluorescence of the thyroid gland limits ICG's usefulness in directing the course of PTX. J. Surg. Oncol. 2016;113:771-774. © 2016 Wiley Periodicals, Inc.

Identification of pathological and normal parathyroid tissue by fluorescent labeling with 5-aminolevulinic acid during endocrine neck surgery

BACKGROUND

When performing parathyroid or thyroid surgery, surgeons must distinguish parathyroid tissue from the surrounding thyroid tissue, to preserve healthy parathyroid tissue while excising diseased thyroid tissue or to completely remove pathological parathyroid lesions. Here, we explored the feasibility of labeling the parathyroid glands for easy identification by administering 5-aminolevulinic acid (5-ALA) orally to patients undergoing endocrine neck surgery, because 5-ALA accumulates in the parathyroid and has a fluorescent metabolite, protoporphyrin IX.

METHODS

Twenty-nine patients about to undergo endocrine (parathyroid or thyroid gland) neck surgery were orally given 5-ALA, a nontoxic substance that occurs naturally in the human body and has no known major side effects. During surgery, we used blue light to excite protoporphyrin IX, the fluorescent metabolite of 5-ALA, and viewed the resulting bright red fluorescence through an optical filter.

RESULTS

In the majority of the patients, the parathyroid glands were defined by a clear fluorescence. In 23 patients with pathological parathyroid tissue, the fluorescence enabled us to identify and completely remove diseased parathyroid tissue. In 3 patients with thyroid disease, we were able to easily remove diseased thyroid tissue, and an accidentally removed parathyroid gland was autotransplanted during surgery.

CONCLUSIONS

In all but a few cases, 5-ALA clearly labeled parathyroid tissue, allowing for its clean removal or preservation according to the purpose of the surgery. This simple, benign technique is extremely useful for identifying parathyroid tissue, whether pathological or normal, during endocrine neck surgery.

Systematic review of intravenous methylene blue in parathyroid surgery

Background

Methylene blue is an intraoperative adjunct for localization of enlarged parathyroid glands. The availability of preoperative and other intraoperative localization methods, and the reported adverse effects of methylene blue make its routine use debatable. The aim of this study was to perform a systematic review of the use of methylene blue in parathyroidectomy.

Methods

A systematic review of English-language literature in MEDLINE and Scopus databases on the use of intravenous methylene blue in parathyroid surgery was carried out.

Results

There were no randomized clinical trials. Thirty-nine observational studies were identified, of which 33 did not have a control arm. The overall median staining rate for abnormal parathyroid glands was 100 per cent. The median cure rates in the methylene blue and no-methylene blue arms were 100 and 98 per cent respectively. Neurotoxicity was reported in 25 patients, all of whom were taking serotonergic medication.

Conclusion

Observational evidence suggests that methylene blue is efficacious in identifying enlarged parathyroid glands. Toxicity appears to be mild in the absence of concomitant use of serotonin reuptake inhibitors. The effectiveness of methylene blue in the context of currently used preoperative and intraoperative localization techniques has yet to be shown.

Intraoperative photodynamic detection of normal parathyroid glands using 5-aminolevulinic acid

OBJECTIVE

It is important to identify and save the normal parathyroid glands during head and neck surgery because of their role in regulating the blood calcium level, yet it is often difficult to localize normal parathyroid glands during surgery. Fluorescence-guided parathyroidectomy in patients with hyperparathyroidism has already proved useful. However, there are few reports of fluorescence-guided localization of normal parathyroid glands in humans. We investigated the utility of fluorescence-guided localization of normal parathyroid glands during thyroidectomy and completed a spectral fluorescence analysis of the accumulation of 5-aminolevulinic acid metabolites in the parathyroid glands.

METHODS

Eight patients with benign thyroid disease and five with malignant thyroid tumors were given 20 mg/kg body weight of 5-aminolevulinic acid orally 5 hours before surgery. After the posterior surface of the thyroid gland was exposed and the recurrent laryngeal nerve was identified, we illuminated the area with a violet-blue light of 405 nm. Tissues showing red fluorescence were biopsied to analyze the spectral fluorescence.

RESULTS

Under the violet-blue light, normal parathyroid glands showed red fluorescence, while the surrounding structures such as the thyroid gland, muscles, and fat remained nonfluorescent. The spectral peak was observed at 635 nm indicating 5-aminolevulinic acid metabolites. Histopathologically, the biopsied tissue corresponded to normal parathyroid glands.

CONCLUSIONS

5-Aminolevulinic acid is useful to localize the normal parathyroid glands during thyroid surgery in humans.

Intraoperative adjuncts in surgery for primary hyperparathyroidism

PURPOSE

This paper is a review of the evidence base to produce recommendations for the use of intraoperative parathyroid hormone (PTH), radioguided parathyroidectomy (RGP), methylene blue (MB), frozen section, and intraoperative neuromonitoring during surgery for primary hyperparathyroidism (PHPT).

MATERIALS AND METHODS

A Medline keyword search of English-language articles led to the production of a draft document, subsequently revised by committee, containing levels of evidence and the grading of recommendations as proposed by the Agency for Healthcare Research and Quality.

RESULTS

Literature review provides the basis for clear recommendations on the use of intraoperative PTH at surgery for PHPT. There is little evidence to support the use of RGP, MB, routine frozen section, and intraoperative neuromonitoring.

History of parathyroid gland surgery: an historical case series

The history of the parathyroid glands is a fascinating one full of famous medical names. The discovery of the glands was followed by laborious research into their anatomy, embryology and pathology and into the physiology of calcium metabolism; this led to the manufacture of hormone substitutes and, finally, to the refinement of surgical techniques. The glands were first identified in 1850 by Sir Richard Owen, conservator of the Hunterian Museum, but it was not until 1880 that the term 'glandulae parathyroideae' was first used. The physiology of parathyroid hormone and calcium metabolism eluded physicians and the forefathers of thyroid surgery alike for several decades more. Patients were treated as curiosities and were documented as untreatable medical patients or as inexplicable thyroid surgery complications. Halsted noticed the 'disastrous results from the loss of the glands' and the resulting tetany, as did Billroth. It is the patients, however, who best illustrate the journey of discovery. In this review, we discuss three cases, highlighting their contributions.

A systematic review of the diagnosis and treatment of primary hyperparathyroidism from 1995 to 2003

OBJECTIVE

To systematically review the current preoperative diagnostic modalities, surgical treatments, and glandular pathologies associated with primary hyperparathyroidism.

STUDY DESIGN

A systematic literature review.

RESULTS

Of the 20,225 cases of primary hyperparathyroidism reported, solitary adenomas (SA), multiple gland hyperplasia disease (MGHD), double adenomas (DA), and parathyroid carcinomas (CAR) occurred in 88.90%, 5.74%, 4.14%, and 0.74% of cases respectively. Tc 99m -sestamibi and ultrasound were 88.44% and 78.55% sensitive, respectively, for SA, 44.46% and 34.86% for MGHD, and 29.95% and 16.20% for DA, respectively. Postoperative normocalcemia was achieved in 96.66%, 95.25%, and 97.69% of patients offered minimally invasive radio-guided parathyroidectomy (MIRP), unilateral, and bilateral neck exploration (BNE). Intraoperative PTH assays (IOPTH) were helpful in approximately 60% of bilateral neck exploration conversion (BNEC) surgeries.

CONCLUSION

The overall prevalence of multiple gland disease (MGD and DA) was lower than often suggested by conventional wisdom. Furthermore, preoperative imaging was less accurate than it is often perceived for accurately imaging MGD. MIRP and UNE were more successful in achieving normocalcemia than is typically quoted. IOPTH was a helpful but not "fool-proof" adjunct in parathyroid exploration surgery.

SIGNIFICANCE

These results support a greater role for the treatment of primary hyperparathyroidism using less invasive approaches. EMB rating: B-3.

The cost-effectiveness of sestamibi scanning compared to bilateral neck exploration for the treatment of primary hyperparathyroidism

This article presents a cost-effectiveness analysis to determine whether preoperative imaging with Tc99m-sestamibi for detection and treatment of solitary adenomas associated with primary hyperparathyroidism is cost-effective compared with routine bilateral neck exploration.

Clinical outcomes and fiscal consequences of bilateral neck exploration for primary idiopathic hyperparathyroidism without preoperative radionuclide imaging or minimally invasive techniques

BACKGROUND

Radionuclide imaging-directed, minimally invasive parathyroid operation is promoted in the surgical literature and public domain as the fastest, most successful, and cheapest means of treating primary idiopathic hyperparathyroidism. The validity of these claims is unproven. This study reviews the treatment outcome results of a large series of patients treated with standard parathyroid operation without preoperative localization studies. Cost comparisons are made between this series and previous reports of selected patients in whom preoperative radionuclide imaging preceded minimally invasive parathyroid operation.

METHODS

Diagnosis, treatment, and outcome data for 688 consecutive patients undergoing first neck exploration for primary idiopathic hyperparathyroidism were prospectively collected. All patients in our series underwent standard bilateral neck exploration without preoperative localization studies. Intraoperative methylene blue was used to aid identification of all parathyroid glands. Surgical findings, pathological diagnosis, operative time, length-of-stay, and treatment success data were collected. Cost data were calculated for our series using the identical calculations used in previous reports. Our outcome and calculated cost data were compared with previous reports by centers advocating scan-directed, minimally invasive parathyroid operation.

RESULTS

Of 2,752 predicted total glands, 2,520 (91.6%) were identified using standard neck exploration without radionuclide localization studies. Single adenoma, with at least 1 normal gland, was found in 542 patients (78.8%), with 8 in a fifth gland. Multiple-gland hyperplasia was identified in 98 patients (14.2%) and of these 22 (3.2%) were double adenomas. Ten patients had parathyroid carcinoma (1.5%), and all received definitive surgical treatment during the primary operation. Cure rates were assessed by measurement of normal serum calcium and parathyroid hormone levels at 3 and 12 months after operation, and were 97.7% in our series. Mean operating time for the entire series was 65 minutes, decreased to 35 minutes in patients with single adenomas, and mean recovery room time was 30 minutes. Mean total costs for patients undergoing standard exploration for single adenoma was US dollars 1,107, and increased to US dollars 1,243 when patients with multigland disease, hyperplasia, or malignancy were included.

CONCLUSIONS

Our series demonstrates operative times and treatment outcomes with costs that are approximately one-third less than those for scan-directed, minimally invasive operation for primary idiopathic hyperparathyroidism. Thus, claims that scan-directed parathyroid operation is the cheapest, fastest, and most successful means of treatment are not supported by these data.

Methylene blue and sestamibi: complementary tools for localizing parathyroids

OBJECTIVE

To determine the value and correlation between sestamibi scan and methylene blue staining for localization of parathyroid glands in patients with primary hyperparathyroidism.

STUDY DESIGN

Nonrandomized convenience sample, followed prospectively.

METHODS

Twenty-three consecutive patients underwent 24 operations for primary hyperparathyroidism. All patients underwent preoperative technetium 99m-sestamibi planar scintigraphy, preoperative administration of 7.5 mg/kg methylene blue initiated within 60 minutes of surgical incision, and surgical neck exploration supervised by a single surgeon.

RESULTS

All patients were cured of hypercalcemia. Sensitivity for sestamibi and for methylene blue staining was 76% and 79%, respectively. Specificity for sestamibi and for methylene blue was 98% and 93%, respectively. Agreement between sestamibi and methylene blue was 96%.

CONCLUSIONS

Sestamibi scanning and methylene blue staining are useful, complementary localizing tools for patients undergoing surgery for primary hyperparathyroidism. When used together, these studies decrease operative time, justify unilateral exploration in patients with parathyroid adenoma, and increase the ease of identification of hyperplastic parathyroid glands.