Improved preoperative planning for directed parathyroidectomy with 4-dimensional computed tomography

BACKGROUND

Four-dimensional computed tomography (4D-CT) provides both functional and highly detailed anatomic information about parathyroid tumors. The purpose of this study was to compare 4D-CT with sestamibi imaging and ultrasonography as methods for the accurate preoperative localization of hyperfunctioning parathyroid glands before parathyroidectomy.

METHODS

A study of 75 patients with primary hyperparathyroidism was performed at a tertiary-care institution. Sestamibi imaging, ultrasonography, and 4D-CT were performed on each patient preoperatively. Results of the imaging studies were compared with operative findings, pathologic data, and biochemical measurements to assess the sensitivity and specificity of each of the imaging modalities.

RESULTS

4D-CT demonstrated improved sensitivity (88%) over sestamibi imaging (65%) and ultrasonography (57%), when the imaging studies were used to localize (lateralize) hyperfunctioning parathyroid glands to 1 side of the neck. Moreover, when used to localize parathyroid tumors to the correct quadrant of the neck (ie, right inferior, right superior, left inferior, or left superior), the sensitivity of 4D-CT (70%) was significantly higher than sestamibi imaging (33%) and ultrasonography (29%).

CONCLUSION

4D-CT provides significantly greater sensitivity than sestamibi imaging and ultrasonography for precise (quadrant) localization of hyperfunctioning parathyroid glands. This allows improved preoperative planning, particularly for the case of reoperation. In addition to the data that are provided, we present a novel classification scheme for use in parathyroid localization.

99Tcm sestamibi--a new agent for parathyroid imaging

Parathyroid imaging using 99Tcm sestamibi has been carried out prior to surgery in five patients with hyperparathyroidism and the results compared with a standard preoperative localization technique using 201Tl (thallous chloride). The 99Tcm sestamibi correctly localized all abnormal glands and showed higher parathyroid to thyroid uptake in three of four parathyroid adenomas. Both agents showed localization in a thyroid adenoma. The higher uptake of sestambi and better imaging properties of its 99Tcm radiolabel means that the agent may replace thallium for routine preoperative parathyroid localization.

A new approach to parathyroidectomy

OBJECTIVE

To decrease the operative time for parathyroidectomy in patients with hypercalcemic (primary) hyperparathyroid disease, a combination of preoperative localization of a parathyroid tumor with an effective nuclear scan (scintigram) and intraoperative monitoring of parathyroid hormone (quick parathyroid hormone measurement) to ensure excision of all hyperfunctioning tissue was studied.

SUMMARY BACKGROUND DATA

For many years, persistent hypercalcemia after parathyroidectomy (3% to 10%) has been constant and is usually due to the surgeon's failure to remove all hyperfunctioning glands. A marked decrease in parathormone level after excision of a single large gland predicts operative success and a return to normal calcium levels. Conversely, persistent high levels of parathyroid hormone indicate excess secretion by another gland(s) and the need for further exploration. Recently Tc-99m-sestamibi (MIBI) scintigraphy was shown to be more effective in localizing parathyroid tumors than previous methods. A combination of both techniques could be useful to the surgeon if they improve the operative success rate and are cost-effective.

METHODS

Parathyroidectomy was performed on 18 patients with primary hyperparathyroid disease, with tumors localized by MIBI scintigrams. When excision of the identified parathyroid gland was accomplished, the operation was terminated and quick parathyroid hormone was measured to confirm that all hyperfunctioning tissue was removed.

RESULTS

Sixteen patients with positive results of scintigram had successful parathyroidectomies confirmed by quick parathyroid hormone measurement with a cervical approach. Two patients with mediastinal tumors localized by MIBI scintigraphy could not be resected using this approach. One false-positive/false-negative scintigram was obtained. Compared with patients having parathyroidectomy without localization and hormone monitoring, the average operative time was shortened from 90 to 36 minutes.

CONCLUSIONS

Localization and successful excision of parathyroid tumors with confirmation that no other hyperfunctioning glands were present by quick parathyroid hormone monitoring can predict a return to normal calcium levels and a decrease in operative time in parathyroidectomy.

Parathyroid imaging: technique and role in the preoperative evaluation of primary hyperparathyroidism

OBJECTIVE

This article discusses the commonly used techniques for imaging the parathyroid glands and their role in the preoperative evaluation of patients with primary hyperparathyroidism.

CONCLUSION

The importance of sonography and sestamibi scintigraphy in the preoperative evaluation of patients with primary hyperthyroidism has increased with the adoption of minimally invasive parathyroidectomy techniques at most medical centers. When the results of these studies are concordant, the cure rates of minimally invasive surgery equal those of traditional bilateral neck exploration.

Comparison of SPECT/CT, SPECT, and planar imaging with single- and dual-phase (99m)Tc-sestamibi parathyroid scintigraphy

Various methodologies for (99m)Tc-sestamibi parathyroid scintigraphy are in clinical use. There are few direct comparisons between the different methods and even less evidence supporting the superiority of one over another. Some reports suggest that SPECT is superior to planar imaging. The addition of CT to SPECT may further improve parathyroid adenoma localization. The purpose of our investigation was to compare hybrid SPECT/CT, SPECT, and planar imaging and to determine whether dual-phase imaging is advantageous for the 3 methodologies.

METHODS

Scintigraphy was performed on 110 patients with primary hyperparathyroidism and no prior neck surgery. Of these, 98 had single adenomas and are the subject of this review. Planar imaging and SPECT/CT were performed at 15 min and 2 h after injection. Six image sets (early and delayed planar imaging, SPECT, and SPECT/CT) and combinations of the 2 image sets were reviewed for adenoma localization at 13 possible sites. Each review was scored for location and certainty of focus by 2 reviewer groups. Surgical location served as the standard. Sensitivity, specificity, area under the curve, positive predictive value, negative predictive value, and kappa-values were determined for each method.

RESULTS

The overall kappa-coefficient (certainty of adenoma focus) between reading groups was 0.68 (95% confidence interval, 0.66-0.70). The highest values were for dual-phase studies that included SPECT/CT. Dual-phase planar imaging, SPECT, and SPECT/CT were statistically significantly superior to single-phase early or delayed imaging in sensitivity, area under the curve, and positive predictive value. Neither single-phase nor dual-phase SPECT was statistically superior to dual-phase planar imaging. Early-phase SPECT/CT in combination with any delayed imaging method was superior to dual-phase planar imaging or SPECT for sensitivity, area under the curve, and positive predictive value.

CONCLUSION

Early SPECT/CT in combination with any delayed imaging method was statistically significantly superior to any single- or dual-phase planar or SPECT study for parathyroid adenoma localization. Localization with dual-phase acquisition was more accurate than with single-phase (99m)Tc-sestamibi scintigraphy for planar imaging, SPECT, and SPECT/CT.

Ultrasonography for preoperative localization of enlarged parathyroid glands in primary hyperparathyroidism: comparison with (99m)technetium sestamibi scintigraphy

OBJECTIVE

To determine the utility of ultrasonography for the preoperative localization of enlarged parathyroid glands in primary hyperparathyroidism, and to compare this method with (99m)technetium sestamibi scintigraphy.

DESIGN

The results of ultrasonography for localization of enlarged parathyroid glands were determined in 120 consecutive patients with primary hyperparathyroidism and compared with findings at surgery (n = 86) and with the results of (99m)technetium sestamibi scintigraphy (n = 99).

PATIENTS

All patients had biochemically documented primary hyperparathyroidism based on elevated serum calcium and 'intact' parathyroid hormone measured by immunoassay. Patients with prior parathyroid surgery or secondary hyperparathyroidism were excluded.

MEASUREMENTS

High-resolution ultrasonography was performed by a single observer. (99m)Technetium sestamibi scintigraphy was performed using early and delayed (2-h) views, and correlated with simultaneous thyroidal 123I uptake in most patients.

RESULTS

Ultrasonography detected putative enlarged parathyroid glands in 92 of 120 unselected patients (77%). It correctly predicted surgical findings in 64 of 86 patients undergoing surgery (74%), including 61 of 72 patients with solitary eutopic parathyroid adenomas (84%), but only two of eight patients with solitary ectopic adenomas, and only one of six patients with multigland parathyroid disease. Sestamibi scintigraphy was positive in 87 of 99 unselected patients (88%), a higher proportion than ultrasonography (P < 0.05), reflecting superior sensitivity for the detection of ectopic parathyroid adenomas. For 74 patients undergoing parathyroid surgery who underwent both imaging tests there was no statistically significant difference between ultrasonography and sestamibi scintigraphy in ability to correctly predict surgical findings (74%vs. 82%, respectively) or in positive predictive value (93%vs. 90%, respectively). However, sestamibi scintigraphy was clearly more sensitive for ectopic parathyroid adenomas, providing correct localization in 8/8 cases. When one test was negative, testing with the second method was usually positive, improving the likelihood of a positive result to 98% when both tests were employed.

CONCLUSIONS

Ultrasonography can be a sensitive and accurate method for preoperative localization of enlarged parathyroid glands in primary hyperparathyroidism, comparable in overall utility to sestamibi scintigraphy. These results suggest that a strategy of initial testing with one or the other method, followed by the alternate imaging test if the first test is negative, would provide correct parathyroid imaging in most patients without prior parathyroid surgery.

Randomized clinical trial of intraoperative parathyroid gland angiography with indocyanine green fluorescence predicting parathyroid function after thyroid surgery

BACKGROUND

Hypoparathyroidism, the most common complication after thyroid surgery, leads to hypocalcaemia and significant medical problems. An RCT was undertaken to determine whether intraoperative parathyroid gland angiography with indocyanine green (ICG) could predict postoperative hypoparathyroidism, and obviate the need for systematic blood tests and oral calcium supplementation.

METHODS

Between September 2014 and February 2016, patients who had at least one well perfused parathyroid gland on ICG angiography were randomized to receive standard follow-up (measurement of calcium and parathyroid hormone (PTH) on postoperative day (POD) 1 and systematic supplementation with calcium and vitamin D; control group) or no supplementation and no blood test on POD 1 (intervention group). In all patients, calcium and PTH levels were measured 10-15 days after thyroidectomy. The primary endpoint was hypocalcaemia on POD 10-15.

RESULTS

A total of 196 patients underwent ICG angiography during thyroid surgery, of whom 146 had at least one well perfused parathyroid gland on ICG angiography and were randomized. None of these patients presented with hypoparathyroidism, including those who did not receive calcium supplementation. The intervention group was statistically non-inferior to the control group (exact 95 per cent c.i. of the difference in proportion of patients with hypocalcaemia -0·053 to 0·053; P = 0·012). Eleven of the 50 excluded patients, in whom no well perfused parathyroid gland could be identified by angiography, presented with hypoparathyroidism on POD 1, and six on POD 10-15, which was significantly different from the findings in randomized patients (P = 0·007).

CONCLUSION

ICG angiography reliably predicts the vascularization of the parathyroid glands and obviates the need for postoperative measurement of calcium and PTH, and supplementation with calcium in patients with at least one well perfused parathyroid gland. Registration number: NCT02249780 (http://www.clinicaltrials.gov).

Radionuclide imaging of the parathyroid glands

The parathyroid glands, which usually are situated behind the thyroid gland, secrete parathyroid hormone, or PTH, which helps maintain calcium homeostasis. Primary hyperparathyroidism results from excess parathyroid hormone secretion. In secondary hyperparathyroidism, the normal PTH effect on bone calcium release is lost. Serum PTH rises, causing generalized hyperplasia. In tertiary hyperparathyroidism, a complication of secondary hyperparathyroidism, normal feedback mechanisms governing PTH secretion are lost, parathyroid gland sensitivity to PTH decreases, and the threshold for inhibiting PTH secretion increases. 99mTc sestamibi, or MIBI, the current radionuclide study of choice for preoperative parathyroid localization, can be performed in various ways. The "single-isotope, double-phase technique" is based on the fact that MIBI washes out more rapidly from the thyroid than from abnormal parathyroid tissue. However, not all parathyroid lesions retain MIBI and not all thyroid tissue washes out quickly, and subtraction imaging is helpful. Many MIBI avid thyroid lesions also accumulate pertechnetate and iodine, and subtraction reduces false positives. Single-photon emission computed tomography provides information for localizing parathyroid lesions, differentiating thyroid from parathyroid lesions, and detecting and localizing ectopic parathyroid lesions. The most frequent cause of false-positive MIBI results is the solid thyroid nodule. Other causes include thyroid carcinoma, lymphoma, and lymphadenopathy. False-negative results occur because of several factors. Lesion size is important. Cellular function also may be important. Parathyroid tissue that expresses P-glycoprotein does not accumulate MIBI. Parathyroid adenomas that express either P-glycoprotein or the multidrug resistance related protein MRP are less likely to accumulate MIBI. MIBI scintigraphy is less sensitive for detecting hyperplastic parathyroid glands. In secondary hyperparathyroidism, MIBI uptake is more closely related to cell cycle than to gland size. Mitochondria-rich oxyphil cells presumably account for MIBI uptake in parathyroid lesions. Fewer oxyphil cells, and hence fewer mitochondria, may explain both lower uptake and rapid washout of MIBI from some lesions. MIBI is also less sensitive for detecting multigland disease than solitary gland disease.

Ambulatory parathyroidectomy for primary hyperparathyroidism

OBJECTIVE

To evaluate whether the combined application of preoperative localization and intraoperative monitoring of intact parathyroid hormone (iPTH) levels could facilitate safe outpatient parathyroidectomy.

DESIGN

Consecutive patients, who had no antecedent social or medical conditions mandating hospitalization, were prospectively offered ambulatory parathyroidectomy with a mean follow-up of 7 months (range, 1-25 months).

SETTING

Tertiary care referral center

PATIENTS

From 85 patients who had primary hyperparathyroidism with hypercalcemia and elevated iPTH levels, 57 were offered outpatient parathyroidectomy. Nineteen patients were asymptomatic, 3 had hypercalcemic crisis, and the others gave a history of renal stones or had complaints consistent with bone disease.

INTERVENTIONS

Technetium Tc 99m sestamibi scintiscans were used for preoperative localization. Monitoring iPTH levels during parathyroidectomy quantitatively assured the surgeon (G.L.I. only) when all hyperfunctioning glands were excised.

MAIN OUTCOME MEASURE

The number of patients without complications and with short operative times who were discharged without hospital admission or overnight stay.

RESULTS

The combination of preoperative localization of abnormal parathyroid glands and a decline in circulating iPTH levels predicting postoperative normocalcemia after excision of all hyperfunctioning glands resulted in successful parathyroidectomy in 84 of 85 patients. A decreased operative time (average, 52 minutes) with minimal neck dissection permitted outpatient parathyroidectomy in 42 of 57 eligible patients.

CONCLUSIONS

The combination of preoperative parathyroid scintiscan localization and iPTH level monitoring during surgery permitted successful parathyroidectomy in an ambulatory setting in half of a consecutive series of patients with primary hyperparathyroidism. The safety, success, and likely cost savings of this approach suggest wider application.

The EANM practice guidelines for parathyroid imaging

INTRODUCTION

Nuclear medicine parathyroid imaging is important in the identification of hyperfunctioning parathyroid glands in primary hyperparathyroidism (pHPT), but it may be also valuable before surgical treatment in secondary hyperparathyroidism (sHPT). Parathyroid radionuclide imaging with scintigraphy or positron emission tomography (PET) is a highly sensitive procedure for the assessment of the presence and number of hyperfunctioning parathyroid glands, located either at typical sites or ectopically. The treatment of pHPT is mostly directed toward minimally invasive parathyroidectomy, especially in cases with a single adenoma. In experienced hands, successful surgery depends mainly on the exact preoperative localization of one or more hyperfunctioning parathyroid adenomas. Failure to preoperatively identify the hyperfunctioning parathyroid gland challenges minimally invasive parathyroidectomy and might require bilateral open neck exploration.

METHODS

Over a decade has now passed since the European Association of Nuclear Medicine (EANM) issued the first edition of the guideline on parathyroid imaging, and a number of new insights and techniques have been developed since. The aim of the present document is to provide state-of-the-art guidelines for nuclear medicine physicians performing parathyroid scintigraphy, single-photon emission computed tomography/computed tomography (SPECT/CT), positron emission tomography/computed tomography (PET/CT), and positron emission tomography/magnetic resonance imaging (PET/MRI) in patients with pHPT, as well as in those with sHPT.

CONCLUSION

These guidelines are written and authorized by the EANM to promote optimal parathyroid imaging. They will assist nuclear medicine physicians in the detection and correct localization of hyperfunctioning parathyroid lesions.

Serial evaluation of parathyroid size by ultrasonography is another useful marker for the long-term prognosis of calcitriol pulse therapy in chronic dialysis patients

To clarify whether the changes of parathyroid size have any correlations with the long-term prognosis of calcitriol pulse therapy, we examined the time course of serum levels of parathyroid hormone (PTH) and size of parathyroid glands in 14 chronic dialysis patients during and after the oral calcitriol pulse therapy. In 5 patients without any detectable glands, secondary hyperparathyroidism was easily controlled by calcitriol pulse therapy and then by conventional oral active vitamin D therapy. In 2 patients with detectable gland(s) in whom size of all parathyroid glands as well as PTH hypersecretion regressed to normal by calcitriol pulse therapy, secondary hyperparathyroidism could then remain controlled at least for 12 months after switching to conventional oral active vitamin D therapy. In contrast, in 7 patients in whom size of all parathyroid glands did not regress to normal by calcitriol pulse therapy, secondary hyperparathyroidism relapsed after switching to the conventional therapy, even if PTH hypersecretion could be controlled temporarily. Our findings suggest that the time course of parathyroid hyperplasia detected by ultrasonography is an important determinant of the efficacy and the prognosis of calcitriol pulse therapy. Thus, the change of parathyroid gland size as well as PTH hypersecretion should be taken into account for the management of secondary hyperparathyroidism.

Predictors of Single-Gland vs Multigland Parathyroid Disease in Primary Hyperparathyroidism

HYPOTHESIS

Preoperative clinical, biochemical, and imaging studies could be used to reliably select patients with single-gland primary hyperparathyroidism who could undergo minimally invasive parathyroidectomy and to determine whether additional perioperative testing is necessary.

DESIGN

Retrospective analysis.

SETTING

Tertiary referral center.

PATIENTS

A total of 238 patients who underwent neck surgical exploration and parathyroidectomy for primary hyperparathyroidism from January 7, 2002, to December 23, 2004.

MAIN OUTCOME MEASURES

Demographic, clinical, biochemical, and imaging factors that predict single-gland vs multigland parathyroid disease, and biochemical cure.

RESULTS

Of the 238 patients, 75.2% had a single adenoma, 21.4% had asymmetric 4-gland hyperplasia, and 3.4% had double adenomas. A biochemical cure was achieved in 99.2% of the patients. Preoperative calcium and intact parathyroid hormone levels were significantly higher (P = .03 and .04, respectively) and ultrasound and sestamibi scan results were more likely to be positive (both P<.001) in single-gland primary hyperparathyroidism. A dichotomous scoring model based on preoperative total calcium level (>/=3 mmol/L [>/=12 mg/dL]), intact parathyroid hormone level (>/=2 times the upper limit of normal levels), positive ultrasound and sestamibi scan results for 1 enlarged gland, and concordant ultrasound and sestamibi scan findings reliably distinguished single-gland vs multigland cases (P<.001). The positive predictive value of this scoring model to correctly predict single-gland disease was 100% for a total score of 3 or higher.

CONCLUSIONS

Preoperative biochemical and imaging study results reliably distinguished single-gland vs multigland parathyroid disease in primary hyperparathyroidism. Our findings suggest that patients with a score of 3 or higher can undergo a minimally invasive parathyroidectomy without the routine use of intraoperative parathyroid hormone or additional imaging studies, and those with a score of less than 3 should have additional testing to ensure that multigland disease is not overlooked.

Parathyroid glands: combination of (99m)Tc MIBI scintigraphy and US for demonstration of parathyroid glands and nodules

PURPOSE

To determine the appropriate choice of imaging techniques for localization of nodular lesions of parathyroid glands.

MATERIALS AND METHODS

First, computed tomographic (CT), magnetic resonance (MR), ultrasonographic (US), and technetium 99m methoxyisobutyl-isonitrile (MIBI) scintigraphic images in 49 patients with primary hyperparathyroidism were retrospectively evaluated. A single-blind, prospective study that included 16 patients with primary hyperparathyroidism was then conducted. MR, US, scintigraphic, and color Doppler US images of the neck were obtained and analyzed.

RESULTS

In the retrospective study, CT, MR imaging, and US had low sensitivity (13%, 17%, and 27%, respectively) and specificity (39%, 65%, and 65%, respectively). Scintigraphy had 57% sensitivity and 85% specificity. In the prospective study, the use of latest-generation MR and US equipment and the participation of experienced operators led to improved sensitivity and specificity for these techniques. The combination of US and scintigraphy resulted in improved sensitivity (96%), specificity (83%), and positive and negative predictive values (88% and 94%, respectively), relative to the results obtained with either method alone. Doppler US was of little help in the setting of small glands.

CONCLUSIONS

The combination of (99m)Tc MIBI scintigraphy and US performed by well-trained operators with up-to-date instruments appeared to be the best diagnostic tool for the preoperative diagnosis of parathyroid disease.

Intraoperative Near-infrared Imaging for Parathyroid Gland Identification by Auto-fluorescence: A Feasibility Study

BACKGROUND

Parathyroid glands (PGs) can be particularly hard to distinguish from surrounding tissue and thus can be damaged or removed during thyroidectomy. Postoperative hypoparathyroidism is the most common complication after thyroidectomy. Very recently, it has been found that the parathyroid tissue shows near-infrared (NIR) auto-fluorescence which could be used for intraoperative detection, without any use of contrast agents. The work described here presents a histological validation ex vivo of the NIR imaging procedure and evaluates intraoperative PG detection by NIR auto-fluorescence using for the first time to our knowledge a commercially available clinical NIR imaging device.

METHODS

Ex vivo study on resected operative specimens combined with a prospective in vivo study of consecutive patients who underwent total or partial thyroid, or parathyroid surgery at a comprehensive cancer center. During surgery, any tissue suspected to be a potential PG by the surgeon was imaged with the Fluobeam 800 (®) system. NIR imaging was compared to conventional histology (ex vivo) and/or visual identification by the surgeon (in vivo).

RESULTS

We have validated NIR auto-fluorescence with an ex vivo study including 28 specimens. Sensitivity and specificity were 94.1 and 80 %, respectively. Intraoperative NIR imaging was performed in 35 patients and 81 parathyroids were identified. In 80/81 cases, the fluorescence signal was subjectively obvious on real-time visualization. We determined that PG fluorescence is 2.93 ± 1.59 times greater than thyroid fluorescence in vivo.

CONCLUSIONS

Real-time NIR imaging based on parathyroid auto-fluorescence is fast, safe, and non-invasive and shows very encouraging results, for intraoperative parathyroid identification.

Sestamibi parathyroid imaging

Since the introduction of technetium-99m (99mTc) sestamibi (hexakis-2-methoxyisobutyl isonitrile) as a parathyroid imaging agent in 1989, many investigators using several different imaging protocols have reported uniformly excellent results for localization of parathyroid adenomas. Exact localization of hyperplastic parathyroid glands has not met with as much success. However, the results of multiple comparative studies suggest that the diagnostic utility of sestamibi protocols equals or exceeds other noninvasive, nonscintigraphic imaging strategies, including high-resolution ultrasound, computed tomography, and magnetic resonance imaging. Two different, but not necessarily mutually exclusive imaging strategies have been used: subtraction imaging using iodine-123 (123I) or 99mTc sodium pertechnetate as the thyroid agent, and sestamibi dual-phase imaging, which takes advantage of differential washout of sestamibi from thyroid and parathyroid tissue. Sestamibi subtraction imaging has been shown to have greater sensitivity for abnormal parathyroid glands compared with thallium-201 subtraction imaging using pooled data, 87% versus 71%, respectively. Dual-phase sestamibi imaging protocols are much more variable in their conduct and have a much greater variability in sensitivity, 43% to 91%, but with a pooled sensitivity of 73%. Data suggest that dual phase techniques are at least as sensitive, and in optimized protocols, superior to, thallium-201 subtraction techniques. This superiority is attributed to the favorable washout kinetics of sestamibi and the superior imaging characteristics of the 99mTc label. Specificity and positive predictive value for both sestamibi techniques are very high, typically greater than 90% and at least equal to thallium-subtraction protocols, although specificity may be slightly lower for sestamibi subtraction techniques. Therefore, sestamibi protocols are the scintigraphic procedure of choice for parathyroid imaging. Dual-phase sestamibi protocols are more robust and lend themselves to single photon emission computer tomography (SPECT) imaging, and may be followed sequentially by subtraction techniques if results are inconclusive. Despite the excellent results of sestamibi parathyroid imaging, it is unclear whether this accuracy can compete with the even better success of an experienced surgeon in initial surgeries for hyperparathyroidism, and routine preoperative imaging before initial surgery is still controversial. However, sestamibi parathyroid imaging is an excellent addition to a correlative imaging approach in reoperations for persistent and recurrent hyperparathyroidism.

Impact of autofluorescence-based identification of parathyroids during total thyroidectomy on postoperative hypocalcemia: a before and after controlled study

BACKGROUND

The clinical impact of intraoperative autofluorescence-based identification of parathyroids using a near-infrared camera remains unknown.

METHODS

In a before and after controlled study, we compared all patients who underwent total thyroidectomy by the same surgeon during Period 1 (January 2015 to January 2016) without near-infrared (near-infrared- group) and those operated on during Period 2 (February 2016 to September 2016) using a near-infrared camera (near-infrared+ group). In parallel, we also compared all patients who underwent surgery without near-infrared during those same periods by another surgeon in the same unit (control groups). Main outcomes included postoperative hypocalcemia, parathyroid identification, autotransplantation, and inadvertent resection.

RESULTS

The near-infrared+ group displayed significantly lower postoperative hypocalcemia rates (5.2%) than the near-infrared- group (20.9%; P < .001). Compared with the near-infrared- patients, the near-infrared+ group exhibited an increased mean number of identified parathyroids and reduced parathyroid autotransplantation rates, although no difference was observed in inadvertent resection rates. Parathyroids were identified via near-infrared before they were visualized by the surgeon in 68% patients. In the control groups, parathyroid identification improved significantly from Period 1 to Period 2, although autotransplantation, inadvertent resection and postoperative hypocalcemia rates did not differ.

CONCLUSION

Near-infrared use during total thyroidectomy significantly reduced postoperative hypocalcemia, improved parathyroid identification and reduced their autotransplantation rate.

Advantages of combined technetium-99m-sestamibi scintigraphy and high-resolution ultrasonography in parathyroid localization: comparative study in 91 patients with primary hyperparathyroidism

OBJECTIVE

To evaluate the usefulness of the combination of Tc-sestamibi/Tc-pertechnetate subtraction scintigraphy (SS) and high-resolution neck ultrasonography (US) in patients with primary hyperparathyroidism (pHPT) undergoing parathyroidectomy.

DESIGN AND METHODS

Ninety-one patients with proved pHPT were studied, excluding patients with persistent or recurrent disease. There were 65 (71.4%) women and 26 (28.6%) men, with a median age of 59 years (range 18-78 years). All patients underwent both SS and US prior to surgery, and the results were compared with operative and histological findings. The intraoperative quick-parathyroid hormone assay was available for 52 (57.1%) patients. When multiglandular disease was found, both SS and US were considered truly positive only when at least two enlarged parathyroid (PT) glands had been localized.

RESULTS

Eighty-three (91.2%) solitary PT adenomas and three (3.3%) carcinomas were found. Moreover, two (2.2%) patients had a double adenoma and three (3.3%) patients had diffuse PT hyperplasia. The overall sensitivity of combined SS+US was 94.5% (86.8% and 80.4% for SS and US respectively). There was a significant (P<0.05, Student's t-test) difference in size between the PT glands correctly identified and undetected by SS, whereas the site of the removed PT tumors significantly (P<0.05, Fisher exact test) influenced only the US sensitivity.

CONCLUSIONS

When the preoperative localization of the PT glands is chosen, the combination of SS and US represents a reliable noninvasive localization technique and should be considered for use in each patient with pHPT undergoing surgery.

Is 18F-fluorocholine-positron emission tomography/computerized tomography a new imaging tool for detecting hyperfunctioning parathyroid glands in primary or secondary hyperparathyroidism?

CONTEXT

Preoperative ultrasonography and scintigraphy using (99m)Tc-sestamibi are commonly used to localize abnormal parathyroid glands. In cases of discrepant results between scintigraphy and ultrasonography, it is important to rely on another diagnostic imaging modality. (18)F-fluorodeoxyglucose (FDG) and (11)C-methionine positron emission tomography (PET) have been studied, but are imperfect to detect abnormal parathyroid glands. Recently, first cases of abnormal parathyroid glands taking-up radiolabelled choline were discovered incidentally in men referred to (11)C-choline or (18)F-fluorocholine (FCH)-PET/CT for prostate cancer. We checked if FCH uptake was a general feature of adenomatous or hyperplastic parathyroid glands.

METHODS

FCH-PET/CT was performed in 12 patients with primary (n = 8) or secondary hyperparathyroidism (1 dialyzed, 3 grafted) and with discordant or equivocal results on preoperative ultrasonography (US) and/or (123)I/(99m)Tc-sestamibi dual-phase scintigraphy. The results of the FCH-PET/CT were evaluated, with surgical exploration and histopathologic examination as the standard of truth.

RESULTS

On a per-patient level, the detection rate of FCH-PET/CT (at least one FCH focus corresponding to an abnormal parathyroid gland in a given patient) was 11/12 = 92%. FCH-PET/CT detected 18 foci interpreted as parathyroid glands and correctly localized 17 abnormal parathyroid glands (7 adenomas and 10 hyperplasias). On a per-lesion level, FCH-PET/CT results were 17 TP, 2 false negative ie, a lesion-based sensitivity of 89%, and 1 false positive.

CONCLUSION

As the main result of this pilot study, we show that in patients with hyperparathyroidism and with discordant or equivocal results on scintigraphy or on ultrasonography, adenomatous or hyperplastic parathyroid glands can be localized by FCH-PET/CT with good accuracy. Furthermore, FCH-PET/CT can solve discrepant results between preoperative ultrasonography and scintigraphy and has thus a potential as a functional imaging modality in the detection of abnormal parathyroid glands. Our preliminary results are encouraging and prompt us to further evaluate FCH-PET/CT as a functional imaging agent in patients with biochemical hyperparathyroidism.

Scan-directed unilateral cervical exploration for parathyroid adenoma: a legitimate approach?

Thallium-Technetium isotope subtraction scanning was used routinely as a preoperative localization investigation in 90 patients with primary hyperparathyroidism who were submitted to "first-time" cervical exploration from 1985 to 1988. When the scintigram demonstrated a single focus of activity suggesting the site of a solitary parathyroid adenoma, a scan-directed exploration was carried out. If the tumor was found at the location suggested by the scan, it was then removed and the ipsilateral normal parathyroid was biopsied. The contralateral side of the neck was not explored in these patients. A total of 48 patients underwent unilateral cervical exploration while the remaining 42 individuals had a standard bilateral neck operation performed. The difference in operating times for patients who had a solitary adenoma and who underwent unilateral and bilateral neck exploration, respectively, was statistically highly significant (71 minutes versus 97 minutes, p less than 0.001). At mean follow-up of 16.8 months, no patient who had a unilateral neck exploration performed for solitary parathyroid adenoma demonstrated persistent or recurrent hypercalcemia.

Impact of Gland Morphology and Concomitant Thyroid Nodules on Preoperative Localization of Parathyroid Adenomas

OBJECTIVES

Primary hyperparathyroidism (pHPT) is a common endocrine disease. The aim of this study was to assess the effect of the presence of thyroid nodules, adenoma weight, and ectopic localization on the sensitivity of different imaging studies in patients with hyperparathyroidism.

STUDY DESIGN

A series of 125 patients with pHPT who underwent low-frequency ultrasonography, high-frequency ultrasonography, Thallium-Technetium scintigraphy, sestamibi scintigraphy, and combined technique was reviewed retrospectively. Patients were divided in two groups depending on the presence or absence of thyroid nodules.

RESULTS

The overall sensitivity of low-frequency ultrasonography, high-frequency ultrasonography, Thallium-Technetium scintigraphy, sestamibi scintigraphy, and combined technique was 69%, 89%, 71%, 86%, and 98%, respectively. The sensitivity of these imaging studies was 94%, 100%, 94%, 96%, and 100%, respectively, in our patients with no thyroid nodules but decreased to 54%, 84%, 54%, 81%, and 79%, respectively, in the presence of thyroid nodules. The parathyroid adenoma weight in true-positive imaging studies was significantly higher than those in false-positive and false-negative imaging studies. The numbers of ectopic parathyroid adenomas were found to be higher in the group of parathyroid adenomas undetected with ultrasonography when compared with ultrasonographically detected adenomas.

CONCLUSION

In patients with parathyroid adenoma, the sensitivity of imaging studies correlates with the presence of thyroid nodules, adenoma weight, and ectopic localization.

Intraoperative near-infrared autofluorescence imaging of parathyroid glands

OBJECTIVE

To identify parathyroid glands intraoperatively by exposing their autofluorescence using near-infrared light.

METHODS

Fluorescence imaging was carried out during minimally invasive and open parathyroid and thyroid surgery. After identification, the parathyroid glands as well as the surrounding tissue were exposed to near-infrared (NIR) light with a wavelength of 690-770 nm using a modified Karl Storz near-infrared/indocyanine green (NIR/ICG) endoscopic system. Parathyroid tissue was expected to show near-infrared autofluorescence, captured in the blue channel of the camera. Whenever possible the visual identification of parathyroid tissue was confirmed histologically.

RESULTS

In preliminary investigations, using the original NIR/ICG endoscopic system we noticed considerable interference of light in the blue channel overlying the autofluorescence. Therefore, we modified the light source by interposing additional filters. In a second series, we investigated 35 parathyroid glands from 25 patients. Twenty-seven glands were identified correctly based on NIR autofluorescence. Regarding the extent of autofluorescence, there were no noticeable differences between parathyroid adenomas, hyperplasia and normal parathyroid glands. In contrast, thyroid tissue, lymph nodes and adipose tissue revealed no substantial autofluorescence.

CONCLUSION

Parathyroid tissue is characterized by showing autofluorescence in the near-infrared spectrum. This effect can be used to distinguish parathyroid glands from other cervical tissue entities.

Intraoperative Real-Time Localization of Normal Parathyroid Glands With Autofluorescence Imaging

CONTEXT

This biomedical investigation is valuable for identification and localization of parathyroid glands during thyroidectomy, which can provide an intraoperative real-time visual guidance.

OBJECTIVE

The objective of the study was to investigate the feasibility of real-time autofluorescence imaging of the parathyroid glands without exogenous contrast dye for their localization and demonstration of relation to the background tissues.

SETTING

This research was undertaken at Kosin University Gospel Hospital.

METHODS

Sixteen normal parathyroid glands from eight patients with papillary thyroid carcinoma were enrolled. Photo images of the surgical field including the parathyroid and background tissues were taken with a digital camera, 780 nm light-emitting diode to excite the parathyroid, and infrared illuminator to visualize the entire neck. The area-averaged autofluorescence intensity of parathyroid over the area-averaged fluorescence intensity of background tissues was measured.

MAIN OUTCOME MEASURE

The location of the parathyroid gland was verified with a single image.

RESULTS

The area-averaged autofluorescence intensity of parathyroid over the area-averaged fluorescence intensity of background tissues for all parathyroid glands was higher than 1, with a minimum of 1.95 and a maximum of 5.20 (average 2.76, SD 0.79). By our technique, all 16 parathyroid glands were detected (positive predictive value of 100%), and the entire surgical field including the parathyroid and background tissues was visualized as well. The parathyroid glands that were exposed or even covered by connective tissues or blood vessels could be detected with strong emission.

CONCLUSIONS

This method showed the precise localization of the parathyroid glands and demonstrated their relation to background tissue. We believe that this simple, nonexogenous dye technique of anatomical guidance can aid surgeons to preserve parathyroid glands during thyroidectomy.

Reduction of functioning parathyroid cell mass by ethanol injection in chronic dialysis patients

Recent data suggest that the larger parathyroid glands are more resistant to calcitriol therapy than the smaller glands due to more severe reduction of calcitriol receptor number. To control severe secondary hyperparathyroidism resistant to calcitriol pulse therapy in chronic dialysis patients, we introduced repeatable and quantitative ethanol injection(s) into the largest parathyroid gland under ultrasonographic guidance with a specifically modified needle. Efficacy of each injection and the recurrence of hyperparathyroidism were confirmed by color Doppler ultrasonography and could undergo additional ethanol injection(s) into the optimal site. When the ethanol injection(s) into the largest gland was not sufficient to control PTH hypersecretion, we injected ethanol into the next largest gland. We performed 32 injections into 16 parathyroid glands in nine dialysis patients. PTH decreased to less than 200 pg/ml after the final injection in seven patients and they remained controlled either by the following conventional oral active vitamin D or calcitriol pulse therapy. The other two patients, whose PTH decreased but not to less than 200 pg/ml, also became controllable with the following calcitriol pulse therapy. Recurrent nerve palsy was encountered in 2 out of 32 injections, but only transiently. Our data suggest that the measurement of the size of parathyroid glands is an important factor in the management strategy of secondary hyperparathyroidism in chronic dialysis patients, and that ethanol injection(s) into the largest parathyroid gland(s) could be an effective and safe strategy to restore the responsiveness to calcitriol therapy, by reducing the functioning parathyroid cell mass most resistant to calcitriol.

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.