The efficacy of sestamibi parathyroid scintigraphy for directing surgical approaches based on modified interpretation criteria

Preoperative imaging for focused parathyroidectomy: making a good strategy even better

OBJECTIVE

Surgical treatment for primary hyperparathyroidism (pHPT) has undergone a major paradigm shift during the last decades from bilateral cervicotomy with four-gland neck exploration to image-guided focused approaches. The primary objective of the present study was to compare the performances of parathyroid scintigraphy (PS), parathyroid ultrasonography (US), and the combination of both procedures for guiding a focused approach on the basis of modified interpretation criteria.

METHODS

Data from 199 patients operated for apparent sporadic pHPT and evaluated with US and PS using dual-isotope (123)I/(99m)Tc-sestamibi planar pinhole and single-photon emission computed tomography (SPECT) acqusitions were evaluated.

RESULTS

A total of 127 patients underwent a focused approach and the remainder had bilateral cervicotomy. In 42 cases, a focused approach was not performed due to the absence of concordant results between US and PS for a single-gland abnormality. Four patients had persistent disease and three had recurrent disease. A localizing preoperative PS had a sensitivity of 93.3%, positive predictive value of 85.8%, negative predictive value of 73.0%, and accuracy of 83.4% for predicting uniglandular disease. Additional SPECT images accurately localize posterior adenomas that are often missed by US. Compared with PS, US had a lower sensitivity (P<0.01). Our imaging protocol also enabled diagnosis of multiglandular disease in 60.6%.

CONCLUSIONS

PS using a highly sensitive dual-tracer subtraction method is the most accurate technique for directing a focused approach. PS could be sufficient for directing a focused approach in the presence of a negative US in two major circumstances: posterior locations due to acquired ectopia that could be missed by US, and previous history of thyroidectomy due to interpretation difficulties.

Primary hyperparathyroidism patients with positive preoperative sestamibi scan and negative ultrasound are more likely to have posteriorly located upper gland adenomas (PLUGs)

Background

Standard preoperative imaging for primary hyperparathyroidism usually includes sestamibi scanning (MIBI) and ultrasound (US). In a subset of patients with a positive MIBI and a negative US, we hypothesize that the parathyroid adenomas are more likely to be located posteriorly in the neck, where anatomically they are more difficult to detect by US.

Methods

We retrospectively reviewed the records of 661 patients treated for primary hyperparathyroidism between 2004 and 2009 at a tertiary referral center. We included patients who for their first operation had a MIBI that localized a single lesion in the neck and an US that found no parathyroid adenoma. We excluded patients with persistent or recurrent hyperparathyroidism, and patients with MIBIs that were negative, that had more than one positive focus, or that had foci outside of the neck. Sixty-six cases were included in the final analysis.

Results

A total of 54 patients (83%) had a single adenoma, 4 (6%) had double adenomas, and 7 (11%) had hyperplasia. Thirty-three patients (51%) had a single upper gland adenoma; 19 of these (58%) were posteriorly located upper gland adenomas (PLUGs). PLUGs occurred more often on the right side than on the left (P = 0.048, Fisher’s test). PLUGs were also larger than other single adenomas (mean 1.85 vs. 1.48 cm, P = 0.021, t-test). Seventy-six percent of patients successfully underwent a unilateral or focused exploration. Six patients (9%) had persistent disease, which is double our group’s overall average (4–5%).

Conclusions

Primary hyperparathyroid patients with preoperative positive MIBI and negative US are more likely to have PLUGs.

Clinical appraisal of 99m technetium-sestamibi SPECT/CT compared to conventional SPECT in patients with primary hyperparathyroidism and concomitant nodular goiter

BACKGROUND

Although 99m Technetium-sestamibi scintigraphy with single-photon emission computed tomography (SPECT) and, recently, hybrid SPECT/computed tomography (CT) have been claimed to be the preoperative methods of choice for parathyroid localization in patients with primary hyperparathyroidism (PHPT) and concomitant nodular goiter (NG), they have never been compared in this setting. We aimed at testing the hypothesis that SPECT/CT may be superior to SPECT for parathyroid localization in patients with PHPT and NG.

METHODS

Thirty-three patients with PHPT and NG (one or more nodular lesions based on cervical ultrasound) who underwent open parathyroidectomy during 2004-2009 were reviewed. All patients had preoperative 99m Tc-sestamibi planar scintigraphy and SPECT (18 patients) or SPECT/CT (15 patients) after cervical ultrasound. Sensitivity, specificity, and positive predictive value (PPV) (for both correct neck side and quadrant identification) were calculated for the two procedures through comparison with intraoperative findings. In addition, operative times were assessed if the surgery was only for PHPT and not for the six patients who also had thyroidectomy.

RESULTS

The sensitivity of SPECT/CT for correctly identifying the neck side containing an abnormal parathyroid was 93.7% versus 80% for SPECT (p = 0.21, not significant [ns]). The specificity and PPV for this attribute were 92.9% and 93.7%, respectively, for SPECT/CT versus 87.5% and 88.9%, respectively, for SPECT (p = 0.75 and 0.8, ns). SPECT/CT showed higher sensitivity than SPECT (87.5% vs. 55.6%; p = 0.0001) and higher PPV (87.5% vs. 62.5%; p = 0.0022) for correctly identifying the neck quadrant affected by PHPT. The specificity for this was 95.5% for SPECT/CT versus 88.5% for SPECT (p = 0.26, ns). Mean operative time was shorter after SPECT/CT than after SPECT (38 vs. 56 minutes; p = 0.034). One of the patients having SPECT/CT had double adenomas, and two had ectopic parathyroid glands, all of which were recognized preoperatively by this technique. Two of the patients having SPECT had double adenomas, and two had ectopic glands, none of which were recognized preoperatively. No patient had persistent or recurrent PHPT.

CONCLUSIONS

SPECT/CT is superior to SPECT for preoperative imaging of patients with PHPT and NG. We recommend the routine use of SPECT/CT for work-up of all such patients, particularly if minimally invasive parathyroid surgery is planned.

Sestamibi SPECT intensity scoring system in sporadic primary hyperparathyroidism

BACKGROUND

Most cases of sporadic primary hyperparathyroidism (PHP) are due to a single parathyroid adenoma and can be treated with minimally invasive parathyroid exploration guided by sestamibi SPECT imaging and intraoperative parathyroid hormone monitoring. Successful surgery depends on identification of the 10-15% of patients with multiglandular disease. Failed initial parathyroid exploration is both costly and morbid. We examined whether a sestamibi SPECT scoring system could predict anatomic findings in patients with PHP.

METHODS

Prospective data from 1,061 consecutive patients undergoing initial parathyroid exploration for PHP from March 6, 2000 to September 28, 2007 were reviewed. One nuclear medicine physician performed independent blinded review of 577 available dual time-point sestamibi SPECT scans, and scored the results into 1 of 5 categories: 0-negative, 1-possible, 2-probable, 3-definite adenoma, or 4-multiglandular disease. Intraoperative findings and outcomes at >5 months follow-up were examined. Chi-square and nonparametric analyses were used to evaluate variables for correlation.

RESULTS

Among patients with sestamibi SPECT scan results classified as either 0--negative or 1--possible adenoma, only 211/262 (81%) had a single adenoma, compared to 263/288 (91%) patients with scan results classified as 2--probable or 3--definite adenoma (p < 0.001). Positive predictive values increased in stepwise correlation with sestamibi SPECT image intensity: 1--possible 78.5%, 2--probable 94.3%, and 3--definite adenoma 98.8%. Multiglandular disease was present in 31/144 (22%) patients with a 0--negative scan versus 13/166 (8%) patients with a 3--definite adenoma scan (p = 0.0005). Only 7/27 (26%) patients with scans classified as 4-multiglandular had actual multiglandular disease. Negative scan results were associated with a greater risk of operative failure (p < 0.001).

CONCLUSIONS

A simple scoring system based on sestamibi SPECT intensity can predict the likelihood of single adenoma in PHP. Even the best localizing study cannot exclude multiglandular disease preoperatively. Negative sestamibi SPECT scans are associated with a higher rate of operative failure. Because sestamibi SPECT scans of any category do not reliably identify multiglandular disease, expert surgeons must use validated adjuncts to avoid operative failure.

Technetium-99m-sestamibi subtraction scintigraphy vs. ultrasonography combined with a rapid parathyroid hormone assay in parathyroid aspirates in preoperative localization of parathyroid adenomas and in directing surgical approach

OBJECTIVE

To determine the sensitivity and positive predictive value (PPV) of subtraction scintigraphy (SS) vs. ultrasonography (US) of the neck combined with rapid intact parathyroid hormone (iPTH) assay in US-guided fine-needle parathyroid aspirates in preoperative localization of parathyroid adenomas and in directing surgical approach.

DESIGN

The results of SS for localization of parathyroid adenoma were determined in 121 patients with primary hyperparathyroidism (pHPT) and compared with findings at surgery and with the results of US alone (in patients without nodular goitre) and US in combination with the iPTH assay in US-guided fine-needle aspirates (FNAs) of suspicious parathyroid lesions (in patients with concomitant nodular goitre).

PATIENTS

All 121 patients had biochemically documented pHPT; all were referred for first-time surgery.

MEASUREMENTS

SS was performed with 99mTc-sestamibi and 99mTc-pertechnetate. High-resolution US of the neck was performed by a single endocrine surgeon and combined with US-guided FNAs of suspicious parathyroid lesions in all patients with nodular goitre (n = 43).

RESULTS

The sensitivity and PPV of SS were significantly higher in patients without vs. with goitre (89.3% and 95.7%vs. 74.3% and 76.5%, respectively; P < 0.001). The sensitivity and PPV of US were significantly higher in patients without vs. with goitre (96% and 97.3%vs. 67.7% and 71.9%, respectively; P < 0.001). The iPTH assay of US-guided FNAs of suspicious parathyroid lesions in patients with nodular goitre significantly improved both the sensitivity and PPV of US imaging (90.7% and 100%, respectively), allowing for an accurate choice of surgical approach in 118 (97.5%) of 121 patients. SS was more accurate than US alone in detection of ectopic parathyroid adenomas. However, US alone was characterized by a higher sensitivity in detection of small parathyroid adenomas (< 500 mg) at typical sites (P < 0.01).

CONCLUSIONS

Both the sensitivity and PPV of SS and US alone are comparable, with significantly less accurate results obtained in patients with goitre. In cases of equivocal results of US and/or in patients with concomitant goitre, an iPTH assay in US-guided FNAs of suspicious parathyroid lesions may be used to establish the nature of the mass, distinguish between parathyroid and nonparathyroid tissue (goitre, lymph nodes) and improve the accuracy of US parathyroid imaging, allowing for successful directing of surgical approach in a majority of patients.

Appearance of intrathymic parathyroid adenomas on pinhole sestamibi parathyroid imaging

OBJECTIVES

Ectopic inferior parathyroid adenomas (PAs) are frequently located in the anterior mediastinum, quite often in the thymus gland. Correct preoperative localization is particularly helpful for surgical planning. Clinical follow up has shown that most intrathymic adenomas were visualized on pinhole views and located closer to the thyroid than expected. We reviewed the typical appearance of intrathymic PA on pinhole views.

METHODS

We retrospectively reviewed sestamibi pinhole parathyroid imaging performed on 163 patients with primary hyperparathyroidism and final diagnoses established by surgery, histology, intraoperative PTH monitoring, and clinical follow up. Studies showing focal increased activity in the lower pole region of the thyroid were selected and divided into 2 groups, group A (foci that are visually not separable from the thyroid) and group B (foci that are completely separated from the thyroid), and correlated with the final diagnoses.

RESULTS

Of the 163 patients, 102 had 103 clearly abnormal foci in the lower pole region (bilateral lower pole foci in one study). There were 93 foci in group A and 10 foci in group B. Of the 93 foci in group A, there were 80 normally situated inferior PA, 6 descended superior PA, 3 intrathyroidal PA, one hyperplastic parathyroid gland, one thyroid adenoma, one unidentified, and one intrathymic PA. Of the 10 foci in group B, 3 were eutopic inferior PA and 7 were intrathymic PA.

CONCLUSION

Focal increased activity completely separated from the lower pole of thyroid (regardless of the distance of separation) on sestamibi pinhole images indicates a high probability of intrathymic parathyroid adenoma.

Hyperparathyroidism but a negative sestamibi scan: a clinical dilemma

BACKGROUND

The outcomes of patients with biochemically confirmed hyperparathyroidism but a negative Tc-99 Sestamibi scan are unclear. We examined the outcomes and quality of life of patients having surgery and those who had medical therapy.

METHODS

Patients having a diagnosis of hyperparathyroidism with confirmed elevated calcium and parathormone levels, yet negative sestamibi scans were identified. The RAND SF-36 Health Survey was administered via mail to these patients. The patient's charts were then reviewed to verify treatments and to determine outcomes.

RESULTS

Ninety-five patients fitting the criteria were identified. Twenty patients completed all aspects of the study. Ten of the respondents had undergone parathyroidectomy, and 10 had not. The surgical patients scored more favorably in all 8 of the measured parameters than patients treated medically. The differences in 3 domains, physical functioning, pain, and social functioning, were statistically significant.

CONCLUSIONS

Our findings suggest that surgical therapy confers a better quality of life and is superior to medical therapy in the treatment of primary hyperparathyroidism, even in patients having a negative sestamibi scan.

Intrathyroidal Parathyroid Adenoma

A 54-year-old woman was referred for imaging studies after presentation for palpitations and a palpable thyroid nodule. The patient underwent a dual-phase single-agent Tc-99m sestamibi scan followed later by a thyroid ultrasound at an outside hospital. The Tc-99m sestamibi scan showed a marked focus of activity separate from the thyroid bed in the inferior left neck. Thyroid ultrasound showed a dominant calcified nodule in the left lobe of the thyroid, measuring 1.3 cm, as well as 3-mm cystic lesions in both lobes of the thyroid. Also, an iodine-123 scan was performed showing a cold nodule in the left inferior thyroid. During surgery, the patient underwent a left thyroid lobectomy for an intrathyroidal parathyroid adenoma.

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.

[Surgical treatment of primary hyperparathyroidism. A descriptive analysis]

In the last decades the primary hyperparthyroidism has become a common disease, often diagnosed by biochemical chance. The Elche General Hospital Department of Otorhinolaryngology has performed 55 parathyroidectomies between November 1996 and March 2003. Thirty-six cases (65.4%) were diagnosed as primary hyperparathyroidism. This disease usually has few symptoms. Since February 2000, Elche Hospital has available a device for quick appraisal of parathormone rate, allowing us in a few minutes to determine it and with the patient still in the operating theatre. The surgery results were: 25 solitary adenomas, 6 double adenomas and 5 hyperplasic. All patients became normocalcemic, and there were no major complications in this series.

Primary hyperparathyroidism

PURPOSE OF REVIEW

This contribution presents research progress concerning primary hyperparathyroidism (pHPT), and the background for recent notable changes in treatment policy.

RECENT FINDINGS

Research has clarified that most patients with pHPT require surgery due to risk for osteoporosis, renal stones, and possibly silent complications of renal impairment, cardiovascular disease, and common psychiatric disability. Genetic studies have advanced, but the cause of the disease remains unclear for most patients. Localization methods for parathyroid tumors have improved and increased the interest for less invasive operative methods with shorter hospital stays and reduced costs for the patient. It is important to delineate when this really will imply progress and to use the new diagnostic methods in discussions of appropriate treatment strategies. It has also become evident that older pHPT patients especially could benefit from medical treatment of bone mineral deficit, and they may also need vitamin D or vitamin D analogues to prevent progress of the disease.

SUMMARY

pHPT is a common disorder among postmenopausal women, in whom most commonly applied surgical treatment has proven markedly efficient. There is now increased interest to better understand possible causes of the disease and schedule the most efficient surgical and medical treatment and discuss possible prophylaxis.

Enhanced Scintigraphic Protocol Required for Optimal Preoperative Localization Before Targeted Minimally Invasive Parathyroidectomy

At our tertiary care institution, a targeted minimally invasive parathyroidectomy (MIP) is the preferred surgical procedure for primary hyperparathyroidism. Similar to unilateral neck exploration (UNE), preoperative scintigraphic localization of the adenoma in relation to the midline is required. However, in contrast to the abbreviated standard incision for UNE, 2 distinct incision sites, 1 medial and 1 lateral, are available on each side with MIP. The incision site is ultimately chosen based on scintigraphic determination of the adenoma's vascular origin to facilitate ligation and removal. Unfortunately, the scintigraphic location of a parathyroid adenoma does not necessarily reflect the site of its vascular origin. We reviewed our database to identify factors that accurately predict the site of vascular origin of parathyroid adenomas. A retrospective chart review was performed on 125 patients who underwent Tc-99m sestamibi scintigraphy and parathyroidectomy. Scintigraphic localization, surgical findings, and histopathology were recorded. Preoperative image interpretations that were discordant with operative findings were independently reviewed. Scintigraphy identified the presence of an adenoma in 105 of 118 patients (89%) with primary hyperparathyroidism. In 17 of the 105 cases (16%), the scintigraphic interpretation did not accurately reflect the site of superior or inferior vascular origin seen at surgery. In many discordant cases, anterior images were insufficient for determining the vascular origin. The posterior displacement of an adenoma in relation to the thyroid on early lateral images was often critical in determining the superior or inferior vascular origin. Scintigraphic determination of the superior or inferior vascular origin of a parathyroid adenoma directs incision placement for MIP. Imaging protocols should include early lateral images when localizing parathyroid adenomas before minimally invasive parathyroidectomy.

Current issues in hyperparathyroidism

There has been a shift in the referral patterns in recent years that has resulted in increasing numbers of patients being referred to surgeons with a diagnosis of hypercalcemia rather than primary hyperparathyroidism. The surgeon must perform a thorough history, including medications, and laboratory assessment, including serum calcium and parathyroid hormone measurements. A 24-hour urinary calcium excretion should be routinely ordered to exclude FHH. After the diagnosis of primary hyperparathyroidism is made, preoperative localization studies will benefit 78% to 90% of patients, with sestamibi scan being the most commonly used.