Technetium Tc 99m sestamibi scan for localizing abnormal parathyroid glands after previous neck operations: preliminary experience in reoperative cases

Neck Reoperation for Recurrent or Persistent Renal Hyperparathyroidism

BACKGROUND

Patients with renal hyperparathyroidism undergoing parathyroidectomy may experience relapse. Reoperation for persistent or recurrent disease, particularly in the neck region, is challenging and has a high complication rate because of difficult exploration. We aimed to evaluate the effectiveness of neck reoperation in renal hyperparathyroidism.

METHODS

Patients with recurrent or persistent renal hyperparathyroidism who underwent neck reoperation between January 2015 and August 2022 were investigated, focusing on operative findings, perioperative biochemical changes, and significance of intraoperative parathyroid hormone (PTH) measurements.

RESULTS

During reoperation, 35 parathyroid glands were identified and removed from the 26 enrolled patients, with one, two, and three glands retrieved from 19 (73.2%), five (19.2%), and two (7.6%) patients, respectively. Most removed glands (68.6%) were located in the lower neck, followed by the mediastinum, carotid sheath, and upper neck. Successful resection, defined as a postoperative PTH level of <300 pg/mL, was achieved in 21 patients (80.8%). The remaining four (15.4%) and one (3.9%) patients were classified as having persistent and recurrent disease, respectively. The extent of PTH reduction was correlated with specimen weight, specimen volume, and preoperative alkaline phosphatase (ALP) level. The mean intraoperative PTH ratio (10 min after excision/pre-excision) was 0.23, and all patients with persistent or recurrent disease had a PTH ratio >0.3. Severe hypocalcemia (<7.5 mg/dL) occurred in 19 (73.0%) patients after reoperation.

CONCLUSIONS

Neck reoperation is an effective therapeutic option in patients with recurrent or persistent renal hyperparathyroidism. A decrease in PTH level by >70% during reoperation (PTH ratio <0.3) predicts successful resection.

Failed parathyroidectomy: The road ahead

Persistent hyperparathyroidism due to failed parathyroidectomy is an uncommon but challenging problem as re-operation carries higher complication and failure rates. Re-operations can often be performed via a minimally invasive approach by experienced surgeons after localisation using requisite imaging techniques, the preferred sequence of which is still under evolution. A carefully planned operation with additional adjuncts is of utmost importance as parathyroidectomy remains the only curative treatment option.

Recurrence of secondary hyperparathyroidism in patients after total parathyroidectomy with autotransplantation: technical and therapeutic aspects

Recurrence of secondary hyperparathyroidism (rSHPT) in patients after total parathyroidectomy (TPTX) with autotransplantation (AT) represents a major diagnostic and therapeutic challenge. The aim of this retrospective cohort study was to evaluate rSHPT in patients after TPTX with AT and the subsequent surgical treatment. 112 patients with secondary hyperparathyroidism (surgery 1998-2008) were evaluated. In 16 patients, rSHPT was detected, while all of them had been originally operated with TPTX, cervical thymectomy and AT. The recurrence rate of TPTX with AT in our patient cohort was 14.2% (16/112). All the 16 patients with rSHPT suffered from forearm-autotransplant(s) hyperparathyroidism (AT-HPT). AT-HPT was diagnosed after a median of 5.6 years (1.5-11 years). All "forearm" AT-HPT operations were performed using the method of intra-operative parathyroid-hormone measurement. The histopathologic result showed hyperplasia or an adenoma of the reimplanted parathyroid gland (PTG) particles. The parathyroid hormone measurement (PTH) showed normal values in all cases 2 weeks after surgery. In none of the patients persistent hypocalcemia was observed. Our data demonstrates that the high rate of rSHPT in patients after TPTX with AT with renal-insufficiency represents an unsolved problem, often leading to re-operation including possible morbidity. Although we are not showing direct data, we propose, that the alternative method of TPTX without AT, simultaneous cryopreservation and potential metachronous reimplantation could offer an excellent alternative. However, this therapy option needs to be validated in further clinical trials.

Limitations of Tc99m-MIBI-SPECT imaging scans in persistent primary hyperparathyroidism

Background

In primary hyperparathyroidism (PHPT) the predictive value of technetium 99m sestamibi single emission computed tomography (Tc99m-MIBI-SPECT) for localizing pathological parathyroid glands before a first parathyroidectomy (PTx) is 83–100%. Data are scarce in patients undergoing reoperative parathyroidectomy for persistent hyperparathyroidism. The aim of the present study was to determine the value of Tc99m-MIBI-SPECT in localizing residual hyperactive parathyroid tissue in patients with persistent primary hyperparathyroidism (PHPT) after initial excision of one or more pathological glands.

Method

We retrospectively evaluated the localizing accuracy of Tc99m-MIBI-SPECT scans in 19 consecutive patients with persistent PHPT who had a scan before reoperative parathyroidectomy. We used as controls 23 patients with sporadic PHPT who had a scan before initial surgery.

Results

In patients with persistent PHPT, Tc99m-MIBI-SPECT accurately localized a pathological parathyroid gland in 33% of cases before reoperative parathyroidectomy, compared to 61% before first PTx for sporadic PHPT. The Tc99m-MIBI-SPECT scan accurately localized intra-thyroidal glands in 2 of 7 cases and a mediastinal gland in 1 of 3 cases either before initial or reoperative parathyroidectomy.

Conclusions

Our data suggest that the accuracy of Tc99m-MIBI-SPECT in localizing residual hyperactive glands is significantly lower before reoperative parathyroidectomy for persistent PHPT than before initial surgery for sporadic PHPT. These findings should be taken in consideration in the preoperative workup of patients with persistent primary hyperparathyroidism.

Parameters in the Prediction of the Sensitivity of Parathyroid Scanning

OBJECTIVE

Although parathyroid scintigraphy with technetium-99m sestamibi has been shown to be a sensitive and specific test for the detection and localization of parathyroid adenomas in patients with primary hyperparathyroidism, false-negative studies occur. Our goal was to determine whether the presurgical parathyroid hormone level could be used to predict whether a scan would be positive or negative.

MATERIALS AND METHODS

A retrospective review of parathyroid scans was performed. Analysis included patients with surgical confirmation of a parathyroid adenoma and a documented parathyroid hormone (PTH) level obtained within 6 months of the scan. Patients with secondary hyperparathyroidism were excluded. A true-positive study was defined by the surgical finding of an adenoma on the side indicated by the scan. A scan was false-negative if it did not detect the adenoma found at surgery. A scan was false-positive if an adenoma was identified in the wrong side of the neck or if an adenoma was called but not found.

RESULTS

Of 166 scans, 83 met the criteria for inclusion. There were 56 true-positives, 21 false-negatives, and 6 false-positives. The mean PTH in patients with true-positive scans was 367 pg/mL (range, 46-3231 pg/mL) and with false-positive and false-negative scans was 148 pg/mL (range, 46-390 pg/mL). The difference was statistically significant.

CONCLUSION

There is a correlation between the sensitivity of parathyroid scintigraphy and presurgical PTH. The overlap, however, of parathyroid hormone levels in positive and negative scans does not allow one to confidently preselect candidates for preoperative scanning.

Parathyroid re-exploration

Re-operative parathyroid surgery is always a challenge for the endocrine surgeon. This article discusses the issues the parathyroid surgeon must consider before and during re-operative surgery,with special attention to recently introduced adjunctive techniques.

Persistent and recurrent hyperparathyroidism after total parathyroidectomy with autotransplantation

OBJECTIVE

To conduct a retrospective study of 15 patients with persistent (n = 4) and recurrent (n = 11) hyperparathyroidism.

SUMMARY BACKGROUND DATA

Secondary hyperparathyroidism may persist or recur because of hyperfunction of the parathyroid remnant or transplanted parathyroid tissue. It is a great challenge to localize the parathyroid tissue either in the neck or at the arm before surgery.

METHODS

From June 1994 to June 2000, 15 patients with recurrent and persistent secondary hyperparathyroidism were selected for surgery for the removal of parathyroid tissue. The indications for surgery included bone pain, hypercalcemia, general weakness, and skin itching. Their ages ranged from 23 to 66 years. The average period of persistent hyperparathyroidism after total parathyroidectomy with autotransplantation was 3.8 months; that of recurrent hyperparathyroidism was 53 months. Serum levels of calcium, phosphorus, parathyroid hormone (iPTH), and alkaline phosphatase were measured before surgery and 1 week after surgery. Before surgery, the parathyroid gradient in the blood draining the graft-bearing arm versus the contralateral arm was measured. A 99mTc-sestamibi (MIBI) scan was performed including the neck and the arm area, and a computed tomography (CT) scan of the neck was performed to confirm the localization. The neck and mediastinal exploration was done directly at the side of localization under general anesthesia to remove the parathyroid tissue that had been located with the MIBI scan or CT scan. An arm exploration was done under local anesthesia to remove all parathyroid tissues detected in the MIBI scan or palpable masses during surgery. If all glands were removed, 0.5 x 0.5 x 0.5 cm of tissue (60-100 mg) was maintained in situ or the same amount of tissue was reimplanted.

RESULTS

The average ratio of iPTH in the graft-bearing arm to the contralateral arm in the 5 patients with parathyroid tissue in the neck was 1.17 +/- 0.16, and that in the 10 patients with parathyroid at the arm was 14.15 +/- 16.62. A significant difference was found between the two groups. MIBI scans showed parathyroid tissues in the neck in four of five patients and in seven of eight patients at the arm. Computed tomography showed the parathyroid tissues in the neck and mediastinum in five of five patients (100%). Five glands were removed from these five patients, three in the neck, one in the mediastinum, and one in the carotid sheath. In total, 20 glands and 2 half-glands were removed from 10 patients; among these, 14 glands were shown in the MIBI scan. All patients had improvements of symptoms and signs after surgery. Serum levels of calcium, phosphorus, and iPTH decreased rapidly after surgery, but alkaline phosphatase did not.

CONCLUSIONS

With the results obtained from the ratio of iPTH of the graft-bearing arm to the contralateral arm, clinical palpation of the arm, MIBI scan, CT scan, careful surgical exploration, and adequate resection, recurrent and persistent secondary hyperparathyroidism can be successfully treated with surgery in the neck or at the arm.

Pre-surgical localization of ectopic parathyroid glands using three-dimensional CT imaging, 99Tcm sestamibi, and 99Tcm tetrofosmin imaging

We describe two patients with ectopic parathyroid glands evaluated with 99Tcm sestamibi, 99Tcm tetrofosmin, and three-dimensional computed tomography (3D-CT). Radionuclide images of the neck were acquired at 10 min, and at 2-3 h after radiopharmaceutical injection, and showed intense uptake in the ectopic parathyroid tissue. These patients also underwent contrast enhanced CT imaging with 3D reconstructions which were evaluated for ability to visualize critical anatomical structures, e.g. blood vessels and parathyroid glands. Based on 3D-CT images, surgical planning was altered in one of the two patients studied. In conclusion, reconstructed 3D-CT images provided useful anatomical localization of ectopic parathyroid glands identified on 99Tcm sestamibi and 99Tcm tetrofosmin imaging. This anatomical information aided surgical planning of gland resection.

Detection of metastatic parathyroid carcinoma with Tc-99m sestamibi imaging

PURPOSE

To assess the use of Tc-99m sestamibi to localize recurrent and metastatic parathyroid carcinoma.

METHODS

A patient with a history of parathyroid carcinoma that was resected 6 months before had high serum calcium and high serum parathyroid hormone levels. Tc-99m sestamibi imaging was performed to localize the recurrence.

RESULTS

Tc-99 sestamibi imaging detected the recurrence and the metastatic lymph nodes. These findings were confirmed surgically and pathologically.

CONCLUSION

Tc-99m sestamibi can be useful in diagnosing and localizing metastatic parathyroid carcinoma.

Radionuclide scanning in parathyroid diseases

BACKGROUND

New radionuclide agents and scanning procedures have markedly improved preoperative parathyroid gland localization. The aim of this review was to evaluate the results of parathyroid scanning and to clarify its current place in the clinical management of parathyroid diseases.

METHODS

The literature describing the different radioisotopes and available scanning techniques was analysed and their clinical outcome in various parathyroid diseases was evaluated.

RESULTS

Using 99mTc-radiolabelled sestamibi or other 9mTc-labelled cationic complexes, parathyroid scintigraphy detects 87 per cent of solitary adenomas (n=894), 55 per cent of abnormal glands in patients with multiglandular disease (n=303) and 75 per cent of persistent or recurrent lesions in patients with previous neck surgery (n=240). If necessary, three-dimensional imaging techniques can clarify the spatial localization of an ectopic uptake focus. The positive predictive value of the available scanning procedures is over 95 per cent, but false-positive uptake may be encountered.

CONCLUSION

Radionuclide parathyroid gland scanning with 99mTc-labelled cationic complexes is the initial non-invasive method of choice for preoperative parathyroid gland localization in patients at special risk and/or with previous neck exploration. While scanning has also been proposed to facilitate parathyroidectomy, there is no objective evidence to support its routine use before a first-time surgical procedure.

The diagnostic utility of dual phase Tc-99m sestamibi parathyroid imaging

PURPOSE

Primary hyperparathyroidism is a disease of uncertain etiology that results from hypersecretion of parathyroid hormone (PTH) by the parathyroid gland. In most institutions, the preferred imaging protocol utilizes a dual-phase technique with Tc-99m sestamibi which is reported to be more sensitive than earlier protocols involving TI-201 with Tc-99m pertechnetate subtraction. The purpose of this study is to evaluate the accuracy and clinical utility of Tc-99m sestamibi dual-phase scintigraphy for localizing hyperfunctioning parathyroid tissue.

MATERIALS AND METHODS

We retrospectively reviewed thirty-nine consecutive hyperparathyroid patients who received a dual-phase Tc-99m sestamibi parathyroid scan. Thirty-seven of the subjects subsequently underwent a bilateral neck exploration and parathyroidectomy. Each scan interpretation was then correlated with the histopathologic diagnosis and the patients' post-surgical clinical course.

RESULTS

The sestamibi dual-phase imaging protocol correctly localized 21 of 25 parathyroid adenomas and identified 8 out of 10 cases of hyperplasia. Our overall sensitivity and specificity were 83% and 75%, respectively. In addition, four of the adenomas were successfully localized intraoperatively using a gamma probe.

CONCLUSION

Parathyroid imaging with sestamibi appears to be superior to TI-201/Tc-99m pertechnetate subtraction based on the reported results of both techniques at various institutions. Dual-phase sestamibi imaging appears to be useful and cost-effective for presurgical localization of hyperfunctioning parathyroid tissue. In addition, sestamibi imaging in conjunction with an intraoperative probe is a very promising technique that has the potential to provide both localization information of a suspected parathyroid adenoma and to facilitate its surgical removal by reducing operation time.

Sestamibi versus thallium subtraction scintigraphy in parathyroid localization: a prospective comparative study in patients with predominantly mild primary hyperparathyroidism

BACKGROUND

Technetium 99m sestamibi was recently introduced for the preoperative localization of abnormal parathyroid glands in patients with primary hyperparathyroidism with promising results. However, the sensitivity of sestamibi and thallium to detect abnormal parathyroid glands is partly dependent on the gland size. In this study we compared the sensitivity of sestamibi subtraction scintigraphy with thallium subtraction scintigraphy in patients with predominantly mild increase in serum calcium level.

METHODS

Thirty-nine patients with primary hyperparathyroidism were included. The mean (+/-SD) serum level of calcium was 2.75 +/- 0.17 mmol/L. In 28 (72%) of the patients the serum level of calcium was less than 2.85 mmol/L. These patients were classified as having mild abnormalities in serum calcium. All patients were investigated before operation with both sestamibi and thallium subtraction scintigraphy.

RESULTS

In two patients autonomous thyroid adenomas precluded subtraction scintigraphy. Sestamibi subtraction scintigraphy correctly localized 31 (86%) of 36 parathyroid adenomas compared with only 17 (47%) of 36 by thallium subtraction scintigraphy (p < 0.001). There was one false-positive result in the sestamibi group because of a thyroid adenoma, and two of the scans were negative. Both the sestamibi and the thallium subtraction scintigraphy localized one single enlarged gland in all three patients with multiple gland involvement. In no case was multiglandular disease predicted.

CONCLUSIONS

Sestamibi subtraction scintigraphy is superior to thallium subtraction scintigraphy and has a high sensitivity to localize a solitary parathyroid adenoma in patients with mild increase in serum calcium level. The sensitivity decreases in patients with multiglandular parathyroid disease and concomitant thyroid nodular abnormalities.

Recent advances in parathyroid imaging

Although no existing imaging procedure is as effective as an experienced surgeon for locating abnormal parathyroid glands in patients without previous neck surgery, preoperative parathyroid localization is considered essential for patients undergoing reoperations. The need for parathyroid imaging in patients undergoing an initial exploration remains controversial. Scintigraphy with (99m)Tc-sestamibi has largely replaced (99m)Tc-pertechnetate/(201)Tl chloride subtraction scintigraphy for parathyroid imaging because of its superior sensitivity and false-positive rate. Positron emission tomography, another technique recently applied to parathyroid imaging, is of uncertain value at present.