A prospective evaluation of preoperative localization by technetium-99m sestamibi scintigraphy and ultrasonography in primary hyperparathyroidism

99MTc-sestamibi as sole technique in selection of primary hyperparathyroidism patients for unilateral neck exploration

BACKGROUND

Unilateral neck exploration (UNE) is becoming the procedure of choice for treatment of primary hyperparathyroidism (PHPT). The aim of this study was to evaluate the role of (99m)Tc-sestamibi (MIBI) parathyroid scintigraphy as the sole technique in selecting patients for UNE.

METHOD

We selected 136 consecutive PHPT patients who had only 1 solitary uptake at a MIBI were for UNE. The technique was a single dual-phase using MIBI and a subtraction technique with (99m)Tc-pertechnetate. Imaging data were correlated with surgical results.

RESULTS

In 3 cases, the sestamibi scan was falsely positive, 1 had a contralateral location relative to the uptake, and 2 had multiglandular hyperplasia. Overall, the positive predictive value (PPV) of MIBI for detecting a solitary parathyroid adenoma in patients with 1 solitary uptake was 97.8. Sixteen patients (12%) had evidence of multinodular goiter. Overall, the PPV of MIBI was 98.4% (2 false positive among 120 cases) in patients with no multinodular thyroid disease (MNG) and 93.7% (1 false negative among 16 cases) in patients with MNG. The mean duration of the surgical procedure was 34.17 minutes. Mean hospitalization was 0.6 days. Conversion to bilateral neck exploration was performed in 5 patients. After a period of follow-up of 40 months (range, 6-72 months), the cure rate was 98%.

CONCLUSION

Patients with PHPT and unequivocally positive preoperative (99m)Tc-sestamibi can safely be managed with UNE without additional localizing techniques.

Ultrasonography: highly accuracy technique for preoperative localization of parathyroid adenoma

OBJECTIVES/HYPOTHESIS

This study evaluates the accuracy of ultrasonography in guided unilateral parathyroidectomy to treat primary hyperparathyroidism.

STUDY DESIGN

Retrospective study.

METHODS

Two hundred fifty-three patients with primary hyperparathyroidism underwent preoperative ultrasonography. Two groups were defined. Group 1 included the patients in whom the preoperative cervical ultrasound localized one abnormal parathyroid gland; these patients underwent unilateral surgical exploration of the neck under local anesthesia. Group 2 included the patients who had a bilateral neck exploration under general anesthesia when the preoperative examination was equivocal or failed to localize the lesion, when concomitant thyroid pathology indicated thyroidectomy, and when justified by the surgical findings.

RESULTS

Sensitivity and positive predictive value of ultrasonography in detecting abnormal parathyroid gland were 96% and 98%, respectively. Cervical ultrasound correctly identified, 96% and 85% of abnormal glands in groups 1 and 2, respectively. The presence of thyroid nodular disease did not affect ultrasonographic accuracy. Sonographic examination decreased the operative time of parathyroidectomy to an average of 15 minutes. Mediastinal and retroesophageal localizations of abnormal parathyroid gland adversely affected the accuracy of the ultrasound. No cervical hematoma was noted. Transient recurrent laryngeal nerve palsy occurred in four patients. Twenty-three patients required postoperative calcium supplementation for 2 to 4 months, and all were normocalcemic at follow-up.

CONCLUSIONS

Cervical ultrasound is a reliable preoperative exploration allowing parathyroidectomy via unilateral approach under local anesthesia.

Primary hyperparathyroidism: a current perspective

CONTEXT

Primary hyperparathyroidism (P-HPT) is one of the most common of all endocrine disorders. Eighty percent to 85% of cases are due to parathyroid adenomas while hyperplasia and carcinoma account for 10% to 15% and less than 1%, of cases, respectively. The past decade has witnessed remarkable advances in the understanding of the molecular basis of parathyroid hyperplasia and neoplasia. Additionally, imaging studies and the development of the intraoperative assay for parathyroid hormone have transformed the diagnosis and management of patients with these disorders.

OBJECTIVE

To review the pathology of parathyroid lesions associated with P-HPT, their molecular and genetic bases, including heritable hyperparathyroidism syndromes, and their clinical diagnosis and management.

DATA SOURCES

Review of pertinent epidemiology, pathology, radiology, and surgery literature on the diagnosis, classification, and treatment of P-HPT.

CONCLUSIONS

Although heritable causes of P-HPT including multiple endocrine neoplasia 1 and 2A and hyperparathyroidism-jaw tumor syndrome account for a minority of cases of P-HPT, advances in the characterization of the affected genes have provided insights into the genetic basis of sporadic parathyroid neoplasms. Alterations in cyclin D1 and loss of heterozygosity of chromosome 11q in adenomas and hyperplasias have provided support for clonality of these lesions. Parafibromin, the protein product of the HRPT2 gene responsible for hyperparathyroidism-jaw tumor syndrome, has been implicated in the development of sporadic parathyroid carcinomas and loss of immunohistochemical expression of this protein has been suggested to be of value in making the diagnosis of parathyroid carcinoma. Sestamibi scanning and ultrasound have revolutionized the planning of surgical approaches and the intraoperative parathyroid hormone assay has become the standard in guiding completion or extension of surgery.

Impact of adenoma weight and ectopic location of parathyroid adenoma on localization study results

Although the sensitivity of preoperative localization techniques is high for solitary parathyroid adenomas, negative imaging study results are inevitable. The weight and location of the parathyroid adenoma may contribute to the negative results. We aimed to study the impact of adenoma weight and ectopic location of the parathyroid adenoma on ultrasonography and sestamibi scan results. The patients were divided into two groups according to adenoma location. Group 1 consisted of 36 patients with ectopic location, and group 2 consisted of 149 patients with normal location. Parathyroid adenoma weight and the results of imaging studies were determined in all patients. Of 185 patients operated on for hyperparathyroidism, 36 (19.4%) had ectopic parathyroid glands. There was a positive correlation between adenoma weight and positive imaging studies, whereas ectopic location did not correlate with negative imaging study results. There was no significant difference between the ectopic adenoma ratio of patients with negative and positive imaging study results. The weight of the ectopic parathyroid adenoma was significantly lower in patients with negative imaging study results than in patients with positive imaging study results (p = 0.001). According to the analysis of variance, patients with higher-weight adenomas have positive imaging study results irrespective of ectopic location. For both normal and ectopic adenoma locations, adenoma weight was found only to be a factor that positively influences imaging study results.

The management of thyroid nodules in patients with primary hyperparathyroidism

BACKGROUND

Thyroid nodules are found in 12-52% of patients with primary hyperparathyroidism (pHPT). With the increasing use of minimally invasive parathyroidectomy (MIP), there is no standard approach for the management of incidental thyroid nodules in pHPT patients.

METHODS

A survey was conducted of the American Association of Endocrine Surgeons. Information was obtained regarding parathyroidectomy practice patterns, including surgical technique, preoperative localization procedures, and algorithms used in the diagnosis/treatment of incidental thyroid nodules.

RESULTS

The survey response rate was 74%. Sixty-seven percent were high-volume parathyroid surgeons (>5/mo); the majority performed MIP. High-volume surgeons were more likely to use Sestamibi/single photon emitted computed tomography for preoperative localization (40% versus 24%; P = 0.011) and to disregard incidentally discovered thyroid nodules <1 cm (41% versus 22%; P = 0.023). They were less likely to evaluate nodules discovered intraoperatively by frozen section (28% versus 41%; P = 0.081), fine-needle aspiration (13% versus 24%; P = 0.078), or thyroidectomy (24% versus 40%; P = 0.03). Surgeons performing open parathyroidectomy were more likely than those who use MIP to biopsy nodules intraoperatively (32% versus 20%; P < 0.05) and perform simultaneous thyroidectomy (30% versus 10%; P < 0.001).

CONCLUSIONS

Experienced endocrine surgeons disagree about the optimal management of incidental thyroid nodules encountered during parathyroidectomy. Our data suggest that high-volume parathyroid surgeons are less aggressive in their evaluation of thyroid pathology in patients with pHPT. Variation in practice among this experienced group implies even greater variation in the broader surgical community, and in the quality and cost of care for patients with pHPT.

Factors contributing to negative parathyroid localization: an analysis of 1000 patients

BACKGROUND

Localizing studies are the key for determining the optimal surgical strategy in patients with primary hyperparathyroidism (HP). Most of the data in the literature are retrospective in nature and from analysis on a per patient basis. This is a prospective study looking at the characteristics of the patient and the gland that determine the likelihood of an abnormal parathyroid to be detected by ultrasonography (US) and sestamibi scan (MIBI).

METHODS

This is a prospective analysis of 1000 consecutive patients with HP who underwent parathyroidectomy at a tertiary care center. The study group included HP with single gland disease (63%), double adenoma (15%), as well as hyperplasia (15%), familial HP (2%), and secondary/tertiary HP (6%). All patients underwent surgeon-performed neck US followed by MIBI scan. Univariate logistic regression and multivariate analyses were performed on pre- and intraoperative variables.

RESULTS

A total of 1845 abnormal glands were analyzed. Overall, US was superior to MIBI for the detection of abnormal glands in all subgroups. On multivariate analysis, body mass index (BMI), gland size, and gland volume were the statistically significant independent factors predicting detection by both US and MIBI in primary HP. The sensitivity of US was better for single gland disease than for multigland disease in primary HP, but the sensitivity of MIBI was similar in both groups. For a given size, hyperplastic glands in primary HP imaged less well with US and MIBI than in familial or secondary/tertiary HP.

CONCLUSION

This prospective study demonstrates that BMI and gland size independently predict accurate detection of abnormal parathyroid glands by US and MIBI in sporadic primary HP. Understanding the factors that affect the accuracy of parathyroid localization tests will allow the surgeon to develop a successful surgical strategy in a given patient.

Novel criteria for parathyroid hormone levels in parathyroid hormone-guided parathyroid surgery

CONTEXT

Novel criteria for decrease of perioperative parathyroid hormone measurement may improve the accuracy of perioperative quick parathyroid hormone (qPTH)-guided parathyroidectomy.

OBJECTIVE

To assess overall cure rate based on conventional criteria (50% decline of qPTH). Perioperative qPTH levels were evaluated to determine novel criteria for successful parathyroid surgery.

DESIGN

Analysis of perioperative qPTH measurement findings of all consecutive patients undergoing parathyroidectomy for hyperparathyroidism (72 with primary hyperparathyroidism and 28 with secondary or tertiary hyperparathyroidism or multiple endocrine neoplasia I/IIa disease).

RESULTS

Measurement of qPTH (based solely on the criterion of greater than 50% decline of parathyroid hormone) in 72 patients with primary hyperparathyroidism (77 procedures) showed true-positive results in 69, false-positive results in 4, and true-negative results in 4 procedures. In our series, false-positive and true-negative results were associated with high postexcision levels. However, when qPTH declines of greater than 70% and 80% were used in cases of postexcision qPTH levels of 100 to 200 ng/L and greater than 200 ng/L, respectively, no false-positive results were observed.

CONCLUSIONS

Through adherence to these novel criteria, reexploration of the neck could have been prevented in 29% of patients with primary hyperparathyroidism due to multiple gland disease. These novel criteria demand future evaluation to establish their value.

Imaging of anterior mediastinal masses

Multiple different types of anterior mediastinal masses may be encountered on computed tomography (CT) imaging, and many of these lesions are neoplastic in etiology. These include masses arising from the thymus, thyroid and parathyroid glands, as well as lymph nodes, pericardium, and vessels and nerves. Often, the CT attenuation of the mass can be helpful in narrowing down the differential diagnosis, and attenuation values suggesting fat, water or calcium may suggest certain diagnoses; significant enhancement of the mass with intravenous contrast may also be a helpful feature. Lesions with fatty attenuation include teratomas, thymolipomas and Morgagni hernias. Lesions that may manifest the attenuation of water include pericardial and thymic cysts, abscesses, and lymphangiomas, as well as neurogenic and germ cell tumors. Multiple types of lesions may contain calcium, including thyroid goiters and cancers, thymomas, thymic carcinomas and carcinoids, treated lymphoma, germ cell tumors, parathyroid adenomas, and lymph nodes involved with silicosis, sarcoid, tuberculosis, fungal diseases and pneumocystis. Contrast enhancement may be seen in lesions of vascular origin and in vascular neoplasms, such as parathyroid adenomas and Castleman's disease. In addition to CT attenuation values, the exact location and morphology of the mass in question, in conjunction with clinical features such as patient age, gender, signs, symptoms, and laboratory values, can usually lead to a short list of possible etiologies, thereby directing appropriate additional diagnostic procedures or therapeutic approaches.