Sensitivity and Utility of Parathyroid Scintigraphy in Patients with Primary Versus Secondary and Tertiary Hyperparathyroidism

Comparison of parathyroid scintigraphy findings in pediatric and adult patients with secondary hyperparathyroidism

OBJECTIVES

Secondary hyperparathyroidism (sHPT) is a compensatory complication of chronic kidney disease. The aim of this study was to compare PS findings in pediatric and adult patients with sHPT.

METHODS

This study included 50 pediatric and 50 adult patients with sHPT. Parathyroid scintigraphy was performed with Tc-99m sestamibi. After radiopharmaceutical injection, early-phase (15 min) and late-phase (60-90 min) images were acquired. Planar images were interpreted visually for the presence / number of active foci compatible with a parathyroid lesion, the presence and degree of uptake in skeletal structures, and the degree of thyroid sestamibi uptake. Parathyroid surgery was performed in 21 pediatric and 28 adult patients.

RESULTS

Serum PTH and ALP values were significantly higher in pediatric than in adult patients ( P < 0.05 for each). In operated patients, on a lesion-based analysis, the sensitivity of PS in pediatric and adult patients were 40% and 71%, respectively. A nonlocalizing scan was observed in 24% of pediatric patients. Pediatric patients had a higher incidence of reduced thyroid sestamibi uptake (42% versus 2%). Skeletal sestamibi uptake was detected in 40% of pediatric and 30% of adult patients and the degree of uptake was higher in pediatric patients.

CONCLUSIONS

The results revealed more significant changes in the biochemical profile of pediatric compared with adult patients with sHPT. The sensitivity of PS was lower, and the likelihood of a nonlocalizing scan was higher in pediatric patients. The results may also suggest more severe skeletal findings in pediatric patients. Reduced thyroid sestamibi uptake in children needs further evaluation.

Parathyroid Imaging

Primary hyperparathyroidism (1° HPT) is a relatively common endocrine disorder usually caused by autonomous secretion of parathormone by one or several parathyroid adenomas. 1° HPT causing hypercalcemia, kidney stones and/or osteoporosis should be treated whenever possible by parathyroidectomy. Accurate preoperative location of parathyroid adenomas is crucial for surgery planning, mostly when performing minimally invasive surgery. Cervical ultrasonography (US) is usually performed to localize parathyroid adenomas as a first intention, followed by 99mTc- sestamibi scintigraphy with SPECT/CT whenever possible. 4D-CT is a possible alternative to 99mTc- sestamibi scintigraphy. Recently, 18F-fluorocholine positron emission tomography/computed tomography (18F-FCH PET/CT) has made its way in the clinics as it is the most sensitive method for parathyroid adenoma detection. It can eventually be combined to 4D-CT to increase its diagnostic performance, although this results in higher dose exposure to the patient. Other forms of hyperparathyroidism consist in secondary (2° HPT) and tertiary hyperparathyroidism (3° HPT). As parathyroidectomy is not usually part of the management of patients with 2° HPT, parathyroid imaging is not routinely performed in these patients. In patients with 3° HPT, total or subtotal parathyroidectomy is often performed. Localization of hyperfunctional glands is an important aid to surgery planning. As 18F-FCH PET/CT is the most sensitive modality in multigland disease, it is the preferred imaging technic in 3° HPT patients, although its cost and availability may limit its widespread use in this setting.

18F-Fluorocholine PET/CT Compared with Current Imaging Procedures for Preoperative Localization of Hyperfunctioning Parathyroids in Patients with Chronic Kidney Disease

Hyperparathyroidism (HPT) in patients with chronic kidney disease (CKD) includes secondary (sHPT) and tertiary hyperparathyroidism (tHPT). Considering that the role of preoperative imaging in the clinical setting is controversial, in the present study we have retrospectively compared pre-surgical diagnostic performances of ¹⁸F-Fluorocholine (¹⁸F-FCH) PET/CT, cervical ultrasonography (US), parathyroid scintigraphy, and 4D-CT in a group of 30 patients with CKD and HPT (18/12 sHPT/tHPT), 21 CKD G5 including 18 in dialysis, and 9 kidney transplant recipients. All patients underwent ¹⁸F-FCH, and 22 had cervical US, 12 had parathyroid scintigraphy, and 11 had 4D-CT. Histopathology was the gold standard. Seventy-four parathyroids were removed: 65 hyperplasia, 6 adenomas, and 3 normal glands. In the whole population, in a per gland analysis, ¹⁸F-FCH PET/CT was significantly more sensitive and accurate (72%, 71%) than neck US (25%, 43%), parathyroid scintigraphy (35%, 47%), and 4D-CT (40%, 47%). The specificity of ¹⁸F-FCH PET/CT (69%) was lower than that of neck US (95%) and parathyroid scintigraphy (90%), without, however, achieving significance. ¹⁸F-FCH PET/CT was more accurate than all other diagnostic techniques when sHPT and tHPT patients were considered separately. ¹⁸F-FCH PET/CT sensitivity was significantly higher in tHPT (88%) than in sHPT (66%). Three ectopic hyperfunctioning glands (in three different patients) were all detected by ¹⁸F-FCH PET/CT, two by parathyroid scintigraphy, and none by cervical US and 4D-CT. Our study confirms that ¹⁸F-FCH PET/CT is an effective preoperative imaging option in patients with CKD and HPT. These findings may be of greater importance in patients with tHPT (who could benefit from minimally invasive parathyroidectomy) than in patients with sHPT, who often undergo bilateral cervicotomy. In these cases, preoperative ¹⁸F-FCH PET/CT may be helpful in locating ectopic glands and may guide the surgical choice for gland preservation.

Preoperative Imaging in Renal Transplant Patients with Tertiary Hyperparathyroidism

BACKGROUND

Tertiary hyperparathyroidism following kidney transplantation is most commonly characterized by 4-gland hyperplasia, but single and double adenomatous disease has been demonstrated in this population as well. It is unknown whether preoperative imaging can assist in identifying patients who may qualify for focused surgery for adenomatous disease.

MATERIALS AND METHODS

We performed a retrospective review of our patient database from 1998-2018 for patients with tertiary hyperparathyroidism following renal transplant. Patient charts were reviewed for patient demographics, laboratory values, preoperative imaging, operative findings, pathology, and complications.

RESULTS

We identified 113 patients with tertiary hyperparathyroidism following renal transplant who underwent parathyroidectomy. There were 51 females and 62 males with a mean age of 53.4 ± 13.4 years. Median preoperative calcium and PTH were 10.9 mg/dl (IQR 10.3-11.2) and 228 pg/ml (IQR 118-305). Preoperative ultrasound was performed in 60 patients. Of these, 11 (18%) were negative, 38 (63%) showed 1-2 adenomas, and 11 (18%) showed ≥ 3 adenomas. 99mTc-sestamibi parathyroid scintigraphy was performed in 101/113 patients. Of these, 11 (11%) were negative, 62 (61%) showed 1-2 areas of discordant sestamibi uptake, and 28 (28%) showed ≥ 3 areas of discordant uptake. Ultimately, 19 (17%) patients had a single adenoma removed, 16 (14%) had 2 adenomas removed, and (69%) had multi-gland disease. There were 26 ectopic glands found in 21 patients, 42.3% of which were identified on preoperative imaging. 94.1% of patients were eucalcemic at last follow-up, mean (± SD) 5.8 ± 3.6 years. Adenomas that were visualized on ultrasound were larger on pathology than those non-visualized (997 ± 120 mg (mean ± SE) vs. 388 ± 109 mg, p = 0.0003). This was also true for parathyroid scintigraphy (647 ± 41 mg vs. 355 ± 51 mg, p = 0.0001).

CONCLUSION

In patients with tertiary hyperparathyroidism, preoperative imaging can aid in predicting which patients will have 1-2 gland disease. In patients with 1-2 gland disease on congruent ultrasound and nuclear medicine imaging studies, the accuracy increases to 59%. Preoperative imaging can help identify ectopic glands. Larger adenomas are more likely to be identified on both imaging modalities.

Surgical Management of Secondary Hyperparathyroidism

Secondary hyperparathyroidism (SHPT) affects a majority of patients with chronic kidney disease (CKD) of stage 3 or worse. Despite the development of calcimimetics and their effectiveness in treating SHPT, many patients continue to fail medical management and should be referred to a parathyroid surgeon. In this narrative review, we summarize the indications for surgical referral, preoperative planning, intraoperative strategies to guide resection, and postoperative management. In the absence of universal guidelines, it can be difficult to determine when it is appropriate to make this referral. The majority of studies evaluating parathyroidectomy (PTX) for SHPT use the criteria of parathyroid hormone level (PTH) >800 pg/ml with hypercalcemia and/or hyperphosphatemia, which may be accompanied by symptoms such as bone pain and pruritis that can improve after surgery. Although the reported utility of the various imaging modalities (i.e., 99m-technetium-sestamibi scintigraphy with computed tomography [SPECT/CT], CT, or ultrasound) is highly variable in SHPT, SPECT/CT appears to be the most sensitive. Intraoperatively, PTH monitoring is effective in predicting long-term cure of SHPT but not in predicting hypoparathyroidism. Ectopic and supernumerary parathyroid glands are common in these patients and are often implicated in persistent or recurrent disease. Postoperatively, patients are at risk of severe hypocalcemia and hungry bone syndrome requiring close monitoring and replenishment.

Preoperative F-18 fluorocholine PET/CT for the detection of hyperfunctioning parathyroid glands in patients with secondary or tertiary hyperparathyroidism: comparison with Tc-99m sestamibi scan and neck ultrasound

OBJECTIVES

Currently, neck ultrasound is the preferred preoperative imaging in patients with secondary/tertiary hyperparathyroidism, and the use of Tc-99m sestamibi scan is limited in these patients. We conducted this study to compare the diagnostic utilities of F-18 fluorocholine PET/CT, Tc-99m sestamibi scintigraphy, and neck ultrasound for localizing hyperfunctioning parathyroid glands in secondary/tertiary hyperparathyroidism.

METHODS

We prospectively enrolled 30 dialysis patients with a diagnosis of secondary/tertiary hyperparathyroidism; of these, 27 participants underwent all three imaging modalities, including dual-phase F-18 fluorocholine PET/CT (PET acquired 5 and 60 min after tracer injection), dual-phase Tc-99 m sestamibi SPECT/CT, and neck ultrasound. All patients underwent parathyroidectomy after imaging. We compared the lesion-based sensitivity, specificity, and accuracy of the three image tools using histopathology as the reference.

RESULTS

A total of 27 patients (107 lesions) underwent all three imaging modalities and entered the final analysis. The lesion-based sensitivities of F-18 fluorocholine PET/CT, Tc-99m sestamibi, and ultrasound were 86%, 55%, and 62%, respectively (both p < 0.001, when comparing F-18 fluorocholine PET/CT to Tc-99 m sestamibi scan and to ultrasound). F-18 fluorocholine PET/CT, Tc-99m sestamibi, and ultrasound had similar specificities of 93%, 80%, and 87%, respectively. The accuracy of F-18 fluorocholine PET/CT (87%) was significantly higher than that of Tc-99m sestamibi (59%) and ultrasound (65%) (both p < 0.001). F-18 fluorocholine PET/CT identified more hyperplastic glands than ultrasound in 52% (14/27) patients. The sensitivity of F-18 fluorocholine PET/CT reached 95% for hyperplastic parathyroid masses as low as 200 mg.

CONCLUSIONS

F-18 fluorocholine PET/CT shows superior accuracy over the conventional imaging modalities in patients with secondary or tertiary hyperparathyroidism. The combination of F-18 fluorocholine PET/CT and neck ultrasound may enable better surgical planning in these patients.

REGISTRATION IDENTIFICATION NUMBER

NCT04316845.

Management of Post-transplant Hyperparathyroidism and Bone Disease

Significant advances in immunosuppressive therapies have been made in renal transplantation, leading to increased allograft and patient survival. Despite improvement in overall patient survival, patients continue to require management of persistent post-transplant hyperparathyroidism. Medications that treat persistent hyperparathyroidism include vitamin D, vitamin D analogues, and calcimimetics. Medication side effects such as hypocalcemia or hypercalcemia, and adynamic bone disease, may lead to a decrease in the drugs. When medical management fails to control persistent post-transplant hyperparathyroidism, treatment is a parathyroidectomy. Surgical techniques are not uniform between centers and surgeons. Undergoing the surgery may include a subtotal technique or a technique including total parathyroid gland resection with partial heterotopic gland reimplantation. In addition, there are possible post-surgical complications. The ideal treatment for persistent post-transplant hyperparathyroidism is the treatment and prevention of the condition while patients are being managed for their late-stage chronic kidney disease and end-stage renal disease.

Techniques for parathyroid localization with ultrasound

Four-gland parathyroid exploration has been the gold standard for parathyroid surgery until recently. Emphasis is now placed on minimally invasive and focused parathyroidectomy. In conjunction with functional sestamibi scanning, ultrasonography permits accurate localization of enlarged parathyroid glands in the vast majority of patients with hyperparathyroidism. Consequently, ultrasound technology applied to parathyroid pathology facilitates directed surgical therapy and minimally invasive applications. As such, ultrasonography holds great promise as a tool that enables cost-effective and advanced patient care.

Imaging of the thyroid and parathyroid glands

Current multimodal imaging techniques offer practicing providers the adequate framework to plan and accomplish care for patients with thyroid and parathyroid disorders. Available imaging modalities include ultrasonography (US), nuclear scintigraphy, computed tomography (CT), and magnetic resonance imaging (MRI). US remains the most cost-effective and the safest approach for the initial evaluation of the thyroid gland. Parathyroid subtraction scintigraphy provides localization of pathologic parathyroid glands with the greatest sensitivity. Localizing imaging studies allow for surgical planning with minimal risk and morbidity to the patient. CT scan and MRI play an adjunctive role in the further characterization of neck pathology.

The usefulness of preoperative dual-phase 99mTc MIBI-scintigraphy and IO-PTH assay in the treatment of secondary and tertiary hyperparathyroidism

BACKGROUND

Persistent secondary or tertiary hyperparathyroidism (HPT) results from failure to remove enough hyperfunctioning parathyroid tissue. Ectopically situated parathyroid glands and supernumerary glands make failure more likely. Recurrent HPT after subtotal Ptx is usually due to regrowth of the remaining parathyroid tissue. Recurrence may also develop from a hyperplastic supernumerary gland or rarely from parathyromatosis. Recurrent HPT after total Ptx with autotransplantation is usually due to overgrowth of the autograft or for the previously mentioned reasons.

METHODS

Since 1995, 464 patients with SHPT or THPT were treated surgically; intraoperative parathormone (PTH) was measured in 277 patients. Sixty-eight patients also had a preoperative MIBI scan. We compared the preoperative MIBI scan results with intraoperative findings, parathyroid gland weight and histology. We questioned whether MIBI uptake corresponded to parathyroid gland size and weight. We also correlated the number of Ki67 nuclear positive cells with MIBI uptake. For SHPT in group I with 145 patients, neither intraoperative PTH (IO-PTH) assay nor MIBI scanning was done. In group II with 163 patients IO-PTH was used and in group III with 48 patients both IO-PTH and MIBI scanning was used. For THPT in group I with 42 patients, neither IO-PTH assay nor MIBI scanning was done. In group II with 46 patients IO-PTH was used and in group III with 20 patients both IO-PTH and MIBI scanning was used.

RESULTS

Parathyroid weight correlated directly with MIBI uptake. No correlation, however, occurred between MIBI uptake and parathyroid histology or between Ki67 staining and MIBI scanning. For SHPT in group I the persistence rate was 6.2% and recurrence rate 11%; in group II the persistence rate was 4.9% and recurrence rate 4.9%; in group III the persistence rate was 2%, and recurrence 4.2% (P < 0.05 between group I and III for persistence and recurrence). We obtained similar results in THPT, but recurrence was 0 in groups II and III, also when only 3 glands were removed, probably due to asymmetric hyperplasia commonly seen in this particular population (P < 0.05 regarding recurrence between group I and II-III, no difference between group II and III).

CONCLUSION

In conclusion our findings support that the surgeon experience is a very important factor for good results in patients with SHPT and THPT. Preoperative MIBI scanning and IO-PTH are helpful but not essential except in reoperations.

The use of pre-operative imaging and intraoperative parathyroid hormone level to guide surgical management of tertiary hyperparathyroidism from X-linked hypophosphatemic rickets: a case report

Introduction

To describe the use of combined preoperative imaging and intraoperative parathyroid hormone as a novel approach in the surgical management of a patient with tertiary hyperparathyroidism associated with X-linked hypophosphatemic rickets.

Case presentation

We present the first documented description of combined preoperative imaging and intraoperative parathyroid hormone as well as a review of the literature surrounding the surgical management of tertiary hyperparathyroidism in the setting of X-linked hypophosphatemic rickets.

A 23 year-old female with X-linked hypophosphatemic rickets and renal impairment presented with symptomatic hypercalcemia and tertiary hyperparathyroidism. She had failed medical management and presented for surgical evaluation. Technitium-99 m Sestamibi SPECT imaging and parathyroid ultrasound were used to localize the enlarged parathyroid glands preoperatively. Intraoperative findings correlated well with pre-operative imaging. She underwent successful subtotal parathyroidectomy for four-gland hyperplasia, using intraoperative parathyroid hormone guidance. Despite severe post-operative bone hunger, her serum calcium normalized and she experienced resolution of her preoperative symptoms.

Conclusion

X-linked hypophosphatemic rickets is an uncommon disorder of phosphate metabolism resulting in bone deformity. Patients are predisposed to the development of secondary hyperparathyroidism due to chronic vitamin D supplementation which may progress to tertiary hyperparathyroidism with autonomous parathyroid function. Preoperative evaluation with Technitium-99 m Sestamibi SPECT and ultrasound imaging, as well as the use of intraoperative parathyroid hormone are effective in guiding surgical resection. Subtotal parathyroidectomy with cryopreservation is indicated to produce operative cure and limit the risk of recurrence. Although these patients are susceptible to severe postoperative bone hunger, appropriate supplementation with intravenous and oral calcium can minimize hypocalcemic symptoms.

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.

Value of Sestamibi Scans in Tertiary Hyperparathyroidism

OBJECTIVES

To determine the value of preoperative Tc-sestamibi scans and the incidence of ectopic glands in tertiary hyperparathyroidism.

DESIGN

Prospective, non-randomized analysis of a consecutive cohort of surgical patients from the Medical College of Georgia Thyroid/Parathyroid Center.

MATERIALS AND METHODS

A consecutive series of patients with tertiary hyperparathyroidism undergoing parathyroidectomy was analyzed. Demographic data, preoperative Tc-sestamibi scintigraphy results, location of diseased glands, pre- and postoperative calcium, and parathyroid hormone levels were collected.

RESULTS

Twenty-one patients underwent parathyroidectomy for tertiary hyperparathyroidism between March 2004 and September 2006. Of these 21 patients, 3 were re-operative cases for persistent hypercalcemia and each was found to have a single diseased gland. Of the 18 patients undergoing first time surgery, 15 had four-gland hyperplasia, 2 patients had single adenomas, and 1 patient had a double adenoma. Nine of the 21 patients (43%) had ectopic glands (2 of these patients had 2 ectopic glands each). The overall sensitivity of the preoperative Tc-sestamibi scintigraphy was 76% and was not significantly different when comparing patients with ectopic glands (78%) and those without (75%).

CONCLUSIONS

Tc sestamibi scintigraphy has high positive predictive value and sensitivity in patients with tertiary hyperparathyroidism. Sestamibi scanning is particularly valuable in this patient population since the incidence of ectopic glands may be higher than previously recognized.

Usefulness of preoperative Tc-mibi parathyroid scintigraphy in secondary hyperparathyroidism

BACKGROUND AND AIMS

The usefulness of Tc-mibi parathyroid scintigraphy (Tc-PS) in planning parathyroidectomy for secondary hyperparathyroidism is not well known. The aim of this study was to review our experience with Tc-PS concerning: (1) the identification of hyperplastic glands, (2) detection of major ectopias and (3) prevention of recurrences.

PATIENTS AND METHODS

Thirty-three consecutive patients undergoing first-time subtotal parathyroidectomy for renal hyperparathyroidism had a dual-phase planar Tc-PS performed, and glands were classified as detected, weak, or not detected. The number and position of visualized glands were determined. Parathyroid weight, histology, and their relationship to Tc-PS were recorded after surgery.

RESULTS

Of 132 potential glands, 48 (35%) were localized on the Tc-PS and 128 (96.9%) were identified intraoperatively. Tc-PS positive/weak glands were heavier than nonlocalized glands. Tc-PS contributed to successful surgery in four patients with a single difficult gland each (three retrieved from the neck and one--fifth gland--requiring mediastinotomy). There was one persistence (3%) because of a missed fourth undescended inferior parathyroid gland. Two recurrences 2 years after surgery were due to a fifth thoracic gland not shown in the preoperative Tc-PS.

CONCLUSIONS

Preoperative Tc-PS helped in the intraoperative identification of moderate or major ectopias in 4/33 patients but was not useful to prevent recurrences from highly ectopic glands not visualized before first-time surgery.