Parathyroid Imaging: The Importance of Dual-Radiopharmaceutical Simultaneous Acquisition with 99mTc-Sestamibi and 123I

Determinants and clinical significance of negative scintigraphic findings in primary hyperparathyroidism: a retrospective observational study

AIM

In patients with recurrent primary hyperparathyroidism (pHPT) or preceding thyroid operation, scintigraphic localization of the pathological parathyroid gland is sometimes unsuccessful. Reason for diagnostic failure, and its clinical relevance is poorly understood.

METHODS

This retrospective observational study in patients suffering from a pHPT evaluated independent predictors of a negative preoperative scintigraphy (SC) result, and its relevance for intraoperative outcome using logistic regression analysis.

RESULTS

Among 86 pHPT patients scheduled for parathyroid operation, 63 (73%) had a history of a preceding thyroid or parathyroid operation. Preoperative SC could not identify an adenoma in 30 patients (34.9%), and in 12 patients (14.0%), the surgeon was subsequently unable to localize abnormal parathyroid tissue. Preoperative parathyroid hormone concentration was the only significant independent predictor of a negative SC finding (non-linear and indirect association). Independent from surgical history, an unsuccessful intraoperative focus localization was exclusively predicted by preoperative ultrasonographic (US) and SC findings (OR per diagnostic category 2.98; 95%-CI 1.03-8.58, p=0.043, and OR 2.26; 95%-CI: 1.10-4.63, p=0.027, respectively). Compared to exclusive US, however, the combination of SC and US significantly increased the sensitivity and predictive power to identify patients at a high risk for a complicated surgical procedure.

CONCLUSION

In patients before parathyroidectomy, a low preoperative parathyroid hormone concentration is significantly associated with a high likelihood for a negative SC finding. Combining US with SC before operation significantly increases the chance to identify patients prone to negative intraoperative findings.

Diagnostic Rechallenge with 18F-FCH PET/CT Often Allows Minimally Invasive Parathyroidectomy While Maintaining Exceptional Cure Rates

BACKGROUND

Minimally invasive parathyroidectomy (MIP) has gained acceptance as the preferred surgical procedure for management of primary hyperparathyroidism (pHPT). Appropriate selection of patients for a MIP is a crucial step in its utilization. The aim of the study was to evaluate the role of ¹⁸F-FCH PET/CT as second-line imaging for accurately directing MIP.

METHODS

This is a retrospective single-center study. Seventy-two patients with biochemical evidence of pHPT and a non-conclusive or negative first-line imaging (ultrasound and dual isotope subtraction scintigraphy) received ¹⁸F-FCH PET/CT between January 2018 and February 2020. All imaging studies were performed at our institution. Assessment of therapeutic changes and outcomes was performed.

RESULTS

of the 72 patients imaged with ¹⁸F-FCH PET/CT, 54 subsequently underwent parathyroidectomy. When considering the ability of ¹⁸F-FCH PET/CT alone to predict a uniglandular disease, the sensitivity, specificity, PPV and NPV were 92.7% (95%CI: 80.1-98.5), 46.2% (19.2-74.9), PPV 87.3% (80.5-92) and NPV 61.2% (31.4-84.5), respectively. When we combined the data provided by ¹⁸F-FCH PET/CT with the data already collected from 1^st line imaging we were able to complete a minimally invasive surgery in 38 of the 41 (92%) patients with a uniglandular disease. Thirteen patients (24%) had a multiglandular disease, all of them except one underwent bilateral neck exploration based on the data collected by all imaging modalities combined. Overall, cure was achieved in 53 (98%) patients.

CONCLUSION

¹⁸F-FCH PET/CT, interpreted along with first-line imaging results in selected patients, can better facilitate utilization of MIS while maintaining exceptional cure rates.

Contemporary Multimodality Imaging of Primary Hyperparathyroidism

Primary hyperparathyroidism (PHPT) is a disorder characterized by hypercalcemia and an elevated or inappropriately normal parathyroid hormone level. Classic features include bone pain, fractures, renal impairment, nephrolithiasis, and mental disturbance. However, most cases of PHPT are now asymptomatic at diagnosis or associated with nonspecific neurocognitive changes. The most frequent cause of PHPT is a solitary adenoma that secretes parathyroid hormone without the normal suppressive effect of serum calcium. A smaller number of cases can be attributed to multigland disease. Parathyroidectomy is curative and is considered for nearly all affected patients. Although PHPT is primarily a clinical and biochemical diagnosis, imaging is key to the localization of adenomas, which can lie in conventional locations adjacent to the thyroid gland or less commonly at ectopic sites in the neck and mediastinum. In addition, accurate localization facilitates the use of a minimally invasive or targeted surgical approach. Frequently used localization techniques include US, parathyroid scintigraphy, and four-dimensional CT. Second- and third-line modalities such as MRI, PET/CT, and selective venous sampling with or without parathyroid arteriography can increase confidence before surgery. These localization techniques, along with the associated technical aspects, relative advantages, and drawbacks, are described. Local expertise, patient factors, and surgeon preference are important considerations when determining the type and sequence of investigation. A multimodality approach is ultimately desirable, particularly in challenging scenarios such as multigland disease, localization of ectopic adenomas, and persistent or recurrent PHPT. Online supplemental material is available for this article. ^©RSNA, 2022.

ACR Appropriateness Criteria® Parathyroid Adenoma

Hyperparathyroidism is defined as excessive parathyroid hormone production. The diagnosis is made through biochemical testing, in which imaging has no role. However, imaging is appropriate for preoperative parathyroid gland localization with the intent of surgical cure. Imaging is particularly useful in the setting of primary hyperparathyroidism whereby accurate localization of a single parathyroid adenoma can facilitate minimally invasive parathyroidectomy. Imaging can also be useful to localize ectopic or supernumerary parathyroid glands and detail anatomy, which may impact surgery. This document summarizes the literature and provides imaging recommendations for hyperparathyroidism including primary hyperparathyroidism, recurrent or persistent primary hyperparathyroidism after parathyroid surgery, secondary hyperparathyroidism, and tertiary hyperparathyroidism. Recommendations include ultrasound, CT neck without and with contrast, and nuclear medicine parathyroid scans. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Primary Hyperparathyroidism: Defining the Appropriate Preoperative Imaging Algorithm

Primary hyperparathyroidism is a common and potentially debilitating endocrine disorder for which surgery is the only curative treatment. Preoperative imaging is always recommended, even in cases of conventional bilateral neck exploration, with a recognized role for ^99mTc-sestamibi scintigraphy in depicting ectopic parathyroid lesions. Scintigraphy can also play a major role in guiding a targeted, minimally invasive parathyroidectomy. However, the ability to recognize multiple-gland disease (MGD) varies greatly depending on the imaging protocol used. Preoperative diagnosis of MGD is important to reduce the risks of conversion to bilateral surgery or failure. In this article we discuss imaging strategies before first surgery as well as in the case of repeat surgery for persistent or recurrent primary hyperparathyroidism. We describe a preferred algorithm and alternative options. Dual-tracer ^99mTc-sestamibi/¹²³I subtraction scanning plus neck ultrasound is the preferred first-line option. This approach should improve MGD detection and patient selection for minimally invasive parathyroidectomy. Second-line imaging procedures in case of negative or discordant first-line imaging results are presented. High detection rates can be obtained with ¹⁸F-fluorocholine PET/CT or with 4-dimensional CT. The risk of false-positive results should be kept in mind, however. Adding a contrast-enhanced arterial-phase CT acquisition to conventional ¹⁸F-fluorocholine PET/CT can be a way to improve accuracy. We also briefly discuss other localization procedures, including ¹¹C-methionine PET/CT, MRI, ultrasound-guided fine-needle aspiration, and selective venous sampling for parathyroid hormone measurement.

Combined versus subtraction-only technique in parathyroid scintigraphy: effect on scan interpretation

INTRODUCTION

Parathyroidectomy is the choice of treatment for patients with primary and tertiary hyperparathyroidism. Scintigraphic, preoperative localization of hyperfunctioning parathyroid tissue depends on either a delayed washout technique, a subtraction technique, or a combination of the two. The rationale for adopting a combination approach is its presumed superior sensitivity, but there is limited evidence to support this strategy at the cost of patient inconvenience and impact on departmental workflows.

OBJECTIVE

To determine whether a combined technique detects any additional lesions during scan interpretation compared to using subtraction-only technique in patients undergoing parathyroid scintigraphy before surgery.

METHODS

A retrospective analysis was performed of parathyroid scans at Tygerberg Hospital between January 2012 and April 2018. Scans were reinterpreted by consensus by three readers, blinded to the original interpretation. A McNemar discordant pairs analysis was then performed.

RESULTS

A total of 97 participant scans were reviewed (female: 71; mean age: 50.8 years). The number of patients with primary, secondary, and tertiary hyperparathyroidism were 63, 21, and 13, respectively. A total of 192 lesions were identified in this study. While both combined and subtraction-only approaches identified hyperfunctioning parathyroid lesions, only four lesions were identified using the combined technique that were missed by the subtraction technique. This result was not statistically significant (P = 0.125).

CONCLUSION

Based on our findings, the combined parathyroid scintigraphic technique does not improve lesion detection and may be dispensed with. Doing so will enhance patient convenience and comfort and improve departmental workflows without compromising lesion detection.

Parathyroid scintigraphy in primary hyperparathyroidism: comparison between double-phase and subtraction techniques and possible affecting factors

PURPOSE

Parathyroid scintigraphy is superior to other imaging techniques in detecting hyperfunctioning parathyroid glands. It is mainly performed using double-phase or dual-tracer subtraction methods. Neither of the techniques is perfect and different protocols are being used. We aimed to evaluate the accuracy of double-phase and subtraction methods in detecting abnormal gland as well as the potential effects of coexisting thyroid disease and clinical-laboratory data.

METHODS

We considered patients with primary hyperparathyroidism who underwent parathyroid surgery, after a parathyroid scintigraphy between April 2015 and February 2017. Sixty-eight patients were included; in 45 cases (66.2%), a thyroid disease was coexistent. Diagnostic performances of the two techniques were compared. The effect of thyroid disease and clinical-pathological data on examination interpretation was considered.

RESULTS

Double-phase scintigraphy showed higher sensitivity and accuracy in detecting the exact abnormal gland compared to the digital subtraction (90% and 75% vs. 76% and 66%, respectively). For double-phase technique, sensitivity and accuracy were higher in cases with no thyroid disease when compared to those with thyroid disease (92% and 86% vs. 88% and 69%, respectively). Similarly, for digital subtraction, sensitivity and accuracy were higher in the absence of thyroid disease compared to their presence (84% and 79% vs. 70% and 58%, respectively). There was no significant variation in the performance of both techniques, considering clinical-laboratory data.

CONCLUSIONS

Double-phase scintigraphy has been more accurate than digital subtraction. The presence of thyroid disease could be a possible limit, affecting the subtraction more than the double-phase technique. Clinical data did not influence the scintigraphic outcome.

Comparison of hyperparathyroidism types and utility of dual radiopharmaceutical acquisition with Tc99m sestamibi and 123I for localization of rapid washout parathyroid adenomas

Tc99m-sestamibi dual-time imaging is a standard tool for localization of adenomas/hyperplasia in hyperparathyroidism. We investigated the degree and causes of localization failure among different types of hyperparathyroidism. Pre-operative parathyroid hormone levels and size of the gland were major determinants of Tc99m-sestamibi positivity; ¹²³I scan may be helpful in localization failures.

INTRODUCTION

Tc99m-sestamibi dual-time imaging is a standard tool for localization of adenomas/hyperplasia in hyperparathyroidism. However, parathyroid adenomas/hyperplasia has been reported to washout as fast as normal thyroid tissue ("rapid washout") which may lead to diagnostic failure. We aimed to evaluate the determinants of rapid washout and to determine the role of subtraction imaging for detection of parathyroid adenomas/hyperplasia with rapid washout.

METHODS

Retrospective analysis of patients with hyperparathyroidism who have undergone Tc99m-sestamibi dual-time imaging and parathyroid surgery. Rapid washout was correlated to the type of hyperparathyroidism in surgically confirmed cases. Biochemical and pathological data were reviewed.

RESULTS

A total of 135 hyperparathyroidism patients met the inclusion criteria. Ninety-six (72%), 29 (21%), and 10 (7%) had primary, secondary, and tertiary hyperparathyroidisms, respectively. Rapid washout was identified in 28/87 glands (32%), 14/53 glands (26%), and 1/16 glands (6%) with primary, secondary, and tertiary hyperparathyroidisms, respectively. Glands that were positive on late-phase Tc99m-sestamibi scans were significantly large being 1.7 (IQR 1.4-2.3) vs. 1.45 (IQR 1-2) cm (p = 0.003). High parathyroid hormone levels (PTH) were associated with early-phase Tc99m-sestamibi positivity in both primary (p = 0.01) and secondary hyperparathyroidism (p = 0.03) but not with last phase (p = 0.11, p = 0.37, respectively). Correlative imaging with subtraction scintigraphy was positive in 14/16 (87.5%) parathyroid adenomas.

CONCLUSION

Pre-operative PTH levels and size of the gland were major determinants of Tc99m-sestamibi positivity on early-phase Tc99m-sestamibi scans, whereas size is an independent predictor of late-phase Tc99m-sestamibi positivity. Subtraction scintigraphy might be a useful tool in suspected cases of rapid washout adenomas/hyperplasia.

Update of the role of Nuclear Medicine techniques in the pre-surgical localization of primary hyperparathyroidism

Primary hyperparathyroidism is one of the most frequent endocrine disorders. Its diagnosis is biochemical. Imaging techniques are not useful for the diagnosis of this pathology; they are just tools for pre-surgical localization. In this continuing education, we will analyze the different imaging modalities used in this indication, focusing on Nuclear Medicine. The most commonly used imaging technique in this context is the parathyroid scintigraphy, nowadays double phase protocol with ^99mTc-MIBI and the double tracer with ^99mTc-MIBI/^99mTc-pertechnetate, associated in the first case to SPECT or SPECT/CT, in an early or late phase. The PET/CT with different tracers is showing good results, especially applied to cases of failure in the pre-surgical scintigraphic localization. We expose the results of the morphological imaging techniques as well as the usefulness of combining techniques.

Preoperative parathyroid localization using joint planar imaging

The conventional approach for preoperative parathyroid localization with the dual ^99mTc-sestamibi (^99mTc-MIBI) and ^99mTc-pertechnetate (^99mTcO₄^- ) scintigraphy technique obtains the differential image by subtracting images from the two scans; the former depicts both the thyroid and parathyroid glands while the latter depicts the thyroid only. In this study, we developed a novel method based on Poisson noise modeling and maximum-likelihood estimation to generate the differential image in an iterative fashion using both planar images jointly. We demonstrated improved performance of our joint method as compared with the subtraction method in both phantom and patient studies. In the phantom study, we acquired two noise-free planar datasets using ^99mTc on an in-house thyroid phantom and a "lesion" bead (representing a parathyroid gland) with the same attenuation background as the thyroid phantom. These two planar datasets were combined and scaled to simulate noise-free clinical MIBI (four lesion-to-background contrast (LBC) values: 1.2, 1.3, 1.4 and 1.5), and ^99mTcO₄^- datasets. One-hundred Poisson noise realizations were generated for each datasets. The mean and standard deviation (SD) of the lesion contrast in the differential images were computed for both the subtraction and the joint methods. We also applied both the subtraction and the joint methods to one parathyroid patient dataset. The voxel-wise mean-to-SD ratios in four hyperfunctioning parathyroid lesions were calculated. The phantom results showed that the joint method at the 50^th iteration yielded a significant SD reduction compared with the subtraction method ranging from 20% to 45% (p <; 0.05). Similarly, the voxel-wise mean-to-SD ratios were substantially improved in the patient study from 0.40-1.60 (subtraction) to 2.68-3.16 (joint).

99mTc-Sestamibi/123I Subtraction SPECT/CT in Parathyroid Scintigraphy: Is Additional Pinhole Imaging Useful?

Objectives

This retrospective study evaluated whether the use of additional anterior ^99mTc-sestamibi/¹²³I pinhole imaging improves the outcome of ^99mTc-sestamibi/¹²³I subtraction SPECT/CT in parathyroid scintigraphy (PS).

Materials and Methods

PS using simultaneous dual-isotope subtraction methods and an acquisition protocol combining SPECT/CT and planar pinhole imaging was performed for 175 patients with primary or secondary hyperparathyroidism. All patients who proceeded to surgery with complete postsurgery laboratory findings were included in this study (n = 94). SPECT/CT images alone and combined with pinhole images were evaluated.

Results

There were 111 enlarged parathyroid glands of which 104 and 108 glands were correctly visualized by SPECT/CT (seven false positives) or SPECT/CT with pinhole (three false positives), respectively. Both sensitivity and specificity were higher with combined SPECT/CT with pinhole than with SPECT/CT alone (97% versus 94% and 99% versus 98%, resp., not significant). The false-positive rate was 6% with SPECT/CT and decreased to 3% using combined SPECT/CT with pinhole.

Conclusion

^99mTc-sestamibi/¹²³I subtraction SPECT/CT is a highly sensitive and specific protocol for PS. The use of additional anterior pinhole imaging increases both sensitivity and specificity of PS, although this increase is not statistically significant.

Preoperative Localization Studies in Primary Hyperparathyroidism

Primary hyperparathyroidism (pHPT) is the third most frequently seen endocrine disease and it is the most common cause of hypercalcemia seen in ambulatory patients. PHPT is most often (80%-85%) caused by a single parathyroid adenoma, followed by double adenoma (4%-5%), multiple gland hyperplasia (10%-15%), and parathyroid carcinoma (<1%). The diagnosis of pHPT is biochemically established and the only curative treatment is surgery. Since the cause of pHPT is typically single-gland disease, it is possible to determine the majority of pathological glands with preoperative localization methods and use the minimally invasive parathyroidectomy (MIP) approach. MIP has become the standard treatment for pHPT in selected patients. There are both noninvasive and invasive preoperative localization methods. Noninvasive methods currently used include ultrasonography (US), parathyroid scintigraphy, 4-dimensional computed tomography (CT), magnetic resonance imaging, and positron emission tomography-CT with 18F-fluoroquinolone and 11C-methionine. Preoperative invasive localization methods include parathyroid hormone (PTH) measurement with fine-needle aspiration biopsy, lateralization with PTH measurement via bilateral jugular vein sampling, selective venous sampling, and parathyroid arteriography. The aim of this study was to evaluate preoperative localization studies used in cases of pHPT.

Parathyroid Imaging with Simultaneous Acquisition of 99mTc-Sestamibi and 123I: The Relative Merits of Pinhole Collimation and SPECT/CT

The objective of this study was to determine the relative utility of 3 state-of-the-art parathyroid imaging protocols: single-time-point simultaneous acquisition of (99m)Tc-sestamibi and (123)I images with pinhole collimation in the anterior and bilateral anterior oblique projections, single-time-point simultaneous acquisition of (99m)Tc-sestamibi and (123)I images with SPECT/CT, and the combination of the first and second protocols.

METHODS

Fifty-nine patients with surgical proof of parathyroid adenomas were evaluated retrospectively. All 3 protocols included perfectly coregistered subtraction images created by subtracting the (123)I images from the (99m)Tc-sestamibi images, plus an anterior parallel-hole collimator image of the neck and upper chest. The pinhole protocol was performed first, followed by the SPECT/CT protocol. Three image sets were derived from each study in each patient according to the above protocols. Two experienced observers recorded the size, location, and degree of certainty of any identified lesion.

RESULTS

The 59 patients had 61 adenomas. For the 2 observers combined, the localization success rate was 88% for the pinhole protocol, 69% for the SPECT/CT protocol, and 81% for the combined protocol. The pinhole protocol detected more adenomas than the SPECT/CT protocol and missed fewer adenomas than either the SPECT/CT protocol or the combined pinhole and SPECT/CT protocol (P < 0.01). The 2 protocols that included SPECT/CT provided superior anatomic information relative to the location and size of the parathyroid adenomas.

CONCLUSION

The pinhole protocol localized significantly more adenomas than the SPECT/CT protocol. However, the protocols that included SPECT/CT provided more anatomic information than pinhole imaging alone.

A comparison between 11C-methionine PET/CT and MIBI SPECT/CT for localization of parathyroid adenomas/hyperplasia

OBJECTIVE

The purpose of this study was to compare the sensitivity of single-photon emission computed tomography/computed tomography (SPECT/CT) using 99mTc-sestamibi (MIBI) with that of PET/CT using 11C-methionine (MET) for localization of parathyroid adenomas/hyperplasia in primary hyperparathyroidism.

MATERIALS AND METHODS

Twenty-three patients with primary hyperparathyroidism were analyzed. Fifteen patients underwent surgery, and the remaining eight did not, but these patients were clinically diagnosed as having primary hyperparathyroidism. Patients underwent both MET PET/CT and MIBI SPECT/CT scanning. The sensitivities of both modalities were evaluated on a per-patient basis, and on a per-lesion basis for parathyroid lesions detected by surgery. The size of the parathyroid adenoma/hyperplasia and serum intact parathyroid hormone levels were compared with the results of each of the two modalities.

RESULTS

Per-patient sensitivities of MET PET/CT and MIBI SPECT/CT were 65 and 61%, respectively. Per-lesion sensitivities of MET PET/CT and MIBI SPECT/CT were 91 and 73% for histologically confirmed adenomas and 30 and 30% for hyperplastic glands, respectively. No significant differences were observed between the two modalities. The size of uptake-positive lesions was significantly larger than that of uptake-negative lesions in both modalities. Intact parathyroid hormone levels showed no significant difference between uptake-positive and uptake-negative patients in both modalities.

CONCLUSION

The sensitivities of MET PET/CT and MIBI SPECT/CT were comparable. MET PET/CT has a complementary role in localizing parathyroid adenomas/hyperplasia when MIBI SPECT/CT is inconclusive.

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.

(99m)Technetium Sestamibi-(123)Iodine Scintigraphy Is More Accurate Than (99m)Technetium Sestamibi Alone before Surgery for Primary Hyperparathyroidism

Objectives. Studies comparing outcome of single-^99mTc-methoxyisobutylisonitrile (^99mTc-sestamibi) and dual-tracer ^99mTc-sestamibi scintigraphy in combination with ¹²³I before primary surgery of primary hyperparathyroidism (PHPT) are scarce. Methods. We compared ^99mTc-sestamibi/¹²³I and ^99mTc-sestamibi in a single-centre retrospective series of 269 PHPT patients. The results were related to laboratory, surgical and histological findings. Results. ^99mTc-sestamibi/¹²³I and ^99mTc-sestamibi were positive in 206 (76.6%) and 111 (41.3%) of 269 patients, respectively (P < 0.001). Accuracies for ^99mTc-sestamibi/¹²³I and ^99mTc-sestamibi were 63.4% and 34.9%, respectively (96% CI, P < 0.001). Prevalence of multiglandular disease was 15.2%. In multiglandular disease, ^99mTc-sestamibi/¹²³I and ^99mTc-sestamibi revealed 43.8 and 22.1% of pathological glands, respectively (P < 0.001). Cure rate was similar for patients with (191/206; 92.7%) and without (59 of 63; 93.7%) a positive ^99mTc-sestamibi/¹²³I finding. Duration of targeted surgery (one or two quadrants) was 21 and 15 minutes shorter than bilateral neck exploration, respectively (both P < 0.001). Higher serum calcium (P = 0.014) and PTH (P = 0.055) concentrations and larger tumours (P < 0.001) characterized the 206 patients with a positive preoperative scan who were cured by removal of a single adenoma. Conclusions. ^99mTc-sestamibi/¹²³I scintigraphy is more accurate than ^99mTc-sestamibi before surgery of PHPT. However, outcome of surgery is not determined by scintigraphy alone.

Incremental value of CT in the localization of parathyroid adenomas

The diagnosis of hyperparathyroidism rests on clinical and biochemical laboratory criteria. Once the diagnosis is established, it is the function of diagnostic imaging to pre-operatively find the suspected parathyroid adenoma. Traditionally, nuclear medicine techniques such as 99mTc-Sestamibi scan and ultrasound evaluation have been the mainstay in finding the neoplasm. However, results are not always satisfactory, and accurately identifying parathyroid adenomas, especially when they are multiple, remains a challenge. We report a case where careful correlation with contrast-enhanced diagnostic CT scan of the neck helped localize two parathyroid adenomas.

Diagnosis and preoperative imaging of multiple endocrine neoplasia type 2: current status and future directions

Multiple endocrine neoplasia type 2 (MEN2) is a rare autosomal dominant syndrome caused by mutations in the RET protooncogene and is characterized by a strong penetrance of medullary thyroid carcinoma (all subtypes) and is often accompanied by pheochromocytoma (MEN2A/2B) and primary hyperparathyroidism (MEN2A). The evaluation and management of MEN2-related tumours is often different from that of sporadic counterparts. This review article provides an overview of clinical manifestations, diagnosis and surgical management of MEN2 patients. This review also presents applications of the most up-to-date imaging modalities to MEN2 patients that are tightly linked to the clinical management and aims to guide physicians towards a rationale for the use of imaging prior to prophylactic thyroidectomy, initial surgery and reoperations for persistent/recurrent disease. This review also concludes that, in the near future, it is expected that these patients will indeed benefit from newly developed positron emission tomography approaches which will target peptide receptors and protein kinases. Identification of MEN2-specific radiopharmaceuticals will also soon arise from molecular profiling studies. Furthermore, subtotal (cortical-sparing) adrenalectomy, which is a valid option in MEN2 for avoiding long-term steroid replacement, will benefit from an accurate estimation through imaging of differential adrenocortical function.

Parathyroid scintigraphy in renal hyperparathyroidism: the added diagnostic value of SPECT and SPECT/CT

Secondary hyperparathyroidism (sHPT) is a major complication for patients with end-stage renal disease on long-term hemodialysis or peritoneal dialysis. When the disease is resistant to medical treatment, patients with severe sHPT are typically referred for parathyroidectomy (PTx), which usually improves biological parameters as well as clinical signs and symptoms. Unfortunately, early surgical failure with persistent disease may occur in 5%-10% of patients and recurrence reaches 20%-30% at 5 years. Presently, the use of parathyroid scintigraphy in sHPT is usually limited to the management of surgical failures after initial PTx. This review describes the strengths and limitations of typical (99m)Tc-sestamibi imaging protocols, and highlights the potential benefits of using parathyroid scintigraphy in the initial workup of surgical patients.