Selective venous sampling supports localization of adenoma in primary hyperparathyroidism

Comparison of biochemical markers and technetium 99m methoxyisobutylisonitrile imaging in primary and secondary hyperparathyroidism

OBJECTIVE

To investigate the differences in biochemical marker levels and the extent of lesion visualization on technetium 99m methoxyisobutylisonitrile (^99mTc-MIBI) imaging between primary hyperparathyroidism (PHPT) and secondary hyperparathyroidism (SHPT).

METHODS

Nineteen patients with PHPT and 14 patients with SHPT were enrolled in the study, all of whom underwent routine ^99mTc-MIBI dual-phase planar imaging, single-photon emission computed tomography combined with computed tomography (SPECT/CT fusion) imaging, and serum biochemical and hormonal investigations prior to surgery. The target-to-non-target (T/NT) ratios were calculated based on images from the early and delayed phases of ^99mTc-MIBI planar imaging and also based on SPECT/CT fusion imaging. The volume of the parathyroid glands was measured following their excision.

RESULTS

A total of 62 parathyroid glands were removed: 14 parathyroid adenomas and five parathyroid carcinomas in PHPT patients; and 18 parathyroid adenomas, 17 parathyroid hyperplasia lesions, and eight instances of nodular hyperplasia with adenoma in SHPT patients. The median volume of the lesions in PHPT and SHPT was 1.69 cm³ and 0.52 cm³ respectively, and the difference between them was statistically significant (P = 0.001). The median T/NT ratios calculated at the early phase of ^99mTc-MIBI planar imaging, the delayed phase of ^99mTc-MIBI planar imaging, and the subsequent SPECT/CT fusion imaging were 1.51, 1.34, and 2.75, respectively, in PHPT, and 1.46, 1.30, and 1.38, in SHPT, respectively. The T/NT ratio difference between PHPT and SHPT on the SPECT/CT fusion imaging was statistically significant (P = 0.002). The histopathology subtypes of the lesions were associated with significant differences in two areas: the T/NT ratios on the SPECT/CT fusion imaging and the volume of the lesions (P=0.002, P<0.001).

CONCLUSION

The proportion of positive findings on ^99mTc-MIBI dual-phase planar imaging and the T/NT ratios of ^99mTc-MIBI SPECT/CT fusion imaging were higher in PHPT than in SHPT. The volume of parathyroid lesions in SHPT was smaller than in PHPT.

An Approach to a Patient With Primary Hyperparathyroidism and a Suspected Ectopic Parathyroid Adenoma

Primary hyperparathyroidism (PHPT) is characterized by hypercalcemia driven by excess parathyroid hormone (PTH) secretion. PHPT is a common endocrine condition with a prevalence of 1 to 7 cases per 1000 adults. PHPT typically presents in the fifth or sixth decade and shows significant female preponderance. Solitary hyperfunctioning parathyroid adenomas account for 85% to 90% of PHPT cases. The remaining 10% to 15% include cases of multiglandular disease (multiple adenomas or hyperplasia) and, rarely, parathyroid carcinoma (1%). Ectopic parathyroid adenomas may arise due to abnormal embryological migration of the parathyroid glands and can be difficult to localize preoperatively, making surgical cure challenging on the first attempt. The potential existence of multiglandular disease should be considered in all patients in whom preoperative localization fails to identify a target adenoma or following unsuccessful parathyroidectomy. Risk factors for multiglandular disease include underlying genetic syndromes (eg, MEN1/2A), lithium therapy, or previous radiotherapy. In addition to multifocal disease, the possibility of an ectopic parathyroid gland should also be considered in patients requiring repeat parathyroid surgery. In this article, we use illustrative clinical vignettes to discuss the approach to a patient with primary hyperparathyroidism (PHPT) and a suspected ectopic parathyroid adenoma.

Selective venous sampling in primary hyperparathyroidism: Is it worth doing?

BACKGROUND

Accurate preoperative localization of the culprit gland is the key point for the surgical treatment of primary hyperparathyroidism. Conventional imaging techniques (ultrasound and Tc99m sestamibi scintigraphy) are usually adequate for preoperative localization. However, in some patient groups, additional imaging modalities may be required since noninvasive techniques may fail. In this study, we aimed to evaluate the diagnostic value of selective parathyroid venous sampling in patients with unclear noninvasive localization tests.

METHODS

Among 513 cases who underwent parathyroidectomy due to primary hyperparathyroidism, twelve cases (2.3%) were undergone selective parathyroid venous sampling and were included in the study. Age, sex, presenting symptom, presence of a genetic disease, medical and surgical history, serum calcium (Ca)-parathormone (PTH) levels (preoperative, intraoperative, and postoperative), imaging reports (US, SM, and SVS), surgery reports, pathology reports, and complications were retrospectively reviewed.

RESULTS

Seven cases (58.3%) had persistent primary hyperparathyroidism and one patient (8.3%) had past surgical history of total thyroidectomy. The remaining four patients (33.3%) had no previous neck surgery. T he sensitivity of selective venous sampling was 75%. According to the medical history, accurate localization was achieved in 85.7% of persistent cases and 60% of primary cases. Eight cases (66.6%) underwent unilateral neck exploration and four cases (33.3%) underwent four gland exploration. A single adenoma was detected in ten cases (90.9%) while one patient (9.1%) had double adenoma.

Questionable value of [99mTc]-sestamibi scintigraphy in patients with pHPT and negative ultrasound

PURPOSE

A successful focused surgical approach in primary hyperparathyroidism (pHPT) relies on accurate preoperative localization of the parathyroid adenoma (PA). Most often, ultrasound is followed by [^99mTc]-sestamibi scintigraphy, but the value of this approach is disputed. Here, we evaluated the diagnostic approach in patients with surgically treated pHPT in our center with the aim to further refine preoperative diagnostic procedures.

METHODS

A single-center retrospective analysis of patients with pHPT from 01/2005 to 08/2021 was carried out followed by evaluation of the preoperative imaging modalities to localize PA. The localization of the PA had to be confirmed intraoperatively by the fresh frozen section and significant dropping of the intraoperative parathyroid hormone (PTH) levels.

RESULTS

From 658 patients diagnosed with pHPT, 30 patients were excluded from the analysis because of surgery for recurrent or persistent disease. Median age of patients was 58.0 (13-93) years and 71% were female. Neck ultrasound was carried out in 91.7% and localized a PA in 76.6%. In 23.4% (135/576) of the patients, preoperative neck ultrasound did not detect a PA. In this group, [^99mTc]-sestamibi correctly identified PA in only 25.4% of patients. In contrast, in the same cohort, the use of [¹¹C]-methionine or [¹¹C]-choline PET resulted in the correct identification of PA in 79.4% of patients (OR 13.23; 95% CI 5.24-33.56).

CONCLUSION

[¹¹C]-Methionine or [¹¹C]-choline PET/CT are superior second-line imaging methods to select patients for a focused surgical approach when previous ultrasound failed to identify PA.

Pediatric hyperparathyroidism: review and imaging update

Hyperparathyroidism, due to increased secretion of parathyroid hormones, may be primary, secondary or tertiary. Most pediatric patients with sporadic primary hyperparathyroidism will be symptomatic, presenting with either end-organ damage or nonspecific symptoms. In younger patients with primary hyperparathyroidism, there is a higher prevalence of familial hyperparathyroidism including germline inactivating mutations of the calcium-sensing receptor genes that result in either neonatal severe hyperparathyroidism or familial hypocalciuric hypercalcemia. Parathyroid scintigraphy and ultrasound are complementary, first-line imaging modalities for localizing hyperfunctioning parathyroid glands. Second-line imaging modalities are multiphase computed tomography (CT) and magnetic resonance imaging. In pediatrics, multiphase CT protocols should be adjusted to optimize radiation dose. Although, the role of these imaging modalities is better established in preoperative localization of hyperfunctioning parathyroid glands in primary hyperparathyroidism, the same principles apply in secondary and tertiary hyperparathyroidism. In this manuscript, we will review the embryology, anatomy, pathophysiology and preoperative localization of parathyroid glands as well as several subtypes of primary familial hyperparathyroidism. While most of the recent imaging literature centers on adults, we will focus on the issues that are pertinent and applicable to pediatrics.

Preoperative Localization for Primary Hyperparathyroidism: A Clinical Review

With increasing use of minimally invasive parathyroidectomy (PTx) over traditional bilateral neck exploration in patients with primary hyperparathyroidism (PHPT), accurate preoperative localization has become more important to enable a successful surgical outcome. Traditional imaging techniques such as ultrasound (US) and sestamibi scintigraphy (MIBI) and newer techniques such as parathyroid four-dimension computed tomography (4D-CT), positron emission tomography (PET), and magnetic resonance imaging (MRI) are available for the clinician to detect the diseased gland(s) in the preoperative workup. Invasive parathyroid venous sampling may be useful in certain circumstances such as persistent or recurrent PHPT. We review the diagnostic performance of these imaging modalities in preoperative localization and discuss the advantages and weaknesses of these techniques. US and MIBI are established techniques commonly utilized as first-line modalities. 4D-CT has excellent diagnostic performance and is increasingly performed in first-line setting and as an adjunct to US and MIBI. PET and MRI are emerging adjunct modalities when localization has been equivocal or failed. Since no evidence-based guidelines are yet available for the optimal imaging strategy, clinicians should be familiar with the range and advancement of these techniques. Choice of imaging modality should be individualized to the patient with consideration for efficacy, expertise, and availability of such techniques in clinical practice.

Atypical presentations of parathyroid gland pathology: A pictorial review

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Adenoma, carcinoma and hyperplasia cause parathyroid gland enlargement.

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Mimics include thyroid nodules and cystic structures in the head and neck.

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Enlarged parathyroid glands can enhance variably following contrast administration.

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Hyperparathyroidism can present acutely with respiratory compromise.

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Syndromic associations.

Primary hyperparathyroidism is associated with significant morbidity and mortality. It is in this day and age, an eminently treatable condition which relies heavily on preoperative imaging to localise enlarged parathyroid glands. The imaging appearances of parathyroid gland enlargement are varied; this paper seeks to address some of its more unusual manifestations with an emphasis on its atypical enhancement patterns, mimics and associations. An enlarged glands may also present as an ‘incidentaloma’ in head and neck imaging performed for entirely different indications, or as part of sporadic or familial syndrome. Radiologists are in a good position to expedite the relevant investigations and curative treatment, and knowledge of the spectrum of imaging appearances is crucial.

Low-radiation of technetium-99m-sestamibi and single-photon emission computed tomography/computed tomography to diagnose parathyroid lesions

We compared preoperative regular activity and low-activity radiology-based predictions with real surgical and pathological findings for parathyroidectomy surgery. The study retrospectively analyzed 54 consecutive cases (2009–2016) for benign tumor removal. Technetium-99m (Tc-99m)-sestamibi was used as a diagnostic radiopharmaceutical for diagnostic dual-phase parathyroid scintigraphy and single-photon emission computed tomography/computed tomography. We assessed images obtained with the radiation activity of 925 megabecquerel (MBq) and images obtained with the activity of 185 MBq. The study compared preoperative evaluation of tumor presence, multiplicity, location, and the type of pathology with actual data that were revealed during the operation and pathological investigation. The agreement between preoperative radiological prediction and actual location, number, and type of the parathyroid lesions was achieved in 98.4% (n = 61/62 lesions). The agreement between 925 MBq-based and 185-MBq based investigations was 100%. The agreement between radiological and pathological findings was 100% for both investigations. Our data suggest that the radioactivity of 185 MBq applied in the evaluation of the parathyroid glands provides results similar to the currently used 925–1110 MBq if used for diagnostic dual-phase parathyroid scintigraphy with Tc-99m-sestamibi. Such radioactivity may reduce the exposure to radiation of the patients and the staff without compromising results of the investigation.