Ultrasound for localization in primary hyperparathyroidism

A contemporary analysis of the pre- and intraoperative recognition of multigland parathyroid disease

BACKGROUND

Despite advances in biochemical and radiological identification of parathyroid gland enlargement, primary hyperparathyroidism (PHPT) due to sporadic multigland parathyroid disease (MGPD) remains a perioperative diagnostic dilemma. Failure to recognise MGPD pre- or intraoperatively may negatively impact surgical cure rates and result in persistent PHPT and ongoing patient morbidity.

METHODS

We have conducted a comprehensive review of published literature in attempt to determine factors that could aid in reliably diagnosing sporadic MGPD pre- or intraoperatively. We discuss preoperative clinical features and examine pre- and intraoperative biochemical and imaging findings concentrating on those areas that give practicing surgeons and the wider multi-disciplinary endocrine team indications that a patient has MGDP. This could alter surgical strategy.

CONCLUSION

Biochemistry can provide diagnosis of PHPT but cannot reliably discriminate parathyroid pathology. Histopathology can aid diagnosis between MGPD and adenoma, but histological appearance can overlap. Multiple negative imaging modalities indicate that MGPD may be more likely than a single parathyroid adenoma, but the gold standard for diagnosis is still intraoperative identification during BNE. MGPD remains a difficult disease to both diagnose and treat.

Positive predictive values of ultrasound-guided fine-needle aspiration with parathyroid hormone assay and Tc-99m sestamibi scintigraphy in sporadic primary hyperparathyroidism

OBJECTIVES

Ultrasonography (US) and Tc-99m sestamibi scintigraphy (SS) are usually performed as preoperative imaging modalities for patients with sporadic primary hyperparathyroidism (SPHP). Fine-needle aspiration (FNA) under US guidance for parathyroid hormone (PH) assay can enhance the diagnostic accuracy of US. The main aim of the present study was to compare positive predictive values between US-FNA and SS. The secondary aim was to draw up a decision-tree for FNA and SS.

METHODS

The single-center retrospective study included patients with previously non-operated SPHP. They underwent US-guided FNA, PET-CT SS, and 18 F-choline scintigraphy if the first two methods were inconclusive. PH washout level was considered pathological when greater than the serum PH level. Postoperative histology data were correlated to imaging data.

RESULTS

In total, 117 patients were included, with a mean age of 64 years (range, 26-89 years). A single adenoma was identified on pathology in 101 patients (89%). FNA findings were pathologic for 64 patients (55%), with a mean PH level of 2,604ng/L [range, 585-9,074ng/L], higher than the serum level of 179ng/L [range, 60-1,000ng/L]. US-guided FNA showed sensitivity, specificity, and positive and negative predictive values (PPV, NPV) of respectively 72%, 92%, 99% and 28%, compared to 89%, 42%, 93% and 32% for SS. The rate of error in locating the parathyroid gland was 8% for US-guided FNA versus 12% for SS. Comparison of the two methods showed better sensitivity for SS (P=0.0052) and better specificity for FNA (P=0.0143), with no significant difference in PPV or NPV. 18 F-choline scintigraphy detected the hyperfunctioning parathyroid in 11 out of the 15 patients.

CONCLUSION

PPV did not significantly differ between FNA and SS. US-guided FNA performed by an experienced operator could be a simple first-line method for more than 50% of patients with non-operated SPHP, with 99% PPV. In case of negative or doubtful FNA findings, SS can be performed in second line.

A Bibliometric Analysis of the Landscape of Parathyroid Carcinoma Research Based on the PubMed (2000–2021)

Introduction

The purpose of this study was to assess the landscape of parathyroid carcinoma research during the last 22 years using machine learning and text analysis.

Method

In November 2021, we obtained from PubMed all works indexed under the mesh subject line “parathyroid carcinoma”. The entire set of search results was retrieved in XML format, and metadata such as title, abstract, keywords, mesh words, and year of publication were extracted for bibliometric evaluation from the original XML files. To increase the specificity of the investigation, the Latent Dirichlet allocation (LDA) topic modeling method was applied.

Results

The paper analyzed 3578 papers. The volume of literature related to parathyroid cancer has been relatively flat over the past 22 years. In the field of parathyroid cancer research, the most important topic of clinical interest is the differential diagnosis. Ultrasound and MIBI are the most commonly used imaging methods for localization. In terms of basic research, the mechanisms of gene mutation and local tumor recurrence are the focus of interest.

Conclusion

There are huge unmet research needs for parathyroid carcinoma. Improving the diagnosis rates of parathyroid cancer by clinicians and establishing new and reliable molecular pathological markers and new image localization techniques will continue to be the focus of future research.

A Retrospective Cohort Study of the Utility of Ultrasound, 99mTc-Sestamibi Scintigraphy, and Four-Dimensional Computed Tomography for Pre-Operative Localization of Parathyroid Disease To Facilitate Minimally Invasive Parathyroidectomy

Background

This study investigated the utility of ultrasound (US), 99mTc-Sestamibi scintigraphy (Sestamibi), and four-dimensional computed tomography (4DCT) for pre-operative localization of a single abnormal parathyroid gland prior to minimally invasive parathyroidectomy (MIP) to determine the optimum pre-operative scans to facilitate a MIP.

Methods

Patients with primary hyperparathyroidism who underwent curative parathyroidectomy at Broomfield Hospital, Mid and South Essex NHS Foundation Trust between 2009 and 2018 were included. Diagnostic performance parameters and the agreement between US, Sestamibi, and 4DCT were evaluated. Cohen’s κ was used to assess the strength of agreement between imaging modalities.

Results

At localizing pathology to the correct side of the neck, Sestamibi had the highest sensitivity (87%), followed by US (76%) and 4DCT (64%). 4DCT had a positive predictive value (PPV) of 95%, similar to Sestamibi (96%), but higher than US (92%). Amongst patients who underwent both US and Sestamibi, the abnormal parathyroid gland was localized to the same area by both imaging modalities in 77% of patients (Cohen’s κ: 0.383). Following an inconclusive US or Sestamibi scan, or discordance between the two modalities, 4DCT was correct at localization in 63% of patients.

Conclusion

Sestamibi has the highest sensitivity and PPV for accurately localizing parathyroid pathology. The addition of US to a positive Sestamibi scan adds little additional value. 4DCT is the preferred imaging modality following an inconclusive Sestamibi or US.

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.

Pre-operative imaging workup for surgical intervention in primary hyperparathyroidism: A tertiary referral center experience

PURPOSE

Preoperative imaging in patients with primary hyperparathyroidism provides important localization information, allowing the surgeon to perform a focused surgery. However there are no evidence-based guidelines suggesting which preoperative imaging should be used, resulting in a risk of excessive prescription of exams and waste of economic resources. The main purpose of this study was to describe our experience on the performance of various imaging techniques for the preoperative localization of abnormal parathyroid gland/s, with a focus on the sensitivity and specificity of each technique. Secondly, we carried out an analysis of the cost utility of each technique in order to determine the most clinical and cost-effective combination of localization studies.

MATERIALS AND METHODS

Records of 336 patients who underwent parathyroidectomy were retrospectively examined comparing imaging and intraoperative/histopathologic findings to evaluate the accuracy in parathyroid detection of each imaging technique. Costs were determined by regional health system reimbursement.

RESULTS

We found that the sensitivity of color Doppler US was significantly higher than SPECT (p 0,023), while the sensitivity of 4D-CT was significantly better than US (p 0,029) and SPECT (p 0,0002).

CONCLUSIONS

In experienced hands color Doppler US is a highly sensitive technique especially in patients with no thyroid diseases. In patients with concomitant thyroid pathology, the combination of US and 4D-CT represents a reliable localization technique.

Performance of F-18 Fluorocholine PET/CT for Detection of Hyperfunctioning Parathyroid Tissue in Patients with Elevated Parathyroid Hormone Levels and Negative or Discrepant Results in conventional Imaging

Objective

Our aim was to assess the diagnostic performance of F-18 fluorocholine (FCH) positron emission tomography/computed tomography (PET/CT) in detecting hyperfunctioning parathyroid tissue (HPT) in patients with elevated parathyroid hormone levels with negative or inconclusive conventional imaging results and to compare the findings with those obtained using technetium-99m sestamibi (MIBI) scintigraphy and neck ultrasonography (US).

Materials and Methods

Images of 105 patients with hyperparathyroidism who underwent FCH PET/CT, dual-phase MIBI parathyroid scintigraphy (median interval: 42 days), and neck US were retrospectively analyzed. The gold standard was histopathological findings for 81 patients who underwent parathyroidectomy and clinical follow-up findings in the remaining 24 patients. Sensitivities, positive predictive values (PPVs), and accuracies were calculated for all imaging modalities.

Results

Among the 81 patients who underwent parathyroidectomy, either parathyroid adenoma (n = 64), hyperplasia (n = 9), neoplasia (n = 4), or both parathyroid adenoma and hyperplasia (n = 1) were detected, except 3 patients who did not show HPT. Of the 24 (23%) patients who were followed-up without operation, 22 (92%) showed persistent hyperparathyroidism. FCH PET/CT showed significantly higher sensitivity than MIBI scintigraphy and US in detection of HPT (p < 0.01). Sensitivity, PPV, and accuracy of FCH PET/CT were 94.1% (95/101), 97.9% (95/97), and 92.4% (97/105), respectively. The corresponding values for MIBI scintigraphy and US were 45.1% (46/102), 97.9% (46/47), and 45.7% (48/105) and 44.1% (45/102), 93.8% (45/48), and 42.9% (45/105), respectively. Among the 35 patients showing negative MIBI scintigraphy and neck US findings, 30 (86%) showed positive results on FCH PET/CT. FCH PET/CT could demonstrate ectopic locations of HPT in 11 patients whereas MIBI and US showed positive findings in only 6 and 3 patients, respectively.

Conclusion

FCH PET/CT is an effective imaging modality for detection of HPT with the highest sensitivity among the available imaging techniques. Therefore, FCH PET/CT can be recommended especially for patients who show negative or inconclusive results on conventional imaging.

Parathyroid cancer: An update

Parathyroid cancer (PC) is a rare malignant tumor which comprises 0.5-5% of patients with primary hyperparathyroidism (PHPT). Most of these cancers are sporadic, although it may also occur as a feature of various genetic syndromes including hyperparathyroidism-jaw tumor syndrome (HPT-JT) and multiple endocrine neoplasia (MEN) types 1 and 2A. Although PC is characterized by high levels of serum ionized calcium (Ca) and parathyroid hormone (PTH), the challenge to the clinician is to distinguish PC from the far more common entities of parathyroid adenoma (PA) or hyperplasia, as there are no specific clinical, biochemical, or radiological characteristic of PC. Complete surgical resection is the only known curative treatment for PC with the surgical approach during initial surgery strongly influencing the outcome. In order to avoid local recurrence, the lesion must be removed en-bloc with clear margins. PC has high recurrence rates of up to 50% but with favorable long-term survival rates (10-year overall survival of 60-70%) due to its slow-growing nature. Most patients die not from tumor burden directly but from uncontrolled severe hypercalcemia. In this article we have updated the information on PC by reviewing the literature over the past 10 years and summarizing the findings of the largest series published in this period.

Vascular flow on doppler sonography may not be a valid characteristic to distinguish colloid nodules from papillary thyroid carcinoma even when accounting for nodular size

Background

The purpose of this study was to test the hypothesis that there is no significant difference in vascular flow patterns between cytopathologically-proven colloid nodules and papillary thyroid carcinoma (PTC) even when adjusting for nodule size.

Methods

Doppler vascular flow patterns in 200 colloid nodules and 166 nodules with PTC were retrospective reviewed independently by 2 neuroradiologists blinded to the cytopathological results. Absence of vascular flow, perinodular and/or intranodular flow, and diffuse vascular flow were recorded. The vascular flow patterns were compared without (Fisher exact test) and with (Kruskal-Wallis test) an adjustment for nodular size. Using the most common flow pattern as the reference group, multiple logistic regression was used to compare the flow patterns. Sample skewness was calculated to determine degree of symmetry of the size distribution for each vascular flow category.

Results

No significant difference was found in the tested vascular flow patterns between colloid nodules and PTC both without and with an adjustment for nodular size (P>0.05). Intranodular flow only was the largest group (n=111/366) and used as the reference for multiple logistic regression. No significant difference was noted between the vascular flow patterns (P>0.05). Sample skewness showed that nodules were generally smaller in size with outliers of larger size on the opposite end of the spectrum.

Conclusions

Independent of nodule size the absence or presence of vascular flow is not significantly different between colloid nodules and PTC. Therefore, vascular flow may not be useful in distinguishing between colloid nodules and PTC.

American Head and Neck Society Endocrine Surgery Section update on parathyroid imaging for surgical candidates with primary hyperparathyroidism

Health care consumer organizations and insurance companies increasingly are scrutinizing value when considering reimbursement policies for medical interventions. Recently, members of several American Academy of Otolaryngology-Head & Neck Surgery (AAO-HNS) committees worked closely with one insurance company to refine reimbursement policies for preoperative localization imaging in patients undergoing surgery for primary hyperparathyroidism. This endeavor led to an AAO-HNS parathyroid imaging consensus statement (https://www.entnet.org/content/parathyroid-imaging). The American Head and Neck Society Endocrine Surgery Section gathered an expert panel of authors to delineate imaging options for preoperative evaluation of surgical candidates with primary hyperparathyroidism. We review herein the current literature for preoperative parathyroid localization imaging, with discussion of efficacy, cost, and overall value. We recommend that planar sestamibi imaging, single photon emission computed tomography (SPECT), SPECT/CT, CT neck/mediastinum with contrast, MRI, and four dimensional CT (4D-CT) may be used in conjunction with high-resolution neck ultrasound to preoperatively localize pathologic parathyroid glands. PubMed literature on parathyroid imaging was reviewed through February 1, 2019.

Choline PET/CT in parathyroid imaging: a systematic review

One of the most promising imaging techniques in primary hyperparathyroidism is PET/CT with choline-based tracers. To investigate the current evidence of these tracers in localizing parathyroid adenoma, a systematic review was performed. A comprehensive literature search was carried out and eligible studies were analyzed. Data were extracted, the level of evidence was scored, and performance data were pooled to calculate the weighted detection rate. Eleven articles were included in this study. The pooled detection rate was 97 and 94% on per patient-based and per lesion-based analysis, respectively. There was considerable heterogeneity between studies and the level of evidence was determined to be 3a-, following Oxford criteria. Choline PET/CT has shown favorable results in detection of hyperfunctioning parathyroid tissue and may replace conventional technetium-99m-sestamibi scintigraphy in preoperative planning of parathyroid surgery. However, the quality of current evidence is moderate, and additional high-quality studies are needed to confirm these numbers.

Solitary Parathyroid Adenoma Localization in Technetium Tc99m Sestamibi SPECT and Multiphase Multidetector 4D CT

BACKGROUND AND PURPOSE

Minimally invasive parathyroid surgery relies critically on image guidance, but data comparing the efficacy of various imaging modalities are scarce. Our aim was to perform a blinded comparison of the localizing capability of technetium Tc99m sestamibi SPECT, multiphase multidetector 4D CT, and the combination of these 2 modalities (technetium Tc99m sestamibi SPECT + multiphase multidetector 4D CT).

MATERIALS AND METHODS

We reviewed the records of 31 (6 men, 25 women; median age, 56 years) consecutive patients diagnosed with biochemically confirmed primary hyperparathyroidism between November 2009 and March 2010 who underwent preoperative technetium Tc99m sestamibi SPECT and multiphase multidetector 4D CT performed on the same scanner with pathologic confirmation by resection of a single parathyroid adenoma. Accuracy was determined separately for localization to the correct side and quadrant using surgical localization as the standard of reference.

RESULTS

Surgical resection identified 14 left and 17 right parathyroid adenomas and 2 left inferior, 12 left superior, 11 right inferior, and 6 right superior parathyroid adenomas. For left/right localization, technetium Tc99m sestamibi SPECT achieved an accuracy of 93.5% (29 of 31), multiphase multidetector 4D CT achieved 96.8% accuracy (30 of 31), and technetium Tc99m sestamibi SPECT + multiphase multidetector 4D CT achieved 96.8% accuracy (30 of 31). For quadrant localization, technetium Tc99m sestamibi SPECT accuracy was 67.7% (21 of 31), multiphase multidetector 4D CT accuracy was 87.1% (27 of 31), and technetium Tc99m sestamibi SPECT + multiphase multidetector 4D CT accuracy was 93.5% (29 of 31). Reader diagnostic confidence was consistently ranked lowest for technetium Tc99m sestamibi SPECT and highest for technetium Tc99m sestamibi SPECT + multiphase multidetector 4D CT.

CONCLUSIONS

For left/right localization of parathyroid adenomas, all modalities performed equivalently. For quadrant localization, technetium Tc99m sestamibi SPECT + multiphase multidetector 4D CT is superior to technetium Tc99m sestamibi SPECT.

Correlation of surgeon-performed parathyroid ultrasound with the Perrier classification and gland weight

BACKGROUND

Ultrasound localisation of parathyroid glands correlates with gland weight. We hypothesise that gland identification is also dependent on anatomical location. Perrier et al. have described a uniform and reliable nomenclature for parathyroid locations. We aimed to correlate surgeon-performed ultrasound (SUS) with intra-operative Perrier classification and gland weight.

METHODS

Review of a prospectively maintained single operator SUS database of 194 patients referred with non-familial primary hyperparathyroidism (PHPT) at a tertiary centre between 2010 and 2015. Patients underwent MIBI localisation as well as on table SUS. Intra-operative pathological gland locations were classified according to the Perrier nomenclature.

RESULTS

Mean weight of pathological glands found and missed by SUS was 1.07 ± 0.1 g and 0.48 ± 0.08 g respectively (p = 0.0001, unpaired t test). The weight of glands identified was greater than that of missed glands for each of the Perrier locations (p < 0.001, Mann-Whitney). The proportion of pathological glands found at each Perrier location varied significantly (p < 0.0001, Chi Square); so we find proportionally more B-, D-, E- and F-type glands and miss more A- and C-type glands. The median weight of glands missed on SUS varied significantly across the Perrier groups (Kruskal-Wallis, p = 0.0034) and suggests that SUS can miss quite large glands (> 0.5 g) in locations B, C and F; whereas missed glands in locations A, D and E were all small (< 0.5 g).

CONCLUSION

Whilst gland identification correlates well with gland weight, anatomical location has a significant impact on failure of localisation irrespective of gland weight. For the surgeon operating on PHPT patients with negative US localisation, particular attention should be paid to locations C, D and A as these are the sites where pathological glands are most often missed on pre-operative US.

Differentiation of parathyroid carcinoma and adenoma by preoperative ultrasonography

Background Parathyroid carcinomas (PTC) are very rare. There have been a few studies on the contribution of ultrasound (US) in the diagnosis of PTC compared with parathyroid adenomas (PTA). Purpose To identify the differences between US findings of PTC and PTA in patients with primary hyperparathyroidism (PHPT). Material and Methods We enrolled seven patients with PTC and 32 consecutive patients with PTA whose diagnoses were confirmed by surgery at our institution between March 1994 and June 2015. We retrospectively compared the US features of the two groups, as well as the demographic, clinical, and biochemical characteristics (age, gender, palpability, and serum ionized calcium and parathyroid hormone [PTH] levels). Results The patients with PTC and PTA did not exhibit significant differences in terms of mean age (59.0 years versus 51.1 years; P = 0.2063), sex distribution (male:female, 4:3 versus 1:3; P = 0.1716), mean PTH levels (2855.0 pg/mL versus 1821.5 pg/mL; P = 0.2067), and mean ionized calcium levels (1.7 mMol/L versus 1.5 mMol/L; P = 0.1585) except palpability ( P < 0.0001). On US images, the PTCs were significantly larger (3.5 cm versus 1.9 cm; P = 0.0133) and exhibited higher incidences of heterogeneous echotexture ( P = 0.0002), irregular shape ( P < 0.0001), non-circumscribed margin ( P < 0.0001), intra-nodular calcifications ( P = 0.014), and local invasion ( P = 0.0004) compared to the PTAs. Conclusion In preoperative patients with PHPT, PTCs are differentiated from PTAs by their palpability and significant US features: large size, heterogeneous echotexture, irregular shape, non-circumscribed margin, intra-nodular calcifications, and local invasion.

Sonographic Evaluation of Intrathyroid Metastases

OBJECTIVES

Intrathyroid metastases from extrathyroid primary tumors are rare. Clinical findings may be subtle, but detection of intrathyroid metastases has improved with sonography. The objective of this study was to evaluate the sonographic appearance of intrathyroid metastases.

METHODS

Patients with thyroid masses with cytopathologic features matching those of an extrathyroid primary tumor were retrospectively identified. The appearances of intrathyroid metastases on sonography were reviewed for the following features: size, margin regularity, echogenicity, echotexture, vascularity on power or color Doppler ultrasonography, and the presence or absence of any associated cervical adenopathy.

RESULTS

The study included 52 patients. The most frequent primary tumor sites were lung, head and neck, and breast. Intrathyroid metastases presented as a discrete nodule in 34 patients and as diffuse infiltration of the gland in 18 patients. The discrete nodules ranged in size from 1.1 to 5.6 cm (mean ± SD, 2.5 ± 1.2 cm). Thirty-three lesions (63%) had irregular margins, and 19 (37%) had well-defined margins. Most of the lesions were heterogeneously hypoechoic (n = 50, 96%). Vascularity was present in 32 of 50 measured lesions (64%) that were evaluated with Doppler sonography. Cervical adenopathy was present in 37 patients (71%).

CONCLUSIONS

Intrathyroid metastases have sonographic characteristics similar to those described for both benign and malignant thyroid diseases. In patients with a previous or current extrathyroid malignancy, thyroid nodules or diffuse infiltration of the thyroid gland on sonography should be viewed as a potential intrathyroid metastasis and evaluated via ultrasound-guided fine-needle aspiration regardless of the site of the primary tumor.

Parathyroid ultrasonography: the evolving role of the radiologist

Previously, radiologists played a limited role in the treatment of parathyroid disease, primary focusing on the preoperative localization of parathyroid lesions responsible for hyperparathyroidism. But, the widespread use of high-resolution ultrasound has lead to the increasing detection of parathyroid incidentalomas (PTIs). Consequently, radiologists may be required to differentiate PTIs from thyroid lesions, which is most reliably accomplished through the fine needle aspiration-parathyroid hormone analysis. Various nonsurgical treatment modalities for hyperfunctioning parathyroid lesions have been developed with some efficacy. Especially for symptomatic nonfunctioning parathyroid cysts, simple aspiration is a first-line procedure for diagnosis and treatment, while ethanol ablation is a subsequent treatment modality for recurrent cases.