Actual role of color-doppler high-resolution neck ultrasonography in primary hyperparathyroidism: a clinical review and an observational study with a comparison of 99mTc-sestamibi parathyroid scintigraphy

The detection of pathological parathyroid glands is facilitated by identifying vascular features on ultrasound: the potential benefit of a low-frequency vascular probe

PURPOSE

To evaluate the potential benefit of adding a low frequency vascular probe to the conventional pre-operative ultrasound examination of patients with primary hyperparathyroidism.

METHODS

A prospective cohort of 136 patients with primary hyperparathyroidism underwent a conventional ultrasound examination of the neck with a high frequency ( > 10 MHz) linear ultrasound probe, followed by an add-on examination with a low frequency vascular probe. For each ultrasound probe, and for every potential parathyroid lesion, the presence of a feeding vessel, a polar placement of the feeding vessel, and the presence of a vascular arch was recorded.

RESULTS

A total of 146 ultrasound lesions were evaluated for vascularity by each probe. For both ultrasound probes, the odds of a hyperfunctioning parathyroid gland being correctly identified increased with the number of visible vascular features. The vascular probe identified a significantly higher number of vascular features among ultrasound true positive glands compared with the conventional probe (p < 0.0001). Among histopathologically verified pathological parathyroid glands, the vascular probe identified 20% more feeding vessels, 27% more polar placements of the feeding vessel, and 65% more vascular arches than the high frequency probe. However, the diagnostic confidence score for true positive glands did not differ significantly between the probes (p = 0.11).

CONCLUSION

The addition of a low frequency vascular probe increases the number of visible vascular features in hyperfunctioning parathyroid glands, which facilitates their preoperative detection. Whether or not this can increase the diagnostic confidence of ultrasound examiners has yet to be substantiated.

Update in imaging tests used for the localization of parathyroid pathology

Preoperative localization of parathyroid pathology, generally a parathyroid adenoma, can be difficult in some cases due to the anatomical variants that these glands present. The objective of this review is to analyse the different imaging techniques used for preoperative localization of parathyroid pathology (scintigraphy, ultrasound, CT, MRI and PET). There is great variability between the different tests for the preoperative localization of parathyroid pathology. The importance of knowing the different diagnostic options lies in the need to choose the most suitable test at each moment and for each patient for an adequate management of primary hyperparathyroidism (PHP) with surgical criteria.

Differentiating thyroid nodules parathyroid lesions using 2D-shear-wave elastography: a novel approach for enhanced diagnostic accuracy

Differentiating between thyroid and parathyroid lesions by means of ultrasound can be a challenge in some cases. This study explores the diagnostic efficacy of bidimensional shear wave elastography planewave ultrasound (2D SWE PLUS) as an auxiliary technique in distinguishing these superficial structures. We evaluated 86 cases, presenting with concurrent thyroid nodules and hyperparathyroidism, through conventional ultrasound and 2D SWE PLUS, employing an Aixplorer Supersonic Mach30 with a 5-18 MHz linear probe. Statistically significant differences were observed for the elasticity index (EI) between parathyroid and normal thyroid tissue (p<0.0001, U=291), and between parathyroid lesions and thyroid nodules (p<0.0001, U=248.5). An area under the curve (AUC) of 0.961, with an optimal cut-off value of ≤8.9 kPa, was established to effectively distinguish parathyroid tissue from normal thyroid tissue (sensitivity of 91.9%; specificity of 97.5%). Furthermore, an AUC of 0.963 and an optimal cut-off of 9.24 kPa (sensitivity of 94.2%, specificity of 91.1%) were determined for parathyroid vs thyroid lesions. Elasticity values were significantly elevated in the cancer group compared to benign thyroid nodules (p<0.0001). Our findings suggest that 2D SWE PLUS is an effective tool in differentiating between thyroid nodules and parathyroid lesions, enhancing diagnostic performance in neck ultrasonography.

Evaluation of Surgeon-Performed Ultrasonography With or Without Contrast Enhancement vs Scintigraphy in Patients With Primary Hyperparathyroidism

Importance

Scintigraphy and ultrasonography are common imaging modalities for the preoperative localization of enlarged parathyroid glands in primary hyperparathyroidism. When comparing the 2 modalities, the benefits of ultrasonography in terms of convenience, patient comfort, duration, cost, and lack of radiation should be taken into account.

Objective

To investigate whether surgeon-performed ultrasonography, with or without contrast-enhanced ultrasonography (CEUS), is noninferior to scintigraphy for localizing pathological parathyroid glands in patients with primary hyperparathyroidism.

Design, Setting, and Participants

Prospective, paired, noninferiority cohort study performed at a high-volume tertiary referral center for parathyroidectomy with blinded examiners and a 6-month follow-up. Participants were adults (age ≥18 years) referred for parathyroidectomy due to primary hyperparathyroidism. Of 207 eligible patients, 35 were excluded, leaving 172 enrolled in the study. Inclusion lasted from September 2019 until February 2021. Follow-up ended in December 2021.

Exposures

99mTechnetium-pertechnetate/99mtechnetium-sestamibi subtraction scintigraphy with 99mtechnetium-sestamibi single-photon emission computed tomography/computed tomography, followed by surgeon-performed ultrasonography and CEUS.

Main Outcomes and Measures

The sensitivity of each imaging modality in localizing pathological parathyroid glands, calculated on a per-quadrant and a per-patient basis, respectively. The a priori noninferiority margin was a lower 95% confidence limit for the difference in sensitivity not falling below -10%.

Results

Out of 172 participants, 139 (80.8%) were women, the median (range) age was 65 (24-87) years, and the median (IQR) follow-up was 200.5 (181-280.25) days. Quadrant sensitivity (95% CI) was 70.9% (63.2%-78.5%) for ultrasonography, 68.4% (60.4%-76.5%) for ultrasonography plus CEUS, and 67.0% (60.0%-74.0%) for scintigraphy. The sensitivity difference (95% CI) compared with scintigraphy was 3.9% (-4.1% to 11.8%) for ultrasonography and 1.5% (-6.4% to 9.3%) for ultrasonography plus CEUS, establishing noninferiority for both modalities. Per-patient sensitivity was 81.4% (74.8%-86.9%) for ultrasonography and 79.1% (72.2%-84.9%) for both scintigraphy and ultrasonography plus CEUS. The sensitivity difference compared with scintigraphy was 2.3% (-6.8% to 11.4%) for ultrasonography and 0.0% (-9.1% to 9.1%) for ultrasonography plus CEUS, establishing noninferiority for both modalities.

Conclusions and Relevance

In this cohort study, conventional ultrasonography by an experienced parathyroid surgeon-sonographer was noninferior to scintigraphy and may constitute a valid first-line imaging modality in patients with primary hyperparathyroidism, even without the addition of CEUS. Further imaging should be reserved for cases that are equivocal or nonlocalizing on ultrasonography.

The Dark Side of Ultrasound Imaging in Parathyroid Disease

The diagnosis of parathyroid diseases by imaging still has some intrinsic technical limitations due to the differential diagnosis of different structures of the neck that mimic the parathyroid glands. In this view, ultrasound (US) is an established, low-cost, and non-invasive imaging technique that still represents the first-line approach for evaluating patients with parathyroid disease. The objective of this article is to provide a comprehensive review of the applications of USs in clinical practice, discussing the histopathological and US characteristics of the parathyroid glands in normal and pathological conditions, the advantages of preoperative imaging, and novel updates on the most useful and currently available multiparameter US techniques.

Parathyroid Imaging: Past, Present, and Future

The goal of parathyroid imaging is to identify all sources of excess parathyroid hormone secretion pre-operatively. A variety of imaging approaches have been evaluated and utilized over the years for this purpose. Ultrasound relies solely on structural features and is without radiation, however is limited to superficial evaluation. 4DCT and 4DMRI provide enhancement characteristics in addition to structural features and dynamic enhancement has been investigated as a way to better distinguish parathyroid from adjacent structures. It is important to recognize that 4DCT provides valuable information however results in much higher radiation dose to the thyroid gland than the other available examinations, and therefore the optimal number of phases is an area of controversy. Single-photon scintigraphy with 99mTc-Sestamibi, or dual tracer 99mTc-pertechnetate and 99mTc-sestamibi with or without SPECT or SPECT/CT is part of the standard of care in many centers with availability and expertise in nuclear medicine. This molecular imaging approach detects cellular physiology such as mitochondria content found in parathyroid adenomas. Combining structural imaging such as CT or MRI with molecular imaging in a hybrid approach allows the ability to obtain robust structural and functional information in one examination. Hybrid PET/CT is widely available and provides improved imaging and quantification over SPECT or SPECT/CT. Emerging PET imaging techniques, such as 18F-Fluorocholine, have the exciting potential to reinvent parathyroid imaging. PET/MRI may be particularly well suited to parathyroid imaging, where available, because of the ability to perform dynamic contrast-enhanced imaging and co-registered 18F-Fluorocholine PET imaging simultaneously with low radiation dose to the thyroid. A targeted agent specific for a parathyroid tissue biomarker remains to be identified.

Contrast-Enhanced Ultrasound Qualitative and Quantitative Characteristics of Parathyroid Gland Lesions

Background and Objectives: preoperative differentiation of enlarged parathyroid glands may be challenging in conventional B-mode ultrasound. The aim of our study was to analyse qualitative and quantitative characteristics of parathyroid gland lesions, using multiparametric ultrasound protocol—B-mode, Colour Doppler (CD), and contrast-enhanced ultrasound (CEUS)—and to evaluate correlation with morphology in patients with hyperparathyroidism (HPT). Materials and Methods: consecutive 75 patients with 88 parathyroid lesions and biochemically confirmed HPT prior to parathyroidectomy were enrolled in the prospective study. B-mode ultrasound, CD, and CEUS were performed with the subsequent qualitative and quantitative evaluation of acquired data. We used 1 mL or 2 mL of intravenous ultrasound contrast agent during the CEUS examination. Correlation with post-surgical morphology was evaluated. Results: seventy parathyroid adenomas were hypoechoic and well contoured with increased central echogenicity (44.3%), peripheral-central vascularization (47%), and polar feeding vessel (100%). Twelve hyperplasias presented with similar ultrasound appearance and were smaller in volume (p = 0.036). Hyperplasias had a tendency for homogenous, marked intense enhancement vs. peripherally enhanced adenomas with central wash-out in CEUS after quantitative analysis. No significant difference was observed in contrasting dynamics, regardless of contrast media volume use (1 mL vs. 2 mL). We achieved 90.9% sensitivity and 72.7% specificity, 93% positive predictive value (PPV), 87.3% negative predictive value (NPV), and 87.3% accuracy in the differentiation of parathyroid lesions prior to post-processing. In a quantitative lesion analysis, our sensitivity increased up to 98%, specificity 80%, PPV 98%, and NPV 80% with an accuracy of 96.4%. Conclusions: CEUS of parathyroid lesions shows potential in the differentiation of adenoma from hyperplasia, regardless of the amount of contrast media injected. The quantitative analysis improved the sensitivity and specificity of differentiation between parathyroid lesions. Hyperplasia was characterized by homogeneous enhancement, fast uptake, and homogeneous wash-out appearance; adenoma—by peripheral uptake, central wash-out, and reduced hemodynamics. The use of CEUS quantification methods are advised to improve the ultrasound diagnostic role in suspected parathyroid lesions.

Direct Comparison of Preoperative Imaging Modalities for Localization of Primary Hyperparathyroidism: A Systematic Review and Network Meta-analysis

Importance

Accurate preoperative localization of primary hyperparathyroidism (pHPT) is an important and challenging issue for a successful parathyroidectomy. Although new imaging modalities have been introduced during the past decade, direct comparative studies on advanced imaging techniques are limited.

Objective

To compare the performance of different preoperative imaging modalities for the localization of pHPT by performing a network meta-analysis (NMA).

Data Sources

PubMed, Embase, and the Cochrane Library were searched from the earliest available indexing date through September 28, 2020.

Study Selection

The inclusion criteria were diagnostic tests with sensitivities of 2 or more different preoperative imaging modalities for the same indivduals.

Data Extraction and Synthesis

Two researchers independently reviewed the literature according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses extension statement of health care intervention guidelines for network meta-analyses.

Main Outcomes and Measures

After classifying various imaging modalities into 8 representative imaging categories, the pooled estimation between the odds ratio and 95% credible intervals (CrIs) was calculated in the sensitivity for localization of pHPT. The surface under the cumulative ranking curve (SUCRA) values were obtained to calculate the probability of each imaging modality being the most effective diagnostic method.

Results

A total of 8495 patients from 119 direct comparative studies using 2 or more imaging modalities for localization of pHPT were included. The sensitivity of choline positron emission tomography and computed tomography (PET-CT) was significantly higher than that of technetium 99m sestamibi single-photon emission computed tomography (MIBI SPECT) in both patient-based and lesion-based analyses (patient-based analysis: odds ratio, 5.22; 95% CrI, 2.36-11.80; lesion-based analysis: odds ratio, 17.70; 95% CrI, 5.79-60.10). Among 8 representative imaging modality categories, choline PET-CT showed the highest SUCRA value in both patient-based and lesion-based analyses. In patient-based analysis after 2010, choline PET-CT showed the highest SUCRA value, followed by the CT category, although MIBI SPECT had the highest SUCRA value in analysis before 2009.

Conclusions and Relevance

The results from this network meta-analysis suggest that choline PET-CT showed the best performance in both patient-based and lesion-based analyses and that choline PET-CT would be the best preoperative imaging modality for localization of pHPT.

Carotid-femoral pulse wave velocity is significantly increased in newly diagnosed hypertensive patients with primary hyperparathyroidism and significantly related with serum calcium level

BACKGROUND

Primary hyperparathyroidism (PHP) is a rare cause of secondary hypertension (HT), but in patients with PHP, HT is very common and 20-80% of patients have HT. The aim of this study was to evaluate the change in carotid-femoral pulse wave velocity (CF-PWV) in hypertensive patients with PHP, and was to determine the clinical, laboratory, and echocardiographic parameters associated with CF-PWV.

METHODS

The study included 83 newly diagnosed hypertensive patients with PHP and 83 patients with newly diagnosed essential HT without PHP. All patients underwent echocardiography and CF-PWV measurements.

RESULTS

In patients with PHP, blood urea nitrogen, hs-CRP, uric acid, serum and urine calcium, parathyroid hormone level, CF-PWV value, LV wall thickness, LVMI, aortic and left atrium (LA) diameter, and presence of LVH and CF-PWV > 10 m/s were higher, and serum phosphorus levels were lower. Serum calcium, LA diameter, and LVMI values were closely correlated with CF-PWV. In the ROC analysis, the AUROC was calculated as 0.825 for calcium level to determine the patients with increased CF-PWV. When the serum calcium value was taken as 10 mg/dL, it was determined with CF-PWV > 10 m/s were 79.5% sensitivity and 78.2% specificity.

CONCLUSION

CF-PWV significantly increases in newly diagnosed hypertensive patients with PHP and significantly related to serum calcium level. To protect against target organ damage, high serum calcium levels should be monitored as well as blood pressure in hypertensive patients with PHP.