Shear wave elastography and parathyroid adenoma: A new tool for diagnosing parathyroid adenomas

Imaging Recommendations for Diagnosis and Management of Primary Parathyroid Pathologies: A Comprehensive Review

Parathyroid pathologies are suspected based on the biochemical alterations and clinical manifestations, and the predominant roles of imaging in primary hyperparathyroidism are localisation of tumour within parathyroid glands, surgical planning, and to look for any ectopic parathyroid tissue in the setting of recurrent disease. This article provides a comprehensive review of embryology and anatomical variations of parathyroid glands and their clinical relevance, surgical anatomy of parathyroid glands, differentiation between multiglandular parathyroid disease, solitary adenoma, atypical parathyroid tumour, and parathyroid carcinoma. The roles, advantages and limitations of ultrasound, four-dimensional computed tomography (4DCT), radiolabelled technetium-99 (99mTc) sestamibi or dual tracer 99mTc pertechnetate and 99mTc-sestamibi with or without single photon emission computed tomography (SPECT) or SPECT/CT, dynamic enhanced magnetic resonance imaging (4DMRI), and fluoro-choline positron emission tomography (18F-FCH PET) or [11C] Methionine (11C -MET) PET in the management of parathyroid lesions have been extensively discussed in this article. The role of fluorodeoxyglucose PET (FDG-PET) has also been elucidated in this article. Management guidelines for parathyroid carcinoma proposed by the American Society of Clinical Oncology (ASCO) have also been described. An algorithm for management of parathyroid lesions has been provided at the end to serve as a quick reference guide for radiologists, clinicians and surgeons.

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.

Multi-modality parathyroid imaging: A shifting paradigm

The goal of parathyroid imaging in hyperparathyroidism is not diagnosis, rather it is the localization of the cause of hyperparathyroidism for planning the best therapeutic approach. Hence, the role of imaging to accurately and precisely localize the abnormal parathyroid tissue is more important than ever to facilitate minimally invasive parathyroidectomy over bilateral neck exploration. The common causes include solitary parathyroid adenoma, multiple parathyroid adenomas, parathyroid hyperplasia and parathyroid carcinoma. It is highly imperative for the radiologist to be cautious of the mimics of parathyroid lesions like thyroid nodules and lymph nodes and be able to differentiate them on imaging. The various imaging modalities available include high resolution ultrasound of the neck, nuclear imaging studies, four-dimensional computed tomography (4D CT) and magnetic resonance imaging. Contrast enhanced ultrasound is a novel technique which has been recently added to the armamentarium to differentiate between parathyroid adenomas and its mimics. Through this review article we wish to review the imaging features of parathyroid lesions on various imaging modalities and present an algorithm to guide their radiological differentiation from mimics.

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.

Shear wave elastography for differentiating parathyroid neoplasms with malignant diagnosis or uncertain malignant potential from parathyroid adenomas: initial experience

OBJECTIVE

Parathyroid carcinoma (PC) and atypical parathyroid tumor (APT) are rare parathyroid disorders carrying the risk of recurrence of varying degrees. This study aims to explore the value of 2D-shear wave elastography (SWE) in the discrimination of PC/APT among suspicious parathyroid lesions.

METHODS AND MATERIALS

In this prospective study, patients with primary hyperparathyroidism and suspicious parathyroid lesions on ultrasonography (US) were recruited. All the lesions were assessed by SWE before surgery. The velocity (m/s), Young's modulus (Kpa), and elastogram of SWE were compared between pathologically proven parathyroid carcinoma or atypical parathyroid tumor (Group1) and parathyroid adenoma (Group2). All the SWE parameters were displayed at the setting of 50 or 70 kPa. Correlations between SWE and the lesion size as well as biochemical parameters were analyzed.

RESULTS

36 target lesions were enrolled for analysis. The mean shear wave velocity (SWV) between the two groups was 2.4 m/s vs 1.9 m/s, respectively, while the mean Young's modulus was 11.1 kPa vs 18.2 kPa, respectively. The cut-off values are 2.35 m/s and 17.05 kPa correspondingly. The sensitivity and specificity of the selecting cut-off values were 0.56 vs 0.63 and 0.95 vs 1.0 (area under the curve [AUC]: 0.813 vs 0.852 [95% confidence interval (CI): 0.669-0.956 vs 0.720-0.983]; p <  0.001, p <  0.001; respectively). In contrast, the max SWV and Young's modulus showed a better sensitivity of 0.75 and 0.81, respectively. The "colored lesion" and "stiff rim" patterns on the elastogram are more indicated in parathyroid carcinoma and atypical parathyroid tumor, whereas the negative elastogram prevails in parathyroid adenoma. The SWV and Young's modulus of the parathyroid lesions were independent of the tumor size, but the max SWV and Young's modulus slightly correlated with serum parathyroid hormone concentration (PTH) (r = 0.398, p = 0.016; r = 0.396, p = 0.017).

CONCLUSIONS

2D-shear wave elastography plays a useful role in the preoperative assessment of parathyroid lesions with suspicious malignancy. The mean SWV and Young's modulus are advised as the favored diagnostic parameter with the best AUC and excellent specificities, while the max SWV and Young's modulus are more sensitive to distinguish the PC and APT compared with other parameters.

Shear-Wave-Elastography in Neurofibromatosis Type I

Ultrasound shear wave elastography (SWE) is an increasingly used imaging modality that expands clinical ultrasound by measuring the elasticity of various tissues, such as the altered elasticity of tumors. Peripheral nerve tumors are rare, have been well-characterized by B-mode-ultrasound, but have not yet been investigated with SWE. Given the lack of studies, a first step would be to investigate homogeneous peripheral nerve tumors (PNTs), histologically neurofibromas or schwannomas, which can occur in multiple in neurofibromatosis type 1 and 2 (NF1 and 2), respectively. Hence, we measured shear wave velocity (SWV) in 30 PNTs of 11 patients with NF1 within the median nerve. The SWV in PNTs ranged between 2.8 ± 0.8 m/s and correlated with their width and approximate volume but not with their length or height. Furthermore, we determined the extent to which PNTs alter the SWV of the median nerve for three positions of the wrist joint: neutral (zero-degree), individual maximal flexion and maximal extension. Here, SWV was decreased in NF1 patients compared to age- and sex-matched controls (p = 0.029) during maximal wrist extension. We speculate that the presence of PNTs may have a biomechanical impact on peripheral nerves which has not been demonstrated yet.

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.

Methods of identification of parathyroid glands in thyroid surgery: A literature review

Intra-operative identification and preservation of parathyroid glands is an important but challenging aspect of thyroid surgery. Failure to do so may lead to transient or permanent hypocalcaemia, where the latter represents a serious complication causing life-long morbidity. It would be beneficial, therefore, if a simple and reliable modality can be developed to assist in the identification of parathyroid glands intra-operatively. The aim of this literature review is to provide an overview of intra-operative modalities used to identify parathyroid glands with a particular focus on near-infrared autofluorescence (NIRAF). Twenty-seven studies were considered relevant in this literature review. Several modalities have been used to aid parathyroid gland identification, including Raman spectroscopy, indocyanine green angiography, and NIRAF. NIRAF technology allows parathyroid glands to spontaneously give off light (autofluorescence) when exposed to near-infrared light at a wavelength of 785 nm, creating a contrast between tissues to allow intra-operative differentiation. Studies utilising NIRAF technology were able to identify 76.3%-100% of parathyroid glands intra-operatively. Furthermore, two randomised controlled trials comparing NIRAF and white light showed that the use of NIRAF was able to significantly increase the mean number of parathyroid glands detected and reduce the incidence of post-operative hypocalcaemia. NIRAF is an emerging tool that has been shown to increase the number of intra-operative parathyroid gland identification and reduce the rate of post-operative hypocalcaemia in a safe and reproducible manner. Future trials are needed to evaluate the real-life impact of NIRAF technology in outcomes of patients following thyroid surgery.

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.

Diagnostic Role of Four-Dimensional Computed Tomography for Preoperative Parathyroid Localization in Patients with Primary Hyperparathyroidism: A Systematic Review and Meta-Analysis

We sought to systematically evaluate diagnostic performance of four-dimensional computed tomography (4D-CT) in the localization of hyperfunctioning parathyroid glands (HPGs) in patients with primary hyperparathyroidism (pHPT). We calculated the pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratios (DOR) of 4D-CT on a per-lesion level, as well as pooled sensitivity and positive predictive value (PPV) on a per-patient level with 95% confidence intervals (CIs). Additionally, we plotted summary receiver operating characteristic (SROC) curves and evaluated the areas under the curves (AUC). A total of 16 studies were included in the analysis. Their pooled sensitivity, specificity, PLR, NLR, and DOR of 4D-CT on per-lesion level were 75% (95%CI: 66–82%), 85% (95%CI: 50–97%), 4.9 (95%CI: 1.1–21.3), 0.30 (95%CI: 0.19–0.45), and 17 (95%CI: 3–100), respectively, with an AUC of 81% (95%CI: 77–84%). We also observed heterogeneity in sensitivity (I² = 79%) and specificity (I² = 94.7%), and obtained a pooled sensitivity of 81% (95%CI: 70–90%) with heterogeneity of 81.9% (p < 0.001) and PPV of 91% (95%CI: 82–98%) with heterogeneity of 80.8% (p < 0.001), based on a per-patient level. Overall, 4D-CT showed moderate sensitivity and specificity for preoperative localization of HPG(s) in patients with pHPT. The diagnostic performance may improve with 4D-CT’s promotion to first-line use on a lesion-based level, further research is needed to confirm the results.

Shear Wave Elastography in Patients with Primary and Secondary Hyperparathyroidism

OBJECTIVES

In this study, we aim to determine the elastographic characteristics of both primary and secondary hyperparathyroidism using shear wave elastography. We also aim to evaluate the elastographic differences between them, as well as the differences between the parathyroid, thyroid, and muscle tissue, in order to better identify a cutoff value for the parathyroid tissue.

METHODS

In this prospective study, we examined a total of 68 patients with hyperparathyroidism, divided into two groups; one group consisted of 27 patients with primary hyperparathyroidism and the other group consisted of 41 selected patients with confirmed secondary hyperparathyroidism. The elasticity index (EI) was determined in the parathyroid, thyroid, and muscle tissue. The determined values were compared to better identify the parathyroid tissue.

RESULTS

The median value of mean SWE values measured for parathyroid adenomas from primary hyperparathyroidism was 4.86 kPa. For secondary hyperparathyroidism, the median value of mean SWE was 6.96 KPa. The median (range) presurgical values for parathormone (PTH) and calcium were 762.80 pg/mL (190, 1243) and 9.40 mg/dL (8.825, 10.20), respectively. We identified significant elastographic differences between the two groups (p < 0.001), which remained significant after adjusting elastographic measures to the nonparametric parameters, such as the parathormone value and vitamin D (p < 0.001). The cutoff values found for parathyroid adenoma were 5.96 kPa and for parathyroid tissue 9.58 kPa.

CONCLUSIONS

Shear wave elastography is a helpful tool for identifying the parathyroid tissue, in both cases of primary and secondary hyperparathyroidism, as there are significant differences between the parathyroid, thyroid, and muscle tissue. We found a global cutoff value for the parathyroid tissue of 9.58 kPa, but we must keep in mind that there are significant elastographic differences between cutoffs for primary and secondary hyperparathyroidism.

Preoperative and Intraoperative Methods of Parathyroid Gland Localization and the Diagnosis of Parathyroid Adenomas

Accurate pre-operative determination of parathyroid glands localization is critical in the selection of minimally invasive parathyroidectomy as a surgical treatment approach in patients with primary hyperparathyroidism (PHPT). Its importance cannot be overemphasized as it helps to minimize the harmful side effects associated with damage to the parathyroid glands such as in hypocalcemia, severe hemorrhage or recurrent laryngeal nerve dysfunction. Preoperative and intraoperative methods decrease the incidence of mistakenly injuring the parathyroid glands and allow for the timely diagnosis of various abnormalities, including parathyroid adenomas. This article reviews 139 studies conducted between 1970 and 2020 (49 years). Studies that were reviewed focused on several techniques including application of carbon nanoparticles, carbon nanoparticles with technetium sestamibi (99m Tc-MIBI), Raman spectroscopy, near-infrared autofluorescence, dynamic optical contrast imaging, laser speckle contrast imaging, shear wave elastography, and indocyanine green to test their potential in providing proper parathyroid glands' localization. Apart from reviewing the aforementioned techniques, this study focused on the applications that helped in the detection of parathyroid adenomas. Results suggest that applying all the reviewed techniques significantly improves the possibility of providing proper localization of parathyroid glands, and the application of indocyanine green has proven to be the 'ideal' approach for the diagnosis of parathyroid adenomas.

Shear Wave Elastography versus Strain Elastography in Diagnosing Parathyroid Adenomas

OBJECTIVES

The aim of the study was to compare elastographic means in parathyroid adenomas, using shear wave elastography and strain elastography.

METHODS

This prospective study examined 20 consecutive patients diagnosed with primary hyperparathyroidism and parathyroid adenoma, confirmed by biochemical assay, technetium-99 sestamibi scintigraphy, and pathology report, after parathyroid surgery. All patients were examined on conventional 2B ultrasound, 2D shear wave elastography, and strain elastography. We determined using 2D shear wave elastography (SWE) the elasticity index (EI) in parathyroid adenoma, thyroid parenchyma, and surrounding muscle and examined using strain elastography the parathyroid adenoma, and determined the strain ratio with the thyroid tissue and muscle tissue.

RESULTS

All patients had positive sestamibi scintigraphy and underwent surgery, with confirmation of parathyroid adenoma in all cases. The mean parathormone (PTH) value before surgery was 153.29 pg/ml (36.5, 464.8) and serum calcium concentration was 10.5 mg/dl (9, 11.5). We compared using 2D-SWE and strain elastography parathyroid adenoma with thyroid tissue and with surrounding muscle. The mean EI measured by SWE in parathyroid adenoma was 4.74 ± 2.74 kPa and in thyroid parenchyma was 11.718 ± 4.206 kPa (mean difference = 6.978 kPa, p < 0.001), and the mean EI value in muscle tissue was 16.362 ± 3.829 kPa (mean difference = 11.622, p < 0.001). Using ROC analysis, we found that an EI below 7 kPa correctly identifies parathyroid tissue. We evaluated parathyroid adenomas using strain elastography by color mapping and strain ratio as a semiquantitative measurement; however, we could not find any statistical correlation comparing the strain ratio obtained from the parathyroid adenoma with the thyroid tissue (p=0.485).

CONCLUSION

Ultrasound elastography is a helpful tool in identifying parathyroid adenomas. A cutoff value below 7 kPa can be used in 2D-SWE. Color maps in strain elastography without adding strain ratio can be used, parathyroid adenoma being identified as score 1 in the Rago criteria.

Diagnosis of Parathyroid Adenomas with New Ultrasound Imaging Modalities

Ultrasound technology is becoming an integral part of diagnosing parathyroid adenomas. Careful ultrasound evaluation with b-mode, shear wave elastography, and three-dimensional (3D) of parathyroid adenomas may improve localization and outcome.

Introduction: A 60-year-old woman was referred for the evaluation of hyperparathyroidism. This patient gave her informed consent. She had a history of hypothyroidism and thyroid nodules. She was being treated with levothyroxine 50 mcg daily. Routine testing revealed hypercalcemia. The serum calcium was 11.2 (nL range 8.7–10.2 mg/dL), creatinine was 0.69 (nL range 0.57–1.00 mg/dL), intact parathyroid hormone (PTH) was 70 (nL range 15–65 pg/mL), phosphorus was 2.7 (nL range 2.5–4.5 mg/dL), vitamin D was 38.7 (30–100 ng/mL), and 24 hours urine calcium was 362.9 (100–300 mg/24 hour). The neck ultrasound showed two lesions one superior/posterior and the other in the inferior/posterior aspect of the right thyroid lobe measuring 11.6 × 4.4 × 9.7 mm and 14.6 × 5.0 × 10.0 mm, respectively. Both lesions resembled parathyroid adenomas. Shear wave velocity (SWV) measurements for the superior and inferior lesions were 1.67 and 1.77 m/second, respectively. For the adjacent thyroid tissue SWV was 2.3 m/second, significantly higher. 3D ultrasound examination demonstrated a polar artery in both lesions.

A sestamibi scan showed a probable right parathyroid adenoma and she was referred for surgery. She was found to have two right parathyroid adenomas in the superior and inferior poles corresponding with the ultrasound finding. Intraoperative PTH level decreased from 139.9 to 17 pg/mL postresection. Six weeks after surgery, her calcium and PTH were normal.

Materials and Methods: This patient was evaluated in our clinic with ultrasound imaging, including b-mode, shear wave elastography (SWE), and 3D ultrasound.

Discussion: Most patients with primary hyperparathyroidism have a single parathyroid adenoma. Other causes include glandular hyperplasia, multiple adenomas, and parathyroid carcinoma.^1,2 This case shows two parathyroid adenomas in the neck posterior to the right thyroid lobe. The role of ultrasound in diagnosing parathyroid adenomas is becoming more prominent because of improved technology, low cost, and noninvasive nature.

With this case we illustrate that SWE can be an added value to b-mode ultrasound in diagnosing parathyroid adenomas. Our previous publication in the Journal of European Radiology reported that SWV measurement of parathyroid adenomas may enhance other sonographic parameters to predict the diagnosis. In our view, parathyroid adenomas appear to have a more homogenous texture and lower tissue stiffness when compared with the thyroid gland.³ This case confirms our prior findings.

It can be challenging to differentiate parathyroid adenomas from lymph nodes (LNs) and ectopic thyroid tissue at level 6, with b-mode ultrasound. A combination of 3D ultrasound images with 3D color Doppler (CD) might improve our ability to identify the polar artery and enhance differentiation from LN. 3D technology might improve the view by adding coronal view to current b-mode that comprises of transverse and longitudinal views. This is a preliminary report, and more studies need to be done.

Conclusion: Combining multiple image modalities, including b-mode, shear wave elastography, and 3D technology, may improve our ability to identify parathyroid adenomas. Parathyroid adenomas have a lower SWV compared with thyroid tissue. 3D ultrasound technology may enhance view of polar artery when adding 3D CD. This challenging case illustrates the utility of these additional modalities.

No competing financial interests exist.

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Shear Wave Elastography in Diagnosing Secondary Hyperparathyroidism

This study evaluates the diagnostic value of two-dimensional shear wave elastography (2 D-SWE) technique in the evaluation of hyperplastic parathyroid glands in cases with secondary and tertiary hyperparathyroidism. A total of 59 patients (end-stage renal disease, under supplemental dialysis program) with visible parathyroid hyperplastic glands on ultrasound, confirmed by biochemical assay and scintigraphy, were enrolled; they were examined on grayscale ultrasound and 2 D shear wave elastography. We determined the elasticity index (EI) in the parathyroid gland, thyroid parenchyma and surrounding muscles, and the elasticity ratio of hyperplastic parathyroid glands compared to muscle, specifically sternocleidomastoid muscle. Patients presented fibrocystic bone disease with secondary hyperparathyroidism induced by end-stage chronic kidney disease; being on prolonged chronic dialysis therapy, they had positive sestamibi scintigraphy and high values of serum parathormone (1141.04 pg/mL). Nodules placed posterior to the thyroid capsule that were cystic, had a hypoechoic aspect, and were homogenous with an independent afferent artery were found. Mean EI in the parathyroid gland was 7.83 kPa, the median value in thyroid parenchyma was 13.76 kPa, and mean muscle EI value was 15.78 kPa. The observed mean parathyroid/muscle SWE ratio was 0.5356 and the value for parathyroid/normal thyroid parenchyma was 0.5995. Using receiver operating characteristic (ROC) analysis, we found that EI below 9.74 kPa correctly identifies parathyroid tissue, with a sensitivity of 94.8%, specificity of 90.7%, and accuracy of 92.26% when compared to normal thyroid tissue. Compared with the muscle tissue, we identified that EI below 9.98 kPa has a sensitivity, specificity, and accuracy of 93.8%, 90.7%, and 91.75%, respectively. Ultrasound elastography is a helpful tool in identifying parathyroid hyperplasia in patients with chronic kidney disease. A cutoff value of 9.98 kPa can be used in 2 D-SWE for accurate diagnosis of parathyroid disease.

Ultrasound elastography score and strain index in different parathyroid lesions

BACKGROUND

Despite significant improvement in imaging quality and advanced scientific knowledge, it may still sometimes be difficult to distinguish different parathyroid lesions. The aims of this prospective study were to evaluate parathyroid lesions with ultrasound elastography and to determine whether strain index can help to differentiate parathyroid lesions.

METHODS

Patients with biochemically confirmed hyperparathyroidism and localised parathyroid lesions in ultrasonography were included. All patients underwent B-mode US and USE examination. Ultrasound elastography scores and strain index of lesions were determined. Strain index was defined as the ratio of strain of the thyroid parenchyma to the strain of the parathyroid lesion.

RESULTS

Data of 245 lesions of 230 patients were analysed. Histopathologically, there were 202 (82.45%) parathyroid adenomas, 26 (10.61%) atypical parathyroid adenomas, and 17 (6.94%) cases of parathyroid hyperplasia. Median serum Ca was significantly higher in atypical parathyroid adenoma patients than parathyroid hyperplasia patients (P = 0.019) and median PTH was significantly higher in APA compared to PA patients (P < 0.001). In 221 (90.2%) of the parathyroid lesions, USE score was 1 or 2. The median SI of atypical parathyroid adenomas was significantly higher than parathyroid adenomas and hyperplasia lesions (1.5 (0.56-4.86), 1.01 (0.21-8.43) and 0.91 (0.26-2.02), respectively, P = 0.003).

CONCLUSION

Our study revealed that SI of parathyroid lesions as well as serum calcium, parathyroid hormone levels, and B-mode US features may help to predict the atypical parathyroid adenoma. Ultrasound elastography can be used to differentiate among parathyroid lesions and guide a surgical approach.

A new tool for diagnosing parathyroid lesions: angio plus ultrasound imaging

Background

Our aim was to examine the potential value of angio plus ultrasound imaging in diagnosing parathyroid lesions. Angio plus ultrasound imaging uses a new paradigm in Doppler performance, which allows for a better detection of flow in small vessels while maintaining workflow of conventional color flow imaging characteristics.

Methods

Thirty parathyroid lesions, composed of 26 histopathologically diagnosed adenoma and 4 hyperplasia (two hyperplasia in the same patient), from 29 consecutive patients (6 men and 23 women; median age: 53 years, range: 25-78 years) were evaluated using both color Doppler and angio plus ultrasound imaging. The polar vessel (visible or invisible), number and distribution (peripheral, central, and both) of blood flow signals were compared between the two techniques.

Results

On color Doppler, the polar vessel was visible in 6 (20%) lesions. The median number of blood flow signals was 6 [3-23]. The distribution of peripheral, central and both was shown in 4 (13.3%), 9 (30%), and 15 (50%) lesions respectively, and no blood signals was shown in 2 (6.7%) lesions. On angio plus ultrasound imaging, the polar vessel was visible in 16 (53.3%) lesions. The median number of blood flow signals was 3 [0-18]. The distribution of peripheral, central and both was shown in 1 (3.3%), 4 (13.3%), and 25 (83.3%) lesions respectively. There was significant difference between color Doppler and angio plus ultrasound imaging in the detection of the polar vessel, number and distribution of blood flow signals.

Conclusions

The typical polar vessel and increased vascularity commonly associated with parathyroid lesions may be obtained with angio plus ultrasound imaging. Angio plus ultrasound imaging can improve the detection rate and distribution characteristics of blood flow signals of parathyroid lesions. Further research is needed to clarify the clinical meaning of increased blood flow information, such as the differentiation of parathyroid lesions from other lesions.

Sonoelastographic evaluation for benign neck lymph nodes and parathyroid lesions

Aim: The aim of the study was to evaluate the performance of real-time strain sonoelastography for comparison of perithyroidal lymph nodes of Hashimoto thyroiditis patients, jugular lymph nodes of healthy individuals and parathyroid lesions. Material and methods: Fifty parathyroid lesions (Group 1), 52 lymph nodes in Hashimoto thyroiditis patients (Group 2) and 51 reactive jugular lymph nodes (Group 3) were examined by ultrasound, and elastography was performed for a total of 95 patients. Real-time strain sonoelastography using elasticity score (E-index) was performed. The differences in E-index between the three groups were evaluated. Results: The mean E-index and size of parathyroid lesions were 2.30 ± 0.91 and 13.46 ± 5.69 mm, respectively. Parathyroid hyperplasia was detected by parathyroidectomy in two patients (2/37; 5%) with a total of four lesions (4/50; 8%). The remaining lesions were considered as adenomas. The mean E-index and size in Group 2 were 2.70 ± 0.93 and 7.83 ± 3.35 mm, respectively. The mean E-index and size in Group 3 were 1.88 ± 0.59 and 11.60 ± 4.96 mm, respectively. There were statistically significant differences between the groups in terms of E-index (p <0.01). Conclusions: When reactive jugular lymph nodes, perithyroidal lymph nodes of Hashimoto thyroiditis patients and parathyroid lesions are compared, it seems that strain sonoelastography indices add a benefit to routine practice in the differential diagnosis of parathyroid lesions and benign neck lymph nodes.

Shear wave elastography in the diagnostics of parathyroid adenomas-new application of the method

PURPOSE

Shear wave elastography (SWE) was described as valuable tool in the diagnostics of distinct types of thyroid lesions, thyroiditis and several other non-thyroidal conditions, such as liver inflammation and fibrosis or diagnostics of breast lesions. The aim of the current study was to assess the appearance of parathyroid adenomas in SWE and to check prospectively if SWE can be valuable additional tool in the diagnostics of pathologically enlarged parathyroids.

METHODS

Patients with parathyroid adenomas confirmed by histopathology were included. Subjects with benign thyroid lesions were enrolled to the control group. Elasticity of parathyroid adenomas and benign thyroid nodules was measured and compared.

RESULTS

Sixty five patients with parathyroid adenomas and 35 patients with 51 benign thyroid nodules were included. Parathyroid adenomas where significantly more elastic than benign thyroid nodules-mean elasticity of the lesion was 5.2 ± 7.2 vs. 24.3 ± 33.8 kPa, respectively. Relative mean elasticity (in comparison with surrounding thyroid tissue) was 0.30 ± 0.36 and 2.8 ± 3.9, respectively.

CONCLUSIONS

SWE can be useful tool in the diagnostics of parathyroid adenomas. Enlarged parathyroids are significantly more elastic than benign thyroid lesions. Low elasticity of the lesion constitutes feature with high negative prognostic value, allowing for reliable exclusion of suspicion of parathyroid adenomas.

Multiparametric ultrasonography and ultrasound elastography in the differentiation of parathyroid lesions from ectopic thyroid lesions or lymphadenopathies

To evaluate the accuracy of ultrasound elastography with Elastoscan^TM Core Index in the differential diagnosis of parathyroid lesions from ectopic thyroid nodules and lymph nodes. Seventy nine patients with repeatedly high levels of circulating intact parathyroid hormone, normal vitamin D and renal function tests, with an ultrasound scan showing a neck lesion, sharply demarcated from the thyroid lobules, were consecutively enrolled. Ultrasound with and without Color Doppler and ultrasound elastography were performed before histological examination. All ultrasound features, vascularization and ultrasound elastography diagnostic performance were assessed using ROC curves. Histological examination confirmed 47 parathyroid lesions, 18 thyroid ectopic nodules and 14 reactive lymph nodes. In distinguishing parathyroid from thyroid nodules, shape had a 100 % sensitivity (95 % CI 92.4-100) and 50 % specificity (95 % CI 37.2-64.7), cleavage had a 85.1 % sensitivity (95 % CI 72.3-92.6) and 77.8 % specificity (95 % CI 65.1-88) while peripheral vascularization had a sensitivity of 91.5 (95 % CI 79.6-97.6) and specificity of 72.2 (95 % CI 46.5-90.3). An Elastoscan^TM Core Indexof 1.28 was 46 % sensitive (95 % CI 33.4-58.7) and 77 % specific (95 % CI 66.2-89.1) in discriminating parathyroid lesions from thyroid nodules. An Elastoscan^TM Core Index of 1.0 was 78 % sensitive (95 % CI 65.1-88) and 71 % specific (95 % CI 56-81.3) in discriminating parathyroid lesions from lymph nodes (p = 0.045). An Elastoscan^TM Core Index greater than 2.58 had a 100 % sensitivity (95 % CI 43.8-100) and 95.4 % specificity (95 % CI 38.3-99.7) in discriminating malignant from benign parathyroid nodules. Elastoscan^TM Core Index was significantly higher in thyroid nodules than in reactive lymph nodes (1.18 ± 0.62, p = 0.008). The ultrasound features of cleavage and peripheral vascularization help to differentiate parathyroid from thyroid nodules. Elastoscan^TM Core Index can improve ultrasound discrimination of parathyroid lesions from lymph nodes. The Elastoscan^TM Core Index is significantly higher in malignant than in benign parathyroid lesions.

2D-Shear Wave Elastography in the Evaluation of Parathyroid Lesions in Patients with Hyperparathyroidism

BACKGROUND AND AIMS

2D-shear wave elastography (2D-SWE) is a relatively new elastographic technique. The aim of the present study is to determine the values of the elasticity indexes (EI) measured by 2D-SWE in parathyroid benign lesions (adenomas or hyperplasia) and to establish if this investigation is helpful for the preoperative identification of the parathyroid adenoma.

MATERIAL AND METHODS

The study groups were represented by 22 patients with primary or tertiary hyperparathyroidism, diagnosed by specific tests, and 43 healthy controls, in whom the thyroid parenchyma was evaluated, in order to compare the EI of the thyroid tissue with those of the parathyroid lesions.

RESULTS

The mean EI measured by 2D-SWE in the parathyroid lesions was 10.2 ± 4.9 kPa, significantly lower than that of the normal thyroid parenchyma (19.5 ± 7.6 kPa; p = 0.007), indicating soft tissue. For a cutoff value of 12.5 kPa, the EI assessed by 2D-SWE had a sensitivity of 93% and a specificity of 86% (AUC = 0.949; p < 0.001) for predicting parathyroid lesions.

CONCLUSION

A value lower than 12.5 kPa for the mean EI measured by 2D-SWE can be used to confirm that the lesion/nodule is a parathyroid adenoma.