Parathyroid sonography: imaging and intervention

Normal Parathyroid Glands Are Most Often Seen on Neck Ultrasound

RATIONALE AND OBJECTIVES

The dogma is that normal parathyroid glands (PTGs) are not visible on ultrasound (US). Recently, several studies have shown that PTGs present these US features: ovoid structure, homogeneous and hyperechoic. The primary objective was to assess the detection rate, standard size and locations of normal PTGs in a population of patients consulting for thyroid US exam. The secondary objective was to determine if the presence of a goiter or a thyroiditis could modify the visualization of normal PTGs.

METHOD

Single-center prospective study on 192 patients based on the typical US appearance previously described to identify one or more PTGs.

RESULTS

One or more PTGs were visualized in 75% of patients (144/192). They were visualized preferentially at the lower pole of the thyroid gland and in the infra-thyroid region (66%). The mean (± SD) size of normal PTGs was 5.68 mm (± 1,42 mm)×4.05 mm (± 1,03 mm)×2,68 mm (± 0,61 mm) and mean volume was 33.3 mm3 (± 17.75 mm3). The presence of a goiter made the search for PTGs more difficult whereas the presence of thyroiditis facilitated it.

CONCLUSION

The US detection rate of PTGs is high (75%). The identification of PTGs could be particularly useful in the preoperative assessment before total thyroidectomy or parathyroid surgery. It could reduce the risk of postoperative hypoparathyroidism and improve the accuracy of postoperative US surveillance of thyroid cancer. Better knowledge of the usual anatomical location of normal PTGs could also enable better detection of abnormal glands.

Ultrasonographic features of normal parathyroid glands confirmed during thyroid surgery in adult patients

PURPOSE

This study was performed to examine the ultrasonography (US) features of normal parathyroid glands (PTGs) that were identified on preoperative US and subsequently confirmed during thyroid surgery.

METHODS

This retrospective study included a consecutive sample of 161 patients (mean±standard deviation age, 56±14 years; 128 women) with 294 normal PTGs identified on preoperative US PTG mapping and confirmed during thyroidectomy. A presumed normal PTG on US was defined as a small, round to oval, hyperechoic structure in the central neck. These presumed normal PTGs, as identified on preoperative US, were mapped onto thyroid computed tomography images and diagrams of the thyroid gland and neck. During the preoperative real-time US examinations, the location, size, shape, echogenicity, echotexture, and intraglandular vascular flow of the identified presumed PTGs were assessed. These characteristics were compared between superior and inferior PTGs using the generalized estimating equation method.

RESULTS

The typical US features of homogeneous hyperechogenicity without intraglandular vascular flow were observed in 267 (90.8%) normal PTGs, while atypical features, including isoechogenicity (1.0%), heterogeneous echotexture with focal hypoechogenicity (5.8%), and intraglandular vascular flow (3.7%), were noted in 27 (9.2%). Inferior PTGs were more frequently identified in posterolateral (36.1% vs. 5.3%) and thyroid pole locations (29.9% vs. 5.3%), and less frequently in posteromedial locations (29.2% vs. 88.0%), compared to superior PTGs (P<0.001 for each comparison).

CONCLUSION

Most normal PTGs displayed the typical US features of homogeneous hyperechogenicity without intraglandular vascular flow. However, in rare cases, normal PTGs exhibited atypical features, including isoechogenicity, heterogeneous echotexture with focal hypoechogenicity, and intraglandular vascular flow.

US Features of the Parathyroid Glands: An Intraoperative Surgical Specimen Study

Purpose

This study aimed to evaluate the US features of the parathyroid glands (PTGs) using surgical specimens of normal PTGs obtained during thyroid surgery.

Materials and Methods

This study included 34 normal PTGs from 17 consecutive patients who underwent thyroid surgery between December 2020 and March 2021. All normal PTGs were histologically confirmed by intraoperative frozen-section biopsy for autotransplantation. Surgically resected parathyroid specimens were scanned in sterile normal saline using high-resolution US prior to autotransplantation. The US features of echogenicity (hyperechogenicity or hypoechogenicity), echotexture (homogeneous or heterogeneous), size, and shape (ovoid or round) were retrospectively evaluated. The echogenicity of the three PTGs was compared with that of the thyroid parenchyma of the resected thyroid specimens in two patients.

Results

All PTGs showed hyperechogenicity similar to that of gauze soaked in normal saline. Homogeneous hyperechogenicity was observed in 32/34 (94.1%) patients, and the echogenicity of the three PTGs was hyperechoic compared with that of the thyroid parenchyma. The long diameter of the PTGs ranged from 5.1 mm to 9.8 mm (mean, 7.1 mm) and the shape of the PTGs was ovoid in 33/34 (97.1%) patients.

Conclusion

The echogenicity of normal PTG specimens was consistently hyperechoic, and the small ovoid homogeneously hyperechoic structure was a characteristic US feature of the PTGs.

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.

Diagnosis of parathyroid incidentaloma detected on thyroid ultrasonography: the role of fine-needle aspiration cytology and washout parathyroid hormone measurements

PURPOSE

The aim of this study was to assess the diagnostic role of fine-needle aspiration cytology (FNAC) and analyze factors associated with false-negative FNAC results in patients with parathyroid incidentaloma who were referred for ultrasonography (US)-guided fine-needle aspiration (FNA) of thyroid nodules.

METHODS

In this study, 121 patients with suspected parathyroid lesions were enrolled. The patients underwent US-guided FNAC with measurements of washout parathyroid hormone (PTH) between January 2015 and May 2020. The diagnostic performance of FNAC for the diagnosis of parathyroid lesions was assessed using surgical results and elevated washout PTH as a reference standard. The clinical and radiologic features associated with false-negative results on FNAC for the diagnosis of parathyroid lesions were evaluated.

RESULTS

Among the 121 nodules assessed, 38 were parathyroid lesions (31.4%), and 83 were non-parathyroid lesions (68.6%). The diagnostic performance of FNAC for parathyroid incidentaloma showed a sensitivity of 31.6% (12/38), specificity of 100% (83/83), positive predictive values of 100% (12/12), negative predictive values of 76.1% (83/109), and accuracy of 78.5% (95/121). The FNAC results of non-parathyroid lesions included thyroid nodules, lymph nodes, neurogenic tumors, and fat tissue. True-positive results on FNAC were significantly associated with performing FNA twice (58.3% vs. 23.1%, P=0.043).

CONCLUSION

Considering the low sensitivity of FNAC, measuring washout PTH in addition to FNAC may help accurately diagnose parathyroid incidentaloma on thyroid US. Further, the falsenegative rate for FNAC can be reduced by obtaining two or more FNA samples.

Comparative Effectiveness of MRI, 4D-CT and Ultrasonography in Patients with Secondary Hyperparathyroidism

Objective

Accurate preoperative localization of abnormal parathyroid glands is crucial for successful surgical management of secondary hyperparathyroidism (SHPT). This study was conducted to compare the effectiveness of preoperative MRI, 4D-CT, and ultrasonography (US) in localizing parathyroid lesions in patients with SHPT.

Methods

We performed a retrospective review of prospectively collected data from a tertiary-care hospital and identified 52 patients who received preoperative MRI and/or 4D-CT and/or US and/or ^99mTc-MIBI and subsequently underwent surgery for SHPT between May 2013 and March 2020. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of each imaging modality to accurately detect enlarged parathyroid glands were determined using histopathology as the criterion standard with confirmation using the postoperative biochemical response.

Results

A total of 198 lesions were identified intraoperatively among the 52 patients included in this investigation. MRI outperformed 4D-CT and US in terms of sensitivity (P < 0.01), specificity (P = 0.455), PPV (P = 0.753), and NPV (P = 0.185). The sensitivity and specificity for MRI, 4D-CT, and US were 90.91%, 88.95%, and 66.23% and 58.33%, 63.64%, and 50.00%, respectively. The PPV of combined MRI and 4D-CT (96.52%) was the highest among the combined 2 modalities. The smallest diameter of the parathyroid gland precisely localized by MRI was 8×3 mm, 5×5 mm by 4D-CT, and 5×3 mm by US.

Conclusion

MRI has superior diagnostic performance compared with other modalities as a first-line imaging study for patients undergoing renal hyperparathyroidism, especially for ectopic or small parathyroid lesions. We suggest performing US first for diagnosis and then MRI to make a precise localization, and MRI proved to be very helpful in achieving a high success rate in the surgical treatment of renal hyperparathyroidism in our own experience.

Parathyroid venous sampling for the preoperative localisation of parathyroid adenoma in patients with primary hyperparathyroidism

Preoperative localisation studies are essential for parathyroidectomy in patients with primary hyperparathyroidism. If the location of abnormal parathyroid glands cannot be identified through non-invasive studies, parathyroid venous sampling (PVS) may be employed. In this study, we evaluated the utility of preoperative PVS in parathyroid surgery. Patients with primary hyperparathyroidism who underwent preoperative PVS at Severance Hospital between January 2015 and June 2020 were identified. Patients for whom the results of non-invasive imaging studies were inconsistent or negative underwent PVS. The results of PVS were compared with operative findings and pathologic results. For 14 patients, the results of preoperative ultrasonography and ^99mTc-sestamibi single-photon emission computed tomography (SPECT) were negative; for 20 patients, either the result of only one test was positive, or the results of the two tests were inconsistent. With respect to the lateralisation of diseased adenoma, the results of PVS and pathological examination were inconsistent only for one patient in either group (total: 2/34 patients). This study showed that PVS could be used effectively for preoperative localisation in patients with primary hyperparathyroidism in whom the location of diseased parathyroid glands cannot be determined through non-invasive image studies.

Diagnostic Performance of 18F-Choline Positron Emission Tomography/Contrast-Enhanced Computed Tomography in Adenoma Detection in Primary Hyperparathyroidism after Inconclusive Imaging: A Retrospective Study of 215 Patients

Simple Summary

Primary hyperparathyroidism is a common pathology. Its curative treatment is based on surgery with precise localisation of the affected parathyroid glands. Our retrospective study aimed to assess the diagnostic performance of a novel imaging method called ¹⁸F-choline positron emission tomography/contrast-enhanced computed tomography (PET/ceCT) in adenoma detection after inconclusive imaging. ¹⁸F-choline PET/ceCT presented excellent diagnostic performance as a second-line imaging method. These results confirm its utility, and it could replace Tc99m-sestamibi single photon emission CT/CT as the first-line imaging method in patients with primary hyperparathyroidism.

Abstract

This large, retrospective, single-centre study evaluated the diagnostic performance of ¹⁸F-choline positron emission tomography/contrast-enhanced computed tomography (PET/ceCT) in preoperative parathyroid adenoma detection in primary hyperparathyroidism cases after negative/inconclusive ultrasound or other imaging findings. We included patients who underwent surgery and ¹⁸F-choline PET/ceCT for inconclusive imaging results between 2015 and 2020. We compared the ¹⁸F-choline PET/ceCT results with surgical and histopathological findings and identified the variables influencing the correlation between ¹⁸F-choline PET/ceCT and surgical findings. Of 215 enrolled patients, 269 glands (mean lesion size, 10.9 ± 8.0 mm) were analysed. There were 165 unilocular and 50 multilocular lesions; the mean preoperative calcium level was 2.18 ± 0.19 mmol/L. Among 860 estimated lesions, 219 were classified as true positive, 21 as false positive, and 28 as false negative. The per-lesion sensitivity was 88.66%; specificity, 96.57%; positive predictive value, 91.40%; and negative predictive value, 95.39%. The detection and cure rates were 82.0% and 95.0%, respectively. On univariate and multivariate analyses, the maximum standardised uptake value (SUVmax), lesion size, and unilocularity correlated with the pathologic findings of hyperfunctioning glands. ¹⁸F-choline PET/ceCT presents favourable diagnostic performance as a second-line imaging method, with SUVmax, lesion size, and unilocularity predicting a high correlation between the ¹⁸F-choline PET/ceCT and surgical findings.

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.

Evaluation of efficacy of ultrasound-guided microwave ablation in primary hyperparathyroidism

PURPOSE

We aimed to evaluate the clinical efficacy and safety of ultrasonographically (US)-guided percutaneous microwave ablation (MWA) in the treatment of primary hyperparathyroidism (PHPT).

METHODS

A total of 35 patients who received MWA treatment in our hospital between August, 2019 and January, 2021 were retrospectively analyzed. Serum parathyroid hormone (PTH), calcium, phosphorus levels, and improvement in clinical symptoms were recorded before and after MWA. All patients were followed up for 6 months. Paired-sample t-tests and paired sample Wilcoxon signed-rank tests were used to indicate PTH, calcium, and P levels before and after ablation. Postoperative complications were statistically analyzed to evaluate the therapeutic effect of MWA on PHPT patients.

RESULTS

A total of 38 parathyroid nodules in 35 PHPT patients were completely ablated at one time. These results indicated that MWA could effectively destroy parathyroid tissue and decrease the concentrations of PTH, calcium, and phosphorus compared with those before MWA, and the effect was sustained. Moreover, MWA improved clinical symptoms, and improved quality of life of patients. None of patients developed tracheal and esophageal injuries, peripheral hematoma, infection, or other serious complications.

CONCLUSION

US-guided MWA has shown to be an effective and safe approach to treat PHPT patients.

Ultrasound Identification of Normal Parathyroid Glands

Ultrasound has become indispensable for identification of thyroid and parathyroid pathology, but normal parathyroid glands have historically been considered too subtle to accurately detect. Inability to identify and protect parathyroid glands can result in hypoparathyroidism and hypocalcemia during thyroidectomy surgery as well as misinterpretation of central neck structures in the postoperative neck. Advances in ultrasound resolution have opened the door to novel applications for this technology. In this study, we report the first surgeon-performed ultrasound identification of normal parathyroid glands in a series of 6 patients, confirmed by parathyroid tissue aspirate or parathyroid autofluorescence. Recognition of normal parathyroid glands using ultrasound can be valuable for preventing postoperative hypoparathyroidism and in increasing the accuracy of postsurgical ultrasound surveillance.

Cystic Parathyroid Adenomas: An Enigmatic Entity and Role of Tc-99 m Sestamibi Scintigraphy

OBJECTIVE

Functional cystic lesion of the parathyroid gland is a rare cause of primary hyperparathyroidism (PHPT). They have been postulated to arise from the hemorrhage and cystic degeneration in the parathyroid adenoma (PA). We intended to analyze their scintigraphic and histopathological findings since available literature is sparse.

METHODS

Dual-phase ^{99 m}Tc-sestamibi planar and SPECT/CT scans performed from January 2014 to January 2020 in patients presenting with PHPT were retrospectively analyzed. The clinical, biochemical, and ultrasound features were collected. Planar and SPECT/CT imaging parameters were analyzed. Detailed histopathological analysis, along with post-surgical clinical and biochemical features of the patients who underwent surgery, was reviewed with a mean follow-up of 21.8 ± 20.1 months.

RESULTS

Of the 979 scans analyzed, 10 showed cystic parathyroid lesions (M:F- 3:7, mean age 45.6 ± 15 years, range: 23-66). The predominant presenting features in patients were abdominal pain and renal stone disease, present in 60% of the patients. On planar scintigraphy, 90% of the patients had tracer avid distinct lesions, whereas tracer activity was seen in the solid part of the cystic lesions in all 10 patients on SPECT/CT, with cystic areas showing an attenuation of 23.1 ± 7.6 HU. Eight of these patients underwent surgery, with all showing PA with cystic changes on histopathology. Two of these patients also showed hemorrhage within the cystic spaces.

CONCLUSION

Hemorrhage within a PA may give rise to cystic parathyroid lesions with PHPT. ^{99 m}Tc-sestamibi scintigraphy with dual-phase imaging and SPECT/CT may help in detecting this rare entity.

The role of preoperative ultrasound, contrast-enhanced ultrasound, and 99mTc-MIBI scanning with single-photon emission computed tomography/X-ray computed tomography localization in refractory secondary hyperparathyroidism

OBJECTIVE

The aim of our study was to evaluate the role of preoperative US, CEUS, and 99mTc-MIBI scanning with SPECT/CT in localizing diseased parathyroid glands in cases of refractory secondary hyperparathyroidism (SHPT).

MATERIAL AND METHODS

Using pathological results as the gold standard, we compared the operative findings with the preoperative localization of each modality in 73 nodules and evaluated the accuracy, and sensitivity of each modality and combinations of the four modalities.

RESULTS

The sensitivity of US, CEUS, 99mTc-MIBI and SPECT/CT was 98.59%, 94.37%, 50.70% and 78.87%, respectively. US had the highest sensitivity of the four imaging methods and the diagnostic sensitivity of US and CEUS was superior to that of 99mTc-MIBI (p < 0.001 and p < 0.001) and SPECT/CT (p = 0.001 and p = 0.012). In addition, we found that the sensitivity of the combination of US with CEUS, US with 99mTc-MIBI and/or SPECT/CT, CEUS with 99mTc-MIBI and/or SPECT/CT, US with CEUS and two other imaging modalities (99mTc-MIBI and/or SPECT/CT) was 98.59%, 100%, 95.77%, and 100%, respectively.

CONCLUSIONS

The combination of US with SPECT/CT is the best choice for the comprehensive preoperative localization of glands in refractory SHPT. CEUS can elevate the accuracy of US in differential diagnosis via the interpretation of dynamic microvascular features.

Minimally Invasive Treatment for Benign Parathyroid Lesions: Treatment Efficacy and Safety Based on Nodule Characteristics

OBJECTIVE

This study aimed to evaluate the efficacy and safety of ultrasound (US)-guided minimally invasive treatment in patients with parathyroid lesions.

MATERIALS AND METHODS

This study included 27 patients who had undergone US-guided radiofrequency ablation (RFA) or ethanol ablation (EA) for parathyroid lesions between January 2010 and 2018. RFA was performed in 19 patients with primary hyperparathyroidism (PHPT, n = 11) or secondary hyperparathyroidism (SHPT, n = 8), and EA was performed in eight patients with symptomatic nonfunctioning parathyroid cysts (SNPCs). Nodule size, volume, serum parathyroid hormone (PTH) and calcium levels were recorded before and after treatment. Complications were evaluated during and after treatment.

RESULTS

In patients with PHPT, significant reductions in size and volume were noted after RFA at 6- and 12-month follow-up (all, p < 0.05). Seven nodules nearly completely disappeared (residual volume < 0.1 mL); serum PTH and calcium levels were reduced to normal ranges (7/11, 63.6%). Four patients experienced partial reductions of serum PTH and calcium levels (4/11, 36.4%). In patients with SHPT, three experienced therapeutic response of serum PTH (3/8, 37.5%), while five showed persistent hyperparathyroidism (5/8, 62.5%) within 6 months after RFA. In patients with SNPCs, EA resulted in significant reductions in cyst size and volume (all, p < 0.05) at the last follow-up. A total of four complications (two transient hypocalcemia [RFA], one permanent [RFA], and one transient [EA] hoarseness) were observed.

CONCLUSION

Minimally invasive treatments, such as RFA and EA, may serve as therapeutic alternatives for patients with PHPT or SNPCs; they may have limited usefulness in patients with SHPT.

Acute pancreatitis as an initial manifestation of parathyroid carcinoma: A case report and literature review

RATIONALE

Parathyroid carcinoma is a rare endocrine malignancy. Acute pancreatitis as an initial manifestation of parathyroid carcinoma has been rarely reported.

PATIENT CONCERNS

A 22-year-old woman was admitted to emergency room with a sudden attack of severe epigastric pain.

DIAGNOSES

Acute pancreatitis was diagnosed as elevated levels of serum amylase. During the work-up for acute pancreatitis, patient's abnormally increased serum calcium and bones destruction revealed by abdominal computed tomography (CT) scan raised the suspicion of hyperparathyroidism or malignancy. Elevated serum parathyroid hormone (PTH) levels, parathyroid ultrasound and scintigraphy gave rise to the diagnosis of primary hyperparathyroidism (PHPT) due to a left parathyroid tumor.

INTERVENTIONS

The patient was given a complete tumor excision. After the surgery, parathyroid carcinoma with capsular and vascular invasion was confirmed histologically. A second surgery was then performed, including resection of the ipsilateral thyroid lobe and anterior cervical nodes.

OUTCOMES

Serum calcium and PTH levels returned to normal postoperatively.

LESSONS

Acute pancreatitis accompanied with hypercalcemia should always raise the suspicion of PHPT. The spicule sign, which always suggests the infiltrating pattern growth of tumor, was neglected at first and was observed during a second review of the ultrasound images postoperatively. This specific feature may be predictive for the preoperative diagnosis of parathyroid carcinoma or at least suspicion of malignancy.

Ultrasound detection of normal parathyroid glands: a preliminary study

OBJECTIVE

No previous prospective study has investigated the detection of normal parathyroid glands (PTGs) and their features using real-time ultrasound (US). This study aimed to assess the preoperative US detection of normal PTGs in patients who underwent hemithyroidectomy.

METHODS

Between August and October 2016, 44 patients underwent hemithyroidectomy using a low-collar incision, and 5 were excluded from the study. A single radiologist performed the preoperative US examination in all patients, and the surgical data for the PTGs were obtained by a single surgeon. Based on the surgical findings of PTGs, the preoperative US detection of PTGs was determined.

RESULTS

Of the 39 patients, 3 had no surgical data for PTG (n = 2) and the presence of parathyroid hyperplasia (n = 1). In the 36 remaining patients, in 3 patients, US identification of a normal PTG was corroborated by surgical findings, whereas in 2 patients, US findings differed from surgical findings, and in 31 patients, US did not detect a normal PTG. The successful US detection rate of normal PTG was only 8.3% (3/36).

CONCLUSIONS

US cannot be used for identification of normal PTGs.

Diagnostic value of endoscopic ultrasonography for preoperative localization of parathyroid adenomas

The most common cause of primary hyperparathyroidism (PHPT) is a single, sporadic parathyroid adenoma. Ultrasonography (US) and (99m)Technetium methoxyisobutylisonitrile ((99m)Tc-MIBI) scintigraphy are the imaging methods most widely used to localize parathyroid adenomas. The purpose of the present study was to determine the diagnostic value and accuracy of endoscopic ultrasonography (EUS) for localizing parathyroid adenoma compared with those of US and (99m)Tc-MIBI scintigraphy. Forty-seven patients with a PHPT diagnosis and who were recommended for surgery were enrolled in this study. An endoscopist who was blinded to the previous US and (99m)Tc-MIBI scintigraphy results performed the EUS in each patient. Thirty-nine female and eight male patients with PHPT were evaluated. The presence of adenoma was confirmed by subsequent postsurgical pathology results. One case was excluded because the histopathological evaluation was compatible with a lymph node, although the lesion was detected using three different imaging modalities preoperatively. The locations of the parathyroid adenomas were correctly documented by US in 39 patients (84.7 %) by (99m)Tc-MIBI scintigraphy in 35 (76.0 %), and by EUS in 44 (95.6 %) of 46 patients. EUS located all 31 adenomas detected previously with US and (99m)Tc-MIBI scintigraphy. EUS also successfully located three adenomas that could not be identified by US and (99m)Tc-MIBI scintigraphy. The positive predictive value and diagnostic accuracy of EUS, US, and (99m)Tc-MIBI were 97.7, 97.7, and 95.6 %; 88.6, 97.5, and 86.9 %; and 77.7, 97.2, 76.0 %, respectively. EUS was preferred as the second step imaging tool for detecting parathyroid adenomas that could not be localized by US and (99m)Tc-MIBI scintigraphy.

Causes of discordant or negative ultrasound of parathyroid glands in treatment naïve patients with primary hyperparathyroidism

OBJECTIVES

To describe causes of discordant or negative parathyroid ultrasound and to assess factors influencing them.

MATERIALS AND METHODS

Retrospective review of patients who underwent parathyroidectomy between 2000 and 2012 was done. Imaging findings were compared with operative findings and pathology to identify discrepant (n=60; 32 negative, 28 incorrect) parathyroid ultrasounds.

RESULTS

Fifty (83.3%) patients had parathyroid adenoma, of which 10 (16.6%) were ectopic and three were double adenomas; 8 (13.3%) had multigland hyperplasia and two had parathyroid carcinoma. Discrepant reports were due to incorrect localisation in 8 (13.3%); difficulty in differentiating thyroid from parathyroid lesion in 12 (20%); large and small size in two and three patients, respectively; overcall in 5 (8.3%) and satisfaction of search in 7 (11.7%) patients. There was significant correlation between presence of multi-nodular goitre and incorrect reports (χ(2)=4.112, p=0.04). Experience of ultrasound operators performing initial and second look ultrasound was significantly different (p<0.0001). Second look ultrasound was concordant with surgical findings in 39(65%) patients; 21 (66%) patients with initially negative ultrasound and four out of five extra-mediastinal ectopic lesions. Ten patients with negative initial ultrasound had elongated parathyroid lesion. Scintigraphy was concordant in 44 (73.3%) patients and nine were ectopic.

CONCLUSION

Second look ultrasound performed by experienced operator for negative or discordant initial ultrasound of parathyroid is a useful strategy which will improve the accuracy of parathyroid ultrasound. Being able to differentiate thyroid from parathyroid lesion is a factor which will influence performance of parathyroid ultrasound.

The role of ultrasound elastography in preoperative localization of parathyroid lesions: a new assisting method to preoperative parathyroid ultrasonography

BACKGROUND

After the definition of minimally invasive procedures, preoperative localization of parathyroid lesions is now crucial. False-positive results up to 30% were reported by B-mode grayscale ultrasonography (US) in localization of parathyroid lesions. Parathyroid adenomas are relatively stiff lesions. Ultrasound elastography (USE) can accurately evaluate tissue stiffness and might detect the stiff parathyroid lesions.

OBJECTIVE

The aim of this study is to demonstrate whether USE can detect the level of the stiffness and help the preoperative localization of parathyroid lesions during parathyroid ultrasonography examination.

PATIENTS

The patients who were candidates for parathyroidectomy were prospectively enrolled to this study and were evaluated by USE.

RESULTS

Seventy-two patients with 93 parathyroid lesions underwent parathyroidectomy. Sixty-three patients including three multiple endocrine neoplasia type-1 patients had primary hyperparathyroidism, three patients with chronic renal disease (CRD) had tertiary hyperparathyroidism, three patients with CRD and two renal transplanted patients had persistent secondary hyperparathyroidism. One patient was excluded. While all parathyroid adenomas exhibited high levels of stiffness (score 3 and 4), 17 (63%) out of 27 parathyroid hyperplasia lesions were shown to have significantly higher elasticity. The evaluation of median strain ratios of parathyroid lesions revealed that parathyroid adenomas demonstrated significantly higher levels of stiffness than hyperplasias (P ≤ 0·001).

CONCLUSIONS

This is the first study that evaluates the ultrasound elastographic features of parathyroid lesions. Parathyroid adenomas were shown to appear as stiff lesions, and half of the hyperplasias showed high elasticity. Parathyroid elastography is a novel technique to evaluate parathyroid lesions and might be a guide for surgeons to determine the type of operation to apply.

A comparative study of pre-operative imaging methods in patients with primary hyperparathyroidism: ultrasonography, 99mTc sestamibi, single photon emission computed tomography, and magnetic resonance imaging

AIM

This study compares the accuracy rates achieved in ultrasonography (US), 99mTc-sestamibi (MIBI), single photon emission computed tomography (SPECT), and magnetic resonance imaging (MRI) as imaging methods used in the pre-operative localization of the enlarged parathyroid glands.

SUBJECTS AND METHODS

For the purposes of this study, US, MIBI, SPECT, and MRI were performed on 98 patients with primary hyperparathyroidism (pHPT). All patients underwent parathyroidectomy.

RESULTS

Pre-operative localization of an abnormal parathyroid gland was successfully performed in 82 of the cases scanned with US (83.7%), while the result was 66 in the cases scanned with MIBI (67.3%), 71 of the cases were successfully localized with SPECT (72.4%), while MRI revealed the diseased gland in only 60 of the total cases (61.2%). In MIBI-positive and -negative patients there was a statistically significant difference among cases in terms of adenoma volume (1.30±1.51 vs 0.58±0.91, p<0.05). Sensitivity, specificity and diagnostic accuracy values were 87.2%, 25.0%, and 83.0%; 70.2%, 50.0%, and 69.4%; 75.5%, 50.0%, and 74.5%; 63.8%, 50.0%, and 63.3% for US, MIBI, SPECT, and MRI, respectively. The respective values for sensitivity, specificity, and diagnostic accuracy were 94.9%, 25.0%, and 91.1% when US was combined with MIBI.

CONCLUSIONS

Combining US and MIBI as imaging methods for pre-operative imaging of pHPT often produces more satisfactory results. While the accuracy of US is relatively low in the ectopic localizations, the size of the lesion can be an important factor in the accuracy achieved with MIBI.

Ultrasound features of malignancy in the preoperative diagnosis of parathyroid cancer: a retrospective analysis of parathyroid tumours larger than 15 mm

OBJECTIVE

Nearly all reported parathyroid cancers are >15 mm at presentation. The objective was to identify ultrasound criteria of malignancy in parathyroid lesions of >15 mm in size.

MATERIALS AND METHODS

This study was approved by a local ethics committee. A retrospective review of patients identified from a database from 2004-2009 was performed. All patients underwent ultrasound imaging according to the protocol. Two trained observers categorized findings using the pre-determined features: shape, calcification, pattern of vascularity, local infiltration and internal lesion gray scale appearances.

RESULTS

Sixty-nine patients (mean age 54.3 years, range 19-79 years; male = 16, female = 53) fulfilled the criteria of a parathyroid lesion >15 mm; 8/69 (11.6%) with parathyroid cancer and 61/69 (88.4%) with benign solitary parathyroid adenoma. A high positive predictive value (PPV) for cancer was identified for infiltration (PPV 100%) and calcification (PPV 100%), whilst a high negative predictive value (NPV) was found for the absence of suspicious vascularity (NPV 97.6%), a thick capsule (NPV 96.7) and inhomogeneity (NPV 100%).

CONCLUSION

In lesions >15 mm systematic ultrasound assessment of specific features provides a valuable tool to identify parathyroid cancers before surgery.

Techniques for parathyroid localization with ultrasound

Four-gland parathyroid exploration has been the gold standard for parathyroid surgery until recently. Emphasis is now placed on minimally invasive and focused parathyroidectomy. In conjunction with functional sestamibi scanning, ultrasonography permits accurate localization of enlarged parathyroid glands in the vast majority of patients with hyperparathyroidism. Consequently, ultrasound technology applied to parathyroid pathology facilitates directed surgical therapy and minimally invasive applications. As such, ultrasonography holds great promise as a tool that enables cost-effective and advanced patient care.

Cystic parathyroid adenoma: sonographic features and correlation with 99mTc-sestamibi SPECT findings

OBJECTIVE

The purpose of this study was to describe the typical ultrasound features of cystic parathyroid adenoma.

MATERIALS AND METHODS

A review of a surgical database and electronic medical records from 2006 to 2009 identified the cases of 15 patients who underwent preoperative cervical sonography for primary hyperparathyroidism with subsequent resection of pathologically proven parathyroid adenoma with predominantly cystic components. Two radiologists retrospectively evaluated the preoperative ultrasound images and assessed for cyst complexity, size, location, and color Doppler vascularity. Technetium-99m-sestamibi SPECT findings, surgical and pathologic reports, and the results of parathyroid hormone assay of the cyst fluid also were reviewed.

RESULTS

Most of the cystic adenomas (14/15, 93%) were deep or inferolateral to the adjacent thyroid. The same percentage were elongated and had peripheral nodular components. An echogenic border separating the adenoma from the overlying thyroid was identified in 9 of 15 patients (60%). Color Doppler examination of 14 patients showed feeding vessels with internal color flow to the solid components in 10 patients (71%). Six of 14 patients underwent preoperative or intraoperative sampling of cyst fluid, and the assay showed the parathyroid hormone levels ranged from 1,198 to greater than 5,000 pg/mL. Fourteen of 15 patients underwent preoperative sestamibi SPECT, and the adenoma was definitively localized in four patients (29%). The accuracy of preoperative localization improved to 79% (11/14) when sestamibi SPECT scans were interpreted in correlation with cervical ultrasound images.

CONCLUSION

Awareness of typical sonographic features (location, color Doppler vascularity) may aid radiologists in preoperative localization of parathyroid adenomas, even when cystic degeneration occurs. In cases in which imaging or clinical features are equivocal, the results of cyst fluid sampling and parathyroid hormone assay are confirmatory.

The characteristics of concomitant thyroid nodules cause false-positive ultrasonography results in primary hyperparathyroidism

BACKGROUND

Concomitant thyroid nodules are the most common reason for false-positive ultrasonography (US) results in primary hyperparathyroidism. The aims of this prospective clinical study were to evaluate false-positive US results according to the characteristics of concomitant thyroid nodules and to determine which characteristics of thyroid nodules are important.

STUDY DESIGN

This prospective study included 120 consecutive patients with primary hyperparathyroidism. The patients were divided into 2 groups according to preoperative US results. Group 1 consisted of 32 patients with false-positive US results and group 2 consisted of 88 patients with true-positive US results.

RESULTS

The risk for false-positive US result was increased 25-fold for patients with parathyroid adenoma weight of more than 500 mg (odds ratio [OR], 25; 95% confidence interval [CI], 8.6-74.5), 75-fold for more than 1 posteriorly located thyroid (OR, 75; 95% CI, 19.3-293.4), 358-fold for the presence of exophytic thyroid nodules (OR, 358; 95% CI, 42.3-3036), and 423-fold for the presence of posteriorly located thyroid nodules (OR, 423; 95% CI, 49-3662).

CONCLUSION

Although there was no particular characteristic of concomitant thyroid nodules that contributes to false-positive US results, the posteriorly located thyroid nodules were the strongest correlate for the false-positive US results to other features.

Beneficial effect of endocrinologist-performed ultrasonography on preoperative parathyroid adenoma localization

OBJECTIVE

To evaluate whether endocrinologist-performed ultrasonography improves the localization of parathyroid adenomas in patients with primary hyperparathyroidism.

METHODS

We performed a retrospective analysis of consecutive patients with primary hyperparathyroidism due to a single adenoma who underwent surgery at the Dokuz Eylul University Hospital in Izmir, Turkey, between January 2000 and January 2008. Data regarding the localization of adenomas were obtained from surgical reports. Neck ultrasonography was performed in all patients as first-line imaging. Parathyroid ultrasonography was performed by a staff radiologist between January 2000 and December 2004. Beginning January 2005, parathyroid ultrasonography was performed blindly by an endocrinologist in addition to the staff radiologist. In the case of discordant preoperative localization between the endocrinologist- and radiologist-performed ultrasonography, surgery was performed according to the technetium Tc 99m sestamibi (MIBI) scan and endocrinologist-performed ultrasonography localization results.

RESULTS

A total of 156 patients with primary hyperparathyroidism due to a single adenoma were included. Of the 156 patients, 139 also underwent MIBI scan. Ultrasonography localized 102 parathyroid adenomas (65%). The accuracy of the ultrasonography was improved in patients who underwent endocrinologist-performed ultrasonography. Endocrinologist-performed ultrasonography localized the adenoma correctly in 19 patients for whom the staff radiologist had reported a negative or unsuccessful localization. When ultrasonography results were combined with the MIBI scan findings, parathyroid adenomas were again more likely to be localized in patients who underwent operation after January 2005 and thus had endocrinologist-performed ultrasonography.

CONCLUSION

Our results suggest that endocrinologist-performed ultrasonography improves the preoperative localization of parathyroid adenoma.

Impact of adenoma weight and ectopic location of parathyroid adenoma on localization study results

Although the sensitivity of preoperative localization techniques is high for solitary parathyroid adenomas, negative imaging study results are inevitable. The weight and location of the parathyroid adenoma may contribute to the negative results. We aimed to study the impact of adenoma weight and ectopic location of the parathyroid adenoma on ultrasonography and sestamibi scan results. The patients were divided into two groups according to adenoma location. Group 1 consisted of 36 patients with ectopic location, and group 2 consisted of 149 patients with normal location. Parathyroid adenoma weight and the results of imaging studies were determined in all patients. Of 185 patients operated on for hyperparathyroidism, 36 (19.4%) had ectopic parathyroid glands. There was a positive correlation between adenoma weight and positive imaging studies, whereas ectopic location did not correlate with negative imaging study results. There was no significant difference between the ectopic adenoma ratio of patients with negative and positive imaging study results. The weight of the ectopic parathyroid adenoma was significantly lower in patients with negative imaging study results than in patients with positive imaging study results (p = 0.001). According to the analysis of variance, patients with higher-weight adenomas have positive imaging study results irrespective of ectopic location. For both normal and ectopic adenoma locations, adenoma weight was found only to be a factor that positively influences imaging study results.