Sonography in primary hyperparathyroidism: review with emphasis on scanning technique

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.

Sonographic Features of Atypical and Initially Missed Parathyroid Adenomas: Lessons Learned From a Single-Center Cohort

CONTEXT

Awareness of typical and atypical ultrasonographic (US) features of parathyroid adenomas (PAs) is crucial since US is the most widely used first-line imaging modality.

OBJECTIVE

The purpose of this study was to describe the atypical features of PAs on US and other possible factors leading to a false negative examination in a large single-center cohort.

MATERIALS AND METHODS

The US records of 457 PAs in 445 patients with biochemically proven primary hyperparathyroidism (PHPT) were evaluated in a prospectively maintained database. Atypical size, composition, shape, echogenicity, location, and vascular pattern on US were noted. For patients who previously had at least one negative US examination in referring centers, the main possible reason was defined accordingly.

RESULTS

The study group included 359 female and 86 male patients with PHPT. Typical sonographic features were observed in 231 PAs (51%), whereas 226 (49%) had at least one atypical US feature. The most common atypical features were atypical size (29%), followed by atypical echogenicity (19%), shape (8%), location (7%), and composition (7%), respectively. There were 122 initially missed PAs in all groups. The most frequent main atypical US features leading to false negative examinations were atypical size (22.1%) and atypical location (18.8%). Inexperience was third most common reason (16.3%) for false negative US examinations.

CONCLUSIONS

Almost half of PAs have at least one atypical feature on US. Awareness of the high prevalence of atypical US features could increase the accuracy of US examination and potentially decrease demand for more expensive second-line imaging modalities.

Case report: Microwave ablation is a safe and effective method for primary hyperparathyroidism in pregnancy

Primary hyperparathyroidism (PHPT) is a rare disease in pregnancy and endangers the health of both pregnant women and fetuses. However, the treatments are very limited for PHPT and most of them are unsatisfactory because of the peculiar state in pregnancy. The only curable method is parathyroidectomy which can be safely performed in the second trimester of pregnancy. In this case, we reported a pregnant woman with primary parathyroid adenoma presenting hypercalcemia and severe vomit at the end of first trimester. Finally, she got cured by microwave ablation at the end of first trimester and gave birth to a healthy baby boy.

A New Technique for Localization of Parathyroid Adenoma: Infrared Thermal Scanning of the Neck

Many radiological techniques are used to locate the adenoma preoperatively in cases of primary hyperparathyroidism, but the location of many adenomas still cannot be detected. Since adenomas are hypervascular lesions, their temperature is high. Infrared thermal scanning can reveal local temperature differences in hypervascular lesions. The location of the adenoma could not be determined by preoperative radiological examinations in a 58-year-old male patient who was scheduled for surgery with the diagnosis of primary hyperparathyroidism. By infrared thermal scanning, a nearly 2°F higher temperature was measured in the inferior of the right thyroid lobe compared to the other perithyroidal regions. During the exploration, the adenoma was found at this point and removed. Infrared thermal scanning of the neck is promising as a new technique that can be used both preoperatively and intraoperatively to locate the adenoma in primary hyperparathyroidism cases.

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.

"Before skin incision" high-resolution ultrasound in primary hyperparathyroidism: a new imaging tool for surgeons?

PURPOSE

Various diagnostic methods have been utilized for localizing pathologic parathyroid glands to consequently provide the possibility of avoiding bilateral neck dissection in cases of primary hyperparathyroidism. Scintigraphy, combined with ultrasound, became established as the standard method of localization in the 2000s. The aim of this study was to evaluate the role of the "before skin incision" surgeon-performed ultrasound in determining the improvement in the diagnostic accuracy in a large case series.

METHOD

The method used in this research is a retrospective observational study (study period: between 1-2014 and 12-2020) comparing two patient groups before (control group: 31 patients) and after (study group: 70 patients) the introduction of the ultrasonography surgical protocol: combined preoperative and "before skin incision" surgeon-performed ultrasound.

RESULTS

The sensitivity of the combined preoperative "before skin incision" surgeon-performed ultrasound was 97%, and the positive predictive value was 93% in regard to detecting the number of diseased glands and the appropriate anatomic location (right versus left, upper versus lower). The sensitivity of the parathyroid scan (Tc-MIBI-scintigraphy) was 74%, and the positive predictive value was 92%. The duration of surgery was significantly shorter in the test group (84.7 vs. 66.4 min; Mann‒Whitney U: 0.006). No differences were detected between the two groups in regard to avoiding intraoperative or postoperative complications.

CONCLUSION

The combination of the preoperative "before skin incision" surgeon-performed ultrasound could improve the efficiency of the preoperative location and anatomic classification using the standard literature-suggested diagnostic methods.

Deep learning-based detection of parathyroid adenoma by 99mTc-MIBI scintigraphy in patients with primary hyperparathyroidism

OBJECTIVE

It is important to detect parathyroid adenomas by parathyroid scintigraphy with 99m-technetium sestamibi (^99mTc-MIBI) before surgery. This study aimed to develop and validate deep learning (DL)-based models to detect parathyroid adenoma in patients with primary hyperparathyroidism, from parathyroid scintigrams with ^99mTc-MIBI.

METHODS

DL-based models for detecting parathyroid adenoma in early- and late-phase parathyroid scintigrams were, respectively, developed and evaluated. The training dataset used to train the models was collected from 192 patients (165 adenoma cases, mean age: 64 years ± 13, 145 women) and the validation dataset used to tune the models was collected from 45 patients (30 adenoma cases, mean age: 67 years ± 12, 37 women). The images were collected from patients who were pathologically diagnosed with parathyroid adenomas or in whom no lesions could be detected by either parathyroid scintigraphy or ultrasonography at our institution from June 2010 to March 2019. The models were tested on a dataset collected from 44 patients (30 adenoma cases, mean age: 67 years ± 12, 38 women) who took scintigraphy from April 2019 to March 2020. The models' lesion-based sensitivity and mean false positive indications per image (mFPI) were assessed with the test dataset.

RESULTS

The sensitivity was 82% [95% confidence interval 72-92%] with mFPI of 0.44 for the scintigrams of the early-phase model and 83% [73-92%] with mFPI of 0.31 for the scintigrams of the delayed-phase model in the test dataset, respectively.

CONCLUSIONS

The DL-based models were able to detect parathyroid adenomas with a high sensitivity using parathyroid scintigraphy with 99m-technetium sestamibi.

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

PURPOSE

Primary hyperparathyroidism (PHPT) is a frequent endocrine pathology that has surgical treatment as its only decisive measure. High-Resolution Neck Ultrasonography with color-Doppler (CDHR-NUS) and 99mTechnetium-SestaMIBI Parathyroid Scintigraphy (99mTc-MIBI PS) are the two instrumental exams more commonly used in the preoperatory localization of pathologic parathyroids. The aim of this observational study was to outline-in accordance with the latest scientific literature-the precise role of CDHR-NUS in the environment of PHPT, comparing it with that of Parathyroid Scintigraphy.

METHODS

136 patients operated on for PHPT and underwent CDHR-NUS and 99mTc-MIBI PS preoperatively. The CDHR-NUS was carried out by an expert medical sonographer. The results of the two methods were compared between each other and with the results of the operative act for the evaluation of accordance and diagnostic performances.

RESULTS

PHPT is prevalently due to monoglandular pathology (SGD). The parallel use of CDHR-NUS and of 99mTc-MIBI PS does not determine a significant increase in diagnostic accuracy. The preoperative accordance evaluation between the two methods does not exclude the presence of multiglandular pathology (MGD) with certainty.

CONCLUSIONS

CDHR-NUS is an accurate as well as cost-effective method; its role as a main and eventual unique preoperative localization method in patients affected by PHPT is confirmed. In the presence of expert medical sonographers, the sequential use of the two methods is retained correct and their use in parallel is neither justified nor cost-effective. The preoperative accordance evaluation between the two methods is neither necessary nor indispensable.

The diagnostic value of 4D MRI at 3T for the localization of parathyroid adenomas

PURPOSE

The aim of this study was to assess the feasibility of four-dimensional magnetic resonance imaging (4D MRI) at 3 T for the localization of parathyroid adenomas.

MATERIALS AND METHODS

Preoperative 4D MRI scans, encompassing dynamic contrast-enhanced (DCE) sequences and non-contrast enhanced (non-CE) sequences, including a T2-weighted multipoint Dixon (T2-mDixon) sequence, with in-phase, out-phase, and water-only images, were evaluated retrospectively in 41 patients with surgically proven parathyroid lesions. Two readers who were blinded to the surgical findings independently reviewed the images in two sessions (non-CE sequences alone and non-CE + DCE sequences). The MRI localization of the suspected adenoma in each session and the consensus interpretation of the MRI images, were compared with the surgical results and interobserver agreement was assessed.

RESULTS

By interpreting the non-CE sequences alone, reader 1 correctly localized 34 parathyroid lesions (sensitivity 81.0%, positive predictive value (PPV) 87.2%), and reader 2 correctly localized 34 parathyroid lesions (sensitivity 81.0%, PPV 91.9%). With the addition of DCE sequences, reader 1 correctly identified 35 parathyroid lesions (sensitivity 83.3%, PPV 87.5%), while reader 2 correctly identified 36 parathyroid lesions (sensitivity 85.7%, PPV 92.3%). Overall, MRI detected 38 parathyroid lesions (sensitivity 90.5%, PPV 95.0%). Interobserver agreement was slightly superior in non-CE + DCE sequences compared to non-CE sequences alone (ĸ = 0.796 vs. ĸ = 0.738).

CONCLUSION

4D MRI with DCE sequencing is a reliable method for the localization of parathyroid adenomas.

Challenging pre-surgical localization of hyperfunctioning parathyroid glands in primary hyperparathyroidism: the added value of 18F-Fluorocholine PET/CT

PURPOSE

To evaluate the added value of ¹⁸F-Fluorocholine (¹⁸F-FCH) PET/CT in presurgical imaging of patients with primary hyperparathyroidism (HPT) and challenging localization of the hyper-functioning parathyroid glands.

METHODS

We included 27 consecutive patients with primary HPT (19 F; median age: 58 years), with either (i) non-conclusive pre-surgical localization with ⁹⁹mTc-sestaMIBI scintigraphy and neck ultrasonography (US), (ii) recurrence of previously operated HPT, or (iii) familiar HPT with a suspicion of multiple gland disease. Histological findings and resolution of HPT were considered as the gold standard.

RESULTS

¹⁸F-FCH PET/CT was positive in 24/27 patients. Twenty-one patients underwent surgery with 27 resected lesions (14 adenomas, 11 hyperplastic glands, two hyper-functioning histologically normal glands), with resolution of HPT in 19/21 patients (90%). ¹⁸F-FCH PET/CT localized 22 lesions in 17/21 patients (per patient: sensitivity 81%, positive predictive value (PPV) 94%; per gland: sensitivity 76%, PPV 85%, specificity 91%, negative predictive value (NPV) 86%). ¹⁸F-FCH PET/CT found eight lesions which were undetectable on both ⁹⁹mTc-sestaMIBI scintigraphy and US. In patients with a familial HPT and/or a multiple gland disease, sensitivity was 100 and 79% on a per-patient and a per-gland analysis respectively, while NPV was 63%. In six patients with a persistence or recurrence of previously treated HPT, ¹⁸F-FCH PET/CT localized all lesions, both in sporadic and familiar disease.

CONCLUSIONS

¹⁸F-FCH PET/CT is a promising modality in challenging pre-surgical localization of hyper-functioning parathyroid glands, such as inconclusive standard imaging, recurrence after surgery, or suspected multiple gland disease.

Non-functioning parathyroid cystic tumour: malignant or not? Report of a case

Parathyroid carcinoma (PC) is a very rare endocrine tumour, usually characterized by symptoms such as a neck mass, dysphonia, severe hypercalcemia exceeding 140 mg/L and elevated serum parathyroid hormone levels, even more than 5 times the upper limit of normal. Non-functioning parathyroid cancer is extremely rare and, in this case, its pre-operative diagnosis is often difficult. A 54-year old female patient, referring dysphagia and dysphonia, underwent neck ultrasound and neck CT. A left thyroid nodule, probably cystic, was found. It presented caudal extent on anterior mediastinum causing compression of the left lateral wall of the trachea. The preoperative calcemia was into the normal range. The patient underwent left thyroid lobectomy. Histological exam showed a cystic lesion, immunohistochemically originating from parathyroid that oriented for carcinoma. The 18 months follow-up did not show a residual-recurrent disease. The parathyroid origin of a neck lesion could not be suspected before surgery when specific laboratory tests are not available and clinical effects of hyperparathyroidism syndrome are not present. Histological features are not always sufficient for the differential diagnosis between the parathyroid adenoma and carcinoma. The immunohistochemistry is an useful tool that can aid to reach the definite diagnosis.

Update in Parathyroid Imaging

Primary hyperparathyroidism (PHPT) is characterized by excessive, dysregulated production of parathyroid hormone (PTH) by 1 or more abnormal parathyroid glands. Minimally invasive surgical techniques have created a need for more precise localization of the parathyroid lesion by imaging. A variety of imaging protocols and techniques have been used for this purpose, but no one modality is clearly superior. Nuclear medicine scintigraphy and ultrasound imaging are established modalities, although multiphase or 4-dimensional computed tomography is an emerging modality with several advantages. This review provides a background regarding PHPT and key anatomy, and discusses these alternative parathyroid imaging modalities with updates.

Sensitivity of 3-Dimensional Sonography in Preoperative Evaluation of Parathyroid Glands in Patients With Primary Hyperparathyroidism

OBJECTIVES

Preoperative localization of parathyroid adenomas in patients with primary hyperparathyroidism facilitates targeted surgery. We assessed the sensitivity of 3-dimensional (3D) sonography for preoperative localization of abnormal parathyroid glands.

METHODS

We conducted a retrospective review of patients who underwent parathyroidectomy for primary hyperparathyroidism at a single site at our institution. We compared preoperative 2-dimensional (2D) sonography, 3D sonography, and sestamibi scans with final gland localization at surgery. Two readers reviewed the sonograms to assess inter-reader variability.

RESULTS

From January 2010 through April 2015, 52 patients underwent parathyroidectomy after preoperative 2D sonography, 3D sonography, and sestamibi scans. Three-dimensional sonography had sensitivity of 88-92% compared with 69-71% for 2D sonography for gland localization. In patients in whom sonography and sestamibi scans localized abnormalities to the same side, the sensitivities were 100% (43 of 43) for 3D sonography and 96% (48 of 50) for 2D sonography. Three-dimensional sonography had significantly higher sensitivity for localization of glands smaller than 500 mg compared with 2D sonography (88% versus 58%; P = .012). There was better inter-reader agreement between the radiologists when using 3D sonography (κ = 0.65) compared with 2D sonography (κ = 0.41).

CONCLUSIONS

We found a significantly higher sensitivity and better inter-reader agreement for 3D sonography compared with 2D sonography for preoperative identification of abnormal parathyroid glands, especially among smaller glands.

Parathyroid surgery: from inception to the modern day

Parathyroid surgery has undergone great changes since its inception less than a century ago. It is still the only definitive option available to cure primary or tertiary hyperparathyroidism. This review details the development of parathyroid surgery, our understanding of hyperparathyroidism and the treatment options available. It also discusses the technological advances that have enabled parathyroid localization and prediction of surgical success.

Surveillance Neck Sonography After Thyroidectomy for Papillary Thyroid Carcinoma: Pitfalls in the Diagnosis of Locally Recurrent and Metastatic Disease

A sonographic examination of the neck performed 6 to 12 months after thyroid surgery in patients with differentiated thyroid cancer is strongly recommended by the American Thyroid Association and considered mandatory by the European Thyroid Association for locoregional surveillance. The aim of this article is to review the normal anatomic changes expected after thyroid surgery and the pathologic mimics of thyroid carcinoma recurrence in post-thyroidectomy patients as they appear on neck sonography. We hope to offer some pearls to increase diagnostic confidence in this setting.

Evaluation of preoperative ultrasonographic and biochemical features of patients with aggressive parathyroid disease: is there a reliable predictive marker?

OBJECTIVE

Parathyroid cancer (PC) represents < 1% of cases of PHPT. Tumors demonstrating atypical histopathologic features and don't fulfill criteria for carcinoma are classified as atypical adenomas (APA). The purpose of this study was to determine a biochemical or ultrasonographic feature that can predict aggressive disease requiring more extensive surgery and closer follow-up.

SUBJECTS AND METHODS

Twenty eight patients operated for PHPT and diagnosed with atypical adenoma (23 patients) or carcinoma (5 patients) were enrolled in this study. The control group consisted of 102 patients operated between the same dates and diagnosed with classical PA. Classical adenomas, atypical adenomas, and carcinomas were compared according to their biochemical and ultrasonographic parameters.

RESULTS

Serum Ca levels were significantly higher in the PC group compared with the APA and classical PA groups. Serum median PTH, Serum ALP and UCa was significantly higher in the APA and carcinoma groups compared to the classical PA group. ROC analysis was made to determine the best cut off values for predicting aggressive disease were 12.45 mg/dL, 265.05 pg/mL, 154.5 IU/l, 348.5 mg/day and 21.5 mm for Ca, PTH, ALP, UCa and the adenoma diameter, respectively. Multivariate analysis showed that serum Ca, ALP and isoechoic/cystic appearance were independent predictors for aggressive disease.

CONCLUSION

Preoperatively high PTH, ALP, and UCa levels and large lesions with isoechoic or cystic appearances may be predictive of atypical adenoma or carcinoma in patients being evaluated for PHPT. In such cases, surgeons may prefer en bloc parathyroidectomy to minimally invasive surgery.

Parathyroid carcinoma: A report of six cases with a brief review of the literature

Parathyroid carcinoma (PC) is an uncommon endocrine malignancy and constitutes a rare cause of hyperparathyroidism. The current study presents the clinical features, laboratory findings, sensitivity of imaging modalities, surgical treatment and the long-term outcome of six patients, who were diagnosed with PC and treated in the Department of Head and Neck Surgery, Zhejiang Province Cancer Hospital (Hangzhou, China) over 13 years (February 1999-January 2012). Pre-operative recognition and intraoperative identification of this rare endocrine malignancy is extremely important, but require a high index of clinical suspicion. The primary treatment is surgical en bloc resection of the tumor and any involved surrounding structures, and it is of great importance, as the prognosis depends on the initial surgery. Radiation therapy and chemotherapy showed no evidence of effectiveness on PC, although certain data show a decreased risk of localized disease recurrence with the addition of radiation therapy. The prognosis of PC is variable and post-operative parathyroid hormone levels that do not decrease often indicate a poor prognosis or presence of other metastases.

Accuracy of 2-Phase Parathyroid CT for the Preoperative Localization of Parathyroid Adenomas in Primary Hyperparathyroidism

BACKGROUND AND PURPOSE

Minimally invasive parathyroidectomy requires accurate preoperative localization of suspected adenomas, and multiphase CT allows adenoma characterization while providing detailed anatomic information. The purpose of this study was to assess the feasibility of a protocol using only arterial and venous phases to localize pathologic glands in patients with primary hyperparathyroidism.

MATERIALS AND METHODS

We identified 278 patients with primary hyperparathyroidism who had undergone 2-phase CT with surgical cure. All scans were read prospectively by board-certified neuroradiologists. A neuroradiology fellow retrospectively reviewed images and reports and classified suspected adenomas on the basis of anatomic location. Accuracy was determined by comparing imaging results with surgical findings. The ability of 2-phase CT to localize adenomas to 1 of 4 neck quadrants and lateralize them to the correct side was assessed. Accuracy of identifying multigland disease was also evaluated.

RESULTS

In patients with single-gland disease, the sensitivity and specificity of 2-phase CT to correctly localize the quadrant were 55.4% and 85.9%, respectively. The sensitivity and specificity of correct lateralization were 78.8% and 67.8%, respectively. The sensitivity and specificity to identify multigland disease were 22.9% and 79.5%, respectively.

CONCLUSIONS

While the 2-phase CT protocol in this study demonstrates lower accuracy compared with reports of other techniques, its lower radiation compared with 3- and 4-phase techniques may make it a feasible alternative for preoperative parathyroid localization. Further prospective studies are needed to identify patients for whom this technique is most suitable.

MR appearance of parathyroid adenomas at 3 T in patients with primary hyperparathyroidism: what radiologists need to know for pre-operative localization

OBJECTIVES

To identify frequent MRI features of parathyroid adenomas (PTAs) in patients with primary hyperparathyroidism (PHPT) using a fast protocol with a 3 T magnet.

METHODS

Thirty-eight patients with PHPT underwent a 3 T-MR. All patients had positive US and Tc-99 sestamibi, for a total number of 46 PTAs. T2-weighted IDEAL-FSE and T1 IDEAL-sequences, before and after contrast, were performed. Five features of PTAs were recognised: hyperintensity, homogeneous or "marbled" appearance and elongated morphology on T2-sequences; cleavage plane from thyroid gland on T2-outphase; rapid enhancement in post-contrast T1. Image quality for T2-weighted IDEAL FSE and usefulness for IDEAL post-contrast T1-weighted and T2-outphase sequences were also graded.

RESULTS

PTAs were hyperintense in T2-sequences in 44/46 (95.7%), "marbled" in 30/46 (65.2%) and elongated in 38/46 (82.6%) patients. Cleavage plane was observed in 36/46 (78.3%), and rapid enhancement in 20/46 (43.5%) patients. T2-sequences showed both excellent fat suppression and image quality (average scores of 3.2 and 3.1). T2-outphase images demonstrated to be quite useful (score 2.8), whereas, post-contrast T1 images showed a lower degree of utility (score 2.4).

CONCLUSIONS

A fast protocol with 3.0-T MRI, recognising most common features of PTAs, may be used as a second-line method in the preoperative detection of PTAs.

KEY POINTS

3 T MRI protocol based on T2-weighted IDEAL FSE sequences was used. T2-hyperintensity and elongated morphology are common features of PTAs. 3 T MRI could be used in the preoperative detection of PTAs.

Parathyroid carcinoma

Parathyroid carcinoma is a rare form of endocrine malignancy accounting for only a small minority of cancer cases. Due to the rarity of this cancer, there are no generalized guidelines for its management; however, surgery remains to be the mainstay therapy. The purpose of this article is to review and summarize the available literature on parathyroid carcinoma, while discussing proposed staging systems and the role of available adjuvant therapies.

Three-dimensional sonography in the evaluation of primary hyperparathyroidism

Three-dimensional sonography is useful in the preoperative evaluation of patients with primary hyperparathyroidism. In this pictorial essay, we review the characteristic spectrum of grayscale and Doppler appearances of parathyroid glands on 2-dimensional sonography and demonstrate the additional benefits of 3-dimensional scanning.

Atypical ultrasound features of parathyroid tumours may bear a relationship to their clinical and biochemical presentation

OBJECTIVES

To describe atypical ultrasound features of parathyroid lesions and correlate them with clinical presentation and histopathology.

MATERIALS AND METHODS

Retrospective review of 264 patients with primary hyperparathyroidism who underwent ultrasound imaging prior to parathyroidectomy was performed. Patients with atypical ultrasound findings (n = 26) were identified; imaging findings were correlated with clinical presentation and histopathology.

RESULTS

Twenty-one (80 %) lesions were adenomas, two (8 %) were adenomas with cellular atypia, and three (11.5 %) were carcinomas. Seventeen (65 %) lesions showed cystic change; five (19 %) of them had >50 % cystic change. These lesions were adenomas with cystic degeneration. Cystic degeneration had significant positive correlation with the lesion size and PTH level, but cystic adenomas correlated negatively with lesion weight. Six (23 %) lesions were isoechoic and one (4 %) was hyperechoic; histology predominantly revealed haemorrhage, hyalinisation and fibrosis; one lesion showed fat deposition and another had multiple granulomas within the adenoma. Twenty (83 %) lesions had heterogeneous echotexture and showed combinations of acinar dilatation, necrosis, haemorrhage and fibrosis. Heterogeneous lesions tended to be significantly larger and heavier, and they were associated with higher PTH levels. Four (15 %) lesions had calcifications. Scintigraphy was concordant in 22 (96 %), n = 23. One scintigraphy-negative lesion was a cystic parathyroid adenoma.

CONCLUSION

Atypical ultrasound features of parathyroid lesions pose a diagnostic challenge. Awareness of these features would help improve lesion detection.

TEACHING POINTS

1. Cystic change is significantly related to the size, weight and measured parathyroid hormone levels. 2. Cystic change in parathyroid tumours indicated a slightly higher risk of malignancy. 3. Heterogeneous parathyroid adenomas are larger in size and heavier, and they have higher PTH levels. 4. Awareness of atypical ultrasound features will improve preoperative clinical prediction.

Role of ultrasonography in the management of patients with primary hyperparathyroidism: retrospective comparison with technetium-99m sestamibi scintigraphy

OBJECTIVE

Primary hyperparathyroidism (PHPT) is a common endocrine disorder that can be cured only by parathyroidectomy. Cervical ultrasonography and scintigraphy are the imaging studies most widely used for preoperative localization of the affected glands. The aim of this retrospective comparative study was to define the respective roles of ultrasonography and parathyroid scintigraphy in these cases.

MATERIALS AND METHODS

We analyzed 108 patients who had undergone parathyroidectomies for PHPT following cervical ultrasonographic and scintigraphic examinations. The ultrasound examinations were carried out by an expert physician sonographer in 61 cases and by various physician sonographers with different levels of experience in 47 cases. Sonographic and scintigraphic findings were compared with surgical findings and the diagnostic performance of the two imaging methods was evaluated by means of statistical analysis.

RESULTS

The operator dependency of ultrasonography was confirmed by marked variations in sensitivity related to the experience of the sonographer. When sonography was performed by an expert, the sensitivity of combined use of the two methods was not significantly higher than that of sonography alone.

CONCLUSIONS

In expert hands, the diagnostic yield of ultrasound is appreciably superior. It can therefore be used as the main and possibly sole method for preoperative localization of pathological parathyroid tissues. Combined use of ultrasound and scintigraphy is not cost-effective in these cases. Scintigraphy is indicated only when the ultrasound examination produces negative results.

Clinical review: Parathyroid localization and implications for clinical management

CLINICAL CONTEXT

The prevalence of hyperparathyroidism, especially primary hyperparathyroidism, has increased in recent decades due to improvements in diagnostic techniques with a corresponding surge in parathyroid surgery, leading to the development of focused, minimally invasive surgical approaches. Focused parathyroidectomy is predicated on preoperative localization of suspected parathyroid pathology. As a result, there has been a proliferation of parathyroid imaging modalities and protocols, resulting in confusion about their indications and applications.

EVIDENCE ACQUISITION

Bibliographies from clinical trials and review articles published since 2000 were reviewed and supplemented with targeted searches using biomedical databases. We also employed our extensive clinical experience.

EVIDENCE SYNTHESIS

The best-studied modalities for parathyroid localization are nuclear scintigraphy and sonography and are widely applied as initial studies. Multiple variations exist, and several additional noninvasive imaging techniques, such as computed tomography and magnetic resonance, are described. The exquisite anatomical detail of 4-dimensional computed tomography must be balanced with significant radiation exposure to the thyroid gland. Invasive venous PTH sampling and parathyroid arteriography have important roles in remedial cases. Due to considerable heterogeneity in imaging, multidisciplinary collaboration between endocrinologists, surgeons, and radiologists is beneficial.

CONCLUSIONS

Parathyroid localization is indicated in surgical candidates. Crucial considerations when selecting an imaging study include availability, cost, radiation exposure, local expertise, and accuracy. Additional factors include the patient's anticipated pathology and whether it is de novo or refractory disease. An approach to imaging for patients with primary hyperparathyroidism is presented.

Primary hyperparathyroidism: imaging to pathology

The aim of this review is to describe the multimodal imaging (ultrasound, magnetic resonance, computed tomography, and nuclear medicine) of primary hyperparathyroidism and its correlation to the pathological findings. In the last decades, imaging science has progressed a great deal. Accurate preoperative localization of the involved glands is essential for surgical success.

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 colour Doppler ultrasonography in the preoperative localization of parathyroid adenomas

The aim of the present study was to evaluate the diagnostic accuracy and imaging patterns of colour Doppler ultrasonography (US) and compare it with grayscale US, 99m-Tc methoxyisobutylisonitrile (MIBI) scans, and combined US and MIBI scans in the preoperative diagnosis of parathyroid adenomas in patients with primary hyperparathyroidism (pHPT). From June 2007 to June 2011, 36 consecutive patients (seven men and 29 women) with pHPT underwent grayscale US, colour Doppler ultrasonography (CDUS), and 99m-Tc MIBI scans prior to parathyroidectomy with traditional unilateral neck dissection. All 36 patients with pHPT underwent parathyroidectomy at our university hospital. According to histopathology results, the sensitivity, specificity, and accuracy of MIBI and US scan were 88%, 94%, and 91%, and 70%, 100%, and 85%, respectively. The overall sensitivity and specificity of combined US and MIBI was 97% and 100% respectively. The overall sensitivity, specificity, and accuracy of CDUS in the correct diagnosis of parathyroid adenoma were 97%, 100%, and 98.6%, respectively. The sensitivity and specificity of US in the detection of parathyroid adenoma and differentiating it from other cervical masses reached up to 97% and 100%, respectively, by combining CDUS with grayscale evaluations of parathyroid adenoma.

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.

Assessment of parathyroid glands in hemodialysis patients by using color Doppler sonography

The aim of this study was to assess the role of color and spectral Doppler ultrasound (CDU) in the evaluation of enlarged parathyroid glands in hemodialysis patients with secondary hyperparathyroidism. Fourteen hemodialysis patients with elevated intact parathyroid hormone (iPTH) levels were evaluated prospectively with CDU. The volume of each observed parathyroid gland and the spectral CDU data (velocities, resistance and pulsatility indices, systolic to diastolic ratio, and flow volume output (FVO)) were noted. The biochemical data (iPTH, calcium, phosphate levels), and CDU results were analyzed with the Spearman correlation test. Two patients were excluded, and 27 enlarged parathyroid glands were observed in 12 patients. The mean total volume of enlarged parathyroid glands per patient was 1.95 cm(3) (0.06-5.5 cm(3)). Arterial supply was demonstrated in 78% (21/27) of enlarged parathyroid glands. Mean total FVO of enlarged glands per patient was 238.5 ml/min (620-0 ml/min) and mean iPTH level was 1,477 pg/ml (643-3,132 pg/ml). The positive correlations of total volume (p = 0.022), iPTH (p = 0.024), and FVO (p = 0.022) were statistically significant. In secondary hyperparathyroidism, total volume of the visualized enlarged parathyroid glands and the total of FVOs per patient are positively correlated with iPTH levels which may help clinical management and follow-up of end-stage renal disease patients.

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.

Parathyroid lipoadenomas and lipohyperplasias: clinicopathologic correlations

Parathyroid lipoadenomas and lipohyperplasias are rare histologic variants with both an increase in stromal fat and parenchyma. We report the most comprehensive single institution series of lipoadenomas and lipohyperplasias to date and review the literature. Eight lipoadenomas and 3 lipohyperplasias (27 y period) were reviewed. The mean age was 60.3 years (range: 50 to 77 y) with a female predilection (1.75:1). The most common symptoms on presentation were fatigue (55.6%) and bone/joint pain (44.4%). Only 1 patient was euparathyroid. Ultrasound localized lipoadenomas in 50% of tested cases whereas sestamibi was successful in 71.4%. Despite increased stromal fat (median: 50%), the weight and the appearance of large, occasionally nodular expansions of parathyroid parenchyma within the fatty stroma distinguished lipoadenomas and lipohyperplasias from normal parathyroid tissue; none of the cases were misclassified as normal on frozen section. Mean weight for lipoadenomas was 1553 mg (range: 173 to 4587 mg), whereas the mean weight for lipohyperplasia glands was 389.1 mg. Variant morphologies included follicular patterned, oxyphil predominant, and thymic elements (thymolipoadenoma). In 1 lipohyperplasia case, not all glands were involved. Oil Red O stains showed decreased intracytoplasmic lipid in most cases. Median follow-up was 9.2 months (range: <1 to 51 mo). Only 1 lipohyperplasia patient had persistent hypercalcemia, but was asymptomatic. Lipoadenomas and lipohyperplasias are clinically similar and as histologically diverse as their conventional counterparts. Lipoadenomas are more difficult to localize preoperatively by imaging. Despite the potential difficulty at frozen section, accurate weight documentation and recognition of key histologic features diminish this challenge.

Findings of extrathyroid lesions encountered with thyroid sonography

OBJECTIVE

The purpose of this presentation is to illustrate the normal sonographic anatomy of the anterior neck region and the sonographic findings of various kinds of extrathyroid lesions.

METHODS

Cases of extrathyroid lesions were collected and reviewed retrospectively from our archives. All of the sonographic examinations were performed with high-frequency (5- to 15-MHz) linear array transducers.

RESULTS

The normal sonographic anatomy of the anterior neck region and various pathologic conditions of patients with extrathyroid lesions are discussed.

CONCLUSIONS

Sonography is a useful imaging method for evaluating anterior neck anatomy and various pathologic conditions in patients with extrathyroid lesions.

Parathyroid imaging: technique and role in the preoperative evaluation of primary hyperparathyroidism

OBJECTIVE

This article discusses the commonly used techniques for imaging the parathyroid glands and their role in the preoperative evaluation of patients with primary hyperparathyroidism.

CONCLUSION

The importance of sonography and sestamibi scintigraphy in the preoperative evaluation of patients with primary hyperthyroidism has increased with the adoption of minimally invasive parathyroidectomy techniques at most medical centers. When the results of these studies are concordant, the cure rates of minimally invasive surgery equal those of traditional bilateral neck exploration.