Preoperative evaluation of hyperparathyroidism: the role of dual-phase parathyroid scintigraphy and ultrasound imaging

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.

Bilateral Lymphadenopathy After COVID Vaccine in 18F-Choline PET/MRI Performed for Hyperparathyroidism

ABSTRACT

We describe a case of a 56-year-old woman with primary hyperparathyroidism. 18F-Choline PET/MRI revealed incidental bilateral axillary lymphadenopathy with mild-moderate increased 18F-choline uptake. The patient had her first and third doses of COVID-19 vaccines from the left arm and second dose of vaccine from the right arm before PET examination.

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.

18F-fluorocholine PET/CT semi-quantitative analysis in patients affected by primary hyperparathyroidism: a comparison between laboratory and functional data

INTRODUCTION

This retrospective study aims to establish ¹⁸F-fluorocholine (FCH) positron emission tomography/computed tomography (PET/CT) performance in finding hyperfunctioning parathyroid glands, analyze a potential role for semi-quantitative PET parameters and assess factors that may influence PET/CT outcome.

METHODS

Forty patients with suspect primary hyperparathyroidism (pHPT) and negative/equivocal conventional imaging underwent FCH-PET/CT in our Institution. For every lesion, visual and semi-quantitative analyses were performed on PET/CT images. In qualitative analysis, a lesion was considered positive if a clear focus of uptake, significantly higher than normal thyroid tissue, was identifiable. Ectopic focal uptake was also regarded as positive PET result. Lesion SUV_Max was measured by assigning a spheric VOI to the suspect area of uptake. Thyroid SUV_Mean was assessed by placing a spheric VOI inside the contralateral thyroid lobe, and SUV_ratio was calculated using this background region. All patients were subsequently submitted to surgery and histopathologic workup. Sensitivity, positive predictive value (PPV) and accuracy were calculated based on histopathologic reports for every lesion. Pearson's test was used to assess a correlation between laboratory and histopathologic features with SUVr.

RESULTS

Four out of the 40 patients who underwent surgery for pHPT had more than one histologic proven unhealthy parathyroid and three had papillary thyroid cancer (PTC). A total of 48 lesions were analyzed. We found 42/48 lesions (87.5%) to have true-positive uptake, whereas three lesions (6.7%) had false-positive uptake (PTC). Three histologic proven parathyroid adenomas showed no uptake (6.7%); the sensitivity/PPV were 93.3% and accuracy was 87,8%. Pearson's test showed a significant correlation between PTH values and parathyroid size with SUVr values (r = 0.56 and 0.55, respectively, p < 0.01 for both features).

DISCUSSION

As stated in recent literature, we observed excellent diagnostic sensitivity of FCH-PET/CT in patients with pHPT, providing surgeons a fine tool to optimize treatment. More studies are needed to improve the evaluability of semi-quantitative parameters towards a further improvement of diagnostic accuracy.

Comparison between MIBI-based radiopharmaceuticals for parathyroid scintigraphy: quantitative evaluation and correlation with clinical-laboratory parameters

OBJECTIVE

Parathyroid scintigraphy is mandatory for the identification of hyperfunctioning parathyroid glands in hyperparathyroidism (HPT). The use of ^99mTc-methoxy-isobutyl-isonitrile (MIBI) as radiopharmaceutical for parathyroid scintigraphy is considered the most valid and useful considering its uptake mechanism. Several MIBI-based radiopharmaceuticals are commercially available (i.e., MediMIBI, TechneMIBI, Stamicis). They seem to have similar physico-chemical characteristics and the choice between them is based on commercial criteria, even though some differences in qualitative scintigraphic results have been appreciated. Aims of the study were: first, to compare the scintigraphic quantitative data of MediMIBI, TechneMIBI, and Stamicis, particularly in the view of a personalized medicine approach; second, to investigate the potential effect of clinical-laboratory data on image quality using one of these radiopharmaceuticals.

METHODS

Patients with diagnosis of HPT, who underwent a parathyroid scintigraphy using one of the three MIBI-based radiopharmaceuticals between December 2018 and October 2020, have been retrospectively identified. Parameters derived from regions of interest (ROIs) drawn on three different sites were obtained: a reasonable parathyroid lesion detected, an area in the lateral neck considered as the background, and the hepatic dome as the site of MIBI physiological uptake. Laboratory and clinical data, such as serum calcium, PTH, vitamin D, and creatinine levels, as well as possible drug-mediated interferences were considered.

RESULTS

Among 250 patients included, 83 (33.2%) had the parathyroid scintigraphy using MediMIBI, 84 (33.6%) using TechneMIBI and 83 (33.2%) using Stamicis. The ROIs on the parathyroid uptake at early images, on the background, and on the hepatic dome were statistically different among the three groups (p < 0.05). No significant differences were found in the remaining semi-quantitative parameters among the three groups, not even considering clinical-laboratory data.

CONCLUSIONS

Some differences in semi-quantitative parameters emerged among MIBI-based radiopharmaceuticals for parathyroid scintigraphy. This might justify the different qualitative scintigraphic results obtained using one or another of the cited radiopharmaceuticals.

Prevertebral cervical approach to posterior mediastinum parathyroid adenomas

BACKGROUND

About 4 years ago, we described the pure endoscopic cervical approach to posterior mediastinum parathyroid adenomas, which we called the "prevertebral cervical approach". At that time, we had operated on three patients and did not have enough quality videos to demonstrate this approach. After broadening our experience, we present our results and show this technique through a video.

METHODS

From June 2015 to January 2021, information on patients undergoing the prevertebral cervical approach was obtained from a specific prospective database, including clinical presentation, biochemistry, preoperative imaging, surgical approach and patient outcomes. The step by step technique is described for both right- and left-sided adenomas, by means of a short video clip.

RESULTS

Ten patients were operated on using this technique. Seven adenomas were right-sided and three were left-sided. The mean surgical time was 33 ± 7 min. There were neither intraoperative nor major postoperative complications. Seven patients presented with a slight subcutaneous emphysema, which did not cause complaints. All patients were discharged the day after surgery, except for one patient with a previous open neck removal of four glands due to secondary hyperparathyroidism, which required calcium replacement. Calcium and parathyroid hormone levels were normalised in the other nine patients after surgery. One patient experienced a transient recurrent laryngeal nerve injury which was spontaneously resolved within 1 month. No permanent recurrent laryngeal nerve injury was found. The postoperative cosmetic outcomes were excellent.

CONCLUSION

In our experience, the pure cervical endoscopic approach has shown a high feasibility and short operation time, with excellent postoperative results regarding patient comfort, length of stay and disease cure. This approach also offers a very reasonable procedure cost, and may result in a less aggressive surgical option when compared with thoracic approaches.

Semiquantitative assessment of 99mTc-MIBI uptake in parathyroids of secondary hyperparathyroidism patients with chronic renal failure

OBJECTIVE

To explore the valuably influential factors and improve the diagnostic accuracy and efficiency of ^99mTc-methoxyisobutylisonitrile (MIBI) uptake in parathyroids of secondary hyperparathyroidism (SHPT) patients with chronic renal failure (CRF).

METHODS

The correlation analysis was performed between clinical indices related to CRF and ^99mTc-MIBI uptake intensity TBR (the gray value mean ratio between the parathyroid target and the bilateral neck background, semiquantitatively calculated with ImageJ software). All clinical indices and TBRs were compared by a three- or two-level grouping method of MIBI uptake, which was visually qualitatively assessed. The three-level grouping method comprised slight, medium, and high groups with little, faint, and distinct MIBI concentration in parathyroids, respectively. The two-level grouping method comprised insignificant and significant groups with TBR greater than or less than 0.49-0.71, respectively.

RESULTS

MIBI uptake was significantly positively related to patient age, CRF course, hemodialysis vintage, serum parathyroid hormone (PTH), and alkaline phosphatase (AKP) but was significantly negatively related to serum uric acid (UA). MIBI washout was significantly positively related to patient age but was significantly negatively related to serum phosphorus (P) and calcium (Ca) × P. Oral administration of calcitriol and calcium could significantly reduce the MIBI uptake. MIBI uptake tendency might alter. Such seven indices, namely the MIBI uptake, CRF course, hemodialysis vintage, serum AKP, calcium, cysteine proteinase inhibitor C, and PTH, were comparable between the slight and medium groups but were significantly different between the slight and high groups or between the medium and high groups. The above seven indices plus blood urea nitrogen/creatinine were all significantly different between the insignificant and significant groups. All above significances were with P < 0.05.

CONCLUSIONS

Patient age, CRF course, hemodialysis vintage, serum PTH, AKP, UA, phosphorus, Ca × P, oral administration of calcitriol and calcium, and parathyroids themselves can significantly influence MIBI uptake in parathyroids of SHPT patients with CRF. The two-level grouping method of MIBI intensity should be adopted to qualitatively diagnose the MIBI uptake.

The EANM practice guidelines for parathyroid imaging

INTRODUCTION

Nuclear medicine parathyroid imaging is important in the identification of hyperfunctioning parathyroid glands in primary hyperparathyroidism (pHPT), but it may be also valuable before surgical treatment in secondary hyperparathyroidism (sHPT). Parathyroid radionuclide imaging with scintigraphy or positron emission tomography (PET) is a highly sensitive procedure for the assessment of the presence and number of hyperfunctioning parathyroid glands, located either at typical sites or ectopically. The treatment of pHPT is mostly directed toward minimally invasive parathyroidectomy, especially in cases with a single adenoma. In experienced hands, successful surgery depends mainly on the exact preoperative localization of one or more hyperfunctioning parathyroid adenomas. Failure to preoperatively identify the hyperfunctioning parathyroid gland challenges minimally invasive parathyroidectomy and might require bilateral open neck exploration.

METHODS

Over a decade has now passed since the European Association of Nuclear Medicine (EANM) issued the first edition of the guideline on parathyroid imaging, and a number of new insights and techniques have been developed since. The aim of the present document is to provide state-of-the-art guidelines for nuclear medicine physicians performing parathyroid scintigraphy, single-photon emission computed tomography/computed tomography (SPECT/CT), positron emission tomography/computed tomography (PET/CT), and positron emission tomography/magnetic resonance imaging (PET/MRI) in patients with pHPT, as well as in those with sHPT.

CONCLUSION

These guidelines are written and authorized by the EANM to promote optimal parathyroid imaging. They will assist nuclear medicine physicians in the detection and correct localization of hyperfunctioning parathyroid lesions.

Three-phase four-dimensional computed tomography as a first-line investigation in primary hyperparathyroidism

INTRODUCTION

Parathyroid computed tomography using multiple phases (four-dimensional computed tomography (4DCT) for parathyroid localization was first described in 2006. Since its inception, there has been variable uptake of this technique due to inconsistency of results between institutions and perceived higher radiation dose than technetium-99 sestamibi scans (MIBI). 4DCT has been the primary imaging modality for parathyroid localization at our institution since 2013.

METHODS

A retrospective study of surgically managed patients with primary hyperparathyroidism who had preoperative localization with 4DCT from 2013-2018 was performed.

RESULTS

A total of 353 patients were included for analysis. The positive predictive value (PPV) of our three-phase 4DCT protocol was 93.3%, sensitivity (localized) 85.2% with a 5.8% false-positive rate and 13.9% false-negative (non-localizing) rate when reported by a head and neck radiologist (HNR). Calculated effective dose varied from 4.5 to 8.9mSV. On multivariable logistic regression, reporting by an experienced HNR (P < 0.001) and gland weight > 200 mg (P = 0.002) were significant for higher accuracy, lower false positives and false negatives.

CONCLUSION

A first-line three-phase 4DCT protocol for primary hyperparathyroidism is an accurate technique providing precise anatomical localization of abnormal parathyroid glands, particularly when performed by a specialist HNR. In our practise, it provides the best rate of detection and superior anatomical localization needed for minimally invasive parathyroid surgery, compared to other commonly used localization techniques. It also avoids the need for four gland exploration in the majority of patients with primary hyperparathyroidism.

Predictors of adenoma size and location in primary hyperparathyroidism

Purpose

In primary hyperparathyroidism (PHPT), intraoperative localization of the parathyroid adenoma can be challenging, especially in cases of negative preoperative imaging. Since a focused unilateral parathyroidectomy has benefits compared to a conventional bilateral neck exploration, the question arises whether adenoma size prediction can facilitate a targeted approach. We investigated whether single parathyroid adenoma size can be estimated using preoperative parathyroid hormone (PTH), calcium, and phosphate in patients with PHPT. Preoperative imaging accuracy was evaluated.

Methods

The data of 156 patients who underwent curative parathyroidectomy for single adenoma PHPT were analyzed retrospectively. Information obtained included laboratory data, imaging results, intraoperative data, and final pathology. Imaging accuracy was analyzed descriptively. The association between preoperative biochemical markers and adenoma dimensions was investigated using Spearman’s correlation coefficient and multivariable regression modeling.

Results

Cervical ultrasound correctly predicted adenoma laterality in 95.5%, sestamibi scintigraphy in 80.6%, both had lower true-positive rates for quadrant prediction. Patients with negative imaging results showed higher thyroid volumes than those with positive results. Adenoma volume was positively correlated with preoperative PTH (p < 0.001) and calcium (p < 0.001) and negatively correlated with preoperative phosphate (p = 0.001). Using these preoperative biochemical markers and patient age and BMI, adenoma volume can be significantly predicted using the multivariable regression algorithm.

Conclusion

Cervical ultrasound is superior to scintigraphy for predicting adenoma location and should be the first-choice imaging method, but both methods may be limited by increased thyroid volume. Large adenomas are more likely with higher PTH, higher calcium, and lower phosphate levels. In cases of undetermined adenoma location, an estimation of adenoma volume via our algorithm could corroborate sonographic volume measurements of the suspected adenoma.

Initial clinical experiences using the intraoperative probe-based parathyroid autofluorescence identification system-PTeye™ during thyroid and parathyroid procedures

BACKGROUND AND OBJECTIVE

The Food and Drug Administration has cleared a probe-based near-infrared autofluorescence (NIRAF) detection system called PTeye™ as an adjunct tool for label-free intraoperative parathyroid gland (PG) identification. Since PTeye™ has been investigated only in a "blinded" manner to date, this study describes the preliminary impressions of PTeye™ when used by surgeons without being blinded to the device output.

METHODS

Patients undergoing thyroid and parathyroid procedures were prospectively recruited. Target tissues were intraoperatively assessed with PTeye™. The surgeon's confidence in PG identification was recorded concomitantly with NIRAF parameters that were output in real-time from PTeye™.

RESULTS

A retrospective review of prospectively collected data on 83 patients was performed. PTeye™ was used for interrogating 336 target tissues in 46 parathyroid and 37 thyroid procedures. PTeye™ yielded an overall accuracy of 94.3% with a positive predictive value of 93.0% and a negative predictive value of 100%. An increase in confidence for intraoperative PG identification with PTeye™ was observed by all three participating high-volume surgeons, irrespective of their level of accrued surgical experience.

CONCLUSIONS

Probe-based NIRAF detection with PTeye™ can be a valuable adjunct device to intraoperatively identify PGs for surgeons of varied training and experience.

Recurrent primary hyperparathyroidism: a diagnostic and management dilemma

SUMMARY

Primary hyperparathyroidism requires a surgical approach to achieve a long-term cure. However, post-surgical recurrence significantly complicates the management of this condition. A number of causes for recurrent disease are well understood and several diagnostic modalities exist to localise the culprit parathyroid adenoma although none of them is efficacious in localisation of the recurrent lesion. In this case report, we highlight a novel causative mechanism and describe a unique diagnostic sequence that enabled curative treatment to be delivered.

LEARNING POINTS

In the case described herein, we describe a novel location for a parathyroid adenoma causing recurrent PHPT. The case elucidates well the difficulties presented by such cases in terms of surgical planning and show the utility of PVS in such cases. Based on this case, we make the following recommendations: Meticulous care must be taken to prevent seeding of adenomatous tissue during primary excision. To consider the use of PVS in patients with discordant imaging in the setting of recurrent/persistent PHPT as a method to localise the causative adenoma. Same day PVS and surgery is a viable option for patients who either represent an anaesthetic risk or who are extremely anxious about the prospect of two separate procedures. Disordered calcium homeostasis is an important but forgotten cause of dysphagia which can be extremely debilitating for affected patients.

A retrospective analysis of the diagnostic performance of 11C-choline PET/CT for detection of hyperfunctioning parathyroid glands after prior negative or discordant imaging in primary hyperparathyroidism

Background

Identifying the correct location of a parathyroid adenoma in patients with primary hyperparathyroidism (pHPT) is crucial as it can guide surgical treatment. This study aimed to determine the diagnostic performance of ¹¹C-choline PET/CT in patients with pHPT as a next in-line scan after primary negative or discordant first-line imaging.

Methods

This was a retrospective single-center cohort study. All patients with pHPT that were scanned utilizing ¹¹C-choline PET/CT, after prior negative or discordant imaging, between 2015 and 2019 and who subsequently underwent parathyroid surgery were included. The results of the ¹¹C-choline PET/CT were evaluated lesion-based, with surgical exploration and histopathological examination as the gold standard.

Results

In total, 36 patients were included of which three patients were known to have Multiple Endocrine Neoplasia (MEN) syndrome. In these 36 patients, 40 lesions were identified on ¹¹C-choline PET/CT and 37 parathyroid lesions were surgically removed. In 34/36 (94%) patients a focused parathyroidectomy was performed, in one patient a cervical exploration due to an ectopically identified adenoma, and in one patient a bilateral exploration was performed because of a double adenoma. Overall, per-lesion sensitivity of ¹¹C-choline PET/CT was 97%, the positive predictive value was 95% and the accuracy was 94% for all parathyroid lesions.

Conclusions

In patients with pHPT and prior negative or discordant first-line imaging results, pathological parathyroid glands can be localized by ¹¹C-choline PET/CT with high sensitivity and accuracy.

11C-Methionine PET/CT in patients with primary hyperparathyroidism and inconclusive pre-operative imaging work-up: diagnostic accuracy and role of semi-quantitative analysis

OBJECTIVE

¹¹C-Methionine PET/CT (C-MET) is a promising method in detecting abnormal parathyroid glands in patients with primary hyperparathyroidism (PHPT). The first aim of the study was to evaluate which is the diagnostic role of C-MET in patients with PHPT and inconclusive pre-operative imaging. Second, we aimed to investigate whether C-MET semi-quantitative parameters may reflect biochemical and histological characteristics of involved glands.

METHODS

Patients with PHPT, undergoing C-MET after an inconclusive pre-operative imaging and having a parathyroid surgery, were retrospectively included. C-MET visual and semi-quantitative assessment was performed. Parameters, as SUV_max, SUV_peak, SUV_mean, functional lesion volume (FLV) and total lesion activity (TLA), were measured for each detected lesion; SUV_mean, FLV and TLA were calculated on 40-90% thresholds of SUV_max to define SUV_mean40-90, FLV_40-90 and TLA_40-90, respectively. Results were correlated with patients' clinical-laboratory (calcium and PTH values) and histological data (size and weight of excised glands). Mann-Whitney test was used and P value < 0.05 was considered significant.

RESULTS

Thirty-eight patients (36 female, age: 57.69 ± 15.13 years) were included. Pre-operative median calcium and PTH values were 11.1 mg/dl [interquartile range (IQR) 10.6-11.5] and 154.6 pg/ml (IQR 101.8-227.0), respectively. C-MET showed a parathyroid uptake in 30 out of thirty-eight patients (78.9%). Among 42 nodules excised, C-MET correctly detected the side of the neck (right/left) in 30/42 with sensitivity, specificity and accuracy of 79, 75 and 79%, respectively. C-MET correctly identified the exact position (superior/inferior) in 27/42 with sensitivity, specificity and accuracy of 75, 50 and 71%, respectively. SUV_peak, FLV_50-70 and TLA_40-70 were significantly (P < 0.05) higher in patients with higher PTH results. The histological size resulted significantly (P < 0.05) higher in abnormal glands with higher SUV_max, SUV_peak, FLV_40-80 and TLA_40-90, the weight was higher in glands with higher SUV_peak, SUV_mean40-50, FLV_40-80 and TLA_40-90.

CONCLUSIONS

C-MET showed a good performance in detecting hyperfunctioning parathyroid glands in PHPT patients with inconclusive pre-operative imaging. Semi-quantitative PET-derived parameters closely correlated with PTH as well as with size and weight of the excised gland, thus reflecting some biochemical and histological characteristics of involved glands.

Detecting the Near Infrared Autofluorescence of the Human Parathyroid: Hype or Opportunity?

OBJECTIVE

With the recent approval of 2 NIRAF-based devices for label-free identification of PG by the Food and Drug Administration, it becomes crucial to educate the surgical community on the realistic scope of this emerging technology. Here, we have compiled a review of studies that utilize NIRAF and present a critical appraisal of this technique for intraoperative PG detection.

BACKGROUND

Failure to visualize PGs could lead to accidental damage/excision of healthy PGs or inability to localize diseased PGs, resulting in postsurgical complications. The discovery that PGs have NIRAF led to new avenues for intraoperatively identifying PGs with high accuracy in real-time.

METHODS

Using the following key terms: "parathyroid, near infrared, autofluorescence" in various search engines such as PubMed and Google Scholar, we identified various publications relevant to this review of NIRAF as a technique for PG identification. Articles were excluded if they focused solely on contrast agents, served as commentaries/overviews on NIRAF or were not written in English.

RESULTS

To date, studies have investigated the potential of NIRAF detection for (i) identifying PG tissues intraoperatively, (ii) locating PGs before or after dissection, (iii) distinguishing healthy from diseased PGs, and (iv) minimizing postoperative hypocalcemia after total thyroidectomy.

CONCLUSIONS

Because NIRAF-based identification of PG is noninvasive and label-free, the popularity of this approach has considerably surged. As the present limitations of various technologies capable of NIRAF detection are identified, we anticipate that newer device iterations will continue to be developed enhancing the current merits of these modalities to aid surgeons in identifying and preserving PGs. However, more concrete and long-term outcome studies with these modalities are essential to determine the impact of this technique on patient outcome and actual cost-benefits.

Preoperative Localization of Adenomas in Primary Hyperparathyroidism: The Value of 11C-Choline PET/CT in Patients with Negative or Discordant Findings on Ultrasonography and 99mTc-Sestamibi SPECT/CT

We aimed to assess the value of ¹¹C-choline PET in patients with primary hyperparathyroidism and negative or discordant results on ^99mTc-sestamibi imaging and neck ultrasound. Methods: Eighty-seven such patients were assessed and subsequently underwent parathyroidectomy. PET/CT image data were analyzed semiquantitatively using SUV_max and SUV ratios (target to contralateral thyroid gland and carotid artery). A positive PET/CT result was defined as focal uptake significantly higher than regular thyroid tissue. Ectopic foci were also considered positive. Inconclusive PET/CT cases were defined as a lesion with uptake equal to normal thyroid tissue. If no prominent or ectopic uptake was detectable, the PET/CT result was considered negative. Results: When dichotomizing the ¹¹C-choline PET/CT imaging results by defining lesions with both positive and inconclusive uptake as positive, we found 84 of 92 lesions (91.3%) to have true-positive uptake whereas 8 lesions (8.7%) had false-positive uptake. One lesion showed false-negative uptake; the sensitivity was 98.8%. The corresponding positive predictive value for lesions was 91.3%. The mean SUV_max was 6.15 ± 4.92 in 72 lesions with positive uptake (70 patients) and 2.96 ± 2.32 in 20 lesions with inconclusive uptake (18 patients). Conclusion: These results in a large group of patients indicate that ¹¹C-choline PET/CT is a promising tool for parathyroid adenoma localization when ultrasound and ^99mTc-sestamibi imaging yield negative or discordant results.

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.

Video-assisted thoracoscopic surgery for ectopic mediastinal parathyroid adenoma

Background

Primary hyperparathyroidism (PHPT), caused by an ectopic mediastinal parathyroid adenoma, is uncommon. In the past, when the adenoma was not accessible from the neck, median sternotomy was advocated for safe and successful parathyroidectomy. Video‐assisted thoracoscopic surgical (VATS) parathyroidectomy represents a modern alternative approach to this problem.

Methods

Information on patients undergoing VATS was obtained from a specific database, including clinical presentation, biochemistry, preoperative imaging, surgical approach and patient outcomes. A comprehensive literature review was undertaken to draw comparisons with other publications.

Results

Over a 2‐year period, nine patients underwent VATS parathyroidectomy for sporadic PHPT. Five patients had persistent PHPT following previous unsuccessful parathyroidectomy via cervicotomy, and four had had no previous parathyroid surgery. The median duration of surgery was 90 (range 60–160) min. Eight patients were cured biochemically, with no major complications. One patient required conversion to a median sternotomy for removal of a thymoma that had resulted in false‐positive preoperative imaging.

Conclusion

With appropriate preoperative imaging, multidisciplinary input and expertise, VATS parathyroidectomy is an effective, safe and well tolerated approach to ectopic mediastinal parathyroid adenoma.

Parathyroid scintigraphy in primary hyperparathyroidism: comparison between double-phase and subtraction techniques and possible affecting factors

PURPOSE

Parathyroid scintigraphy is superior to other imaging techniques in detecting hyperfunctioning parathyroid glands. It is mainly performed using double-phase or dual-tracer subtraction methods. Neither of the techniques is perfect and different protocols are being used. We aimed to evaluate the accuracy of double-phase and subtraction methods in detecting abnormal gland as well as the potential effects of coexisting thyroid disease and clinical-laboratory data.

METHODS

We considered patients with primary hyperparathyroidism who underwent parathyroid surgery, after a parathyroid scintigraphy between April 2015 and February 2017. Sixty-eight patients were included; in 45 cases (66.2%), a thyroid disease was coexistent. Diagnostic performances of the two techniques were compared. The effect of thyroid disease and clinical-pathological data on examination interpretation was considered.

RESULTS

Double-phase scintigraphy showed higher sensitivity and accuracy in detecting the exact abnormal gland compared to the digital subtraction (90% and 75% vs. 76% and 66%, respectively). For double-phase technique, sensitivity and accuracy were higher in cases with no thyroid disease when compared to those with thyroid disease (92% and 86% vs. 88% and 69%, respectively). Similarly, for digital subtraction, sensitivity and accuracy were higher in the absence of thyroid disease compared to their presence (84% and 79% vs. 70% and 58%, respectively). There was no significant variation in the performance of both techniques, considering clinical-laboratory data.

CONCLUSIONS

Double-phase scintigraphy has been more accurate than digital subtraction. The presence of thyroid disease could be a possible limit, affecting the subtraction more than the double-phase technique. Clinical data did not influence the scintigraphic outcome.

Optimization of parathyroid 11C-choline PET protocol for localization of parathyroid adenomas in patients with primary hyperparathyroidism

PURPOSE

To evaluate the optimal tracer uptake time, the minimal amount of radioactivity and the inter-observer agreement for 11C-choline positron emission tomography/computed tomography (PET/CT) in patients with primary hyperparathyroidism (pHPT).

METHODS

Twenty-one patients with biochemically proven pHPT were retrospectively studied after injection of 6.3 ± 1.2 MBq/kg 11C-choline. PET data of the first nine patients, scanned for up to 60 min, were reconstructed in 10-min frames from 10- to 60-min postinjection (p.i.), mimicking varying 11C-choline uptake times. Parathyroid adenoma to background contrast ratios were calculated and compared, using standardized uptake values (SUVs). Data was reconstructed with varying scan durations (1, 2.5, 5, and 10 min) at 20-30-min p.i. (established optimal uptake time), mimicking less administered radioactivity. To establish the minimal required radioactivity, the SUVs in the shorter scan durations (1, 2.5, and 5 min) were compared to the 10-min scan duration to determine whether increased variability and/or statistical differences were observed. Four observers analyzed the 11C-choline PET/CT in four randomized rounds for all patients.

RESULTS

SUVpeak of the adenoma decreased from 30 to 40 p.i. onwards. All adenoma/background contrast ratios did not differ from 20- to 30-min p.i. onwards. The SUVs of adenoma in the scan duration of 1, 2.5, and 5 min all differed significantly from the same SUV in the 10-min scan duration (all p = 0.012). However, the difference in absolute SUV adenoma values was well below 10% and therefore not considered clinically significant. The inter-observer analysis showed that the Fleiss' kappa of the 1-min scan were classified as "moderate," while these values were classified as "good" in the 2.5-, 5-, and 10-min scan duration. Observers scored lower certainty scores in the 1- and 2.5-min scans compared to the 5- and 10-min scan durations.

CONCLUSION

The optimal time to start PET/CT scanning in patients with pHPT is 20 min after mean injection of 6.3 MBq/kg 11C-choline, with a recommended scan duration of at least 5 min. Alternatively, the radioactivity dose can be lowered by 50% while keeping a 10-min scan duration without losing the accuracy of 11C-choline PET/CT interpretation.

Secondary and Tertiary Hyperparathyroidism: A Narrative Review

End-stage renal disease is often complicated by the occurrence of secondary and eventually tertiary hyperparathyroidism, characterized by increased parathormone, calcium, and phosphate concentrations. Related symptoms include pruritus and osteodynia, concentration difficulties, and feelings of depression may be present. In the long-term, end-stage renal disease patients with hyperparathyroidism have an increased risk of all-cause and cardiovascular mortality. Among treatment options are vitamin D supplements, phosphate binders, calcimimetics, and surgical parathyroidectomy. Determining the optimal treatment for the individual patient is challenging for nephrologists and endocrine surgeons. This review resumes the pathogenesis of hyperparathyroidism, clinical presentation, required diagnostic work-up, and discusses indications for the available treatment options for patients with secondary and tertiary hyperparathyroidism.

Incremental Value of Sestamibi SPECT/CT Over Dual-Phase Planar Scintigraphy in Patients With Primary Hyperparathyroidism and Inconclusive Ultrasound

Background: We evaluated the incremental value of [^99mTc]sestamibi single photon-emission computed tomography (SPECT)/computed tomography (CT) over planar imaging for localization of abnormal parathyroid tissue in patients with primary hyperparathyroidism.

Methods: Forty-six patients with biochemical evidence of hyperparathyroidism and inconclusive ultrasound underwent sestamibi dual-phase planar scintigraphy and SPECT/CT for preoperative localization of parathyroid adenoma. Imaging findings were compared with histopathological data. Decision tree analysis was performed to evaluate the value of SPECT/CT over planar scintigraphy for classifying patients with or without hyperfunctioning parathyroid tissue. The added value of SPECT/CT was also evaluated by decision curve analysis.

Results: Planar scintigraphy was positive for presence of hyperfunctioning parathyroid in 52% of patients, with sensitivity of 63% and specificity of 100%. SPECT/CT was positive in 80% of patients with sensitivity of 97% and specificity of 100%. At decision tree analysis, after an initial split on planar imaging results, no further split was performed in patients with positive results, while those with negative results were further stratified by SPECT/CT. At decision curve analysis, the model including SPECT/CT was associated with the highest net benefit compared to the model including only planar technique and to a strategy considering that all patients should be treated.

Conclusion: Sestamibi SPECT/CT provides incremental value over dual-phase scintigraphy in preoperative localization of hyperfunctioning parathyroid tissue in subjects with inconclusive ultrasound. Hybrid technique allows a better identification of pathological lesion to perform minimally invasive surgery and showed the highest net benefit, improving selection of surgical approach.

Efficacy of Scintigraphy, Ultrasound and Both Scintigraphy and Ultrasonography in Preoperative Detection and Localization of Primary Hyperparathyroidism

Objective: The aim of our study was to evaluate the efficacy of preoperative dual-phase 99mTc-methoxyisobutylnitrile (MIBI) parathyroid scintigraphy (PS), and ultrasound (US) in primary hyperparathyroidism (pHPT) diagnosis and compare the results with the surgical findings.

Methods: Forty-five patients were enrolled in this study. Preoperative serum parathyroid hormone (PTH) levels, calcium (Ca), phosphate (P), and alkaline phosphatase (AP) levels were measured. All parathyroid patients were evaluated by ultrasonography, dual phase 99mTc-MIBI. Surgical findings were used as a reference standard.

Results: Of the 45 patients included in this study, 30 were females (66.7%) with an age range between 30 years and 70 years (mean age 41± 13). The sensitivity and specificity of 99mTc-MIBI scintigraphy was 97.4% and 71.4%, respectively, while the sensitivity of ultrasound was 94.4% and specificity 44.4%. The sensitivity, specificity, and accuracy of combined scintigraphy and ultrasound was higher-97.4%, 83.3%, and 95.6%, respectively.

Conclusions: The combination of MIBI and US appears promising for localizing parathyroid pathology in patients with primary hyperparathyroidism. The concordance rate is high together with a lower chance of missing concomitant thyroid pathology, which might alter the surgical approach.

Enhancing Parathyroid Gland Visualization Using a Near Infrared Fluorescence-Based Overlay Imaging System

BACKGROUND

Misidentifying parathyroid glands (PGs) during thyroidectomies or parathyroidectomies could significantly increase postoperative morbidity. Imaging systems based on near infrared autofluorescence (NIRAF) detection can localize PGs with high accuracy. These devices, however, depict NIRAF images on remote display monitors, where images lack spatial context and comparability with actual surgical field of view. In this study, we designed an overlay tissue imaging system (OTIS) that detects tissue NIRAF and back-projects the collected signal as a visible image directly onto the surgical field of view instead of a display monitor, and tested its ability for enhancing parathyroid visualization.

STUDY DESIGN

The OTIS was first calibrated with a fluorescent ink grid and initially tested with parathyroid, thyroid, and lymph node tissues ex vivo. For in vivo measurements, the surgeon's opinion on tissue of interest was first ascertained. After the surgeon looked away, the OTIS back-projected visible green light directly onto the tissue of interest, only if the device detected relatively high NIRAF as observed in PGs. System accuracy was determined by correlating NIRAF projection with surgeon's visual confirmation for in situ PGs or histopathology report for excised PGs.

RESULTS

The OTIS yielded 100% accuracy when tested ex vivo with parathyroid, thyroid, and lymph node specimens. Subsequently, the device was evaluated in 30 patients who underwent thyroidectomy and/or parathyroidectomy. Ninety-seven percent of exposed tissue of interest was visualized correctly as PGs by the OTIS, without requiring display monitors or contrast agents.

CONCLUSIONS

Although OTIS holds novel potential for enhancing label-free parathyroid visualization directly within the surgical field of view, additional device optimization is required for eventual clinical use.

The diagnostic value of parathyroid hormone washout in primary hyperparathyroidism patients with negative or equivocal 99 m Tc-MIBI results

BACKGROUND AND OBJECTIVES

The accurate identification of hyper functioning parathyroid gland is needed for definitive surgical treatment in primary hyperparathyroidism. Ultrasonography and 99mTechnetium sestamibi scintigraphy are the two most used methods with varying sensitivities. This study aimed to assess the value of parathyroid hormone (PTH) assay in preoperative ultrasound guided fine needle aspiration (FNA)-PTH washout fluid to verify the correct localisation of lesions with negative or inconclusive scintigraphy results.

METHODS

We evaluated data of 28 lesions in 21 patients who underwent US-guided parathyroid fine-needle aspiration (FNA) with PTH washout, retrospectively. The PTH washout results and the reports of parathyroid surgery and imaging studies were reviewed.

RESULTS

Of operated 28 lesions 23 had positive and 5 had negative washout results. The median FNA-PTH washout was 2315.5 pg/ ml (min-max: 12.3-6978 pg/ ml). The calculated sensitivity of FNA-PTH washout was 85.7% and the specifity was 28.6%. The positive and negative predictive values were 78.3% and 40.0%, respectively.

CONCLUSIONS

FNA-PTH can be used to establish the nature of the lesion, discriminate parathyroid gland from thyroid lesions or cervical lymph nodes, improving the surgical outcomes. It can be used to localise parathyroid lesions preoperatively when negative or discordant ultrasound and scintigraphy findings are obtained.

[18F]Fluorocholine Uptake of Parathyroid Adenoma Is Correlated with Parathyroid Hormone Level

PURPOSE

The aim of the study was to investigate the relationship between [¹⁸F]fluoromethyl-dimethyl-2-hydroxyethylammonium ([¹⁸F]FCh) positron emission tomography (PET) parameters, laboratory parameters, and postoperative histopathological results in patients with primary hyperparathyroidism (pHPT) due to parathyroid adenomas.

PROCEDURES

This retrospective study was conducted in 52 patients with biochemically proven pHPT. [¹⁸F]FCh-PET parameters (maximum standardized uptake value: SUV_max) in early phase (after 2 min) and late phase (after 50 min), metabolic volume, and adenoma-to-background ratio (ABR), preoperative laboratory results (PTH and serum calcium concentration), and postoperative histopathology (location, size, volume, and weight of adenoma) were assessed. Relationship of PET parameters, laboratory parameters, and histopathological parameters was assessed using the Mann-Whitney U test and Spearman correlation coefficient. MRI characteristics of parathyroid adenomas were also analyzed.

RESULTS

The majority of patients underwent a PET/MR scan, 42 patients (80.7 %); 10 patients (19.3 %) underwent PET/CT. We found a strong positive correlation between late-phase SUV_max and preoperative PTH level (r = 0.768, p < 0.001) and between late-phase ABR and preoperative PTH level (r = 0.680, p < 0.001). The surgical specimen volume was positively correlated with the PET/MR lesion volume (r = 0.659, p < 0.001). No significant association was observed between other [¹⁸F]FCh-PET parameters, laboratory parameters, and histopathological findings. Cystic adenomas were larger than non-cystic adenomas (p = 0.048).

CONCLUSIONS

[¹⁸F]FCh uptake of parathyroid adenomas is strongly correlated with preoperative PTH serum concentration. Therefore, the preoperative PTH level might potentially be able to predict success of [¹⁸F]FCh-PET imaging in hyperparathyroidism, with higher lesion-to-background ratios being expected in patients with high PTH. PET/MR is accurate in estimating the volume of parathyroid adenomas.

Selective venous sampling supports localization of adenoma in primary hyperparathyroidism

Background

Selective venous sampling (SVS) is an invasive localization study for persistent or recurrent hyperparathyroidism.

Purpose

To assess the role of SVS in addition to non-invasive imaging for primary hyperparathyroidism (pHPT).

Material and Methods

This study was approved by the institutional review board and included 14 patients who underwent SVS and subsequent parathyroidectomy between January 2014 and April 2017 following a clinical diagnosis of pHPT. All patients underwent pre-SVS non-invasive imaging, including ultrasound, computed tomography (CT), and ^99mTc-MIBI scintigraphy, and sensitivity was assessed using the operative and pathological findings.

Results

In all but one case, a single parathyroid adenoma was responsible for the pHPT; the remaining case exhibited a chemical response following surgical removal of parathyroid tissue. The sensitivity (%) for ultrasound, CT, ^99mTc-MIBI scintigraphy, and SVS was 76.9, 84.6, 69.2, and 76.9, respectively. SVS yielded positive results in four patients with discordant results and one patient with non-detectable results on imaging. In seven patients, a significant increase in the intact parathyroid hormone level was recognized only in the thyroid veins. The procedure time was in the range of 52–183 min (median = 89.5 min).

Conclusion

The addition of SVS to a non-invasive imaging study would be helpful to locate the responsible lesion of pHPT with discordant or non-detectable results on imaging for initial surgical treatment as well.

Localization of parathyroid adenomas using 11C-methionine pet after prior inconclusive imaging

PURPOSE

Minimally invasive parathyroidectomy (MIP) is the recommended treatment in primary hyperparathyroidism (pHPT) for which accurate preoperative localization is essential. The current imaging standard consists of cervical ultrasonography (cUS) and MIBI-SPECT/CT. 11C-MET PET/CT has a higher resolution than MIBI-SPECT/CT. The aim of this study was to determine the diagnostic performance of 11C-MET PET/CT after initial inconclusive or negative localization.

METHODS

We performed a retrospective single center cohort study of patients with pHPT undergoing parathyroid surgery after prior negative imaging and later localization by means of 11C-MET PET/CT between 2006 and 2014. Preoperative localization by 11C-MET PET/CT was compared with later surgical localization, intraoperative quick PTH (IOPTH), duration of surgery, histopathology, and follow-up data. Also, differences in duration of surgery between the groups with and without correct preoperative localization were analyzed.

RESULTS

In 18/28 included patients a positive 11C-MET-PET/CT result corresponded to the surgical localized adenoma (64%). In 3/28 patients imaging was false positive and no adenoma was found. In 7/28 patients imaging was false negative at the side of the surgically identified adenoma. Sensitivity of 11C-MET PET/CT was 72% (18/25). Duration of surgery of correctly localized patients was significantly shorter compared to falsely negative localized patients (p = 0.045).

CONCLUSION

In an intention to treat 11C-MET-PET/CT correctly localized the parathyroid adenoma in 18/28 (64%) patients, after previous negative imaging. A preoperatively correct localized adenoma leads to a more focused surgical approach (MIP) potentially reducing duration of surgery and potentially healthcare costs.

The Significance of 18F-Fluorocholine-PET/CT as Localizing Imaging Technique in Patients with Primary Hyperparathyroidism and Negative Conventional Imaging

OBJECTIVE

The essential prerequisite for focused parathyroidectomy in patients with primary hyperparathyroidism (pHPT) is proper localization of all autonomic tissue. Sensitivity of conventional imaging modalities (ultrasound, ^99mTc-sestamibi scintigraphy/SPECT/CT) is influenced by different factors (i.e., size/weight and position of autonomic tissue) and decreases in the presence of a multinodular goiter. Therefore, a considerable percentage of pHPT patients have negative or equivocal localization studies before surgery. The aim of this study is to evaluate the utility of FCH-PET/CT for preoperative localization in patients with pHPT and negative/equivocal ^99mTc-sestamibi scintigraphy/SPECT/CT and/or ultrasound.

METHODS AND MEASUREMENTS

Between 2014 and 2017, a total of 39 patients with pHPT and negative/equivocal conventional imaging were referred for FCH-PET/CT. In the analysis, we included those (n = 23) who had surgery and a histopathologic workup of the lesions.

RESULTS

19 of 23 patients demonstrated no tracer uptake with ^99mTc-sestamibi scintigraphy/SPECT/CT, 6 patients had an equivocal sonographic lesion, and multinodular goiter was present in 43% (10/23). In 21 of 23 patients, hyperfunctioning parathyroid tissue was identified correctly by FCH-PET/CT [21 true positive, 1 false negative, and 1 false positive; per-patient sensitivity 95.5% (95% confidence interval {CI}, 77.2-99.9)]. 29 lesions were resected [21 true positives, 3 false negatives, 1 false positive, and 4 true negatives; per-lesion sensitivity 87.5% (95% CI, 67.6-97.3)]. All patients were classified as having surgical success according to a decrease of intraoperative parathyroid hormone of ≥50% and normalization of postoperative serum calcium levels.

CONCLUSION

Despite a high prevalence of multinodular goiter, diagnostic accuracy of FCH-PET/CT in our patient group was excellent. Therefore, FCH-PET/CT is a promising new imaging tool in patients with pHPT and negative/equivocal results by conventional imaging techniques.

Impact of preoperative imaging on surgical approach for primary hyperparathyroidism: Data from single institution in India

CONTEXT

Preoperative localization of parathyroid adenoma is essential in deciding the surgical approach of parathyroidectomy.

AIM

To describe clinical and biochemical profile, evaluate preoperative imaging modalities and surgical approach in patients with primary hyperparathyroidism (PHPT).

METHODOLOGY

This was a retrospective study conducted at the single institution. All patients who underwent evaluation and surgery for PHPT from 2011 to 2015 were included in the study.

RESULTS

A total of 100 patients underwent surgery for PHPT. Mean (standard deviation) age was 51.6 (15.9) years with female to male ratio of 1.7:1. Forty patients had severe symptoms, and sixty had mild to moderate symptoms. The sensitivity of technetium-99m hexakis (2-methoxyisobutylisonitrile) (MIBI) scan and ultrasonography (USG) neck in identifying abnormal parathyroid gland was 93% (93/100) and 98% (98/100), respectively. The MIBI scan results of 90/93 (96.7%) patients corresponded with their surgical findings whereas preoperative USG findings of 96/98 patients (98%) showed correlation with operative findings. Intraoperative intact parathyroid hormone (IOPTH) levels at 10 min postexcision were measured in forty patients (minimally invasive parathyroidectomy = 38, bilateral neck exploration = 1, and unilateral neck exploration = 1). All patients except two had <50% fall in IOPTH. Adenoma weight was positively correlated with preoperative intact PTH.

CONCLUSION

We found that USG has higher sensitivity (98%) than MIBI scan (93%) in localizing abnormal parathyroid gland. Moreover, USG had a higher preoperative localization accuracy (93%) than MIBI scan (90%), allowing to choose an appropriate surgical approach. A higher proportion of patients (60%) had mild/asymptomatic form of PHPT.

Evaluation of the minimally invasive parathyroidectomy in patients with primary hyperparathyroidism: A retrospective cohort study

Introduction

An accurate differential diagnosis between single adenoma (SA) and multiglandular disease (MGD) remains difficult in Technetium-99m sestamibi scintigraphy (MIBI)-negative patients with primary hyperparathyroidism (PHPT). The aim of the present study was to evaluate the minimally invasive parathyroidectomy (MIP) in patients with PHPT.

Methods

Clinical records of 48 patients who underwent neck exploration between November 2002 and June 2012 in Kochi Medical School Hospital were reviewed retrospectively to identify candidates that underwent for MIP which was defined as the selective removal of a SA using less invasive surgery.

Results

The preoperative detection rate of lesions using ultrasonography, MIBI, computed tomography, and magnetic resonance imaging was 90%, 83%, 76%, and 55%, respectively. Although all 39 patients in the MIBI-positive group were diagnosed with an SA and subsequently underwent curative MIP, 3 patients in MIBI-negative group (n = 6) were MGD, who underwent neck exploration. Preoperative mean intact parathyroid hormone (419 pg/ml vs. 149 pg/ml; P < 0.01) and alkaline phosphatase levels (746 U/l vs. 277 U/l; P < 0.01) were significantly higher in the SA than MGD group.

Conclusions

In MIBI-negative patients with indications for surgery, MIP should not be carried out without a clear localization of SA, or in MGD.

•

We examined diagnostic accuracy for 48 patients with primary hyperparathyroidism.

•

All 39 patients in the MIBI-positive group were diagnosed with a single adenoma.

•

The preoperative diagnostic accuracy in MIBI-negative patients was only 50%.

•

We advise minimally invasive parathyroidectomy is avoided in MIBI-negative patients.

A rare case of giant parathyroid adenoma presenting with recurrent episodes of pancreatitis

Parathyroid adenomas are usually small in size; (weighing 70 mg–1 g) those weighing more than 2–3 g are classified as giant parathyroid adenomas. Giant parathyroid adenomas are in fact rarely encountered among patients with primary hyperparathyroidism. They are believed to have distinct clinical and biochemical features related to specific genomic alterations. We chanced to manage a unique and possibly the first case of giant parathyroid adenoma (6 cm diameter and weighing 20 g) presenting with recurrent episodes of pancreatitis and discuss its surgical management with an added emphasis on the role of nuclear imaging in its preoperative localization. Our case demonstrates that clinicians should have a high index of suspicion of primary hyperparathyroidism in patients presenting with recurrent episodes of pancreatitis. Timely diagnosis, appropriate preoperative localization techniques, which would include a parathyroid scintigraphy and a focused surgical intervention are crucial to resolve complications and improve outcomes.

Parathyroid surgery: correlation between pre-operative localization studies and surgical outcomes

OBJECTIVE

Pre-operative imaging techniques have enabled minimally invasive parathyroid surgery to supersede the traditional approach to hyperparathyroidism (HPT) surgery, which included cervical exploration. Cervical ultrasound (US) and sestamibi scan (MIBI) are commonly performed, but the results of these localization tests do not always match. This study correlated surgical outcomes with pre-operative localization findings, including matched positive US and MIBI studies, one positive study (US or MIBI), conflicting studies or negative results.

DESIGN

Retrospective medical record review.

PATIENTS

A hundred and sixty nine consecutive patients who underwent parathyroidectomy from January 2005 to December 2012.

MEASUREMENTS

Correlation between surgical outcomes and pre-operative localization tests.

RESULTS

All patients (134F/35M, 59·6 ± 13·5 years of age) had primary HPT. US and MIBI localization studies matched in 76%, whereas 10·7% had positive MIBI only and 8·3% US only. Studies were negative in 3·6% and contradictory in 1·8%. Minimally invasive parathyroidectomy was performed in 87% of the matched group and 89% of the MIBI-only group. Surgical success rate, defined as postoperative normalization of calcium and PTH levels, was similar in patients with a single positive study (MIBI or US) vs double-matched studies (MIBI and US). Patients were followed up for 6 weeks. Overall, pathology was consistent with adenoma in 95%.

DISCUSSION

Parathyroidectomy success rate was similar in patients with primary HPT and MIBI-only or US-only positive localization studies compared to those with matched US/MIBI studies. The results support a clinical algorithm in which positive results from one imaging technique, either MIBI or US, are sufficient to refer a patient for parathyroid surgery.

A Pilot Comparison of 18F-fluorocholine PET/CT, Ultrasonography and 123I/99mTc-sestaMIBI Dual-Phase Dual-Isotope Scintigraphy in the Preoperative Localization of Hyperfunctioning Parathyroid Glands in Primary or Secondary Hyperparathyroidism: Influence of Thyroid Anomalies

We compared (18)F-fluorocholine hybrid positron emission tomography/X-ray computed tomography (FCH-PET/CT) with ultrasonography (US) and scintigraphy in patients with hyperparathyroidism and discordant, or equivocal results of US and (123)I/(99m)Tc-sesta-methoxyisobutylisonitrile (sestaMIBI) dual-phase parathyroid scintigraphy. FCH-PET/CT was performed in 17 patients with primary (n = 11) lithium induced (n = 1) or secondary hyperparathyroidism (1 dialyzed, 4 renal-transplanted).The reference standard was based on results of surgical exploration and histopathological examination. The results of imaging modalities were evaluated, on site and by masked reading, on per-patient and per-lesion bases.In a first approach, equivocal images/foci were considered as negative. On a per-patient level, the sensitivity was for US 38%, for scintigraphy 69% by open and 94% by masked reading, and for FCH-PET/CT 88% by open and 94% by masked reading. On a per-lesion level, sensitivity was for US 42%, for scintigraphy 58% by open and 83% by masked reading, and for FCH-PET/CT 88% by open and 96% by masked reading. One ectopic adenoma was missed by the 3 imaging modalities. Considering equivocal images/foci as positive increased the accuracy of the open reading of scintigraphy or of FCH-PET/CT, but not of US. FCH-PET/CT was significantly superior to US in all approaches, whereas it was more sensitive than scintigraphy only for open reading considering equivocal images/foci as negative (P = 0.04). FCH uptake was more intense in adenomas than in hyperplastic parathyroid glands. Thyroid lesions were suspected in 9 patients. They may induce false-positive results as in one case of oncocytic thyroid adenoma, or false-negative results as in one case of intrathyroidal parathyroid adenoma. Thyroid cancer (4 cases) can be visualized with FCH as with (99m)Tc-sestaMIBI, but the intensity of uptake was moderate, similar to that of parathyroid hyperplasia.This pilot study confirmed that FCH-PET/CT is an adequate imaging tool in patients with primary or secondary hyperparathyroidism, since both adenomas and hyperplastic parathyroid glands can be detected. The sensitivity of FCH-PET/CT was better than that of US and was not inferior to that of dual-phase dual-isotope (123)I/(99m)Tc-scintigraphy. Further studies should evaluate whether FCH could replace (99m)Tc-sestaMIBI as the functional agent for parathyroid imaging, but US would still be useful to identify thyroid lesions.

Incidentalomas during imaging for primary hyperparathyroidism--incidence and clinical outcomes

Background

Imaging for pre-operative localisation of parathyroid glands in primary hyperparathyroidism is now routine. This has led to the detection of incidental lesions (incidentalomas) in other organs, the nature of which is not well characterised.

The aim of this study was to determine the incidence, characteristics and outcomes in patients who had incidental findings on parathyroid imaging.

Methods

Records of patients who underwent imaging for primary hyperparathyroidism over 2 years were reviewed to identify incidental lesions detected on parathyroid imaging. Patients with persistent or renal hyperparathyroidism were excluded. Details on the management of detected incidentalomas were obtained from patient records.

Results

Incidentalomas were identified in 17 of 170 patients (10 %) undergoing parathyroid imaging. Incidentalomas included thyroid (n = 11), breast (n = 3), lateral compartment of the neck (n = 1), lung (n = 1) and clavicle (n = 1). However, no disease of clinical significance needing treatment was detected on further investigation.

Conclusions

Although a significant proportion of patients undergoing parathyroid imaging had incidental lesions detected, these seem to be of little clinical significance. The morbidity and cost of further interventions on these incidentalomas need to be weighed against the benefits of routine imaging in improving outcomes of first-time surgery in patients with primary hyperparathyroidism.

Radiographic evaluation of non-localizing parathyroid adenomas

PURPOSE

Patients with primary hyperparathyroidism routinely undergo preoperative imaging to localize the abnormal gland to facilitate a guided parathyroidectomy. These techniques include neck ultrasound (US), dual phase planar technetium-99m ((99m)TC) sestamibi (MIBI) scans, single photon emission computed tomography (SPECT), combined SPECT/CT, and four dimensional CT scans (4D CT). Despite appropriate preoperative imaging, non-localization of abnormal glands does occur. This study aims to determine whether non-localization is the result of radiologic interpretive error or a representation of a subset of truly non-localizing parathyroid adenomas.

MATERIALS AND METHODS

A retrospective study was performed; two senior radiologists reinterpreted the preoperative imaging (US and MIBI scans) of 30 patients with initially non-localizing studies. All patients underwent parathyroidectomy for primary hyperparathyroidism at a tertiary referral center. Both radiologists were blinded to the scores of his colleague. The results were compared for inter-reader reliability using Cohen's kappa test.

RESULTS

Twenty-nine of thirty nuclear studies were found to be negative on reinterpretation. The readers agreed in 86.67% of their observations, with a kappa (κ) value of 0.706 (SE=±0.131, 95% confidence interval for κ =0.449-0.962). One of eighteen ultrasounds had positive localizations on reexamination, however, the inter-observer agreement was only 55.6%, with a kappa value of 0.351 (SE=±0.139, and 95% confidence interval for κ =0.080-0.623). Overall, no statistically significant difference in preoperative and retrospective interpretation was found.

CONCLUSION

This study identifies a subset of parathyroid adenomas that do not localize on preoperative imaging despite sound radiographic evaluation.

Primary hyperparathyroidism: an analysis of failure of parathyroidectomy

BACKGROUND

Preoperative imaging in patients undergoing surgery for primary hyperparathyroidism (PHPT) is used primarily to facilitate targeted parathyroidectomy. Failure of preoperative localisation mandates a bilateral exploration. It is thought that the results of imaging may also predict the success of surgery. The aims of this study were to assess whether the findings on preoperative localisation influenced outcomes following parathyroidectomy for PHPT and to explore factors underlying failure to cure at surgery.

METHODS

We analysed outcomes of all patients who underwent first-time surgery for PHPT in two centres over a 5-year period to determine an association with demographic characteristics and findings on preoperative imaging. Records of patients not cured by initial surgery were reviewed to explore factors underlying failure to cure.

RESULTS

The failure rate (persistent disease) in the entire cohort was 5 % (25/541) (bilateral neck explorations, 5 %; unilateral exploration, 7 %; targeted approach, 4 %), while two patients developed recurrent disease. In patients who had undergone dual imaging with an ultrasound scan and (99m)Tc-sestamibi scintigraphy, failure rates with "lateralised and concordant" imaging, "nonconcordant" imaging, and "dual-negative" imaging were 2, 9, and 11 %, respectively (p = 0.01). Of the 25 patients with persistent disease, multigland disease (MGD) was present in 52 % (13/25) and ectopic adenoma in 24 % (6/12).

CONCLUSIONS

Patients with PHPT who do not have lateralised and concordant dual imaging are at higher risk of persistent disease. A significant proportion of failures are due to the inability to recognise the presence and/or extent of MGD.

Localization of ectopic and supernumerary parathyroid glands in patients with secondary and tertiary hyperparathyroidism: surgical description and correlation with preoperative ultrasonography and Tc99m-Sestamibi scintigraphy

Introdução

O hiperparatireoidismo é uma consequência metabólica esperada na doença renal crônica (DRC). Paratireoides (PT) ectópicas e/ou supranumerárias podem ser causa de falha cirúrgica nos pacientes submetidos à paratireoidectomia total (PTX).

Objetivo

Definir cirurgicamente a localização das PT, em pacientes com hiperparatireoidismo associado à DRC, correlacionar esses achados com os exames pré-operatórios.

Materiais e métodos

Foi conduzido um estudo retrospectivo com 166 pacientes submetidos à PTX. A localização das PT no intraoperatório foi registrada, sendo classificada como tópica ou ectópica. A localização pré-operatória, definida pela ultrassonografia (USG) e pela cintilografia Tc99m-Sestamibi (MIBI), foi comparada com aos achados cirúrgicos.

Resultados

Nos 166 pacientes, foram identificadas 664 PT. Foram classificadas como tópicas e ectópicas 577 (86,4%) e 91(13,6%) glândulas, respectivamente. Oito PT supranumerárias foram encontradas (7 tópicas e 1 ectópica). As localizações mais comuns de PT ectópicas foram as regiões retroesofágica e tímica. Associadas, a USG e a MIBI não identificaram 56 glândulas (61,5%) ectópicas. Entretanto, a MIBI foi positiva para 69,7% daquelas localizadas nas regiões tímicas e mediastinal.

Conclusão

A presença de glândulas ectópicas e supranumerárias em pacientes com hiperparatireoidismo associado à DRC é significativa. Os exames de imagem pré-operatórios não localizaram a maioria das glândulas ectópicas. A MIBI pode ter importância na identificação de PT nas regiões tímica e mediastinal.

Strategy of operative treatment of hyperparathyroidism using US scan and (99m)Tc-MIBI SPECT/CT

We evaluated the efficacy of technetium-sestamibi ((99m) Tc-MIBI) SPECT/CT for planning parathyroidectomy in cases with primary hyperparathyroidism (pHPT), comparing with planar scintigraphy and ultrasound (US), in an aim to establish the proper surgical strategy according to the preoperative imaging studies. A retrospective review of consecutive 75 pHPT patients who had been operated on was conducted. The results of preoperative imaging modalities and the operative finding were analyzed. Seven cases were found to have multiple hyperplastic glands, and no responsible gland was found in three cases. Four cases underwent only US scan for preoperative imaging. Remaining 61 cases were found to have single adenoma, and were included in the evaluation of localization imaging. US scan, (99m) Tc-MIBI planar scan and (99m) Tc-MIBI SPECT/CT showed accurate localization in 77.0% (47/61), 75.4% (46/61) and 88.5% (46/52) of the evaluable cases, respectively. US and (99m) Tc-MIBI planar scan demonstrated consistent result in 42 cases (68.9%), and those cases showed accurate localization in 90.5% (38/42). When both US and (99m) Tc-MIBI SPECT/CT was consistent, all 37 lesions had been correctly indicated. No clinico-pathological features were suggested to influence in demonstrating the localization, other than only (99m) Tc-MIBI SPECT/CT exhibited 100% sensitivity in ectopic glands. Combination of US and (99m) Tc-MIBI SPECT/CT certainly contributes to the planning of minimally invasive operation in cases with pHPT by indicating correct localization of single adenoma.