Imaging for primary hyperparathyroidism--what beginners should know

4DCT in Discordant Parathyroid Adenoma Scans: Case Series and Meta-Analysis

OBJECTIVE

To evaluate the accuracy of four-dimensional computerized-tomography (4DCT) for localizing parathyroid adenomas (PTAs) in cases with discordant or non-localizing ultrasonography (US) and Technetium-99 sestamibi (MIBI) scans.

DATA SOURCES

Retrospective case series and systematic review.

REVIEW METHODS

A case series and meta-analysis of patients diagnosed with primary hyperparathyroidism and discordant US and MIBI scans who underwent 4DCT prior to surgery. A comprehensive search for all relevant publications in the English literature between December 2006 and March 2022 was conducted for the meta-analysis. Patients undergoing parathyroidectomy between January 2015 and December 2021 were identified from the institutional electronic database for the case series. All studies were analyzed for sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the 4DCT adenoma localization capabilities.

RESULTS

Thirteen retrospective studies that included 379 patients and one case series that included 37 patients were identified and analyzed. A per-patient analysis revealed sensitivity for lateralization to the correct side (n = 181) ranging from 80% to 100% with a fixed effects model of 89% (95%confidence interval [CI]: 82%-93%) and a PPV for lateralization ranging from 63%-95% with a random effects model of 87% (95% CI: 77%-95%). Sensitivity of localization to the correct quadrant (n = 172) ranged from 53% to 100% with a random effects model of 90.4% (95% CI: 76%-99%), and the PPV for localization ranged from 52% to 100% with a random effects model of 82% (95% CI: 73%-89%).

CONCLUSION

4DCT enhances imaging capabilities of localizing PTAs in cases of discordant or non-localizing US and MIBI scans.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:2198-2205, 2024.

Localization of Ectopic Mediastinal Parathyroid Adenomas Using Indigo Carmine Injection for Surgical Management: A Preliminary Report

An ectopic parathyroid adenoma (EPA) is a rare entity. The aim of this study was to report our experience in the preoperative localization and surgical management of EPAs. This was a multicenter retrospective study involving patients diagnosed with an EPA (three males and seven females) from January 2005 to November 2021. The clinical features, preoperative management, and surgical procedures were analyzed. A cervical neck ultrasound was performed in all patients and showed a focus in eight patients. Cervicothoracic enhanced computed tomography was performed in all patients and showed a focus in nine patients. The ^99mTc-MIBI scintigraphy was performed in eight patients and showed uptake in six of them. We performed a neck dissection and thoracotomy in one patient, a thoracoscopy in one patient, surgery with a focused approach in seven patients, four of whom were injected with indigo carmine blue, and surgery with a bilateral approach in one patient. 1 h following the parathyroidectomy, the parathyroid hormone (PTH) concentration was decreased to 40–80% of the baseline value. Establishing a preoperative diagnosis of an EPA is challenging for the surgeon, despite the progress in the morphologic assessment. An intraoperative PTH assay and injection of indigo carmine have been shown to be valuable tools in the appropriate surgical management of an EPA.

Retro-tracheal parathyroid adenoma: A rare location of a common pathology

Ectopic parathyroid adenoma in the mediastinum has been reported in several publications; however, its location in the posterior mediastinum, especially a retro-tracheal location, has been rarely reported. We report a case of a 61-year-old patient who presented with clinical symptoms of malignant hypercalcemia due to a retro-tracheal mediastinal parathyroid adenoma. The surgical excision normalized the phosphocalcic balance with improvement in the patient's clinical symptoms. An ectopic hypersecreting parathyroid adenoma with life-threatening hypercalcemia should prompt radiological assessment and appropriate surgical management to prevent significant clinical complications.

Surgical implications of recent modalities for parathyroid imaging

Clinical or subclinical primary hyperparathyroidism (PHPT) is one of the most common endocrine disorders in the world. Parathyroidectomy is the treatment of choice in symptomatic patients, stabilizing the progression of complications caused by the destruction activity of parathyroid hormone (PTH). Parathyroid surgical techniques have evolved over the years from bilateral neck exploration, to minimally invasive single parathyroid gland exploration, to minimally invasive video-assisted parathyroidectomy. Localization of the abnormal parathyroid gland before surgery is crucial for the operation to be effective. Increased incidences of reoperations of the parathyroid glands and the rapid development of minimally invasive methods led to the development of new localization techniques. The noninvasive studies include ultrasound (US), computed tomography (CT), magnetic resonance (MR) and ^99mTc-methoxyisobutylisonitrile (MIBI) scintigraphy combined with single-photon emission CT (SPECT/CT). Among the latest technologies, the four-dimensional (4D)-CT scan, positron emission tomography (PET)/CT and PET/MR are very promising, and are going to have surgical implications in the future.

Imaging or Fiber Probe-Based Approach? Assessing Different Methods to Detect Near Infrared Autofluorescence for Intraoperative Parathyroid Identification

BACKGROUND

Near infrared autofluorescence (NIRAF) can guide intraoperative parathyroid gland (PG) identification. NIRAF detection devices typically rely on imaging and fiber probe-based approaches. Imaging modalities provide NIRAF pictures on adjacent display monitors, and fiber probe-based systems measure tissue NIRAF and provide real-time quantitative information to objectively aid PG identification. Both device types recently gained FDA approval for PG identification but have never been compared directly.

STUDY DESIGN

Patients undergoing thyroidectomy and/or parathyroidectomy were recruited prospectively. Target tissues were intraoperatively visualized with PDE-Neo II (imaging-based) and concurrently assessed with PTeye (fiber probe-based). For PDE-Neo II, NIRAF images were collected from in situ or excised tissues, alongside the surgeon's interpretation of visualized tissues, and retrospectively analyzed in a blinded fashion. The PTeye was concomitantly used to record NIRAF intensities and ratios from the same tissues in real time.

RESULTS

Twenty patients were enrolled for concurrent evaluation with both systems, which included 33 PGs and 19 nonparathyroid sites. NIRAF imaging demonstrated 90.9% sensitivity, 73.7% specificity, and 84.6% accuracy for PG identification when interpreted in real time by the surgeon compared with 81.8% sensitivity, 73.7% specificity, and 78.8% accuracy where images were quantitatively analyzed post hoc by an independent observer. In parallel, NIRAF detection with PTeye yielded 97.0% sensitivity, 84.2% specificity, and 92.3% accuracy in real time for the same specimens.

CONCLUSIONS

Both NIRAF-based systems were beneficial for identifying PGs intraoperatively. Although NIRAF imaging provides valuable spatial information to localize PGs, NIRAF detection with fiber probe provides real-time quantitative information to identify PGs in presence of ambient room lights.

The value of intraoperative parathyroid hormone assay in the surgery of mediastinal ectopic parathyroid adenoma (A case series)

Background and aims

Ectopic parathyroid adenoma is a rare entity. Its clinical management is challenging due to varying locations in the mediastinum. The aim of our study is to report our experience about the preoperative localization of the ectopic parathyroid adenoma and to emphasize the major role of the intraoperative parathyroid hormone assay in such circumstances.

Methods

It is a monocentric, retrospective study about patients diagnosed with EPA (ectopic parathyroid adenoma) from January 2015 to December 2016. Clinical aspects, preoperative management as well as the surgical procedures have been analyzed.

Results

There were 7 women, with an average age of 59.14 years. Six patients presented with biological disorders of the phosphocalcic metabolism such as spontaneous bone fracture and recurrent renal lithiasis. In one case, EPA was discovered in the setting of malignant hypercalcemia. The topographic preoperative assessment with a cervicothoracic CT (computed tomography) showed spontaneously hyperdense tissular masses of variable localizations in the mediastinum. A Tc-99 m (99mTc - MIBI) scintigraphy was performed in 5 patients and showed uptake in all cases. We performed cervicotomy in 1 case, manubriotomy in 2 patients, neck manubriotomy in 2 cases, total vertical sternotomy in 1 case, and posterolateral thoracotomy in 1 patient. The lesion was localized in the mediastinum in 1 patient in the perithymic fat in 1 case; EPA was laterotracheal in 1 case, retro tracheal in 1 case, intra-thymic in 2 cases, inter-jugulo-carotidian with contact with the left subclavial artery in 1 case, and anterior mediastinal in 1 patient. The 1-h after-parathormonemia following removal of the surgical specimens showed a decrease value of 45 and 80% of the baseline value. No surgical morbidity was noted after an average follow-up of 7.9 months (range of 5–18 months).

Conclusion

The preoperative topographic diagnosis of ectopic parathyroid adenoma is challenging for the surgeon despite progress in the morphological assessment. The intraoperative parathyroid hormone assay is a valuable tool for an appropriate surgical management.

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Thoracic surgeons faced difficulties in the management of ectopic parathyroid adenomas in the mediastinal location.

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The intraoperative assay of parathormonemia helps guide the surgeon in his strategy of complete excision of the ectopic parathyroid adenom

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Hypocalcemia is a constant postoperative complication and its absence may make questionnable the quality of the tumor resection.

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.

An Unusual Mass of Posterior Mediastinum: A Case of Retrotracheal Parathyroid Adenoma Presenting With Primary Hyperparathyroidism

Although parathyroid ectopy in the mediastinum has been the subject of several publications, its location in the posterior mediastinum is very rarely reported. We report a case of a 69-year-old patient who presented with clinical symptoms of malignant hypercalcemia due to a retrotracheal mediastinal parathyroid adenoma. The surgical excision leads to a quick normalisation of the phosphocalcic balance with improvement of the clinical symptoms. Ectopic hypersecreting parathyroid adenoma with life-threatening hypercalcemia should prompt radiological assessment and appropriate surgical management to prevent further clinical complications.

Innovative surgical guidance for label-free real-time parathyroid identification

BACKGROUND

Difficulty in identifying the parathyroid gland during neck operations can lead to accidental parathyroid gland excisions and postsurgical hypocalcemia. A clinical prototype called as PTeye was developed to guide parathyroid gland identification using a fiber-optic probe that detects near-infrared autofluorescence from parathyroid glands as operating room lights remain on. An Overlay Tissue Imaging System was designed concurrently to detect near-infrared autofluorescence and project visible light precisely onto parathyroid gland location.

METHODS

The PTeye and the Overlay Tissue Imaging System were tested in 20 and 15 patients, respectively, and a modified near-infrared imaging system was investigated in 6 patients. All 41 patients underwent thyroidectomy or parathyroidectomy. System accuracy was ascertained with surgeon's visual confirmation for in situ parathyroid glands and histology for excised parathyroid glands.

RESULTS

There was no observable difference between near-infrared autofluorescence of healthy and diseased parathyroid glands. The PTeye identified 98% of the parathyroid gland, whereas the near-infrared imaging system and the Overlay Tissue Imaging System identified 100% and 97% of the parathyroid glands, respectively.

CONCLUSION

The PTeye can guide in real-time parathyroid gland identification even with ambient operating room lights. The near-infrared imaging system performs parathyroid gland imaging with high sensitivity, whereas the Overlay Tissue Imaging System enhances parathyroid gland visualization directly within the surgical field without requiring display monitors. These label-free technologies can be valuable adjuncts for identifying parathyroid glands intraoperatively.

Developing a Clinical Prototype to Guide Surgeons for Intraoperative Label-Free Identification of Parathyroid Glands in Real Time

BACKGROUND

Patients undergoing thyroidectomy may have inadvertent damage or removal of the parathyroid gland(s) due to difficulty in real-time parathyroid identification. Near-infrared autofluorescence (NIRAF) has been demonstrated as a label-free modality for intraoperative parathyroid identification with high accuracy. This study presents the translation of that approach into a user-friendly clinical prototype for rapid intraoperative guidance in parathyroid identification.

METHODS

A laboratory (lab)-built spectroscopy system that measures NIRAF in tissue was evaluated for identifying parathyroid glands in vivo across 162 patients undergoing thyroidectomy and/or parathyroidectomy. Based on these results, a clinical prototype called PTeye was designed with a user-friendly interface and subsequently investigated in 35 patients. The performance of the lab-built system and the clinical prototype were concurrently compared side by side by a single user with 20 patients in each group. The influence of (i) intrapatient and interpatient variability of NIRAF in thyroid and parathyroid glands and (ii) thyroid and parathyroid pathology on intraoperative parathyroid identification were investigated. The effect of blood on NIRAF intensity of parathyroid and thyroid was tested ex vivo with the PTeye system to assess if a hemorrhagic surgical field would affect parathyroid identification. Accuracy of both systems were determined by correlating the acquired data with either visual confirmation by a surgeon for unexcised parathyroid glands or histology reports for excised parathyroid glands.

RESULTS

The overall accuracy of the lab-built system in guiding parathyroid identification was 92.5%, while the PTeye system achieved an accuracy of 96.1%. Unlike the lab-built system, the PTeye could guide parathyroid identification even as the operating room lights remained on and required only 25% of the laser power used by the lab-built setup. Parathyroid glands had elevated NIRAF intensity compared to thyroid and other neck tissues, regardless of thyroid or parathyroid pathology. Blood did not seem to affect tissue NIRAF measurements obtained with both systems.

CONCLUSION

In this study, the clinical prototype PTeye demonstrated high accuracy for label-free intraoperative parathyroid identification. The intuitive interface of the PTeye that can guide in identifying parathyroid tissue in the presence of ambient room lights suggests that it is a reliable and easy-to-use tool for surgical personnel.

Thoracoscopic approach in the treatment of ectopic thymic parathyroid adenoma

Primary hyperparathyroidism is overproduction of parathyroid hormone, causing hypercalcemia. Parathyroid adenomas have been found to be the etiology for 80% of cases of primary hyperparathyroidism, while almost a quarter of them are ectopic. We present a case of ectopic thymic parathyroid adenoma, treated by the thoracoscopic approach. Preoperative computed tomogram and technetium-99-sestamibi imaging showed an adenoma, located in the front mid-mediastinum, approximately 8 × 10 mm in size. Resection of the tumor was indicated according to the persistent hypercalcemia after unsuccessful surgical treatment performed 3 years ago. It was decided to perform a parathyroidectomy during thoracoscopy. The diagnosis of parathyroid adenoma was established on postoperative histopathology staining. The patient was discharged from hospital 5 days after the surgery. We found this minimally invasive operation to be an effective and well-tolerated treatment option, determined by the experience of the surgeon.

Value of 99mTc-MIBI SPECT/CT parathyroid imaging and ultrasonography for concomitant thyroid carcinoma

PURPOSE

We aimed to assess the frequency of carcinoma in cases with suspected parathyroid adenoma and test the value of Tc-methoxyisobutylisonitrile (Tc-MIBI) single-photon emission computed tomography/computed tomography (SPECT/CT) parathyroid imaging and neck ultrasonography in detecting concomitant thyroid carcinoma.

PATIENTS AND METHODS

We enrolled 741 patients with clinically suspected parathyroid adenoma who underwent Tc-MIBI planer scans and SPECT/CT of the skull base, neck, and thorax; patients also underwent ultrasonography within 1 month before SPECT/CT. Each case with suspected lesion was analyzed and correlated with pathology. We estimated the frequency of carcinoma detection on SPECT/CT performed for suspected parathyroid adenoma. The sensitivity, specificity, and accuracy of detecting thyroid carcinoma were estimated for both SPECT/CT and ultrasonography.

RESULTS

In total, 222 patients with 250 pathology results were assessed. Of these, 54 patients showed carcinoma. With respect to the anatomical distribution of the incidental findings, 19 (35.19%) had parathyroid carcinoma, 20 (37.04%) had papillary thyroid carcinoma, three (5.56%) had follicular thyroid carcinoma, six (11.11%) had medullary thyroid carcinoma, and six (11.11%) had other carcinomas. For thyroid carcinoma detection, the sensitivity, specificity, and accuracy were 35.71, 88.16, and 80.49% for SPECT/CT and 73.81, 95.10, and 91.99% for ultrasonography, respectively.

CONCLUSION

The frequency of carcinoma is high on Tc-MIBI SPECT/CT performed for suspected parathyroid adenoma. Although Tc-MIBI SPECT/CT plays an important role in the diagnosis and location of parathyroid adenoma, ultrasonography appears to be more suitable for identifying a concomitant thyroid carcinoma. This may vitally influence the choice of therapeutic regimen in patients with primary hyperparathyroidism.

18F-Fluorocholine PET/CT in the assessment of primary hyperparathyroidism compared with 99mTc-MIBI or 99mTc-tetrofosmin SPECT/CT: a prospective dual-centre study in 100 patients

Purpose

In this prospective study we compared the accuracy of ¹⁸F-fluorocholine PET/CT with that of ^99mTc-MIBI or^99mTc-tetrofosmin SPECT/CT in the preoperative detection of parathyroid adenoma in patients with primary hyperparathyroidism. We also assessed the value of semiquantitative parameters in differentiating between parathyroid hyperplasia and adenoma.

Methods

Both ¹⁸F-fluorocholine PET/CT and ^99mTc-MIBI/tetrofosmin SPECT/CT were performed in 100 consecutive patients with biochemical evidence of primary hyperparathyroidism. At least one abnormal focus on either ¹⁸F-fluorocholine or ^99mTc-MIBI/tetrofosmin corresponding to a parathyroid gland or ectopic parathyroid tissue was considered as a positive finding. In 76 patients with positive findings on at least one imaging modality, surgical exploration was performed within 6 months, and the results were related to histopathological findings and clinical and laboratory findings at 3–6 months as the standard of truth. In 24 patients, no surgery was performed: in 18 patients with positive imaging findings surgery was refused or considered risky, and in 6 patients imaging was negative. Therefore, data from 82 patients (76 undergoing surgery, 6 without surgery) in whom the standard of truth criteria were met, were used in the final analysis.

Results

All patients showed biochemical evidence of primary hyperparathyroidism with a mean serum calcium level of 2.78 ± 0.34 mmol/l and parathormone (PTH) level of 196.5 ± 236.4 pg/ml. The study results in 76 patients with verified histopathology and 3 patients with negative imaging findings were analysed. Three of six patients with negative imaging showed normalized serum PTH and calcium levels on laboratory follow-up at 3 and 6 months, and the results were considered true negative. In a patient-based analysis, the detection rate with ¹⁸F-fluorocholine PET/CT was 93% (76/82), but was only 61% (50/82) with ^99mTc-MIBI/tetrofosmin SPECT/CT. In a lesion-based analysis, the sensitivity, specificity, positive predictive value, negative predictive value and overall accuracy of ¹⁸F-fluorocholine PET/CT in the detection of parathyroid adenoma were 93.7%, 96.0%, 90.2%, 97.4% and 95.3%, respectively, and of ^99mTc-MIBI/tetrofosmin SPECT/CT were 60.8%, 98.5%, 94.1%, 86.3% and 87.7%, respectively. Although ¹⁸F-fluorocholine PET-positive adenomatous lesions showed higher SUVmax values than the hyperplastic glands (6.80 ± 3.78 vs. 4.53 ± 0.40) in the semiquantitative analysis, the difference was not significant (p = 0.236). The mean size (measured as the length of the greatest dimension) and weight of adenomas were 15.9 ± 7.6 mm (median 15 mm, range 1–40 mm) and 1.71 ± 1.86 g (median 1 g, range: 0.25–9 g), respectively. Among the analysed parameters including serum calcium and PTH and the size and weight of parathyroid adenomas, size was significantly different between patients with negative ^99mTc-MIBI/tetrofosmin SPECT/CT and those with positive ^99mTc-MIBI/tetrofosmin SPECT/CT (mean size 13.4 ± 7.6 mm vs. 16.9 ± 7.4 mm, respectively; p = 0.042).

Conclusion

In this prospective study, ¹⁸F-fluorocholine PET/CT showed promise as a functional imaging modality, being clearly superior to ^99mTc-MIBI/tetrofosmin SPECT/CT, especially in the detection and localization of small parathyroid adenomas in patients with primary hyperparathyroidism. SUVmax was higher in parathyroid adenomas than in hyperplasia. However, further evaluation of this modality is needed.

The Significance of Ultrasound in Determining Whether SHPT Patients Are Sensitive to Calcitriol Treatment

This study was to explore the significance of ultrasound in determining whether the patients with secondary hyperparathyroidism (SHPT) are sensitive to calcitriol treatment. According to the decrease value of parathyroid hormone (PTH), 42 SHPT patients were divided into two groups: drug susceptible group and drug insusceptible group. These 42 SHPT patients' ultrasound images were retrospectively analyzed. The morphology, size, number, blood flow, elastic modulus, and perfusion of the parathyroid glands were correlated with drug therapeutic outcome (oral calcitriol). Most SHPT patients with drug susceptible showed volume <438.50 mm³ and number ≤2, with 0-1 structural and vascular patterns, associated with Relative Maximum Intensity (RIMAX) <1.59 and elastic modulus <18.8 kPa, whereas most SHPT patients with drug insusceptible showed volume ≥438.50 mm³ and number ≥3, with 2-3 structural and vascular patterns, associated with Relative Maximum Intensity (RIMAX) ≥1.59 and elastic modulus ≥18.8 kPa. Therefore, ultrasonography in SHPT allows an accurate definition of the morphology, size, number, blood flow, elastic modulus, and perfusion of the parathyroid glands and is useful in determining whether SHPT patients are sensitive to calcitriol treatment.

Comparison of Tc-99m pertechnetate images with dual-phase Tc 99m MIBI and SPECT images in primary hyperparathyroidism

BACKGROUND

The purpose of this study was to evaluate the value of Tc-99m pertechnetate planar, dual-phase MIBI and MIBI-SPECT images in the determination and localization of parathyroid lesions.

MATERIALS AND METHODS

In this study, 38 patients who underwent operation for primary hyperparathyroidism were included. Tc-99m pertechnetate planar-pinhole imaging of the neck and then MIBI planar and SPECT images in supine position was performed. Late SPECT images were acquired 120 minutes after the injection. Early and late MIBI images were quantitatively evaluated.

RESULTS

Of the 38 patients, 30 of them had adenoma, 2 patients had hyperplasia and 6 of them were normal on planar images. Thirty-four of 38 patients were positive on SPECT images. SPECT images of the patients with positive results were matched with pathology results.

CONCLUSION

As a result, Tc-99m pertechnetate planar-pinhole, Tc-99m MIBI planar and SPECT images are useful for localization of parathyroid lesions especially in multinodular thyroid gland. However, US or CT images are necessary for more accurate localization and Tc-99m pertechnetate images are useful for interpreting and comparing with the early and late MIBI images.

Thoracoscopic removal of ectopic mediastinal parathyroid adenoma

Ectopic mediastinal parathyroid adenomas or hyperplasias account for up to 25% of primary hyperparathyroidism cases. Most abnormal parathyroid glands are found in the superior mediastinum within the thymus and can be removed through a cervical incision; however, a few of these glands are not accessible using standard cervical surgical approaches. Surgical resection has traditionally been performed via median sternotomy or thoracotomy. However, recent advancement in video-assisted thoracic surgery techniques has decreased the need for sternotomy or thoracotomy to remove these ectopic parathyroid glands. Here, we report a successful case of video-assisted thoracoscopic removal of a mediastinal parathyroid adenoma.

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.

Surgical treatment of primary hyperparathyroidism: description of techniques and advances in the field

Primary hyperparathyroidism is a disease commonly seen in patients above 60 years of age. It is the most common cause of asymptomatic or symptomatic hypercalcemia, usually found incidentally on routine check-ups. Surgical treatment is the only definitive treatment of choice in the symptomatic patient; however, it can also be employed in asymptomatic patients. First described in 1925, bilateral neck exploration is the gold standard of treatment for primary hyperparathyroidism. The recent interest in minimally invasive surgeries has led to better and improved techniques of neck exploration with improved cosmetic results and lesser chances of transient or permanent hypoparathyroidism due to inadvertent removal of normally functioning parathyroid tissue. These include unilateral neck explorations, minimally invasive parathyroidectomies and minimally invasive radio-guided parathyroidectomy. The intact parathyroid hormone assays have greatly added to the detection of normal and abnormal functioning glands, hence better surgical outcomes.

Efficacy of ⁹⁹mTc-sestamibi SPECT/CT for minimally invasive parathyroidectomy: comparative study with ⁹⁹mTc-sestamibi scintigraphy, SPECT, US and CT

PURPOSE

We evaluated the efficacy of (99m)Tc-sestamibi SPECT/CT for planning minimally invasive parathyroidectomy (MIP), comparing with dual phase (99m)Tc-sestamibi scintigraphy, (99m)Tc-sestamibi SPECT and conventional imaging (US and CT).

METHODS

Thirty-one patients (M:F = 10:21, range 35-78 years old) who showed high serum parathyroid hormone (intact PTH) level were included. (99m)Tc-sestamibi scintigraphy was performed 15 and 150 min after injection of (99m)Tc-sestamibi (555 MBq), and (99m)Tc-sestamibi SPECT/CT was obtained just after the delayed scan. Comparison study between imaging modalities was done by patient-based and lesion location-based analysis. The location of the lesion was confirmed by the operative finding. An operation was performed in 24 patients. Seven patients had normal (99m)Tc-sestamibi SPECT/CT, and followed for more than 6 months after SPECT/CT.

RESULTS

Among 24 patients, parathyroid adenoma was detected in 19 patients and the other 5 had parathyroid hyperplasia (total 35 lesions). (99m)Tc-sestamibi scintigraphy detected abnormal uptake in 15 patients with 24 lesions. Conventional imaging identified abnormal findings in 17 patients with 27 lesions. SPECT detected abnormal findings in 18 patients with 27 lesions. SPECT/CT identified abnormal findings in 24 patients with 35 lesions. SPECT/CT demonstrated 100 % sensitivity in a patient-based analysis. SPECT/CT exhibited significantly better sensitivity than (99m)Tc-sestamibi scintigraphy, SPECT and conventional imaging (p < 0.05). All lesion location was correctly identified to perform MIP. The final clinical diagnosis of 7 normal SPECT/CT patients was secondary hyperparathyroidism on 6 months follow-up.

CONCLUSIONS

We correctly identified the precise location of parathyroid adenomas or hyperplasia by (99m)Tc-sestamibi SPECT/CT which was helpful to perform MIP.

The Utility of Multidetector Computed Tomography for Detection of Parathyroid Disease in the Setting of Primary Hyperparathyroidism

Purpose

The aim of this study was to evaluate the accuracy of multidetector computed tomography (MDCT) in the detection of parathyroid adenoma and hyperplasia in the setting of primary hyperparathyroidism.

Methods

Records of 48 patients with biochemically confirmed primary hyperparathyroidism, who underwent preoperative imaging with 16- or 64-slice contrast-enhanced MDCT and subsequent successful parathyroidectomy over a 3-year period, were reviewed. Two radiologists, blinded to the operative and histologic findings, independently evaluated multiplanar computed tomographic images for all patients.

Results

On pathologic examination, 63 abnormal glands were confirmed in 41 female and 7 male patients (mean age, 63 years). Of the 63 abnormal glands, 40 were adenomatous and 23 were hyperplastic. MDCT demonstrated an 88% (95% confidence interval [CI], 77%–99%) positive predictive value for localizing abnormal hyperfunctioning parathyroid glands. The sensitivity of MDCT in detecting single-gland disease was 80% (95% CI, 68%–92%); whereas the specificity for ruling out hyperfunctioning parathyroid tissue, either adenomatous or hyperplastic, was 75% (95% CI, 51%–99%). The sensitivity for exclusively localizing parathyroid hyperplasia was 17% (95% CI, 2%–33%). The parathyroid adenomas were substantially larger and heavier than their hyperplastic counterparts, with an average weight of 1.51 g (range, 0.08–6.00 g) and 0.42 g (range, 0.02–2.0 g) for adenoma and hyperplasia, respectively.

Conclusions

Contrast-enhanced MDCT demonstrated an 88% positive predictive value for localizing adenomatous and hyperplastic parathyroid glands. The poor sensitivity for detection of multigland disease was likely a result of the smaller size and weight of the abnormal hyperplastic glands.

Near-infrared autofluorescence for the detection of parathyroid glands

A major challenge in endocrine surgery is the intraoperative detection of parathyroid glands during both thyroidectomies and parathyroidectomies. Current localization techniques such as ultrasound and sestamibi scan are mostly preoperative and rely on an abnormal parathyroid for its detection. In this paper, we present near-infrared (NIR) autofluorescence as a nonintrusive, real-time, automated in vivo method for the detection of the parathyroid gland. A pilot in vivo study was conducted to assess the ability of NIR fluorescence to identify parathyroid glands during thyroid and parathyroidectomies. Fluorescence measurements at 785 nm excitation were obtained intra-operatively from the different tissues exposed in the neck region in 21 patients undergoing endocrine surgery. The fluorescence intensity of the parathyroid gland was found to be consistently greater than that of the thyroid and all other tissues in the neck of all patients. In particular, parathyroid fluorescence was two to eleven times higher than that of the thyroid tissues with peak fluorescence occurring at 820 to 830 nm. These results indicate that NIR fluorescence has the potential to be an excellent optical tool to locate parathyroid tissue during surgery.

Minimally Invasive Parathyroid Surgery, The Norman 20% Rule: Is It Valid?

The 20 per cent rule proposed by Norman established a guideline using radioactivity in the minimally invasive radioguided parathyroidectomy (MIRP) technique to localize and confirm removal of an abnormal parathyroid gland in patients with primary hyperparathyroidism. If radioactivity in the resected gland was at least 20 per cent of excision site/background radioactivity, the 20 per cent rule was satisfied. Patients meeting these criteria underwent unilateral MIRP without intraoperative parathyroid hormone assay or intraoperative frozen section. The study aim was to independently evaluate the 20 per cent rule in MIRP patients with primary hyperparathyroidism. Using the University of Louisville Parathyroid Database from January 1, 1999 to December 31, 2007, 216 MIRP patients with complete radioguided and postoperative management data were identified. The average percentage of ex vivo parathyroid gland radioactivity compared with excision site/background radioactivity was 107 per cent with a range from 14 to 388 per cent. For 99 per cent (196/198) radioactivity recorded from the excised gland was at least 20 per cent of radioactivity recorded from the excision site. Normocalcemia was documented in 98.5 per cent (195/198) at 12 month follow-up. Our data supports the 20 per cent rule in that in 99 per cent of MIRP patients the resected gland radioactivity was at least 20 per cent of excision site radioactivity allowing localization and confirmation of an overactive gland without intraoperative parathyroid hormone monitoring or tissue analysis.

Financial and clinical implications of low-energy CT combined with 99m Technetium-sestamibi SPECT for primary hyperparathyroidism

BACKGROUND

(99m)Technetium-sestamibi hybrid SPECT/CT has been favored over conventional SPECT in preoperative evaluation of primary hyperparathyroidism (PHPT) patients. However, the financial implications of CT-image acquisition have never before been published. This prompted us to perform a cost analysis of the aforementioned nuclear procedures.

METHODS

A total of 55 PHPT patients operated on between 2004 and 2009 were studied. Overall, 27 patients underwent SPECT and 28 SPECT/CT. Localization results, as well as diagnostic and clinical cost variations between SPECT and SPECT/CT patients, were compared.

RESULTS

SPECT/CT revealed higher sensitivity than SPECT (96.7 vs 79.3%; P = .011), as well as higher specificity (96.4 vs 82.4%; P = .037) and positive predictive value (PPV) (96.7 vs 83%; P = .038) for correctly identifying the neck-side affected by PHPT. Likewise, SPECT/CT disclosed higher sensitivity (86.7 vs 61.1%; P < .0001), specificity (97.4 vs 90%; P = .022), and PPV (86.7 vs 65.7%; P = .0001) for correct neck-quadrant identification. The mean operative time decreased from 62 min following SPECT to 36 min following SPECT/CT (P < .0001), yielding a mean surgical expense saving of 109.9 <euro>/patient (updated at 2009/2010 billing database). SPECT/CT actually ensures a mean expenditure reduction of 98.7 <euro>/patient (95% CI: 47.96 <euro>-149.42 <euro>), diagnostic costs variation amounting to 11.2 <euro>/procedure.

CONCLUSIONS

SPECT/CT ensures better focus for the surgical exploration, shortens surgical times, and eventually cuts costs when used for localization of parathyroid adenomas.

Primary hyperparathyroidism patients with positive preoperative sestamibi scan and negative ultrasound are more likely to have posteriorly located upper gland adenomas (PLUGs)

Background

Standard preoperative imaging for primary hyperparathyroidism usually includes sestamibi scanning (MIBI) and ultrasound (US). In a subset of patients with a positive MIBI and a negative US, we hypothesize that the parathyroid adenomas are more likely to be located posteriorly in the neck, where anatomically they are more difficult to detect by US.

Methods

We retrospectively reviewed the records of 661 patients treated for primary hyperparathyroidism between 2004 and 2009 at a tertiary referral center. We included patients who for their first operation had a MIBI that localized a single lesion in the neck and an US that found no parathyroid adenoma. We excluded patients with persistent or recurrent hyperparathyroidism, and patients with MIBIs that were negative, that had more than one positive focus, or that had foci outside of the neck. Sixty-six cases were included in the final analysis.

Results

A total of 54 patients (83%) had a single adenoma, 4 (6%) had double adenomas, and 7 (11%) had hyperplasia. Thirty-three patients (51%) had a single upper gland adenoma; 19 of these (58%) were posteriorly located upper gland adenomas (PLUGs). PLUGs occurred more often on the right side than on the left (P = 0.048, Fisher’s test). PLUGs were also larger than other single adenomas (mean 1.85 vs. 1.48 cm, P = 0.021, t-test). Seventy-six percent of patients successfully underwent a unilateral or focused exploration. Six patients (9%) had persistent disease, which is double our group’s overall average (4–5%).

Conclusions

Primary hyperparathyroid patients with preoperative positive MIBI and negative US are more likely to have PLUGs.

Imaging of parathyroid glands

Preoperative imaging studies have an important role in facilitating successful localization of adenomas for surgeons. Their use has increased and parallels the recent growth of minimally invasive parathyroidectomy. Based on findings that scintigraphy is reported to have the highest accuracy for localization of adenomas when compared with anatomic imaging techniques, this article discusses the current role and limitations of imaging, with a focus on scintigraphy, in the evaluation of patients before surgery for hyperparathyroidism.

[Importance of parathyroid SPECT and 99mTc scintigraphy, and of clinical, laboratorial, ultrasonographic and citologic correlation in the pre-operative localization of the parathyroid adenoma - pictorial assay]

OBJECTIVE

In patients with primary hyperparathyroidism, candidates for surgical intervention, the parathyroid pre-operative localization is of fundamental importance in planning the appropriate surgical approach.

MATERIALS AND METHODS

The additional acquisition of SPECT and Technetium-99m images, during parathyroid scintigraphy with Sestamibi, is not common practice. Usually, only planar image acquisition, 15 minutes prior and 2 hours after radiopharmaceutical administration, is performed.

RESULTS

In our experience, the complete protocol in parathyroid scintigraphy increases the accuracy of pre-operative parathyroid localization.

CONCLUSION

The complete utilization of all available nuclear medicine methods (SPECT e 99mTc) and image interpretation in a multidisciplinary context can improve the accuracy of parathyroid scintigraphy.

Recurrent acute pancreatitis as the first and sole presentation of undiagnosed primary hyperparathyroidism

INTRODUCTION

We highlight the pitfalls in delaying the diagnosis of primary hyperparathyroidism (pHPT) in patients with acute pancreatitis as the sole clinical presentation. Primary hyperparathyroidism is a recognised, but rare, cause of acute pancreatitis. Hypercalcaemia caused by undiagnosed pHPT may be the only causative factor of recurrent acute pancreatitis.

PATIENTS AND METHODS

Three patients with multiple admissions for acute pancreatitis were diagnosed having pHPT during the work-up to identify possible causative factors. None of the patients had any other common predisposing factor for acute pancreatitis as revealed by clinical examination, blood tests and imaging. In retrospect, all had abnormally elevated calcium during previous admissions which was not further assessed.

RESULTS

After diagnosis of pPTH, patients underwent bilateral neck exploration and parathyroidectomy. Histology confirmed parathyroid adenomas. The blood calcium level returned to normal and the patients remain well and asymptomatic after operation.

CONCLUSIONS

The role of pHPT as a causative factor is underestimated when managing patients with acute pancreatitis, and frequently the underlying disease remains undiagnosed for a long time. Proper early diagnosis and management prevent unnecessary morbidity.

Hyperparathyroidism-jaw tumor syndrome: a case report

We report the clinical and genetic findings in a 23-year-old woman with hyperparathyroidism-jaw tumor syndrome (HPT-JT). The patient had a family history of primary hyperparathyroidism (PHPT) and uterine fibroma in her mother. The patient presented muscle weakness. The diagnosis of PHPT was confirmed by an elevated parathyroid hormone level above 1450 pg/ml with hypercalcemia and hypercalciuria. X-ray radiographies showed a radiolucent lesion in the right body of the mandible. Bilateral neck exploration was performed. An inferior right parathyroidectomy, a left thyroid lobectomy with isthmectomy and thymectomy were carried out. Histopathological examination of the specimen showed a diffuse hyperplasia of the parathyroid principal cells. The association of PHPT with a right jaw tumor and uterine fibroma suggested the diagnosis of HPT-JT syndrome. Mutation screening of HRPT2 gene was carried out and identified a germline mutation, consisting in a base deletion in exon 1, 85delG, inducing a frameshift. The diagnosis of HPT-JT syndrome is clinically important because of its hereditary component and its high risk of parathyroid malignancy, making a genetic inquiry necessary.

Parathyroid scintigraphy in patients with primary hyperparathyroidism: 99mTc sestamibi SPECT and SPECT/CT

The clinical diagnosis of primary hyperparathyroidism is based largely on serum laboratory test results, as patients often are asymptomatic. Surgery, often with bilateral exploration of the neck, has been considered the definitive treatment for symptomatic disease. However, given that approximately 90% of cases are due to a single parathyroid adenoma, a better treatment may be the selective surgical excision of the hyperfunctioning parathyroid gland after its preoperative identification and localization at radiologic imaging. Scintigraphy and ultrasonography are the imaging modalities most often used for preoperative localization. Various scintigraphic protocols may be used in the clinical setting: Single-phase dual-isotope subtraction imaging, dual-phase single-isotope imaging, or a combination of the two may be used to obtain planar or tomographic views. Single photon emission computed tomography (SPECT) with the use of technetium-99m ((99m)Tc) sestamibi as the radiotracer, especially when combined with x-ray-based computed tomography (CT), is particularly helpful for preoperative localization: The three-dimensional functional information from SPECT is fused with the anatomic information obtained from CT. In addition, knowledge of the anatomy and embryologic development of the parathyroid glands and the pathophysiology of primary hyperparathyroidism aid in the identification and localization of hyperfunctioning glands.

Ultrasound patterns of parathyroid glands in chronic hemodialysis patients with secondary hyperparathyroidism

BACKGROUND

The role ofparathyroid glands (PTG) ultrasonography (US) in hemodialysis patients with secondary hyperparathyroidism (SHPT) is still controversial. The present study aimed at evaluating the relationship between US findings and SHPT degree as well as therapeutic outcome.

METHODS

Twenty hemodialysis patients with moderate SHPT and 15 with severe SHPT underwent US to assess the PTG number, maximum longitudinal diameter (MLD), structural (1-hypoechoic, 2-slight heterogeneous, 3-high heterogeneous, 4-nodular) and vascular patterns (1-slight, 2-medium and 3-high).

RESULTS

PTG number, MLD and US patterns were correlated with iPTH levels. MLD of patients with moderate or severe SHPT was 7.2 +/- 2.3 and 15 +/- 5.1 mm (p < 0.001). Most patients with moderate SHPT showed a single PTG with an MLD <9 mm associated with 1-2 structural and vascular pattern, whereas patients with severe SHPT exhibited more than one PTG with MLD >9 mm and 3-4 structural and vascular patterns. Thirteen patients were responders to treatment and 22 nonresponders. In nonresponders, a higher number of PTG was observed as well as higher echostructural and vascular patterns. In 14 patients who underwent parathyroidectomy, no differences were found between PTG US MLD and pathology diameter. All PTG with evidence of 3-4 structural and vascular score at ultrasound showed nodular hyperplasia at pathological examination.

CONCLUSIONS

The adopted classification of US findings is correlated with SHPT degree and therapeutic outcome and might be an adjunctive predictive method useful to assess the SHPT severity and to plan the therapeutic strategy.

Scintigraphic techniques in primary hyperparathyroidism: from pre-operative localisation to intra-operative imaging

INTRODUCTION

Primary hyperparathyroidism (PHPT) is an increasingly diagnosed disease worldwide. In most cases, PHPT is related to the presence of a solitary parathyroid adenoma (PA). Fifty percent or more of newly diagnosed PHPT patients are asymptomatic, and there is debate among endocrinologists and endocrine surgeons about whether or not such patients should be treated.

LOCALIZATION

Usually, in a PHPT patient with a solitary PA that is well localised pre-operatively, a parathyroidectomy with limited or minimally invasive neck exploration is offered. The diffusion of minimally invasive neck exploration procedures is a consequence of the significant improvement in the accuracy of pre-operative imaging (mainly scintigraphic) techniques; these techniques have changed the surgical strategy to PHPT, from the wide traditional bilateral neck exploration to limited neck exploration.

REVIEW

The present review considers developments during the past 10-15 years with regard to both the accuracy of pre-operative localising imaging techniques and intra-operative minimally invasive procedures in order to provide endocrinologists and endocrine surgeons with further information about the newly available diagnostic and therapeutic tools for use in PHPT patients with a solitary PA.

Surgeon-Performed Ultrasound for Preoperative Localization of Abnormal Parathyroid Glands in Patients with Primary Hyperparathyroidism

BACKGROUND

The introduction of portable ultrasound equipment enables surgeons to perform ultrasound examinations in a clinic setting. This study was undertaken to evaluate surgeon-performed ultrasound (SP-US) in patients with primary hyperparathyroidism (PHPT).

METHODS

Between July 2003 and March 2004, 65 patients with PHPT were evaluated with SP-US and 48 of these patients underwent parathyroid surgery. Among this group of 48 evaluable patients, 47 had preoperative imaging with technetium-99m sestamibi scanning (MIBI), and 12 had an additional ultrasound examination at an external radiology department (RP-US).

RESULTS

All patients were cured of PHPT and the operative findings were used to determine the true status of the parathyroid glands of each patient. Twenty-four (50%) patients had concomitant thyroid nodules which were identified by SP-US, and 4 (8.3%) patients had simultaneous thyroid operations, 2 of which were for thyroid cancer. Considering data for all patients, SP-US had significantly higher sensitivity than MIBI or RP-US (60% vs. 46%, P = 0.013, and 60% vs. 11%, P = 0.004 respectively). Among the patients with a single adenoma, SP-US, MIBI, and RP-US had sensitivities of 83%, 63%, and 13% respectively. The specificities of all three imaging techniques were uniformly high and were not significantly different from each other.

CONCLUSIONS

Surgeon-performed ultrasound is an accurate modality for localizing abnormal parathyroid glands in patients with PHPT, with results that compare favorably with other parathyroid imaging modalities.

Impact of Gland Morphology and Concomitant Thyroid Nodules on Preoperative Localization of Parathyroid Adenomas

OBJECTIVES

Primary hyperparathyroidism (pHPT) is a common endocrine disease. The aim of this study was to assess the effect of the presence of thyroid nodules, adenoma weight, and ectopic localization on the sensitivity of different imaging studies in patients with hyperparathyroidism.

STUDY DESIGN

A series of 125 patients with pHPT who underwent low-frequency ultrasonography, high-frequency ultrasonography, Thallium-Technetium scintigraphy, sestamibi scintigraphy, and combined technique was reviewed retrospectively. Patients were divided in two groups depending on the presence or absence of thyroid nodules.

RESULTS

The overall sensitivity of low-frequency ultrasonography, high-frequency ultrasonography, Thallium-Technetium scintigraphy, sestamibi scintigraphy, and combined technique was 69%, 89%, 71%, 86%, and 98%, respectively. The sensitivity of these imaging studies was 94%, 100%, 94%, 96%, and 100%, respectively, in our patients with no thyroid nodules but decreased to 54%, 84%, 54%, 81%, and 79%, respectively, in the presence of thyroid nodules. The parathyroid adenoma weight in true-positive imaging studies was significantly higher than those in false-positive and false-negative imaging studies. The numbers of ectopic parathyroid adenomas were found to be higher in the group of parathyroid adenomas undetected with ultrasonography when compared with ultrasonographically detected adenomas.

CONCLUSION

In patients with parathyroid adenoma, the sensitivity of imaging studies correlates with the presence of thyroid nodules, adenoma weight, and ectopic localization.

Parathyroid scintigraphy during hypocalcaemia in primary hyperparathyroidism

BACKGROUND

Minimally invasive parathyroid surgery in patients with primary hyperparathyroidism (PHPT) demands high imaging accuracy. By increasing blood flow to the parathyroid adenoma before injection of a perfusion marker, we intended to improve the parathyroid scintigraphy. We have named the technique stimulated parathyroid scintigraphy (SPS).

METHODS

Twenty minutes after injection of 100 MBq (99m)Tc-pertechnetate a thyroid scintigram was performed in 25 patients with PHPT. During the thyroid scintigraphy sodium citrate was infused which lowered plasma calcium by a mean of 14 +/- 1.3%. Then 700 MBq (99m)Tc-sestamibi was injected and another scintigram of the neck was obtained. Perchlorate was given at the end of the sestamibi scintigram to increase the wash-out of (99m)Tc-pertechnetate from the thyroid gland, and after 2 h a delayed scintigram was obtained. A subtraction of the thyroid scintigram from the initial sestamibi scintigram was performed. The results of SPS and a conventional (99m)Tc-sestamibi dual-phase parathyroid scintigraphy were compared with the operative findings. In nine patients the parathyroid adenoma was also localized with ultrasound and the flow pattern before and after citrate infusion was visualized with Doppler technique.

RESULTS

Eighty-eight per cent of the adenomas were localized correctly with the SPS technique compared with 62% at the conventional parathyroid scintigraphy. Tissue perfusion of the nine adenomas increased after citrate infusion.

CONCLUSIONS

SPS has a high accuracy and it is easy to perform. If only subtraction SPS is performed the whole examination can be completed within an hour, which is acceptable for same day surgery.