Hyperfunctioning Parathyroid Tissue Research Articles

Comparing early and delayed [99mTc]Tc-MIBI SPECT/CT parathyroid scans: agreement, confidence levels, and clinical predictive factors

BackgroundParathyroid scan is an important imaging modality for localizing hyperfunctioning parathyroid tissue in patients with hyperparathyroidism. Unfortunately, whether early or delayed timing is the optimal protocol for [99mTc]Tc-MIBI SPECT/CT parathyroid remains under debate. This study aimed to evaluate the agreement and compare the confidence levels of physicians when interpreting early and delayed [99mTc]Tc-MIBI SPECT/CT parathyroid scans. Additionally, it sought to identify clinical factors that related to positive scan result. We conducted a prospective study where the early and delayed [99mTc]Tc-MIBI SPECT/CT was separately interpreted as either positive or negative. Furthermore, these interpretations were categorized based on whether they fell within more or less confidence levels of the readers and were correlated with clinical information.ResultsWe enrolled 39 patients with hyperparathyroidism with 158 possible locations of parathyroid glands. The per-location agreement between the early and delayed scans was moderate (concordant rate: 80.3%, Kappa = 0.558), and the per-patient agreement was slight (concordant rate: 71.8%, Kappa = 0.093). The confidence of interpretation was significantly higher for the delayed scans. Calcium supplementation, low serum parathyroid hormone levels, and low serum phosphate levels were associated with positive early scans. High calcium level and high parathyroid hormone levels were associated with positive delayed scans.ConclusionsOur study highlights the impact of the timing of SPECT/CT in [99mTc]Tc-MIBI parathyroid scans. The different confidence levels between early and delayed scans, along with clinical factors, imply that various factors affect parathyroid scan interpretation, and individualized scanning protocols adjusted for specific settings may be needed to optimize the successful localization of hyperfunctioning parathyroid tissue.

Comparing early and delayed [99mTc]Tc-MIBI SPECT/CT parathyroid scans: agreement, confidence levels, and clinical predictive factors

BackgroundParathyroid scan is an important imaging modality for localizing hyperfunctioning parathyroid tissue in patients with hyperparathyroidism. Unfortunately, whether early or delayed timing is the optimal protocol for [99mTc]Tc-MIBI SPECT/CT parathyroid remains under debate. This study aimed to evaluate the agreement and compare the confidence levels of physicians when interpreting early and delayed [99mTc]Tc-MIBI SPECT/CT parathyroid scans. Additionally, it sought to identify clinical factors that related to positive scan result. We conducted a prospective study where the early and delayed [99mTc]Tc-MIBI SPECT/CT was separately interpreted as either positive or negative. Furthermore, these interpretations were categorized based on whether they fell within more or less confidence levels of the readers and were correlated with clinical information.ResultsWe enrolled 39 patients with hyperparathyroidism with 158 possible locations of parathyroid glands. The per-location agreement between the early and delayed scans was moderate (concordant rate: 80.3%, Kappa = 0.558), and the per-patient agreement was slight (concordant rate: 71.8%, Kappa = 0.093). The confidence of interpretation was significantly higher for the delayed scans. Calcium supplementation, low serum parathyroid hormone levels, and low serum phosphate levels were associated with positive early scans. High calcium level and high parathyroid hormone levels were associated with positive delayed scans.ConclusionsOur study highlights the impact of the timing of SPECT/CT in [99mTc]Tc-MIBI parathyroid scans. The different confidence levels between early and delayed scans, along with clinical factors, imply that various factors affect parathyroid scan interpretation, and individualized scanning protocols adjusted for specific settings may be needed to optimize the successful localization of hyperfunctioning parathyroid tissue.

SAT195 A Curious Case Of Severe Reversible PTH-mediated Hypercalcemia Of Pregnancy

Abstract Disclosure: I. Albanese: None. N. Nicolas: None. S.S. Wing: Grant Recipient; Self; Pfizer Global R&D. Other; Self; Almac Discovery (Independent Contractor). E. Mitmaker: None. L. Vautour: None. Background: Primary hyperparathyroidism is rarely diagnosed in pregnancy as symptoms may overlap with those of pregnancy and biochemical diagnosis may be masked by physiologic changes in calcium homeostasis. Hyperparathyroidism in pregnancy is associated with increased maternal and fetal complications. While mild disease is treated conservatively, moderate to severe disease is generally treated surgically in the second trimester. Safe pharmacotherapy options are limited in pregnancy. Case: A 35-year-old woman G3P1 at 10 weeks presented to our institution with polyuria, bone pain and weakness with labs demonstrating severe hypercalcemia (Calcium total: 3.82mmol/L (normal: 2.12-2.62); PTHi: 12pmol/L (normal: 1.5-9.3)). PTHrP was suppressed. She had a prior history of PTH-mediated hypercalcemia in her first pregnancy. She previously underwent three exploratory surgeries in which only three parathyroid glands were found and removed. The hyperparathyroidism and hypercalcemia persisted post-operatively thus she also required intravenous fluids, calcitonin and cinacalcet. The pregnancy was otherwise uncomplicated. Post-partum, she developed hypoparathyroidism and hypocalcemia. Throughout this current pregnancy, multiple imaging modalities were used (ultrasound, MRI and parathyroid sestamibi), none of which were unable to localize any hyperfunctioning parathyroid tissue. Thus, management was limited to medical therapy. Despite aggressive hydration, calcitonin and cinacalcet, total calcium and PTH levels consistently rose reaching peaks of 4.06mmol/L and 45.4pmol/L, respectively. Given hypercalcemia severity and associated neurological symptoms, she was also given bisphosphonates (pamidronate 60mg and zoledronic acid 4mg). She underwent C-section at 25+3 weeks due to fetal decelerations and placental insufficiency. She again developed hypoparathyroidism and hypocalcemia 1-week post-partum. Genetic testing was negative for any causes of hyperparathyroidism. Discussion: This is a unique case of severe PTH-mediated hypercalcemia in that the exact mechanism is unknown but appears to be pregnancy-mediated and reversible such that it only occurs in pregnancy with subsequent hypoparathyroidism post-partum. Investigations to better elucidate the mechanism of this are ongoing. Presentation: Saturday, June 17, 2023

Brownish limb tumor as a presentation of primary hyperparathyroidism

43-year-old male, with tumor in the anterior region of the right lower limb (figure 1) and biopsy compatible with brown tumor. He presented total serum calcium 12.3 mg/dl and 13 mg/dl (NR: 8.3-10.3), parathormone (PTH) 1057 pg/ml (NR 15-65). With the diagnosis of primary hyperparathyroidism, a 99mTc-MIBI parathyroid scintigraphy with SPECT was requested, which showed hyperfunctioning parathyroid tissue in the projection of the left inferior parathyroid gland. Hand radiographs showed a lytic lesion in punch in the distal phalanx of the first finger of the left hand (figure 2); in the clavicle radiograph: lytic lesion of 10 mm x 8 mm in the right clavicle, no alterations were evidenced in the skull radiograph.

Evolving Role of [18F]Flurocholine PET/CT in Assessing Primary Hyperparathyroidism: Can It Be Considered the First-Line Functional Imaging Approach?

The accurate detection of hyperfunctioning parathyroid tissue (HFPT) is pivotal in the preoperative assessment of primary hyperparathyroidism (PHPT). PET/CT using [18F]fluorocholine ([18F]FCH) showed superior diagnostic performance compared to conventional functional imaging modalities. We aimed to evaluate the diagnostic performance of [18F]FCH PET/CT as a first-line functional imaging approach in patients with clinically diagnosed PHPT. The imaging and clinical data of 321 PHPT patients, including 271 overt PHPT and 50 mild PHPT, who underwent [18F]FCH PET/CT as first-line imaging were analysed in this retrospective study. Histopathology was the reference standard. In case of no available histopathology evaluation (conservative management), imaging and clinical follow-ups were considered reference standards. In the overt group (n = 271), [18F]FCH PET/CT showed sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of 0.99, 0.91, 1.00, 0.80, and 0.99, respectively. Regarding the correlation of the index lesions and initial laboratory data, all [18F]FCH PET/CT parameters (SUVs, SULs, and mSAD) were significantly correlated with the serum iPTH level. Additionally, SUVmax, SULpeak, and mSAD were significantly associated with the serum calcium level. In the mild group (n = 50), [18F]FCH PET/CT showed a sensitivity, specificity, PPV, NPV, and accuracy of 0.93, 0.75, 0.95, 0.67, and 0.90. In conclusion, [18F]FCH PET/CT revealed high diagnostic performance in the detection of HFPTs and the potential to be considered as a first-line imaging modality in the assessment of PHPT, including both overt and mild types. However, its cost-benefit concerning the clinical impact of early PHPT detection should be investigated in future studies.

Does the sonography-scintigraphy correlation affect the success of minimally invasive parathyroid Surgery? Results from a single center

In patients with primary hyperparathyroidism, complete surgical resection of all hyperfunctioning parathyroid tissue is essential. The aim of this study was to evaluate the success rates of minimally invasive parathyroidectomies for primary hyperparathyroidism performed after localization studies with 99mTc-sestamibi (MIBI) scintigraphy and neck ultrasonography (USG). And also, we aimed to determine the factors affecting the success rate in surgery. Retrospective analysis of 58 consecutive patients with a diagnosis of primary hyperparathyroidism who underwent parathyroidectomy between January 2018 and December 2021 in our institution. The patients were evaluated according to Miami criteria and divided into two groups as successful or unsuccessful surgery. Demographic and clinical characteristics of the patients were obtained from hospital records. Surgical success was achieved in 50 (86.2%) of the 58 patients included in the study. In both groups, neck USG and MIBI scintigraphy showed the same localization for the lesion in a correlated manner. The clinical complaints of the patients, preoperative PTH, Ca and 24-hour urinary Ca levels were similar in both groups. In 10 (17.2%) patients, inconsistency in localization was found between USG and MIBI scintigraphy, and surgical failure was found in 4 (40%) of these patients. Surgical failure was statistically significant in patients with inconsistency in localization between USG and MIBI scintigraphy. The sono-scintigraphic scan concordance increases surgical success rates in cases where minimally invasive parathyroid surgery is planned. If there is an inconsistency between USG and MIBI, preoperative four dimentional computed tomography, intraoperative rapid PTH, gamma probe or frozen method can be used. It should be kept in mind that multiple gland pathologies may be more common in addition to solitary adenoma in lesions smaller than 1 cm in USG. In addition, in these cases, as the diagnostic value of scintigraphy is low, surgical success will also decrease.

Ectopic PTH-producing parathyroid cyst inside the thymus: a case report

BackgroundThe hallmark of hyperparathyroidism is hypersecretion of parathyroid hormone (PTH) which results in hypercalcemia and hypophosphatemia. While hypercalcemia due to malignancy is often brought about by PTH-related protein in adults, PTH-producing tumors are quite rare in clinical practice. Additionally, from the point of embryology, it is very difficult to examine ectopic PTH-producing tissue such as ectopic parathyroid glands. Furthermore, clear histopathological criteria are not present.Case presentationA 57-year-old woman was referred to our hospital for hypercalcemia. Her parathyroid hormone (PTH) level was elevated, but there were no enlarged parathyroid glands. Although 99mTc-MIBI confirmed a localized and slightly hyperfunctioning parathyroid tissue in the anterior mediastinum, it was not typical as hyperfunctioning parathyroid. We finally diagnosed her as ectopic PTH-producing cyst-like tumor with venous sampling of PTH. She underwent anterosuperior mediastinal ectopic PTH-producing cyst-like tumor resection. It is noted that intact-PTH concentration of the fluid in the cyst was very high (19,960,000 pg/mL). Based on histopathological findings, we finally diagnosed her as ectopic PTH-producing parathyroid cyst inside the thymus. After resection of anterosuperior mediastinal thymus including ectopic PTH-producing parathyroid cyst, calcium and intact-PTH levels were decreased, and this patient was discharged without any sequelae.ConclusionsWe should know the possibility of superior mediastinal ectopic PTH-producing parathyroid cyst inside the thymus among subjects with ectopic PTH-producing parathyroid glands. Particularly when the cyst is present in the superior mediastinum, it is necessary to do careful diagnosis based on not only positive but also negative findings in 99mTc-MIBI. It is noted that the patient’s bloody fluid in the cyst contained 19,960,000 pg/mL of intact-PTH, and its overflow into blood stream resulted in hyperparathyroidism and hypercalcemia. Moreover, in such cases, the diagnosis is usually confirmed after through histological examination of ectopic PTH-producing parathyroid glands. We think that it is very meaningful to let clinicians know this case.

Detection and localization of hyperfunctioning parathyroid glands on [18F]fluorocholine PET/ CT using deep learning - model performance and comparison to human experts.

In the setting of primary hyperparathyroidism (PHPT), [18F]fluorocholine PET/CT (FCH-PET) has excellent diagnostic performance, with experienced practitioners achieving 97.7% accuracy in localising hyperfunctioning parathyroid tissue (HPTT). Due to the relative triviality of the task for human readers, we explored the performance of deep learning (DL) methods for HPTT detection and localisation on FCH-PET images in the setting of PHPT. We used a dataset of 93 subjects with PHPT imaged using FCH-PET, of which 74 subjects had visible HPTT while 19 controls had no visible HPTT on FCH-PET. A conventional Resnet10 as well as a novel mPETResnet10 DL model were trained and tested to detect (present, not present) and localise (upper left, lower left, upper right or lower right) HPTT. Our mPETResnet10 architecture also contained a region-of-interest masking algorithm that we evaluated qualitatively in order to try to explain the model's decision process. The models detected the presence of HPTT with an accuracy of 83% and determined the quadrant of HPTT with an accuracy of 74%. The DL methods performed statistically worse (p < 0.001) in both tasks compared to human readers, who localise HPTT with the accuracy of 97.7%. The produced region-of-interest mask, while not showing a consistent added value in the qualitative evaluation of model's decision process, had correctly identified the foreground PET signal. Our experiment is the first reported use of DL analysis of FCH-PET in PHPT. We have shown that it is possible to utilize DL methods with FCH-PET to detect and localize HPTT. Given our small dataset of 93 subjects, results are nevertheless promising for further research.

Preoperative Imaging with [18F]-Fluorocholine PET/CT in Primary Hyperparathyroidism.

Primary hyperparathyroidism (pHPT) is a common endocrine disorder due to hyperfunctioning parathyroid glands. To date, the only curing therapy is surgical removal of the dysfunctional gland, making correct detection and localization crucial in order to perform a minimally invasive parathyroidectomy. 18F-Fluorocholine positron emission tomography/computed tomography (18F-FCH PET/CT) has shown promising results for the detection of pHPT, suggesting superiority over conventional imaging with ultrasounds or scintigraphy. A total of 33 patients with pHPT who had negative or equivocal findings in conventional imaging received 18F-FCH PET/CT preoperatively and were retrospectively included. A pathological hyperfunctional parathyroid gland was diagnosed in 24 cases (positive PET, 72.7%), 4 cases showed equivocal choline uptake (equivocal PET, 12.1%), and in 5 cases, no enhanced choline uptake was evident (negative PET, 15.2%). Twelve of the twenty-four detected adenoma patients underwent surgery, and in all cases, a pathological parathyroid adenoma was resected at the site detected by PET/CT. Two of the six patients without pathological choline uptake who received a parathyroidectomy revealed no evidence of parathyroid adenoma tissue in the histopathological evaluation. This retrospective study analyzes 18F-FCH PET/CT in a challenging patient cohort with pHPT and negative or equivocal conventional imaging results and supports the use of 18F-FCH for the diagnosis of hyperfunctional parathyroid tissue, especially in this patient setting, with a 100% true positive and true negative detection rate. Our study further demonstrates the importance of 18F-FCH PET/CT for successful surgical guidance.

The utility of 18F-fluorocholine PET/CT in the imaging of parathyroid adenomas.

The aim of the study was to estimate the sensitivity of ¹⁸F-FCH PET/CT in preoperative localisation of hyperfunctioning parathyroid glands in patients with primary hyperparathyroidism (PHPT). Sixty-five consecutive patients with PHPT, who underwent neck ultrasound (US) and 99mTc/99mTc-MIBI dual-phase parathyroid scintigraphy, were prospectively enrolled. Twenty-two patients had unsuccessful parathyroid surgery prior to the study. PET/CT scans were performed 65.0 ± 13.3 min after injection of 218.5 ± 31.9 MBq of 18F-fluorocholine (FCH). Three experienced nuclear medicine physicians assessed the detection rate of hyperfunctioning parathyroid tissue. Response to parathyroidectomy and clinical follow-up served as a reference test. Per-patient sensitivity and positive predictive value (PPV) were calculated for patients who underwent surgery. ¹⁸F-FCH PET/CT was positive in 61 patients, and negative in 4. US and parathyroid scintigraphy showed positive and negative results in 20, 45 and 17, 48, respectively. US showed nodular goitre in 31 patients and chronic thyroiditis in 9 patients. Parathyroid surgery was performed in 43 (66%) patients. ¹⁸F-FCH PET/CT yielded a sensitivity of 100% (95% CI: 87.99-100) and PPV of 85.7% (95% CI: 70.77-94.06). Similar values were observed in patients with chronic thyroiditis, nodular goitre, and patients after an unsuccessful parathyroid surgery. PET/CT identified hyperparathyroidism complications (kidney stones, osteoporotic bone fractures, and brown tumours) in 11 patients. ¹⁸F-FCH PET/CT effectively detected hyperfunctioning parathyroid tissue and its complications. The method showed excellent sensitivity and positive predictive value, including patients with nodular goitre, chronic thyroiditis, and prior unsuccessful parathyroidectomy. PET/CT performance was superior to neck ultrasound and parathyroid scintigraphy.

ONCOCYTIC INTRATHYROID PARATHYROID ADENOMA MASQUERADING AS HURTHLE CELL NEOPLASM: FINE NEEDLE ASPIRATION CYTOLOGY OF TWO CASES

Ectopic parathyroid adenomas in thyroid tissue are uncommon (0.7 - 6%), and their oncocytic variants are exceedingly rare. We report two cases of intrathyroid parathyroid adenoma which were diagnosed as Hurthle cell adenoma on cytology. Case 1 is a 49-year-old female with a 2.4 cm hypoechoic nodule in the left lateral neck. Electrochemiluminescent immunoassay of the aspirate revealed PTH level of 422 pg/ml, conrming the presence of hyperfunctional parathyroid tissue. Subsequent resection of the left thyroid lobe revealed an enlarged intrathyroidal parathyroid. Case 2 is a 58-year-old female with a 2.1 cm hypoechoic nodule in the posterior-mid left thyroid lobe. Strong overexpression of parathyroid hormone and Chromogranin A genes and low expression of thyrocyte-related genes suggested parathyroid origin of the cells sampled. MEN1 mutation and multiple copy number alterations indicated the neoplastic nature of the nodule. Parathyroid oxyphil cells and oncocytic thyrocytes share cytomorphological ndings and distinguishing them by cytology alone is challenging, especially when the targeted lesion is intrathyroidal. Distinguishing intrathyroid oncocytic parathyroid adenoma from oncocytic thyroid follicular lesions has signicant clinical implications as Bethesda-IV category lesions have 20%–30% risk of malignancy. While stippled chromatin or intracytoplasmic fat vacuoles may be suggestive of parathyroid origin, these are not specic. Classifying the origin of a nodule as parathyroid vs thyroid rests upon the detection of PTH in aspirate material by ECL, immunocytochemistry or next-generation sequencing. In parathyroid aspirates, PTH level 100 pg/mL is suggestive of the presence of PTH-secre ≥ ting tissue at the site biopsied or along the needle track.

Bone and Mineral Metabolism Phenotypes in MEN1-Related and Sporadic Primary Hyperparathyroidism, before and after Parathyroidectomy

Primary hyperparathyroidism (PHPT) is the most common endocrinopathy in multiple endocrine neoplasia type 1 (MEN1). Persistent levels of increased parathyroid hormone (PTH) result in a higher incidence of osteopenia and osteoporosis compared to the general population. Surgical removal of hyper-functioning parathyroid tissue is the therapy of choice. This retrospective study evaluated the effect of parathyroidectomy (PTX) on bone metabolism and bone mass in two series of patients with MEN1 PHPT and sporadic PHPT (sPHPT) by comparing bone metabolism-related biochemical markers and bone mineral density (BMD) before and after surgery. Our data confirmed, in a higher number of cases than in previously published studies, the efficacy of PTX, not only to rapidly restore normal levels of PTH and calcium, but also to normalize biochemical parameters of bone resorption and bone formation, and to improve spine and femur bone mass, in both MEN1 PHPT and sPHPT. Evaluation of single-patient BMD changes after surgery indicates an individual variable bone mass improvement in a great majority of MEN1 PHPT patients. In MEN1 patients, PTX is strongly suggested in the presence of increased PTH and hypercalcemia to prevent/reduce the early-onset bone mass loss and grant, in young patients, the achievement of the bone mass peak; routine monitoring of bone metabolism and bone mass should start from adolescence. Therapy with anti-fracture drugs is indicated in MEN1 patients with BMD lower than the age-matched normal values.

Development of a Rapid Intraoperative Point-of-Care Method Using Tissue Suspension to Differentiate Parathyroid Tissue: A Possible Substitute for Frozen Sections.

We reported that aspartate aminotransferase (AST)/lactate dehydrogenase (LDH) ratio of a tissue suspension can precisely differentiate normal and hyperfunctioning parathyroid tissue (PT) from other tissues. However, in these studies, LDH and AST were measured using the standard method for blood samples, with a turnaround time of approximately 1h, hampering clinical application. Here, we developed a rapid and robust method to differentiate PT instead of using frozen sections. Excised specimens from 28 patients (n = 69) who underwent thyroid or parathyroid surgery between October 2019 and April 2020 were analyzed. AST and LDH were measured in suspensions of PT or other tissues, using both the standard method in the in-facility laboratory and a point-of-care testing device (NX500, Fujifilm, Japan). A good correlation was found between the standard method and NX500 for AST and LDH levels >10IU/L. In the analyses using 52 specimens with ≥ 10IU/L of both AST and LDH measured using the NX500, PT was distinguished with 100% sensitivity and specificity using an optimal cutoff AST/LDH ratio of 0.48. The turnaround time was estimated to be less than 10min. This method could be a cost- and labor-effective alternative to frozen sections to reduce the incidence of postoperative hypoparathyroidism and improve the outcome of primary hyperparathyroidism in low-resource areas.

Dual-tracer radionuclide imaging in hyperparathyroidism: thallium-201 parathyroid scintigraphy revisited.

Tc-sestamibi is the current radiopharmaceutical of choice for the localization of hyperactive lesions of the parathyroid glands in patients with hyperparathyroidism. However, there are multiple factors that adversely affect the accumulation and retention Tc-sestamibi in the hyperfunctioning parathyroid tissue, resulting in a false-negative scan. The objective of this study was to investigate the possibility of an incremental diagnostic role of thallium-201 parathyroid scintigraphy in patients with presumably false-negative Tc-sestamibi scan results. The study comprised of 22 patients including 16 with primary hyperparathyroidism (PHPT) and 6 with secondary hyperparathyroidism where Tc-sestambi scan was initially negative, inconclusive or where additional lesions were suspected on the single-photon computed tomography/computed tomography (SPECT/CT) scan with the CT component identifying lesion(s) without significant Tc-sestamibi uptake. The results of our study show that in 22 patients (5 male, 17 female; age range 26-81; median age 53.4) further imaging with thallium-201 SPECT/CT scan showed 46.5% additional lesions in patients with hyperparathyroidism caused by an adenomatous or hyperplastic parathyroid lesion. In patients with PHPT caused by an adenomatous or hyperplastic parathyroid lesion, further imaging with thallium-201 showed 59% additional hyperactive parathyroid lesions. In patients with secondary hyperparathyroidism, further imaging with thallium-201 SPECT/CT showed additional 33.3% hyperplastic parathyroid lesions. The results of this pilot study strongly advocate a role for thallium parathyroid SPECT/CT imaging in patients with primary and secondary hyperparathyroidism where the initial Tc-sestamibi scan is deemed to be false-negative in the presence of biochemical hyperparathyroidism.

Measurement of the AST to LD Ratio in Parathyroid Tissue Suspension Can Precisely Differentiate a Hyperfunctioning Parathyroid.

Frozen section of excised tissue is used to confirm removal of the etiology of primary hyperparathyroidism in the current era of intraoperative parathyroid hormone measurement and provides safeguards for surgeons. We recently reported that the aspartate aminotransferase (AST)/lactate dehydrogenase (LD) ratio in tissue suspension can accurately distinguish normal parathyroid tissue from other tissues. Therefore, we hypothesized that this ratio may also be applied to distinguish hyperfunctioning parathyroid tissue (HPT) from other tissues. We prospectively analyzed 22 patients who underwent parathyroidectomy for primary hyperparathyroidism (benign, 21; malignant, 1) from July 2018 to October 2019. In total, 27 specimens were examined. Approximately 1 mm3 of minced HPT as confirmed by frozen sections was suspended in 1 mL of normal saline and AST and LD levels were measured. The AST/LD ratios of other tissues (normal parathyroid tissue, thyroid gland, adipose tissue, and others; n = 94) were obtained from our previous report. The AST/LD ratio of benign HPT was consistently higher than that of other tissues (P < 0.001). The optimal cut-off value was 0.36 according to the receiver operating characteristic curve, with 100% sensitivity and specificity. The AST/LD ratio in malignant HPT was also markedly lower than that in benign HPT. This method might be a new adjunct for intraoperative differentiation of HPT with an accuracy and turnaround time comparable with those of frozen sections, minimal cost, and no need for dedicated pathological staff. Additionally, this method might increase the treatment success rate in settings with limited medical resources.

Superior performance of 18F-fluorocholine digital PET/CT in the detection of parathyroid adenomas.

To compare detectability of hyperfunctioning parathyroid tissue (HPT) by digital and analog 18F-fluorocholine PET/CT in patients with primary hyperparathyroidism and negative/inconclusive 99mTc-MIBI scintigraphy-SPECT/CT. Thirty-three patients with primary hyperparathyroidism and negative/inconclusive 99mTc-MIBI scintigraphy-SPECT/CT were prospectively included. All patients accepted to be scanned by digital and analog PET/CT in the same imaging session after a single injection of 18F-fluorocholine. Three nuclear medicine physicians evaluated the digital and analog PET/CT datasets to assess the detection rate of HPT. Maximum standard uptake values (SUVmax) of HPT and locoregional lymph nodes were measured in both systems. HPT was detected in 30/33 patients by the digital system, whereas it was detected in 22/33 patients by the analog system (p < 0.01). Moreover, in 21 of these 33 patients, both systems detected one focal 18F-fluorocholine uptake, and in one patient the digital system detected two foci. Histopathology demonstrated HPT in 32 patients and it was inconclusive in one patient. The digital PET/CT detected HPT in 29 of the 32 patients, and the analog system in 22 of the 32 (p < 0.01). All HPT suspected lesions resected and detected only by the digital system (n = 8) were < 10mm (7.5 ± 1.3mm), while those detected by both systems (n = 22) were > 10mm (13 ± 3.8mm). SUVmax of HPT lesions was significantly higher than SUVmax of locoregional lymph node independently of the PET/CT system used (4.5 ± 1.9 vs. 2.9 ± 1.3, p < 0.0001). Digital PET/CT offers superior performance over analog system in patients with suspected HPT and previous negative/inconclusive imaging examinations, particularly in sub-centimeter lesions. SUVmax can help in the differentiation between HTP and locoregional lymph nodes.

Performance of F-18 Fluorocholine PET/CT for Detection of Hyperfunctioning Parathyroid Tissue in Patients with Elevated Parathyroid Hormone Levels and Negative or Discrepant Results in conventional Imaging.

ObjectiveOur aim was to assess the diagnostic performance of F-18 fluorocholine (FCH) positron emission tomography/computed tomography (PET/CT) in detecting hyperfunctioning parathyroid tissue (HPT) in patients with elevated parathyroid hormone levels with negative or inconclusive conventional imaging results and to compare the findings with those obtained using technetium-99m sestamibi (MIBI) scintigraphy and neck ultrasonography (US).Materials and MethodsImages of 105 patients with hyperparathyroidism who underwent FCH PET/CT, dual-phase MIBI parathyroid scintigraphy (median interval: 42 days), and neck US were retrospectively analyzed. The gold standard was histopathological findings for 81 patients who underwent parathyroidectomy and clinical follow-up findings in the remaining 24 patients. Sensitivities, positive predictive values (PPVs), and accuracies were calculated for all imaging modalities.ResultsAmong the 81 patients who underwent parathyroidectomy, either parathyroid adenoma (n = 64), hyperplasia (n = 9), neoplasia (n = 4), or both parathyroid adenoma and hyperplasia (n = 1) were detected, except 3 patients who did not show HPT. Of the 24 (23%) patients who were followed-up without operation, 22 (92%) showed persistent hyperparathyroidism. FCH PET/CT showed significantly higher sensitivity than MIBI scintigraphy and US in detection of HPT (p < 0.01). Sensitivity, PPV, and accuracy of FCH PET/CT were 94.1% (95/101), 97.9% (95/97), and 92.4% (97/105), respectively. The corresponding values for MIBI scintigraphy and US were 45.1% (46/102), 97.9% (46/47), and 45.7% (48/105) and 44.1% (45/102), 93.8% (45/48), and 42.9% (45/105), respectively. Among the 35 patients showing negative MIBI scintigraphy and neck US findings, 30 (86%) showed positive results on FCH PET/CT. FCH PET/CT could demonstrate ectopic locations of HPT in 11 patients whereas MIBI and US showed positive findings in only 6 and 3 patients, respectively.ConclusionFCH PET/CT is an effective imaging modality for detection of HPT with the highest sensitivity among the available imaging techniques. Therefore, FCH PET/CT can be recommended especially for patients who show negative or inconclusive results on conventional imaging.

Intraoperative Monitoring of Parathormone in the Surgical Treatment of Renal Hyperparathyroidism.

Intraoperative monitoring of parathyroid hormone can confirm the complete excision of hyperfunctional parathyroid tissue, as the plasma half-life of PTH is approximately 5 minutes. The purpose of this study was to analyse the values of parathormon (PTH) and the intraoperative impact in patients with secondary hyperparathyroidism of renal cause (sHPT). A series of 86 patients who were hospitalised in our clinic between February 2015 to December 2018, were included in the study rom. All patients underwent surgery with PTH monitoring. PTH was determined preoperatively, intraoperatively 15 minutes after parathyroidectomy and postoperatively. Out of a total of 86 patients, 6 patients had non-functional renal transplant. 81 patients were operated on per primam and 5 patients were operated for disease recurrence. There were 77 total parathyroidectomies and 4 subtotal parathyroidectomies. One patient had 5 parathyroid glands. There were 4 patients with recurrent hyper-plastic tissue excision. Blood samples were collected intraoperatively through the puncture of the jugular vein. The PTH value was determined by the Elecsys PTH STATÃÂî test. The mean value of preoperative PTH was 1658 pg / mL and decreased to 46.5 pg / mL at the end of the operation. Subsequently, the level of PTH harvested at 3-6 months increased slightly to 59.8 pg / mL. 80 (93%) of patients had elevated preoperative calcium values. Recurrent hyperparathyroidism was found in 1 of the 4 patients who underwent subtotal parathyroidectomy. IPTH value is influenced by the intraoperative manipulation of the parathyroid glands, the individual variability of PTH half-life and the physiological state of the patient. The decrease of PTH measured intraoperatively at 15 minutes after harvest with at least 90% of the preoperative value indicates the success of a total parathyroidectomy, with normalisation of calcium and PTH.

99mTc-MIBI SPECT/CT imaging contribution in the diagnosis of patients with hyperparathyroidism

Introduction: Hyperparathyroidism is presented with increased parathyroid hormone (PTH) secretion due to hyperfunctioning of one or more of the four parathyroid glands. Primary hyperparathyroidism (p-HPT) can be due to parathyroid adenoma, hyperplasia or carcinoma of the parathyroid gland. Secondary hyperparathyroidism (s-HPT) is usually a response to hypocalcaemia and consecutive hyperplasia of the glands. Our aim was to compare the efficacy of 99mTcmethoxyisobutylisonitrile (MIBI) SPECT/CT in identification of the location of the lesion(s) in cases of HPT by comparing these results with the findings of ultrasound (US) and planar scintigraphy. Methods: Forty one consecutive patients (54±17 age, 12 males and 29 females) with primary or secondary hyperparathyroidism were included. All patients were examined by US and afterwards patients underwent conventional double-phase 99mTc-MIBI scintigraphy combined with neck SPECT/CT procedure. Planar images (early and delayed), US and SPECT/CT image sets were evaluated for adenoma localization at the neck and thorax. Regions of interest (ROIs), equal sized, were selected and compared, over the hyperfunctioning parathyroid tissue (accumulated impulses-counts value) and over the contralateral lobe of the thyroid gland (control counts value). Results: The ultrasonography detected 24 positive findings. The late phase of planar scan detected 26 positive findings. SPECT/CT presented with bigger detection rate than late planar phase or US (75.6%, 63.4%, 61.5%) and with higher sensitivity (100%, 83.8%, 77.4%), respectively. Conclusion: The SPECT/CT study seems reliable, sensitive and with added value in diagnosing hyperparathyroidism as a complementary method to planar scintigraphy. US as compatible method, should be performed prior the scintigraphy protocols.

Minimally invasive parathyroidectomy in a community based teaching hospital: The role of dual-phase parathyroid scintigraphy and surgeon experience

Aim: In a community based teaching hospital setting, to explore role of dual-phase parathyroid scintigraphy and surgeon experience in minimally invasive parathyroidectomy.Material and Methods: During 4-year period, from January 2013 to December 2016, 136 of 170 patients those were diagnosed with primary hyperparathyroidism were selected for this retrospective study. For detection of hyper-functioning parathyroid tissue, routine neck ultrasound and 99mTc-MIBI dual phase parathyroid scintigraphy were performed. All scintigraphy scans were evaluated by nuclear medicine physicians and surgeons together. Patients with suspected multiglandular diseases and familial cases were excluded. Enlarged glands were identified by surgeons intraoperatively. Specimens were sent for frozen section analysis.Results: Without using intraoperative parathormone monitoring or gamma probe, combination of neck ultrasound, surgeon-nuclear physician evaluated parathyroid scintigraphy scan and resection of surgeon-identified diseased gland resulted in 100% cure rate for this group of patients. Conclusion: Operative experience of surgeon and review of preoperative parathyroid scintigraphy scan had remarkable impact on outcomes. Minimally invasive parathyroidectomy can be held successfully at community-based hospitals under specific conditions without using intraoperative parathormone or gamma probe.