Comparison between technetium-99m methoxyisobutylisonitrile scintigraphy and ultrasound in the diagnosis of parathyroid adenoma and parathyroid hyperplasia

Primary hyperparathyroidism: diagnostic features and surgical outcomes

BACKGROUND

Primary hyperparathyroidism is characterized by elevated plasma calcium levels due to inappropriate secretion of parathyroid hormone (PTH) in most cases by an adenomatous or hyperplastic parathyroid. We present a retrospective analysis of a large cohort of patients operated on of parathyroidectomy in our center analyzing their diagnostic characteristics, intraoperative match and surgical outcomes.

METHODS

We included patients with benign parathyroid disease who underwent parathyroidectomy associated or not with hemi- or total thyroidectomy at the Sant'Anna University Hospital of Ferrara between September 2003 and September 2022.

RESULTS

In our study 371 patients fulfilled the inclusion criteria. The most widely used preoperative imaging method was ultrasound, followed by 99mTc-sestamibi scintigraphy. In most cases, preoperative imaging correctly localized the affected parathyroid. Considering the intraoperative site of the pathologically affected parathyroid, the majority of pathological parathyroids were located in the lower districts of the neck and a smaller percentage in the upper, intermediate, and ectopic sites. Postoperative complications were infrequent.

CONCLUSIONS

The main challenge in parathyroid surgery lies in the difficulty in localizing the pathological parathyroid at the surgical site, which can lengthen the surgical time by increasing comorbidities. Currently, the results on pathological parathyroid localization are good. Technology needs to be developed toward greater diagnostic accuracy and minimally invasive surgical approaches.

Diagnostic accuracy of ultrasonography and 99m-Technetium Sestamibi scintigraphy for the preoperative localization of Parathyroid Adenoma keeping histopathological findings as reference standard

Objective

To determine the diagnostic accuracy of Ultrasound (US) and 99m-Tc Sestamibi scan in patients with primary hyperparathyroidism (PHPT) for the localization of parathyroid adenoma before surgery keeping Parathyroid histopathology as reference standard.

Method

This three years retrospective study was performed in the Department of Endocrinology, Hayatabad Medical Complex, Peshawar. Patients with PHPT who underwent parathyroidectomy from July 2019 to June 2022 were included in the study. Information relating to localization studies prior to surgical management like US and 99m-Tc Sestamibi scan was documented. These imaging findings were subsequently compared with the findings of parathyroid surgery and histopathology results which were taken as reference standard.

Results

The sensitivity, positive predictive value (PPV) and overall accuracy of US for the preoperative localization of parathyroid adenoma was 77%, 95.7% and 75%, respectively. Whereas the sensitivity, PPV and accuracy of 99m-Tc Sestamibi scintigraphy was 89.5%, 95% and 86% respectively.

Conclusion

Ultrasound despite its cost effectiveness has a lower sensitivity compared to 99m-Tc Sestamibi scintigraphy. Similarly, the sensitivity and overall accuracy of US and 99m-Tc Sestamibi scan when taken in combination is higher compared to either modality. It is thus recommended that the combination of these modalities should be employed to localize the adenomas accurately for surgery of the parathyroid gland for a better outcome.

Advances in the application of auxiliary imaging techniques in parathyroid diseases

Hypoparathyroidism is one of the main complications after total thyroidectomy, severely affecting patients' quality of life. How to effectively protect parathyroid function after surgery and reduce the incidence of hypoparathyroidism has always been a key research area in thyroid surgery. Therefore, precise localization of parathyroid glands during surgery, effective imaging, and accurate surgical resection have become hot topics of concern for thyroid surgeons. In response to this clinical phenomenon, this study compared several different imaging methods for parathyroid surgery, including nanocarbon, indocyanine green, near-infrared imaging techniques, and technetium-99m methoxyisobutylisonitrile combined with gamma probe imaging technology. The advantages and disadvantages of each method were analyzed, providing scientific recommendations for future parathyroid imaging. In recent years, some related basic and clinical research has also been conducted in thyroid surgery. This article reviewed relevant literature and provided an overview of the practical application progress of various imaging techniques in parathyroid surgery.

Do large parathyroid adenomas increase the risk of severe hypercalcemia?

<b><br>Introduction:</b> Primary hyperparathyroidism (PHPT) is mainly caused by parathyroid adenoma (PA). Rare variants of PA, weighing >2.0-3.5 g are called "large" or "giant" adenomas and account for about 1.5% of all PA.</br> <b><br>Aim:</b> The aim of this study was to compare normal-sized and large parathyroid lesions identifying risk factors for severe hypercalcemia.</br> <b><br>Materials and methods:</b> 27 patients with PHPT and parathyroid lesion ≥2.0 cm3 (study group) were compared with 73 patients with PHPT and lesion < 2.0 cm³ (control group). In both groups, the majority were women (81.5% - study group, 90.5% - control group, gender ratios 4.4:9.1, respectively). The patients were examined preoperatively and postoperatively: PTH, creatine, calcium, and phosphate serum and urine concentrations, and calcidiol serum levels were assessed. Preoperative ultrasonography (US) was performed.</br> <b><br>Results:</b> Patients with larger parathyroid lesions had signifficantly higher PTH and calcium serum concentrations and lower serum phosphate and calcidiol concentrations. There were no statistically significant differences in the concentration of creatine in serum and urine, calciuria, or tubular reabsorption of phosphorus (TRP). US relatively underestimated the parathyroid volume by about 0.3-0.4 mL (10% in larger lesions and 43% in smaller ones).</br> <b><br>Conclusions:</b> Due to higher PTH and calcium levels, larger parathyroid adenomas may constitute a higher risk of severe hypercalcemia. In general, US underestimated the parathyroid volume.</br>.

Analysis of false-positive and false-negative results in 99mTc-MIBI SPECT/CT parathyroid imaging

Background

Exact preoperative localization is desirable to perform minimally invasive parathyroidectomy for hyperparathyroidism (HPT). This study aimed to evaluate the diagnostic values of 99mTc-methoxyisobutylisonitrile (99mTc-MIBI) single photon emission computed tomography/computed tomography (SPECT/CT) of parathyroid glands by analyzing the relationship between lesion weight and false-negative (FN) results, as well as to explain the possible reason.

Methods

The data from 314 patients with suspected HPT who underwent 99mTc-MIBI SPECT/CT parathyroid imaging between 2011 and 2022 were retrospectively evaluated. The sensitivity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of parathyroid 99mTc-MIBI SPECT/CT were calculated, and the false-positive (FP) and FN findings were analyzed.

Results

Accurate localization by 99mTc-MIBI SPECT/CT was significantly associated with the parathyroid hormone (PTH) level. The 99mTc-MIBI SPECT/CT for diagnosis/lesion location reached a sensitivity of 84.6%/56.8%, a PPV of 97.3%/98.4%, an NPV of only 23.7%/4.18%, and an accuracy of 83.4%/57.1%, respectively. The largest diameter, shortest diameter, and lesion volume were lower in the FN group than in the TP group. A total of 7 FP cases were found, including 2 cases of thyroid nodules, 4 cases of thyroid tissue, and 1 case of hibernoma. A total of 45 FN patients, including 321 FN lesions, were confirmed, of which parathyroid hyperplasia accounted for 97.8%. Lesion weights greater than 20 µg were able to be detected, but lightweight lesions less than 100 mg were the principal source of FN results, accounting for approximately 39.3%. With lesion weights 0-100, 101-300, 301-1,000, and >1,000 mg, the FN rate was 70.8% (126/178), 51.8% (103/199), 34.6% (81/234), and 8.33% (11/132), respectively.

Conclusions

99mTc-MIBI SPECT/CT parathyroid imaging provides good sensitivity and high specificity in HPT location. Correct localization by 99mTc-MIBI SPECT/CT correlates positively with lesion weight and PTH levels. The smaller the lesion, the higher the FN rate in 99mTc-MIBI SPECT/CT parathyroid imaging, and lesions weighing less than 100 mg are the main source of FN results in 99mTc-MIBI SPECT/CT parathyroid imaging.

Preoperative parathyroid localization. Relevance of MIBI SPECT-CT in adverse scenarios

PURPOSE

Selective parathyroidectomy, the treatment of choice for primary hyperparathyroidism, requires precise preoperative localization. Our purpose was to compare the accuracy and concordance of pre-surgical MIBI parathyroid scintigraphy and ultrasonography, as well as to assess the relevance of hybrid acquisition (SPECT/CT) in compromised circumstances: low-weight or ectopic adenomas, coexisting thyroid disease and re-interventions.

METHODS

The study included 223 patients with primary hyperparathyroidism operated in a single Surgical Unit from August 2016 to March 2021. Preoperative ultrasonography and double-phase MIBI were performed with early SPECT/CT acquisition. A minimally invasive surgical approach was initially attempted, except in patients with concomitant thyroid surgery or multiglandular parathyroid disease.

RESULTS

Selective parathyroidectomy was accomplished in 179 patients (80.2%); cervicotomy and/or thoracoscopy in 44. Removal of the parathyroid lesion was achieved in 211 patients (94.6%), corresponding 204 (96.7%) to adenomas (37 ectopic). The cure rate was 94.2%. Preoperative MIBI SPECT/CT showed higher sensitivity and accuracy (84%; 80%) compared to ultrasound (72%; 71%), being more precise in defining the exact anatomical location (75.8% vs 68.7%). These differences reached statistical significance in ectopic glands. The existence of concomitant thyroid pathology did not decrease the sensitivity of SPECT/CT (84.2%). Mean parathyroid weight was 692.2mg (95%CI: 443.5-941) in MIBI-negative cases and 1145.9mg (95%CI: 983.6-1308.3) in MIBI-positive (p=0.001). Re-intervention was successful in the 8 patients with previous surgery.

CONCLUSION

MIBI SPECT/CT presents greater sensitivity, accuracy and anatomical precision than ultrasound for preoperative parathyroid localization, even in the case of ectopic glands or coexisting thyroid pathology. The weight of the pathological gland is a significantly limiting factor.

Quantitative application of dual-phase 99mTc-sestamibi SPECT/CT imaging of parathyroid lesions: identification of optimal timing in secondary hyperparathyroidism

PURPOSE

In this retrospective study, we compared the maximum standardized uptake values (SUVmax) of parathyroid lesions and the target-to-background ratio (TBR) of parathyroid lesions to thyroid tissue in early-phase single-photon emission computed tomography/computed tomography (SPECT/CT) versus delayed-phase SPECT/CT in patients with secondary hyperparathyroidism (SHPT) in order to determine the optimal timing of 99mTc- methoxyisobutylisonitrile (99mTc-MIBI) SPECT/CT imaging.

METHODS

Seventeen patients with a history of chronic kidney failure stage 5 on hemodialysis, underwent pre-operative parathyroid scintigraphy for detection and localization of parathyroid lesions. Retrospective analysis was conducted for lesions with focal accumulation of 99mTc-MIBI. All patients underwent dual-phase 99mTc-MIBI parathyroid scintigraphy and dual-phase SPECT/CT. SUVmax of parathyroid lesions and thyroid tissues was measured.

RESULTS

Mean SUVmax of parathyroid lesions was 4.86 on early-phase and 2.58 on delayed-phase SPECT/CT, respectively. Mean TBR was 1.14 on early phase and 1.48 on delayed-phase SPECT/CT, respectively. Statistically significant differences in SUVmax and TBR between dual-phase SPECT/CT were observed (P < 0.001).

CONCLUSIONS

Delayed-phase SPECT/CT in SHPT is required because of the better image contrast.

The Dark Side of Ultrasound Imaging in Parathyroid Disease

The diagnosis of parathyroid diseases by imaging still has some intrinsic technical limitations due to the differential diagnosis of different structures of the neck that mimic the parathyroid glands. In this view, ultrasound (US) is an established, low-cost, and non-invasive imaging technique that still represents the first-line approach for evaluating patients with parathyroid disease. The objective of this article is to provide a comprehensive review of the applications of USs in clinical practice, discussing the histopathological and US characteristics of the parathyroid glands in normal and pathological conditions, the advantages of preoperative imaging, and novel updates on the most useful and currently available multiparameter US techniques.

Clinical application of 18F-FCH PET/CT in the diagnosis and treatment of hyperparathyroidism

Objective

We evaluated the difference in parathyroid visualization on ¹⁸F-FCH PET/CT images obtained at 5 and 60 min, and quantitatively analyzed the mode of FCH uptake at different time points, to determine the best imaging time for FCH PET/CT.

Methods

This retrospective study included 73 patients with hyperparathyroidism (HPT) who underwent ¹⁸F-FCH PET/CT imaging between December 2017 and December 2021. The diagnostic efficiency of 5- and 60-min dual time point imaging for the diagnosis of hyperparathyroidism and parathyroid adenoma and hyperplasia, were compared using visual and quantitative analyses.

Results

Dual-time ¹⁸F-FCH PET/CT imaging visual analysis had diagnostic value for HPT. The receiver operating characteristic curve of PET/CT quantitative parameters for the diagnosis of HPT and lesions showed that the parathyroid/thyroid SUVmax ratio for 60-min imaging had a higher sensitivity and specificity (based on patient, sensitivity: 90.90% and specificity: 85.71%; based on focus, sensitivity: 83.06% and specificity: 85.71%) compared to that for 5-min imaging. PET/CT quantitative parameters can distinguish parathyroid adenoma and hyperplasia. The 60-min parathyroid SUVmax value had the highest diagnostic value (cutoff: 3.945; area under the curve: 0.783).

Conclusion

The quantitative parameters of 60min ¹⁸F-FCH PET/CT have more advantages in aiding in the pathologica diagnosis and clinical treatment of HPT.

Primary hyperparathyroidism: Correlation between cervical ultrasound and MIBI scan

Introduction:

The standard gold treatment of primary hyperparathyroidism (PHP) is parathyroidectomy. Imaging in particular, cervical ultrasound (US) and technetium-99 m- méthoxyisobutylisonitrileparathyroid scintigraphy using the single-photon emission computed tomography (TC-99 m-MIBI-SPECT) are always indicated prior to parathyroid surgery, allowing the location of parathyroid adenomas. The objective of our study is to evaluate the contribution of TC-99 m-MIBI-SPECT and US in the preoperative topographic diagnosis of PHP.

Materials and Methods:

this is a descriptive and analytical retrospective study, conducted in our department of Endocrinology, Diabetology and Metabolic Diseases in Hassan II University Hospital of Fez between 2009 and 2018. All patients who received a para-thyroidectomy for PHP were recruited. All patients had received a cervical US and a TC-99 m-MIBI-SPECT. We compared imaging data before surgery with data from intraoperative exploration and anatomopathological findings of surgical samples.

Results:

Forty-eight patients were collected. US correctly identified parathyroid adenoma in 85.40% of patients with PHP versus 89.50% in TC-99 m-MIBI-SPECT. US correctly predicted surgical outecomes in 97.60% of patients and TC-99 m-MIBI-SPECT in 97.72% of cases. Their combination had better results in sensitivity and positive predictive value.

Conclusion:

TC-99 m-MIBI-parathyroid scintigraphy SPECT had a higher probability for solitary parathyroid adenoma compared to cervical US. Its use coupled with the TC-99 m-MIBI-parathyroid scintigraphy SPECT allows reliable preoperative tracking.

Primary Hyperparathyroidism in the Common Orthopaedic Practice

An extensive review of the publications on primary hyperparathyroidism (pHPT) is presented in this report. It has strongly been emphasized in the literature that patients with pHPT may present either with the classical symptomatology or with asymptomatic disease, emerged due to biochemical screening. The clinical and epidemiological presentation of pHPT in western countries has changed profoundly during the past few decades, and bone disease is nowadays a distinct rarity. The introduction of serum calcium screening for osteoporosis and the technological advances in the laboratory assessment of parathyroid hormone have played important roles in early diagnosis. Subsequently, the disease is increasingly being detected as asymptomatic hypercalcaemia without guiding signs or symptoms. A third type of disease, the normocalcaemic variant, has been recently described in the literature. However, the potential diagnosis of pHPT should always be on the orthopaedics’ list of differential diagnoses in female or elderly patients with vertebral fractures and nephrolithiasis, either symptomatic or asymptomatic, as well as when solitary or multiple osteolytic lesions are encountered on the radiographs.

Additionally, a middle aged woman with parathyroid adenoma and subsequent brown tumors detected on the pelvic radiographs is reported. Her initial laboratory findings indicated a minimal increase of the serum calcium, a mild increase of the erythrocyte sedimentation rate, and a significant increase in total serum alkaline phosphatase. Finally, the detection of elevated parathyroid hormone levels indicated the diagnosis of pHPT and necessitated imaging studies of the parathyroid glands, which indicated a parathyroid adenoma. Following successful excision of the parathyroid adenoma, the patient suffered from the hungry bone syndrome. After a follow-up of 20 years, the patient had normal calcium, vitamin D, and parathyroid hormone serum levels, while a pelvic radiograph indicated no significant changes in the appearance of the brown tumors.

Primary Hyperparathyroidism in the Common Orthopaedic Practice

An extensive review of the publications on primary hyperparathyroidism (pHPT) is presented in this report. It has strongly been emphasized in the literature that patients with pHPT may present either with the classical symptomatology or with asymptomatic disease, emerged due to biochemical screening. The clinical and epidemiological presentation of pHPT in western countries has changed profoundly during the past few decades, and bone disease is nowadays a distinct rarity. The introduction of serum calcium screening for osteoporosis and the technological advances in the laboratory assessment of parathyroid hormone have played important roles in early diagnosis. Subsequently, the disease is increasingly being detected as asymptomatic hypercalcaemia without guiding signs or symptoms. A third type of disease, the normocalcaemic variant, has been recently described in the literature. However, the potential diagnosis of pHPT should always be on the orthopaedics’ list of differential diagnoses in female or elderly patients with vertebral fractures and nephrolithiasis, either symptomatic or asymptomatic, as well as when solitary or multiple osteolytic lesions are encountered on the radiographs.

Additionally, a middle aged woman with parathyroid adenoma and subsequent brown tumors detected on the pelvic radiographs is reported. Her initial laboratory findings indicated a minimal increase of the serum calcium, a mild increase of the erythrocyte sedimentation rate, and a significant increase in total serum alkaline phosphatase. Finally, the detection of elevated parathyroid hormone levels indicated the diagnosis of pHPT and necessitated imaging studies of the parathyroid glands, which indicated a parathyroid adenoma. Following successful excision of the parathyroid adenoma, the patient suffered from the hungry bone syndrome. After a follow-up of 20 years, the patient had normal calcium, vitamin D, and parathyroid hormone serum levels, while a pelvic radiograph indicated no significant changes in the appearance of the brown tumors.

ACR Appropriateness Criteria® Parathyroid Adenoma

Hyperparathyroidism is defined as excessive parathyroid hormone production. The diagnosis is made through biochemical testing, in which imaging has no role. However, imaging is appropriate for preoperative parathyroid gland localization with the intent of surgical cure. Imaging is particularly useful in the setting of primary hyperparathyroidism whereby accurate localization of a single parathyroid adenoma can facilitate minimally invasive parathyroidectomy. Imaging can also be useful to localize ectopic or supernumerary parathyroid glands and detail anatomy, which may impact surgery. This document summarizes the literature and provides imaging recommendations for hyperparathyroidism including primary hyperparathyroidism, recurrent or persistent primary hyperparathyroidism after parathyroid surgery, secondary hyperparathyroidism, and tertiary hyperparathyroidism. Recommendations include ultrasound, CT neck without and with contrast, and nuclear medicine parathyroid scans. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

[Preoperative diagnostic value of 99mTc- MIBI SPECT/CT imaging combined with semiquantitative analysis in hyperparathyroidism and factors affecting its efficacy]

OBJECTIVE

To evaluate the diagnostic efficacy of technetium-99m methoxyisobutylisonitrile single photon emission/ computed tomography (^99mTc- MIBI SPECT/CT), ^99mTc- MIBI double- phase scintigraphy (DPS) DPS and ultrasound (US) in preoperative localization of hyperparathyroidism (HPT) and explore the factors affecting the diagnostic efficacy of ^99mTc-MIBI SPECT/CT.

METHODS

We retrospectively analyzed the data of 104 patients with HPT undergoing surgical resection between January, 2015 and July, 2019. Preoperative ^99mTc-MIBI imaging was performed in all the patients, and 82 patients also received US examination preoperatively. Semi-quantitative analysis was used to draw the region of interest and calculate the lesion/ ipsilateral deltoid muscle (T/NT) uptake ratio. The sensitivity and detection performance of ^99mTc-MIBI SPECT/CT, DPS and US in the diagnosis of HPT patients were compared, and the correlations of the T/NT ratios of parathyroid adenoma (PA) and parathyroid hyperplasia (PH) with the expression levels of COX-2 and Bcl-2 were analyzed.

RESULTS

The diagnostic sensitivity of ^99mTc- MIBI SPECT/CT, DPS and US for HPT was 95.19% (99/104), 91.3% (95/104) and 81.71% (67/82), respectively, demonstrating a significantly higher diagnostic sensitivity of ^99mTc-MIBI SPECT/CT than US (χ²=9.59, P=0.008). For PH lesions, ^99mTc-MIBI SPECT/CT had the highest diagnostic sensitivity, followed by DPS and then by US (P < 0.05), but their sensitivity did not differ significantly for PA (P>0.05). The T/NT ratio in fatty hyperplastic glands was significantly lower than that in fat-free hyperplastic glands (P=0.009). In PA, Bcl-2 expression was significantly lower in false negative lesions than in true positive lesions (P=0.046), but Cox-2 expression did not show such a difference (P>0.05). In PH lesions, the expressions of Bcl-2 and Cox- 2 did not differ significantly between false negative than true positive lesions (P>0.05).

CONCLUSIONS

^99mTc-MIBI SPECT/CT has a high sensitivity for HPT localization, and the T/NT ratio is positively correlated with the lesion volume. An increased expression of Bcl-2 in PA lesions and a decreased cell fat content in PH lesions can facilitate the detection of HPT glands by ^99mTc-MIBI SPECT/CT.

Preoperative calcium and parathyroid hormone values are poor predictors of gland volume and multigland disease in primary hyperparathyroidism: A review of 2,000 consecutive patients

OBJECTIVE

Calcium and parathyroid hormone (PTH) values are thought to have a linear relationship in patients with primary hyperparathyroidism and correlate with parathyroid gland size, with higher values predicting single-gland disease. In this modern series, these preoperative values are correlated with operative findings to determine their utility in predicting gland involvement at parathyroid exploration.

METHODS

Two thousand consecutive patients who underwent initial surgery for sporadic primary hyperparathyroidism from 2000 to 2014 were reviewed. All patients underwent a four-gland exploration. Relationships between preoperative calcium and PTH values with per patient total gland volume were examined and stratified by number of involved glands: single adenoma (SA), double adenoma (DA), and hyperplasia (H).

RESULTS

There were 1274 (64%) SA, 359 (18%) DA, and 367 (18%) H cases. There was poor correlation between preoperative calcium and PTH (R=0.37), and both correlated poorly with total gland volume (R<0.40). Subgroup analysis by the number of involved glands similarly showed poor correlation. Mean total gland volume was similar among all subgroups (SA=1.28, DA=1.43, H=1.27 cc, p=0.52), implying individual glands were smaller in multigland disease. SA was found in 53% of patients with calcium ≤10.5 mg/dL and 78% if ≥12 mg/dL (p<0.001).

CONCLUSION

This is the largest series correlating preoperative calcium and PTH values with operative findings of gland size and number of diseased glands. Although a lower calcium value predicts somewhat more multigland disease, the overall poor correlation should make the parathyroid surgeon aware that gland size and multigland disease cannot be predicted by preoperative laboratory testing.

Factors That Affect the Sensitivity of Imaging Modalities in Primary Hyperparathyroidism

BACKGROUND

Cervical ultrasound, 99mTc-sestamibi single-photon emission computed tomography/computed tomography (99mTc-MIBI SPECT/CT), and cervical CT are routinely used in preoperative localization of primary hyperparathyroidism (PHPT). However, false-negative imaging results are also frequently encountered in clinical practice. Exploring the factors that affect the sensitivity of these imaging modalities is important for the surgical management of PHPT patients.

METHODS

Clinical data of 352 PHPT patients hospitalized in our center from January 2011 to December 2015 were retrospectively collected to evaluate the sensitivity of 3 imaging modalities in the preoperative localization of parathyroid lesions. The ROC curve analysis was used to explore the clinical factors affecting the sensitivity of localization, and the cut-point(s) of related factors were determined.

RESULTS

99mTc-MIBI SPECT/CT has the highest sensitivity among the localization modalities commonly used, reaching 91.1% (86.0%-94.8%). When the lengths of parathyroid lesions were ≤1.3 cm, the sensitivity of neck ultrasonography significantly decreased, while the sensitivity of 99mTc-MIBI SPECT/CT decreased with parathyroid lesions ≤1.3 cm or serum PTH≤252 pg/ml. 99mTc-MIBI SPECT/CT was less effective in localizing the hyperplasia lesions. Neck ultrasonography combined with 99mTc-MIBI SPECT/CT can effectively improve the accuracy of preoperative localization of parathyroid lesions to 96.2% (92.7%-98.1%).

CONCLUSIONS

Small parathyroid lesion and mild elevation of serum PTH would reduce the accuracy of parathyroid localization in PHPT patients.

Causes of false negatives in technetium-99 m methoxyisobutylisonitrile scintigraphy for hyperparathyroidism: influence of size and cysts in parathyroid lesions

OBJECTIVE

The aim of this study was to elucidate the causes of false-negative cases of technetium-99 m methoxyisobutylisonitrile scintigraphy (MIBI) for hyperparathyroidism.

METHODS

Consecutive MIBI examinations performed in 154 patients between April 2011 and March 2017 were retrospectively reviewed. Sensitivities of MIBI, CT and US were calculated. The effects of serum calcium, phosphorus, PTH, weight of parathyroid lesions, use of NSAIDs and Ca-channel blocker (CCB), presence of cyst in parathyroid lesions, and a number of lesions observed by MIBI were investigated.

RESULTS

Seventy-nine patients (21 men and 58 women), ranging from 18 to 88 years of age (mean ± SD: 57.6 ± 15.3 years), who underwent parathyroidectomy, were included. MIBI and preoperative US were performed in the 79 patients and single-phase parenchymal contrast-enhanced CT (CE-CT) was performed in 55 patients. A total of 120 parathyroid proliferative nodules were detected by MIBI and US, and 92 lesions were detected by CE-CT. In the lesion base, MIBI detected 82 out of the 120 lesions (sensitivity = 68.3%), US detected 103 out of the 120 lesions (sensitivity = 85.8%), CE-CT detected 63 out of the 92 lesions (sensitivity = 68.5%), and MIBI plus CE-CT detected 72 of the 92 lesions (sensitivity = 78.3%). A significant difference in the sensitivity was found between US and MIBI (P < 0.01), and between US and CT (P < 0.01). In the patient base, MIBI detected 67 out of the 79 patients (sensitivity = 84.8%), US detected 74 out of the 79 patients (sensitivity = 93.7%), CE-CT detected 45 out of the 55 patients (sensitivity = 81.8%), and MIBI plus CE-CT detected 52 out of the 55 patients (sensitivity = 94.5%). No significant difference was observed in any of the comparisons. A significant difference was observed in lesion weight (P < 0.01), single or multiple lesions (P = 0.02), and presence of cyst (P < 0.01) between the MIBI false-negative (n = 38) and the true-positive groups (n = 82).

CONCLUSION

The presence of cyst in parathyroid proliferative lesions as well as small size and multiple number of parathyroid lesions contribute to false negative in parathyroid MIBI scan.

The Utility of Ultrasound in the Preoperative Localization of Primary Hyperparathyroidism: Insights from Pakistan

Objective

We aimed to evaluate and compare the diagnostic performance of ultrasound (US) and 99m-Tc sestamibi scintigraphy for the preoperative localization of primary hyperparathyroidism (PHPT).

Methods

This retrospective study was conducted at the Aga Khan University Hospital in Karachi, Pakistan, and comprised the data of patients with PHPT who underwent parathyroidectomy from 2008 to 2017. Preoperative US and 99m-Tc sestamibi scintigraphy findings were recorded and compared to surgical and histological findings, which were taken as a reference standard.

Results

The sensitivity of US in the preoperative localization of PHPT was 88.3%, positive predictive value (PPV) was 94.6%, and accuracy was 84.1%. The sensitivity of 99m-Tc sestamibi scintigraphy was 90.4%, PPV was 94.3%, and accuracy was 85.7%.

Conclusion

US neck is an efficient tool for the preoperative localization of PHPT, demonstrating a comparable diagnostic yield with 99m-Tc sestamibi, and can serve as a credible first-line imaging modality in a resource-constrained healthcare setup.

Diagnostic performance of ultrasonography, dual-phase 99mTc-MIBI scintigraphy, early and delayed 99mTc-MIBI SPECT/CT in preoperative parathyroid gland localization in secondary hyperparathyroidism

BACKGROUND

Secondary hyperparathyroidism (SHPT) usually requires parathyroidectomy when drug regimens fail. However, obtaining an exact preoperative map of the locations of the parathyroid glands is a challenge. The purpose of this study was to compare the diagnostic performance of US, dual-phase ^99mTc-MIBI scintigraphy, early and delayed ^99mTc-MIBI SPECT/CT in patients with SHPT.

METHODS

Sixty patients with SHPT who were undergoing dialysis were evaluated preoperatively by US, dual-phase ^99mTc-MIBI scintigraphy, early and delayed ^99mTc-MIBI SPECT/CT. Postoperative pathology served as the gold standard. The sensitivity, specificity, and accuracy were determined for each method. Spearman correlation analysis was used to analyse the correlation of hyperplastic parathyroid calcification with serum alkaline phosphatase (ALP) and parathyroid hormone (PTH).

RESULTS

A total of 229 lesions in 60 patients were pathologically confirmed to be parathyroid hyperplasia, with 209 lesions in typical sites, 15 lesions in the upper mediastinum and 5 lesions in the thyroid. A total of 88.33% (53/60) of patients had four lesions. US, early and delayed ^99mTc-MIBI SPECT/CT had significantly higher sensitivity and accuracy than dual-phase ^99mTc-MIBI scintigraphy (P < 0.001). Furthermore, early ^99mTc-MIBI SPECT/CT had significantly higher sensitivity (P < 0.001) and accuracy (P = 0.001 and P < 0.001) than US and delayed ^99mTc-MIBI SPECT/CT. In patients with ectopic hyperplastic parathyroid glands, the sensitivity of early ^99mTc-MIBI SPECT/CT (90%) was significantly higher than that of US (55%) and dual-phase ^99mTc-MIBI scintigraphy (50%) (P < 0.05). The Spearman correlation results showed a significant albeit weak association between calcification and both serum PTH and ALP (P = 0.002).

CONCLUSION

The ability of early ^99mTc-MIBI SPECT/CT to detect hyperplastic parathyroid glands in patients with SHPT is superior to that of US, dual-phase ^99mTc-MIBI scintigraphy and delayed ^99mTc-MIBI SPECT/CT; furthermore, dual-phase ^99mTc-MIBI SPECT/CT is not essential.