Parathyroid Imaging

The Parathyroid Gland: An Overall Review of the Hidden Organ for Radiologists

Parathyroid glands are small endocrine glands that regulate calcium metabolism by producing parathyroid hormone (PTH). These are located at the back of the thyroid gland. Typically, four glands comprise the parathyroid glands, although their numbers may vary among individuals. Parathyroid diseases are related to parathyroid gland dysfunction and can be caused by problems with the parathyroid gland itself or abnormal serum calcium levels arising from renal disease. In recent years, as comprehensive health checkups have become more common, abnormal serum calcium levels are often found incidentally in blood tests, after which several additional tests, including a PTH test, ultrasonography (US), technetium-99m sestamibi parathyroid scan, single-photon-emission CT (SPECT)/CT, four-dimensional CT (4D-CT), and PET/CT, are performed for further evaluation. However, the parathyroid gland remains an organ less familiar to radiologists. Therefore, the normal anatomy, pathophysiology, imaging, and clinical findings of the parathyroid gland and its associated diseases are discussed here.

Primary Hyperparathyroidism: Outcomes of Repeated Imaging After Initial Negative Radiological Localization

BACKGROUND

Radiological localization imaging aids in the identification of abnormal parathyroid glands resulting in primary hyperparathyroidism (PHPT), thereby facilitating minimally invasive parathyroid surgery. Sometimes initial imaging may fail to identify the abnormal gland and imaging may therefore be repeated. This study explored patient outcomes of repeated parathyroid localization imaging, after initial negative gland localization, at a United Kingdom institution.

METHODOLOGY

Data was retrospectively collected and analyzed for patients with PHPT undergoing repeated imaging during a five-year period (2015-2020). The total number of episodes of scanning, types of scans performed, the time interval between scans and the imaging success of gland localization were recorded. We explored the reasons for repeated imaging and attempted to identify any factors that might predict subsequent positive radiological localization.

RESULTS

A total of 45 patients were identified who underwent repeated localizing imaging after first localizing imaging was negative. Of these, 39 did not undergo surgery despite repeat imaging being undertaken; 11 out of these 39 patients (28%) had subsequent positive localization scans. Again, a large proportion of patients were managed conservatively, despite the repeated sets of imaging being done. Patients undergoing three or four sets of repetitive imaging did not have imaging or surgical success.

CONCLUSION

A streamlined parathyroid pathway should be followed whereby patients should be triaged for suitability for surgery prior to repeated imaging. A second set of scans should be offered when patients are unsuitable for conservative management and are willing and fit to undergo surgery. There is no merit to repeating imaging more than twice.

The magic mirror: a novel intraoperative monitoring method for parathyroid glands

The accurate detection of parathyroid glands (PGs) during surgery is of great significance in thyroidectomy and parathyroidectomy, which protects the function of normal PGs to prevent postoperative hypoparathyroidism and the thorough removal of parathyroid lesions. Existing conventional imaging techniques have certain limitations in the real-time exploration of PGs. In recent years, a new, real-time, and non-invasive imaging system known as the near-infrared autofluorescence (NIRAF) imaging system has been developed to detect PGs. Several studies have confirmed that this system has a high parathyroid recognition rate and can reduce the occurrence of transient hypoparathyroidism after surgery. The NIRAF imaging system, like a magic mirror, can monitor the PGs during surgery in real time, thus providing great support for surgeries. In addition, the NIRAF imaging system can evaluate the blood supply of PGs by utilizing indocyanine green (ICG) to guide surgical strategies. The NIRAF imaging system and ICG complement each other to protect normal parathyroid function and reduce postoperative complications. This article reviews the effectiveness of the NIRAF imaging system in thyroidectomies and parathyroidectomies and briefly discusses some existing problems and prospects for the future.

Parathyroid Cystic Adenoma: A Systematic Review and Meta-Analysis

OBJECTIVE

To review diagnostic imaging modalities for parathyroid cystic adenomas (PCA). Since PCAs are a rare (0.5%-1%) subclass of parathyroid adenomas, and due to their cystic component, imaging modalities known to be efficient for diagnosing solid adenomas might fail in localizing them.

METHODS

We conducted a systematic review using the PubMed and Cochrane databases for English articles on PCAs published between 1995 and 2020. A meta-analysis of the retrieved data was performed.

RESULTS

Overall, 39 studies, reporting on a total of 160 patients, were included in the analysis. Two thirds (68%) of the patients were female, with a mean age of 53.9 years. A single cystic adenoma was detected in 98.1% of cases. The mean blood calcium corrected for albumin level was 12.6 ± 2.7 mg/dL, and the mean parathyroid hormone level was 565.5 ± 523.8 pg/mL. The mean PCA sizes as measured by ultrasound (US), computed tomography (CT), and ex vivo measurement were 4.8 ± 3.6, 5.2 ± 3.2, and 3.5 cm, respectively. The median weight was 8.1 g. PCA was detected in 86% of US examinations; 100% of US-guided fine needle aspiration, 4-dimensional computed tomography (4D-CT), or magnetic resonance imaging examinations; and 61% of 99m-technetium sestamibi scan with single-photon emission computed tomography ((99m)Tc-SPECT). (99m)Tc-SPECT showed a significantly lower diagnostic rate than US (odds ratio, 3.589), US-guided fine needle aspiration, CT combined with 4D-CT, and the combination of US, CT, 4D-CT, and magnetic resonance imaging (P < .001).

CONCLUSION

Although US and 4D-CT showed a significantly high rate in diagnosing PCA, (99m)Tc-SPECT showed a lower PCA diagnostic rate. These findings suggest that larger cystic lesions suspected as PCAs should be further evaluated using 4D-CT rather than (99m)Tc-SPECT.

Update on Preoperative Parathyroid Localization in Primary Hyperparathyroidism

Parathyroidectomy is the treatment of choice for primary hyperparathyroidism when the clinical criteria are met. Although bilateral neck exploration is traditionally the standard method for surgery, minimally invasive parathyroidectomy (MIP), or focused parathyroidectomy, has been widely accepted with comparable curative outcomes. For successful MIP, accurate preoperative localization of parathyroid lesions is essential. However, no consensus exists on the optimal approach for localization. Currently, ultrasonography and technetium-99m-sestamibi-single photon emission computed tomography/computed tomography are widely accepted in most cases. However, exact localization cannot always be achieved, especially in cases with multiglandular disease, ectopic glands, recurrent disease, and normocalcemic primary hyperparathyroidism. Therefore, new modalities for preoperative localization have been developed and evaluated. Positron emission tomography/computed tomography and parathyroid venous sampling have demonstrated improvements in sensitivity and accuracy. Both anatomical and functional information can be obtained by combining these methods. As each approach has its advantages and disadvantages, the localization study should be deliberately chosen based on each patient's clinical profile, costs, radiation exposure, and the availability of experienced experts. In this review, we summarize various methods for the localization of hyperfunctioning parathyroid tissues in primary hyperparathyroidism.

Histopathological Features of Parathyroid Adenoma and 18F-Choline Uptake in PET/MR of Primary Hyperparathyroidism

BACKGROUND

The aim of this study was to assess the relationship between the histopathological properties of hyperfunctioning parathyroids and parathyroid 18F-choline uptake.

PATIENTS AND METHODS

A total of 31 parathyroid adenomas were retrospectively analyzed in patients with primary hyperparathyroidism and preoperative 18F-choline PET/MR. PET/MR parameters of parathyroid glands (SUVmax and target-to-background ratio in early-phase [EP] and late-phase [LP]), MRI volume, preoperative parathyroid hormone (PTH) serum concentration, and postoperative histopathology (predominant cell type and growth pattern of adenoma cells, location and size of adenoma) were assessed. The relationship of PET/MR parameters, PTH, and histological parameters was determined using linear regression, Spearman correlation and Kruskal-Wallis test.

RESULTS

The median volume of parathyroid adenoma was 421.78 ± 142.46 mm3 (46.39-4412.69). Adenomas were predominantly composed of chief, water-clear, and oncocytic/oxyphilic cells in 27/31, 2/31, and 2/31 cases, respectively. The growth pattern was predominantly solid, follicular, and trabecular in 18/31, 8/31, and 5/31, respectively. The SUVmax was 6.71 ± 3.39 in EP and 6.91 ± 3.97 in LP. Follicular growth pattern had slightly higher EP SUVmax (trabecular: 4.12 ± 0.56; solid: 6.62 ± 3.19; follicular: 8.56 ± 3.96; P = 0.046). Spearman correlation showed strong positive correlation between volume and both EP and LP SUVmax (0.626; P = 0.0001 and 0.576; P = 0.0001, respectively). Linear regression analysis revealed significant correlation between PTH level and EP and LP SUVmax (both P = 0.001); in contrast, no correlation was found between PTH level and both cell type and growth pattern.

CONCLUSIONS

Our findings suggest that 18F-choline uptake of parathyroid adenomas might be associated both with the histological growth pattern and adenoma volume, but not with a specific cell type.

MRI findings and utility of DWI in the evaluation of solid parathyroid lesions

PURPOSE

To evaluate the MRI findings of solid parathyroid lesions and to elaborate on a possible improvement of MRI detection of parathyroid lesions by the use of additional DWI.

MATERIALS AND METHODS

MRI and DWI properties of pathologically proven 20 solid parathyroid lesions were retrospectively reviewed. Mean ADC values (b50 + b400 + b800/3) of parathyroid lesions were compared with that of normal appearing thyroid parenchyma (TP), sternocleidomastoid muscle (SCM) and jugulodigastric lymph nodes (JDLN).

RESULTS

Of lesions, 4 were parathyroid hyperplasia, 13 parathyroid adenoma and 3 parathyroid adenocarcinoma. All parathyroid lesions were very bright on fat-saturated T2W images. Parathyroid hyperplasia and adenoma were small sized, homogenous, well-defined and low on T1W, high on T2W and avidly enhancing. Parathyroid carcinoma was large sized, ill-defined and very heterogeneous on MRI including DWI. Means ADC values of parathyroid hyperplasia, adenoma, and adenocarcinoma, TP, SCM and JDLN were measured as 2.3 ± 0.14 × 10^-3, 1.7 ± 0.45 × 10^-3, 1.5 ± 1.48 × 10^-3, 0.87 ± 0.40 × 10^-3, 0.55 ± 0.21 × 10^-3 and 0.96 ± 0.33 × 10^-3 mm²/s, respectively. All parathyroid lesions had high diffusion properties comparing other soft tissue structures of head and neck region. By increasing strength (b value) of diffusion tensor on DWI, solid parathyroid lesions still kept their brightness comparing other soft tissue structures of head and neck region because of their high T2 properties.

CONCLUSION

Solid parathyroid lesions had higher diffusion properties comparing other soft tissues structures of head and neck region. This feature makes them easily differentiate from nearby structures on fat-saturated T2W and DWI.

Craniofacial Brown Tumor in Patients with Secondary Hyperparathyroidism to Chronic Renal Failure: Report of Two Cases in Cipto Mangunkusumo Hospital

Brown tumor is a bone lesion that arises in the setting of excess osteoclast activity in hyperparathyroidism. It consists of fibrous tissue, woven bone, and supporting vasculature, while contains no matrix. The characteristic of brown-colored lesion is a result of hemosiderin deposition into the osteolytic cysts. Two cases of young women aged 26 and 29 years old, respectively, are known with a history of end-stage renal disease (ESRD). Dialysis is performed two times/week over the last 7 years. Our patients presented with an intraoral mass of the hard palate since 12 months ago and decreased body height of 10 cm. The lesion causes difficulties in swallowing and talking. Laboratory workup showed elevated parathormone or PTH (3.391 pg/mL and >5.000 pg/mL). Neck ultrasound showed enlargement of the parathyroid glands. Supporting examination to diagnose brown tumor are neck ultrasound, CT of the neck, and parathyroid sestamibi scan. We performed parathyroidectomy. Pathology revealed hyperplasia of the parathyroid. The tumor regressed significantly within 2 weeks following the surgery, and we still observe tumor regression as well as reduction in PTH level. As clinicians, we should be alert to other possible causes of bony lesions. Clinical examination, laboratory finding, and imaging present important information to diagnose brown tumor.

Localisation of ectopic mediastinal parathyroid adenoma by 18F-fluorocholine PET/CT

We report the case of two patients with newly diagnosed primary hyperparathyroidism: a 40-year-old woman during pregnancy and a 60-year-old man with initial hypercalcaemic crisis. In the first case, a bilateral neck exploration with parathyroidectomy during the second trimester of pregnancy was unsuccessful and the patient remained hypercalcaemic. Postpartum imaging assessment with technetium (^99mTc)-sestamibi scintigraphy could not supply conclusive diagnostic results. The use of ¹⁸F-fluorocholine (FCH) positron emission tomography (PET)/CT provided the accurate localisation of an ectopic parathyroid adenoma in the anterior mediastinum which was successfully resected by a thoracoscopic approach. In the second case, ^99mTc-sestamibi scintigraphy was inconclusive as well and FCH-PET/CT localised an ectopic parathyroid adenoma in the mediastinum and thus bilateral neck exploration could be spared. Both patients had surgical cure of their disease.

Selective venous sampling supports localization of adenoma in primary hyperparathyroidism

Background

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

Purpose

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

Material and Methods

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

Results

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

Conclusion

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

Ultrasound detection of normal parathyroid glands: a preliminary study

OBJECTIVE

No previous prospective study has investigated the detection of normal parathyroid glands (PTGs) and their features using real-time ultrasound (US). This study aimed to assess the preoperative US detection of normal PTGs in patients who underwent hemithyroidectomy.

METHODS

Between August and October 2016, 44 patients underwent hemithyroidectomy using a low-collar incision, and 5 were excluded from the study. A single radiologist performed the preoperative US examination in all patients, and the surgical data for the PTGs were obtained by a single surgeon. Based on the surgical findings of PTGs, the preoperative US detection of PTGs was determined.

RESULTS

Of the 39 patients, 3 had no surgical data for PTG (n = 2) and the presence of parathyroid hyperplasia (n = 1). In the 36 remaining patients, in 3 patients, US identification of a normal PTG was corroborated by surgical findings, whereas in 2 patients, US findings differed from surgical findings, and in 31 patients, US did not detect a normal PTG. The successful US detection rate of normal PTG was only 8.3% (3/36).

CONCLUSIONS

US cannot be used for identification of normal PTGs.

Diagnostic performance of computed tomography for parathyroid adenoma localization; a systematic review and meta-analysis

PURPOSE

To perform a systematic review and meta-analysis of the sensitivity and positive predictive value (PPV) of CT for preoperative parathyroid localization in patients with primary hyperparathyroidism (pHPT), and subsequently compare the different protocols and their performance in different patient groups.

MATERIALS AND METHODS

We performed a search of the Embase, Pubmed and Cochrane Library databases to identify studies published between January 1, 2000 and March 31, 2016 investigating the diagnostic value of CT for parathyroid localization in patients with biochemical diagnosis of pHPT. Performance of CT was expressed in sensitivity and PPV with pooled proportion using a random-effects model. Factors that could have affected the diagnostic performance were investigated by subgroup analysis.

RESULTS

Thirty-four studies evaluating a total of 2563 patients with non-familial pHPT who underwent CT localization and surgical resection were included. Overall pooled sensitivity of CT for localization of the pathological parathyroid(s) to the correct quadrant was 73% (95% CI: 69-78%), which increased to 81% (95% CI: 75-87%) for lateralization to the correct side. Subgroup analysis based on the number of contrast phases showed that adding a second contrast phase raises sensitivity from 71% (95% CI: 61-80%) to 76% (95% CI: 71-87%), and that adding a third phase resulted in a more modest additional increase in performance with a sensitivity of 80% (95% CI: 74-86%).

CONCLUSION

CT performs well in localizing pathological glands in patients with pHPT. A protocol with two contrast phases seems to offer a good balance of acceptable performance with limitation of radiation exposure.

Ectopic parathyroid adenoma in the soft palate: a case report

Background

Ectopic parathyroid adenomas can occur in numerous anatomic locations. While ectopic parathyroid adenomas can rarely occur in the pharyngeal region, this has not previously been described in the soft palate.

Case presentation

We report the first case of ectopic parathyroid adenoma within the soft palate. A 59 year old woman presented with hyperparathyroidism. She remained persistently hyperparathyroid after initial parathyroidectomy. Repeat exploration for a lesion suspicious on PET-CT for an ectopic parathyroid adenoma in the parapharyngeal region was unsuccessful in treating the hyperparathyroidism. An ectopic adenoma in the soft palate was eventually discovered. Removal through a transoral approach was successful in treating the hyperparathyroidism.

Conclusions

Ectopic parathyroid adenomas can occur in various anatomical locations that may be missed even with the use of the various imaging modalities. The soft palate should be added to the list of possible ectopic locations high in the neck.

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

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

Radiographic evaluation of non-localizing parathyroid adenomas

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Radioguided Parathyroidectomy with Portable Mini Gamma-Camera for the Treatment of Primary Hyperparathyroidism

Background. A proper localisation of pathological parathyroid glands is essential for a minimally invasive approach in the surgical treatment of primary hyperparathyroidism (PHP). The recent introduction of portable mini gamma-cameras (pMGCs) enabled intraoperative scintigraphic scanning. The aim of our study is to evaluate the efficacy of this new method and compare it with the preoperative localisation surveys. Methods. 20 patients were studied; they were evaluated preoperatively by neck ultrasound and (99mm)Tc-sestaMIBI-scintigraphy and intraoperatively with the pMGC IP Guardian 2. The results obtained from the three evaluations were compared. Results. The pMGC presented a sensitivity of 95%, a specificity of 98.89%, and a diagnostic accuracy of 98.18%, which were higher than those of preoperative ultrasound (sensitivity 55%; specificity 95%; diagnostic accuracy 87%) and scintigraphy with (99mm)Tc-sestaMIBI (sensitivity 73.68%; specificity 96.05%; diagnostic accuracy 91.58%). Conclusions. The pMGC can be used effectively as an intraoperative method to find the correct location of the pathological parathyroid glands. The pMGC is more reliable than the currently used preoperative and intraoperative localisation techniques.

The value and role of low dose methylene blue in the surgical management of hyperparathyroidism

INTRODUCTION

Methylene blue (MB) has been used in the identification of abnormal parathyroid glands in surgery for hyperparathyroidism. Its efficacy and safety profile have been questioned recently and this study sought to demonstrate such aspects in a unit where its use is routine.

METHODS

Prospective data collected over six years in a single surgeon's practice were interrogated to identify factors affecting MB staining, side effects suffered and unusual cases where the dye was invaluable in locating the diseased gland.

RESULTS

A total of 98 patients underwent MB infusion. Of these, 77 cases (78.6%) stained positively with MB and 21 (21.4%) did not. Six patients suffered side effects but there were no cases of neurotoxicity. No positive predictive factors of dye uptake were found. MB was particularly useful in cases of intrathyroidal and ectopic glands as well as improving efficiency in both targeted and open parathyroidectomy.

CONCLUSIONS

This series shows that when used correctly, MB is efficacious in locating diseased parathyroid glands, with similar sensitivity rates to preoperative ultrasonography and radionucleotide imaging. Adverse effects were much lower than published previously, which may be attributed to the low dose of MB used (3.5 mg/kg).

¹⁸F-Fluorocholine PET/CT for localization of hyperfunctioning parathyroid tissue in primary hyperparathyroidism: a pilot study

PURPOSE

Primary hyperparathyroidism is a common endocrine disorder which is diagnosed biochemically and for which therapy is surgical. A prerequisite for minimally invasive surgery, which minimizes morbidity and cost, is accurate localization of the involved gland(s). The aim of this study was to evaluate the usefulness of (18)F-fluorocholine PET/CT for preoperative localization of hyperfunctioning parathyroid tissue.

METHODS

(18)F-Fluorocholine PET/CT and conventional parathyroid scintigraphic imaging consisting of (99m)Tc-sestaMIBI SPECT/CT, (99m)Tc-sestaMIBI dual-phase imaging and (99m)Tc-sestaMIBI/pertechnetate subtraction imaging were performed in 24 patients. The diagnostic performance of the imaging methods was compared against histology as the gold standard and postoperative serum Ca(2+) and iPTH values.

RESULTS

The sensitivity and specificity of (18)F-fluorocholine PET/CT were 92% and 100%, respectively, in contrast to 49% and 100%, 46% and 100%, and 44% and 100% for (99m)Tc-sestaMIBI SPECT/CT, (99m)Tc-sestaMIBI/pertechnetate subtraction imaging and (99m)Tc-sestaMIBI dual-phase imaging, respectively. Combined conventional scintigraphic imaging had a sensitivity and specificity of 64% and 100%, respectively. The performance of (18)F-fluorocholine PET/CT was superior particularly in patients with multiple lesions or hyperplasia.

CONCLUSION

(18)F-Fluorocholine PET/CT appears to be a promising, effective imaging method for localization of hyperfunctioning parathyroid tissue.

Three-dimensional sonography in the evaluation of primary hyperparathyroidism

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

4D-CT for preoperative localization of abnormal parathyroid glands in patients with hyperparathyroidism: accuracy and ability to stratify patients by unilateral versus bilateral disease in surgery-naive and re-exploration patients

BACKGROUND AND PURPOSE

4D-CT is an emerging technique that uses high-resolution images, multiplanar reformats, and perfusion characteristics to identify abnormal parathyroid glands in patients with hyperparathyroidism. This study evaluates the accuracy of 4D-CT for localization and lateralization of abnormal parathyroid glands in preoperative planning for minimally invasive parathyroidectomy vs bilateral neck exploration at a tertiary referral center.

MATERIALS AND METHODS

Radiology, pathology, and operative reports were retrospectively reviewed for 208 patients with hyperparathyroidism who underwent 4D-CT and parathyroid surgery between May 2008 and January 2012. 4D-CT performance in localizing side and site was determined by use of surgical and pathologic findings as a reference.

RESULTS

Of 208 patients, 155 underwent initial surgery and 53 underwent re-exploration parathyroid surgery. No lesions were found in 8 patients (3.8%). A total of 284 lesions were found in 200 patients; 233 were correctly localized by 4D-CT (82.0%). Of the 200 patients with parathyroid lesions, 146 underwent unilateral and 54 bilateral neck exploration. 4D-CT correctly identified unilateral vs bilateral disease in 179 (89.5%) of 200. 4D-CT correctly localized parathyroid lesions in 126 of the unilateral cases (86.3%). In the re-exploration cohort, 4D-CT correctly identified unilateral vs bilateral disease in 46 (95.8%) of 48. There was no statistically significant difference in subgroups stratified by surgery type (primary or subsequent) and number of scan phases (3 or 4) (P > .56).

CONCLUSIONS

4D-CT leverages modern high-resolution CT scanning and dynamic contrast enhancement to localize abnormal parathyroid glands in patients with hyperparathyroidism of any cause and can be used for planning minimally invasive parathyroidectomy vs bilateral neck exploration.

Hyperparathyroidism in chronic kidney disease: complexities within the commonplace

Secondary hyperparathyroidism in patients with chronic kidney disease (CKD) is common and usually caused by associated metabolic abnormalities, in particular, hypocalcaemia and hyperphosphataemia. Nevertheless, other causes of hyperparathyroidism can exist concurrently with CKD, challenging diagnostic interpretation and therapeutic intervention. We present four cases of hyperparathyroidism in patients with CKD that highlight some of these dilemmas.

Validation of the "Perrier" parathyroid adenoma location nomenclature

BACKGROUND

In 2009, the "Perrier" nomenclature was introduced to enhance communications among surgeons and specialists regarding the location of parathyroid adenomas. The purpose of this study was to validate the utility of the nomenclature in a prospective manner at a different institution.

METHODS

A prospective database was created from June 2010 through January 2011 evaluating 108 consecutive patients. In each case, the location of the parathyroid adenoma according to the nomenclature was predicted individually by an attending physician and a resident based on preoperative imaging studies. A radiologist interpreted the images retrospectively. These predictions were compared to the operative findings.

RESULTS

The mean age of the patients was 61 ± 1 years, and 82% were women. The distribution using the nomenclature was as follows: A (adherent to posterior thyroid capsule) 20%; B (tracheoesophageal groove) 27%; C (tracheoesophageal groove but close to the clavicle) 12%; D (directly over the recurrent laryngeal nerve) 2%; E (easy to identify, inferior thyroid pole) 35%; F (fallen into the thymus) 4%. The overall predicting accuracy was significantly higher for the attending physicians than for the residents or the radiologist (78% vs. 64% vs. 25%, P < 0.001). It was 73-92%, 55-77%, and 12-46%, respectively, for locations with more than four patients. The accuracy was not affected by parathyroid hormone or and calcium levels, or the gland weight.

CONCLUSIONS

The "Perrier" nomenclature is reproducible. The most common adenoma locations were B and E in our study, similar to the initial studies. Nevertheless, there is a wide range of preoperative predicting accuracy based on the imaging studies obtained and the interpreter's experience.