Four-dimensional computed tomography for parathyroid localization: a new imaging modality

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

OBJECTIVE

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

DATA SOURCES

Retrospective case series and systematic review.

REVIEW METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

NA Laryngoscope, 134:2198-2205, 2024.

Diagnostic Value of Four-Dimensional Dynamic Computed Tomography for Primary Hyperparathyroidism in Patients with Low Baseline Parathyroid Hormone Levels

Low baseline levels of parathyroid hormone (PTH) are associated with a higher rate of multiglandular disease, lower localization rates of preoperative imaging modalities, and a higher rate of unsuccessful minimally invasive parathyroidectomies. The objective of this study is to assess the diagnostic value of four-dimensional dynamic computed tomography (4D-CT) in localizing primary hyperparathyroidism (pHPT) in patients with low baseline PTH levels, compared to patients with high baseline PTH levels. Patients with pHPT who received a 4D-CT scan as part of their standard diagnostic evaluation were divided into two groups based on the following criteria: (1) preoperative PTH levels less than 100 pg/mL and (2) patients with preoperative PTH levels greater than 100 pg/mL. All patients underwent parathyroidectomy based on 4D-CT findings, with intraoperative parathyroid hormone monitoring. The lesion-based sensitivity of 4D-CT was 88% in patients with low baseline PTH levels and 94.7% in patients with high baseline PTH levels (p = 0.33). However, the success rate of image-guided resection based on 4D-CT findings was 71.4% in the low baseline PTH group compared to 90.6% in the high baseline PTH group (p = 0.06). Our study demonstrated that 4D-CT has a high lesion-based sensitivity in patients with pHPT and low baseline PTH levels but led to a relatively low rate of successful image-guided resection in patients with low baseline PTH levels. Therefore, it is important to exercise increased caution during 4D-CT-guided surgical exploration of patients with low baseline PTH levels to ensure successful surgical resection of all parathyroid lesions.

Educational Review: Intraoperative Parathyroid Fluorescence Detection Technology in Thyroid and Parathyroid Surgery

BACKGROUND

Accurate parathyroid gland (PG) identification is a critical yet challenging component of cervical endocrine procedures. PGs possess strong near-infrared autofluorescence (NIRAF) compared with other tissues in the neck. This property has been harnessed by image- and probe-based near-infrared fluorescence detection systems, which have gained increasing popularity in clinical use for their ability to accurately aid in PG identification in a rapid, noninvasive, and cost-effective manner. All NIRAF technologies, however, cannot differentiate viable from devascularized PGs without the use of contrast enhancement. Here, we aim to provide an overview of the rapid evolution of these technologies and update the surgery community on the most recent advancements in the field.

METHODS

A PubMed literature review was performed using the key terms "parathyroid," "near-infrared," and "fluorescence." Recommendations regarding the use of these technologies in clinical practice were developed on the basis of the reviewed literature and in conjunction with expert surgeons' opinions.

RESULTS

The use of near-infrared fluorescence detection can be broadly categorized as (1) using parathyroid NIRAF to identify both healthy and diseased PGs, and (2) using contrast-enhanced (i.e., indocyanine green) near-infrared fluorescence to evaluate PG perfusion and viability. Each of these approaches possess unique advantages and disadvantages, and clinical trials are ongoing to better define their utility.

CONCLUSIONS

Near-infrared fluorescence detection offers the opportunity to improve our collective ability to identify and preserve PGs intraoperatively. While additional work is needed to propel this technology further, we hope this review will be valuable to the practicing surgeon.

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.

Four-dimensional computed tomography (4D-CT) for preoperative parathyroid localization: A good study but are we using it?

BACKGROUND

Four-dimensional computed tomography (4D-CT) scan to localize abnormal parathyroid glands is diagnostically superior to ultrasound (US) and sestamibi. The implementation of 4D-CT imaging is unknown.

METHODS

The Collaborative Endocrine Surgery Quality Improvement Program (CESQIP) database from 2014 to 2018 was utilized. Patients with hyperparathyroidism undergoing an initial operation were included. The rate of US, sestamibi and 4D-CT performance was calculated for the entire study population, and for each institution.

RESULTS

7,959 patients were included. In 311(3.9%) patients, no preoperative imaging was recorded. Of patients with imaging, US was performed in 6,872(86.3%), sestamibi in 5,094(64.0%), and 4D-CT in 1,630(20.4%). The combination of US and sestamibi was most frequent (3,855, 48.4%). Institutional rates of 4D-CT performance varied from 0.1% to 88.7%.

CONCLUSIONS

Of the imaging modalities, 4D-CT was utilized least frequently and with greatest variability. Given the high accuracy of 4D-CT, efforts to reduce this variation may improve overall preoperative localization in patients with hyperparathyroidism.

4DCT Scanning Technique for Primary Hyperparathyroidism: A Scoping Review

Objective

4DCT for the detection of (an) enlarged parathyroid(s) is a commonly performed examination in the management of primary hyperparathyroidism. Protocols are often institution-specific; this review aims to summarize the different protocols and explore the reported sensitivity and specificity of different 4DCT protocols as well as the associated dose.

Materials and Methods

A literature study was independently conducted by two radiologists from April 2020 until May 2020 using the Medical Literature Analysis and Retrieval System Online (MEDLINE) database. Articles were screened and assessed for eligibility. From eligible studies, data were extracted to summarize different parameters of the scanning protocol and observed diagnostic attributes.

Results

A total of 51 articles were included and 56 scanning protocols were identified. Most protocols use three (n = 25) or four different phases (n = 23). Almost all authors include noncontrast enhanced imaging and an arterial phase. Arterial images are usually obtained 25–30 s after administration of contrast, and less agreement exists concerning the timing of the venous phase(s). A mean contrast bolus of 100 mL is administered at 3-4 mL/s. Bolus tracking is not often used (n = 3). A wide range of effective doses are reported, up to 28 mSv. A mean sensitivity of 81.5% and a mean specificity of 86% are reported.

Conclusion

Many different 4DCT scanning protocols for the detection of parathyroid adenomas exist in the literature. The number of phases does not appear to affect sensitivity or specificity. A triphasic approach, however, seems preferable, as three patterns of enhancement of parathyroid adenomas are described. Bolus tracking could help to reduce the variability of enhancement. Sensitivity and specificity also do not appear to be affected by other scan parameters like tube voltage or tube current. To keep the effective dose within limits, scanning at a lower fixed tube current seems preferable. Lowering tube voltage from 120 kV to 100 kV may yield similar image contrast but would also help lower the dose.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

Detection of parathyroid adenomas with multiphase 4DCT: towards a true four-dimensional technique

Background

Four-dimensional computed tomography (4DCT) is a commonly performed examination in the management of primary hyperparathyroidism, combining three-dimensional imaging with enhancement over time as the fourth dimension. We propose a novel technique consisting of 16 different contrast phases instead of three or four different phases. The main aim of this study was to ascertain whether this protocol allows the detection of parathyroid adenomas within dose limits. Our secondary aim was to examine the enhancement of parathyroid lesions over time.

Methods

For this prospective study, we included 15 patients with primary hyperparathyroidism and a positive ultrasound prior to surgery. We performed 4DCT with 16 different phases: an unenhanced phase followed by 11 consecutive arterial phases and 4 venous phases. Continuous axial scanning centered on the thyroid was performed over a fixed 8 cm or 16 cm coverage volume after the start of contrast administration.

Results

In all patients, an enlarged parathyroid lesion was demonstrated, and the mean lesion size was 13.6 mm. The mean peak arterial enhancement for parathyroid lesions was 384 Hounsfield units (HU) compared to 333 HU for the normal thyroid. No significant difference could be found. The time to peak (TTP) was significantly earlier for parathyroid adenomas than for normal thyroid tissue: 30.8 s versus 32.3 s (p value 0.008). The mean slope of increase (MSI) of the enhancement curve was significantly steeper than that of normal thyroid tissue: 29.8% versus 22.2% (p value 0.012). The mean dose length product was 890.7 mGy cm with a calculated effective dose of 6.7 mSv.

Conclusion

Our 4DCT protocol may allow better visualization of the pattern of enhancement of parathyroid lesions, as enhancement over time curves can be drawn. In this way, wash-in and wash-out of contrast in suspected lesions can be readily demonstrated. Motion artifacts are less problematic as multiple phases are available. Exposure to our proposed 4DCT technique is comparable to that for classic helical 4DCT. Careful selection of parameters (lowering kV and SNR) can help to further reduce the dose.

Accuracy of 4-Dimensional Computed Tomography for Localization in Primary Hyperparathyroidism

BACKGROUND

The etiology of primary hyperparathyroidism (PHP) is single-gland adenoma in most patients. Imaging localization of single-gland disease allows for a focused operation. We sought to determine the accuracy of imaging for localizing a solitary parathyroid adenoma.

METHODS

A single-institution retrospective review was performed of adult patients with PHP undergoing parathyroidectomy from January 2017 through December 2018. Surgeon-performed ultrasound (US), four-dimensional computed tomography (4DCT), and sestamibi were assessed for localization of a parathyroid adenoma yielding a single-gland parathyroidectomy. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated for each imaging modality.

RESULTS

One hundred fifty-four patients underwent parathyroidectomy for PHP during the study period, with 100 patients meeting inclusion criteria with a mean age of 61.1 (SD 10) y and 80% women. Mean calcium was 11.1 mg/dL (SD 0.7) and mean PTH was 116 pg/mL (SD 66). All 100 patients had surgeon-performed US with 17 localized, 51 patients had 4DCT with 41 (80%) localized, and 69 patients had sestamibi with 53 (77%) localized. Eighty-two patients underwent successful unilateral parathyroidectomy, 18 required bilateral neck exploration. US was the most specific imaging modality at 94%. Accuracy of imaging localization was 32% for US, 70% for sestamibi, and 86% for 4DCT.

CONCLUSIONS

Surgeon-performed US is a highly specific imaging modality for preoperative localization of solitary parathyroid adenoma in patients with PHP. 4DCT is the most accurate imaging localization study and should be considered for patients with a nonlocalized US.

Primary Hyperparathyroidism Presenting as Recurrent Pancreatitis Due to Parathyroid Adenoma

Recurrent attacks of acute pancreatitis as initial manifestation of primary hyperparathyroidism is rare. We report two cases of young women presenting with recurrent attacks of pancreatitis due to parathyroid adenoma. After surgical excision of the parathyroid adenoma, symptoms of pancreatitis resolved, and serum parathormone and calcium levels returned to normal.

Utility of a Second 99mTc-MIBI Scintigraphy Before Reoperation for Patients With Persistent Sporadic Primary Hyperparathyroidism: Results of a Retrospective Multicenter Study

BACKGROUND

Persistent primary hyperparathyroidism (PHPT) occurs in 2.5% to 15% of cases after parathyroidectomy. Few studies have evaluated the best pre-reoperative imaging approaches for persistent sporadic PHPT. This retrospective multicenter study aimed to evaluate the benefit of a second pre-reoperative ^99mTc-methoxy-isobutyl-isonitrile (MIBI) scintigraphy for patients with persistent PHPT who had a ^99mTc-MIBI before their initial surgery.

METHODS

The study enrolled 50 patients with persistent sporadic PHPT who had reoperation between 2006 and 2016 in three French University Hospitals (Angers, Nantes, and La Pitié Salpêtrière-Paris). Preoperative ^99mTc-MIBI scan was performed before each operation.

RESULTS

After the reoperation, 42 patients (84%) were cured. By the second ^99mTc-MIBI, 31 patients (62%) had a removed gland identified. A new pathologic gland was identified by a second ^99mTc-MIBI in 25 patients (50%), and this imaging permitted correction of an initial surgical error in six patients (12%). A second ^99mTc-MIBI showed a sensitivity of 63%, a specificity of 89%, a positive predictive value (PPV) of 78%, and a negative predictive value (NPV) of 80%. A concordant second ^99mTc-MIBI and ultrasonography (17 patients) showed a sensitivity of 70%, a specificity of 81%, a PPV of 70%, and an NPV of 81%.

CONCLUSIONS

Performing a second ^99mTc-MIBI scan permitted 62% of the persistent PHPT patients to be cured, allowing identification of new pathologic glands in 50% of the cases and correction of an initial surgical error in 12% of the cases, with high specificity and PPV. These results reinforce the fact that a second ^99mTc-MIBI scan should be performed at first intention before reoperation of patients with persistent PHPT, regardless of the result from the initial ^99mTc-MIBI scan.

Multiphase Iodine Contrast-Enhanced SPECT/CT Outperforms Nonenhanced SPECT/CT for Preoperative Localization of Small Parathyroid Adenomas

PURPOSE

The aim of this study was to assess the value of intravenously contrast-enhanced CT in conjunction with Tc-MIBI SPECT for preoperative localization of parathyroid adenoma.

METHODS

One hundred ninety-two patients with primary hyperparathyroidism were enrolled in the study between May 2015 and May 2017. The patients underwent a preoperative "one-stop shop" examination with Tc-MIBI SPECT/CT by using dual time-point (10 and 90 minutes) protocol and both nonenhanced CT and contrast-enhanced CT acquisition in the arterial and venous phase, 35 and 75 seconds, respectively, after contrast medium injection start. For 149 patients, the imaging results could be correlated to those at surgery and histopathology.

RESULTS

The median adenoma weight was 330 mg. The addition of contrast-enhanced CT increased the sensitivity from 81.1% to 89.9% (P = 0.003). The specificity of nonenhanced SPECT/CT was similar to contrast-enhanced CT (96.1% vs 97.9%; P = 0.077). For patients with uniglandular disease (n = 140, 94.0%), the sensitivity increased from 86.4% to 93.6% (P = 0.021) and the specificity from 96.2% to 97.9% (P = 0.118) by adding contrast-enhanced CT. In patients with multiglandular disease (n = 9, 6.0%), adding contrast-enhanced CT improved detection sensitivity from 42.1% to 63.2%. However, these patients were few and significance was not reached (P = 0.125).

CONCLUSIONS

In this cohort, with generally small parathyroid adenomas, the sensitivity in preoperative localization was greatly improved by adding contrast-enhanced CT to Tc-MIBI SPECT/CT.

A rural perspective on minimally invasive parathyroidectomy: optimal preoperative imaging and patient outcomes

BACKGROUND

Our retrospective review of prospectively collected data evaluated the efficacy of minimally invasive parathyroidectomy (MIP) and compared preoperative imaging modalities in a rural referral centre.

METHODS

Patients with a diagnosis of primary hyperparathyroidism underwent surgeon-performed ultrasound (SUS) and technetium-99 m sestamibi (MIBI). Radiologist-performed ultrasound (RUS) was sought when the diagnosis remained in doubt. Four-dimensional computed tomography (4DCT) first replaced RUS in mid-2014, then MIBI as a frontline modality in 2015. MIP was conducted if possible and bilateral neck exploration (BNE) when localization remained doubtful. Treatment was evaluated by histopathology and serum parathyroid hormone and calcium levels at 6 weeks.

RESULTS

A total of 122 of 165 (73.9%) glands were removed by MIP and 43 of 165 (26.1%) by BNE. Of 15 cases with non-localizing preoperative investigations, one patient had a negative BNE. A total of 160 of 165 (97.0%) patients underwent a successful operation, with five (3.0%) suffering persistent post-operative hypercalcaemia. SUS had a sensitivity of 79.4% (131/165) and a positive predictive value (PPV) of 97.0% (131/135). MIBI had a sensitivity of 60.0% (81/135) and a PPV of 95.3% (81/85). RUS produced a sensitivity of 65.5% (76/116) and PPV of 98.7% (76/77). When used as a second-line modality, 4DCT had a sensitivity of 76.9% (10/13) and PPV of 100%. The sensitivity and PPV were 85.7% (18/21) and 94.7% (18/19) after 4DCT's promotion to first-line use.

CONCLUSION

MIP can be safely performed in rural centres of adequate volume. We recommend that operations be guided by SUS with routine use of an adjunctive modality. Our study has seen 4DCT replace MIBI in this regard.

Evaluation of the radiation dose exposure and associated cancer risks in patients having preoperative parathyroid localization

OBJECTIVE The study aimed to evaluate the total effective and organ absorbed radiation doses associated with three- and four-phase parathyroid computed tomography (CT) and sestamibi scans used for the preoperative localisation of parathyroid adenomas in a cohort of patients with primary hyperparathyroidism at a single institution. We aimed to assess the risk of cancer incidence for the organs demonstrating the highest absorbed doses for the different imaging techniques, and more specifically determine the risk for our cohort of patients. METHODS Fifty patients with primary hyperparathyroidism had both multiphase CT and sestamibi scans. The Imaging Performance Assessment of CT Scanners (ImPACT) calculator was used to estimate the patient-effective and organ-absorbed radiations doses for all the CT examinations. For sestamibi scans, the US Nuclear Regulatory Commission NUREG/CR-6345 publication was used to estimate the dose for each patient. The attributable risks of cancer were calculated using the Health Protection Agency HPA-CRCE-028 publication. RESULTS The mean patient total effective doses were 15.9% ± 2.8 mSv, 20.2% ± 2.8  mSv and 5.6 ± 0.24 mSv for three-phase CT, four-phase CT and sestamibi examinations, respectively. In our cohort, the highest attributable lifetime risk was for lung cancer (0.03%) after multiphase CT. This compared with a tenfold lower risk for thyroid cancer (0.003%). After sestamibi, the highest risk was for colon cancer (0.06%). CONCLUSIONS Multiphase CT is associated with a higher radiation dose and thus a higher potential risk of cancer, but this risk is low in the older population that constituted the majority of our cohort.

Pursuing the second ipsilateral gland during minimally invasive video-assisted parathyroidectomy

BACKGROUND

In patients with primary hyperparathyroidism (PHPT) and preoperative imaging suggesting a solitary parathyroid adenoma (SPA), focused parathyroidectomy is most often curative. Even so, large studies show up to 3% of patients experience persistent or recurrent PHPT. Unilateral neck exploration (UNE) aiming to identify the SPA and the other ipsilateral parathyroid may reduce this failure rate. We hypothesized that: (i) minimally invasive video-assisted (MIVA) approach would facilitate UNE and (ii) this would be a clinically relevant strategy.

METHODS

Prospective case series of a consecutive cohort of PHPT patients (with preoperative diagnosis of SPA), who underwent MIVA-UNE. A 15 mm collar incision and endoscopic magnification were utilized to both excise the SPA and seek the ipsilateral parathyroid gland.

RESULTS

From 2009 to 2014, 132 patients were offered MIVA-UNE (age: 63.0 (interquartile range: 11.2); females: 94 (71.2%); symptomatic: 89 (67.4%); mean serum corrected calcium: 2.7 (standard deviation: 0.9) mmol/L; mean serum parathyroid hormone: 16.8 (standard deviation: 11.8) pmol/L). Conversion from MIVA-UNE to open UNE was required in 14 (10.6%) patients (excluded from subsequent analysis). MIVA-UNE was concluded in 118 patients. The second ipsilateral parathyroid was identified in 62 (52.5%) patients and in 13 (11.0%) it appeared enlarged and was excised. Histopathology confirmed five (4.2%) of these glands to be hyperplastic.

CONCLUSION

MIVA-UNE allows identification of the second ipsilateral parathyroid in about half the patients. This approach helped to diagnose and treat unexpected multigland disease in almost 5% of patients.

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

Purpose

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

Methods

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

Results

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

Conclusion

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

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.

Preoperative 4D CT Localization of Nonlocalizing Parathyroid Adenomas by Ultrasound and SPECT-CT

Objective

To evaluate 4-dimensional (4D) computed tomography (CT) for the localization of parathyroid adenomas previously considered nonlocalizing on ultrasound and single-photon emission CT with CT scanning (SPECT-CT). To measure radiation exposure associated with 4D-CT and compared it with SPECT-CT.

Study Design

Case series with chart review.

Setting

University tertiary hospital.

Subjects and Methods

Nineteen adults with primary hyperparathyroidism who underwent preoperative 4D CT from November 2013 through July 2014 after nonlocalizing preoperative ultrasound and technetium-99m SPECT-CT scans. Sensitivity, specificity, predictive values, and accuracy of 4D CT were evaluated.

Results

Nineteen patients (16 women and 3 men) were included with a mean age of 66 years (range, 39-80 years). Mean preoperative parathyroid hormone level was 108.5 pg/mL (range, 59.3-220.9 pg/mL), and mean weight of the excised gland was 350 mg (range, 83-797 mg). 4D CT sensitivity and specificity for localization to the patient’s correct side of the neck were 84.2% and 81.8%, respectively; accuracy was 82.9%. The sensitivity for localizing adenomas to the correct quadrant was 76.5% and 91.5%, respectively; accuracy was 88.2%. 4D CT radiation exposure was significantly less than the radiation associated with SPECT-CT (13.8 vs 18.4 mSv, P = 0.04).

Conclusion

4D CT localizes parathyroid adenomas with relatively high sensitivity and specificity and allows for the localization of some adenomas not observed on other sestamibi-based scans. 4D CT was also associated with less radiation exposure when compared with SPECT-CT based on our study protocol. 4D CT may be considered as first- or second-line imaging for localizing parathyroid adenomas in the setting of primary hyperparathyroidism.

Diagnostic value and clinical impact of complementary CT scan prior to surgery for non-localized primary hyperparathyroidism

INTRODUCTION

Successful localization is mandatory for focused parathyroidectomy. If ultrasound and sestamibi scan are negative, bilateral neck exploration is necessary. We examined the contribution of complementary computed tomography (CT) scan to identify the affected parathyroid gland.

METHODS

Between November 1999 and April 2014, 25 patients (20 females and 5 males; mean age 67 ± 11 years) with negative or dubious standard imaging (ultrasound and sestamibi scan) underwent CT scan prior to parathyroidectomy and were included in this study. Fifteen patients had had previous neck surgery for parathyroidectomy (n = 11) or thyroidectomy (n = 4). Thin-slice CT (n = 9) or four-dimensional (4D) CT imaging (n = 16) was used. Cure was defined as >50 % post-excision fall of intraoperatively measured parathyroid hormone or fall into the normal range, confirmed by normocalcaemia at least 6 months after surgery.

RESULTS

Preoperative CT scan provided correct localization in 13 out of 25 patients (52 %) and was false positive once. Parathyroidectomy was performed by a focused approach in 11 of these 13 patients as well as in 1 patient guided by intraoperatively measured parathyroid hormone (ioPTH). Thirteen patients required bilateral neck exploration. The cure rate was 96 % (24/25 patients). One patient has persistent primary hyperparathyroidism (pHPT) and one a recurrent disease. Six patients presented a multiglandular disease.

CONCLUSION

A CT scan identifies about half of abnormal parathyroid glands missed by conventional imaging and allows focused surgery in selected cases.