Prospective Validation of Two 4D-CT-Based Scoring Systems for Prediction of Multigland Disease in Primary Hyperparathyroidism

Primary hyperparathyroidism: predictors of sporadic multi-gland disease

In this review, we discuss the definition, prevalence, and etiology of sporadic multiglandular disease (MGD), with an emphasis on its preoperative and intraoperative predictors. Primary hyperparathyroidism (PHPT) is the third-most common endocrine disorder, and multiglandular parathyroid disease (MGD) is a cause of PHPT. Hereditary MGD can be definitively diagnosed with detailed family history and genetic testing, whereas sporadic MGD presents a greater challenge in clinical practice, and parathyroidectomy for MGD is associated with a higher risk of surgical failure than single gland disease (SGD). Therefore, it is crucial to be able to predict the presence of sporadic MGD in a timely manner, either preoperatively or intraoperatively. Various predictive methods cannot accurately identify all cases of sporadic MGD, but they can greatly optimize the management of MGD diagnosis and treatment and optimize the cure rate. Future research will urge us to investigate more integrative predictive models as well as increase our understanding of MGD pathogenesis.

Predicting multigland disease in primary hyperparathyroidism using ultrasound and clinical features

Background

The identification of multigland disease (MGD) in primary hyperparathyroidism (PHPT) patients is essential for minimally invasive surgical decision-making.

Objective

To develop a nomogram based on ultrasound (US) findings and clinical factors to predict MGD in PHPT patients.

Materials and methods

Patients with PHPT who had surgery between March 2021 and January 2022 were consecutively enrolled to this study. Biochemical and clinicopathological data were recorded. US images were analyzed to extract US features for prediction. Logistic regression analyses were used to identify MGD risk factors. A nomogram was constructed based on these factors and its performance evaluated by area under the receiver operating characteristic curve (AUC), calibration curve, Hosmer-Lemeshow tests, and decision curve analysis (DCA).

Results

A total of 102 PHPT patients were included; 82 (80.4%) had single-gland disease (SGD) and 20 (19.6%) had MGD. Using multivariate analyses, MGD was positively correlated with age (odds ratio (OR) = 1.033, 95% confidence interval (CI): 0.190-4.047), PTH levels (OR = 1.001, 95% CI: 1.000-1.002), multiple endocrine neoplasia type 1 (MEN1) (OR = 29.730, 95% CI: 3.089-836.785), US size (OR = 1.198, 95% CI: 0.647-2.088), and US texture (cystic-solid) (OR = 5.357, 95% CI: 0.499-62.912). MGD was negatively correlated with gender (OR = 0.985, 95% CI: 0.190-4.047), calcium levels (OR = 0.453, 95% CI: 0.070-2.448), and symptoms (yes) (OR = 0.935, 95% CI: 0.257-13.365). The nomogram showed good discrimination with an AUC = 0.77 (0.68-0.85) and good agreement in predicting MGD in PHPT patients. Also, 65 points was recommended as a cut-off value, with specificity = 0.94 and sensitivity = 0.50.

Conclusion

US was useful in evaluating MGD. Combining US and clinical features in a nomogram showed good diagnostic performance for predicting MGD.

Parathyroid 4D-CT in Primary Hyperparathyroidism: Exploration of Size Measurements for Identifying Multigland Disease and Guiding Biochemically Successful Parathyroidectomy

Background: In patients with primary hyperparathyroidism (PHPT), bilateral neck exploration is necessary for multigland disease (MGD), whereas minimally-invasive parathyroidectomy is often preferred for single-gland disease (SGD). An existing system (4D-CT MGD score) for differentiating SGD and MGD using preoperative parathyroid CT considers the size of only the largest candidate lesion. Objective: To assess utility of second-largest lesion size on parathyroid CT for differentiating SGD from MGD, as well as of individual gland size for predicting need for surgical removal, and to derive optimal size thresholds for these purposes. Methods: This retrospective study included patients with PHPT who underwent biochemically successful parathyroidectomy after preoperative parathyroid CT. Clinical radiology reports were reviewed to classify reported candidate parathyroid lesions as low-, intermediate- or high-confidence. Resected hypercellular parathyroid lesions were correlated with clinically reported candidate lesions. Patients were classified as having SGD or MGD using operative and pathology reports, independent of CT findings. One observer retrospectively determined estimated volume (0.52 x length x width x height) and maximum diameter of clinically reported high-confidence lesions, as well as examinations' 4D-CT MGD scores. Diagnostic performance was assessed. Results: The sample comprised 62 patients (41 women, 21 men; median age 65 years; 47 with SGD, 15 with MGD), with 151 candidate lesions, including 106 high-confidence lesions. Based on second-largest high-confidence lesions, estimated volume at 60-mm³ threshold achieved 53% sensitivity and 96% specificity, while maximum diameter at 7-mm threshold achieved 67% sensitivity and 96% specificity; 4D-CT MGD score ≥3 achieved 47% sensitivity and 68% specificity. For predicting need to remove a gland for successful parathyroidectomy, estimated volume at 114-mm3 threshold achieved 84% sensitivity and 97% specificity, and at 55-mm3 threshold achieved 93% sensitivity and 87% specificity; maximal diameter at 7-mm threshold achieved 93% sensitivity and 84% specificity. Conclusion: Estimated volume and maximum diameter of high-confidence candidate lesions can differentiate SGD from MGD and identify individual glands requiring removal for successful parathyroidectomy. Differentiating SGD and MGD may be aided by considering both first- and second-largest high-confidence lesions. Clinical Impact: The findings will help identify patients likely to require bilateral neck explorations, informing preoperative patient counseling and individualized operative planning.

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.

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.

Usefulness of the Wisconsin and CaPTHUS indices for predicting multiglandular disease in patients with primary hyperparathyroidism in a southern European population

Background

Focused parathyroidectomy is a safe technique for the treatment of primary hyperparathyroidism. The CaPTHUS score and the Wisconsin index are preoperative diagnostic tools designed to distinguish between single- and multigland disease. The aim of the study is to evaluate the usefulness of these models for predicting multiglandular disease in a European population.

Methods

Retrospective review of a database of patients operated upon for primary hyperparathyroidism at a referral center. The sensitivity, specificity, positive and negative predictive values, and reliability of both scores for the prediction of multiglandular disease, were calculated. Receiver operating characteristic (ROC) curves were constructed to assess the sensitivity and specificity of CaPTHUS score and Wisconsin Index for predicting single-gland disease. A level of P<0.05 was accepted as significant.

Results

Two hundred and eighty-one patients who underwent successful surgery from January 2001 to December 2018 were included. Single-gland disease was detected in 92.5%, and 73.7% had a CaPTHUS score of ≥3. The sensitivity, specificity, positive and negative predictive values of this model for predicting single-gland disease with a score of ≥3 were 76.9%, 66.7%, 96.6%, and 18.9% respectively. The area under the curve value of the CaPTHUS score for predicting single-gland disease was 0.74. A Wisconsin Index >2,000 and an excised gland weight above one gram presented a positive predictive value for single-gland disease of 92.5%.

Conclusions

Despite the good performance of both scales, the established cut-off points did not definitively rule out parathyroid multiglandular disease in our population. In cases with a minimal suspicion of this condition, additional intraoperative techniques must be used, or bilateral neck explorations should be performed.

Parathyroid 4D CT: What the Surgeon Wants to Know

Parathyroid four-dimensional (4D) CT is an increasingly used and powerful tool for preoperative localization of abnormal parathyroid tissue in the setting of primary hyperparathyroidism. Accurate and precise localization of a single adenoma facilitates minimally invasive parathyroidectomy, and localization of multiglandular disease aids bilateral neck exploration. However, many radiologists find the interpretation of these examinations to be an intimidating challenge. The authors review parathyroid 4D CT findings of typical and atypical parathyroid lesions and provide illustrative examples. Relevant anatomy, embryology, and operative considerations with which the radiologist should be familiar to provide clinically useful image interpretations are also discussed. The most important 4D CT information to the surgeon includes the number, size, and specific location of candidate parathyroid lesions with respect to relevant surgical landmarks; the radiologist's opinion and confidence level regarding what each candidate lesion represents; and the presence or absence of ectopic or supernumerary parathyroid tissue, concurrent thyroid pathologic conditions, and arterial anomalies associated with a nonrecurrent laryngeal nerve. The authors provide the radiologist with an accessible and practical approach to performing and interpreting parathyroid 4D CT images, detail what the surgeon really wants to know from the radiologist and why, and provide an accompanying structured report outlining the key information to be addressed. By accurately reporting and concisely addressing the key information the surgeon desires from a parathyroid 4D CT examination, the radiologist substantially impacts patient care by enabling the surgeon to develop and execute the best possible operative plan for each patient. ^©RSNA, 2020.

Localization of Parathyroid Disease in Reoperative Patients with Primary Hyperparathyroidism

The localization of persistent or recurrent disease in reoperative patients with primary hyperparathyroidism presents challenges for radiologists and surgeons alike. In this article, we summarize the relevant imaging modalities, compare their accuracy in identifying reoperative disease, and outline their advantages and disadvantages. Accurate localization by preoperative imaging is a predictor of operative success, whereas negative or discordant preoperative imaging is a risk factor for operative failure. Ultrasound is a common first-line modality because it is inexpensive, accessible, and radiation-free. However, it is highly operator-dependent and less accurate in the reoperative setting than in the primary setting. Sestamibi scintigraphy is superior to ultrasound in localizing reoperative disease but requires radiation, prolonged imaging times, and reader experience for accurate interpretation. Like ultrasound, sestamibi scintigraphy is less accurate in the reoperative setting because reoperative patients can exhibit distorted anatomy, altered perfusion of remaining glands, and interference of radiotracer uptake. Meanwhile, four-dimensional computed tomography (4DCT) is superior to ultrasound and sestamibi scintigraphy in localizing reoperative disease but requires the use of radiation and intravenous contrast. Both 4DCT and magnetic resonance imaging (MRI) do not significantly differ in accuracy between unexplored and reoperative patients. However, MRI is more costly, inaccessible, and time-consuming than 4DCT and is inappropriate as a first-line modality. Hybrid imaging with positron emission tomography and computed tomography (PET/CT) may be a promising second-line modality in the reoperative setting, particularly when first-line modalities are discordant or inconclusive. Lastly, selective venous sampling should be reserved for challenging cases in which noninvasive modalities are negative or discordant. In the challenging population of reoperative patients with PHPT, a multimodality approach that utilizes the expertise of high-volume centers can accurately localize persistent or recurrent disease and enable curative parathyroidectomy.

Factors Associated With Discordance Between Preoperative Parathyroid 4-Dimensional Computed Tomographic Scans and Intraoperative Findings During Parathyroidectomy

Importance

Parathyroid 4-dimensional computed tomographic scans (4D-CTs) have emerged as an accurate and cost-effective initial localization study for patients with primary hyperparathyroidism. However, potential limitations and factors affecting the accuracy of preoperative 4D-CTs remain poorly defined.

Objectives

To characterize factors associated with missed parathyroid lesions on preoperative 4D-CTs and to investigate patterns of commonly observed errors.

Design, Setting, and Participants

A prospectively accrued patient database was analyzed from September 1, 2011, through October 31, 2016. The study was performed in a tertiary referral center. Consecutive patients with primary hyperparathyroidism undergoing preoperative 4D-CTs and subsequent parathyroidectomy were included in the study.

Main Outcomes and Measures

Discordance between preoperative 4D-CTs and intraoperative findings in the number and location of abnormal parathyroid lesions.

Results

Of 411 patients studied (mean [SD] age, 59 [14] years; 325 [79.1%] female), 123 (29.9%) had discordance between preoperative 4D-CTs and intraoperative findings. Among the 411 patients, 75 (18.2%) had major discordance, including incorrectly localized adenoma on the contralateral side of the neck, missed double adenoma, and absence of any abnormal lesion detected on 4D-CTs. Compared with concordant cases, discordant cases had higher frequencies of multigland disease (66.7% [82 of 123] vs 24.3% [70 of 288], P < .001) and multinodular goiter or thyroid nodule (40.7% [50 of 123] vs 29.2% [84 of 288], P = .02). Missed parathyroid lesions were smaller (mean [SD], 0.86 [0.29] vs 1.24 [0.50] cm; P < .001) and were more likely to be in the inferior position (65.4% [87 of 133] vs 38.1% [177 of 465], P < .001). Parathyroid lesion size of 10 mm or less (odds ratio [OR], 4.37; 95% CI, 2.24-8.54), multigland disease (OR, 7.63; 95% CI, 3.49-16.69), multinodular goiter or thyroid nodule (OR, 1.82; 95% CI, 1.01-3.28), and parathyroid lesion in the inferior position (OR, 6.82; 95% CI, 3.10-14.99) were independently associated with discordant 4D-CT results.

Conclusions and Relevance

Multigland disease was most strongly associated with discordance between preoperative 4D-CTs and intraoperative findings, followed by parathyroid lesion in the inferior position and parathyroid lesion size of 10 mm or less. Awareness of these potential pitfalls may allow surgeons to better leverage this new localization technique in preoperative planning and intraoperative troubleshooting.