Solitary Parathyroid Adenoma Localization in Technetium Tc99m Sestamibi SPECT and Multiphase Multidetector 4D CT

Papillary Thyroid Carcinoma Infiltrating a Parathyroid Adenoma: A Case Report

Primary hyperparathyroidism due to parathyroid adenoma with concurrent papillary thyroid carcinoma is rare. Less frequently described is the histological interplay between these pathologies. This report describes the case of a 70-year-old female patient who presented with symptomatic hypercalcemia. Subsequent imaging was indicative of a left inferior lobe parathyroid adenoma and highly suspicious for left inferior lobe thyroid carcinoma. A subtotal thyroidectomy with isolated parathyroidectomy was performed. Postoperatively, the patient demonstrated normalization of calcium levels, parathyroid hormone, and resolution of symptoms. Histological evaluation demonstrated direct parathyroid adenoma invasion by the papillary thyroid carcinoma. This report demonstrates that although rare, parathyroid adenoma and papillary thyroid carcinoma can coexist and have the potential to complicate management.

Update in imaging tests used for the localization of parathyroid pathology

Preoperative localization of parathyroid pathology, generally a parathyroid adenoma, can be difficult in some cases due to the anatomical variants that these glands present. The objective of this review is to analyse the different imaging techniques used for preoperative localization of parathyroid pathology (scintigraphy, ultrasound, CT, MRI and PET). There is great variability between the different tests for the preoperative localization of parathyroid pathology. The importance of knowing the different diagnostic options lies in the need to choose the most suitable test at each moment and for each patient for an adequate management of primary hyperparathyroidism (PHP) with surgical criteria.

Four-dimensional computed tomography as first-line imaging in primary hyperparathyroidism, a retrospective comparison to conventional imaging in a predominantly single adenoma population

BACKGROUND

To determine the use of four-dimensional CT as first-line imaging compared to the traditional combination of ultrasound and [99mTc]Tc-Sestamibi SPECT.

MATERIALS AND METHODS

Retrospective review of preoperative imaging in patients with primary hyperparathyroidism, who underwent parathyroidectomy between 2012 and 2021. In one group, the combination ultrasound and [99mTc]Tc-Sestamibi SPECT was used as first-line imaging (n = 54), in the other group four-dimensional CT was the first-line imaging modality (n = 51). Sensitivity and positive predictive value were calculated on patient, lateralisation and localisation level. The need for additional imaging was also assessed for both groups.

RESULTS

Four-dimensional CT had a significantly higher sensitivity compared to the combination of ultrasound/[99mTc]Tc-Sestamibi SPECT on patient and localisation level (70.6% vs. 51.9%, p = 0.049 and 60.8% vs. 35.2%, p = 0.009 respectively). Sensitivity for lateralisation also appeared higher, but did not reach significance (62.7% vs. 44.4%, p = 0.060). Positive predictive value was not significantly higher for four-dimensional CT compared to ultrasound and [99mTc]Tc-Sestamibi SPECT (88.9% vs. 85.7% for lateralisation and 86.1% vs. 67.9% for localisation respectively). Additional imaging was required in 14 patients with four-dimensional CT as first-line imaging (27.4%) consisting of 2 ultrasound/[99mTc]Tc-Sestamibi SPECT and 13 [18F]fluorocholine PET/CT, compared to 24 patients with ultrasound/[99mTc]Tc-Sestamibi SPECT as first-line imaging (44.4%), requiring 22 four-dimensional CT and 9 [18F]fluorocholine PET/CT.

CONCLUSIONS

Four-dimensional CT as the sole first-line parathyroid imaging modality had higher sensitivity than the combination of ultrasound and [99mTc]Tc-Sestamibi SPECT, therefore requiring fewer additional procedures. Although the most costly, [18F]fluorocholine PET/CT was the most effective technique to localise parathyroid adenoma in case all other imaging was negative.

Four-Dimensional Computed Tomography for Parathyroid Adenoma Localization: A Pre-Operative Imaging Protocol

OBJECTIVE

Primary hyperparathyroidism (PHPT) affects approximately 0.86% of the population, with surgical resection as the treatment of choice. A 4D computed tomography (CT) is a highly effective tool in localizing parathyroid adenomas; however, there is currently no defined role for 4D CT when stratified against ultrasonography (USG) and nuclear medicine Technetium Sestamibi SPECT/CT (SES) imaging.

STUDY DESIGN

Retrospective Study.

SETTING

University Hospital.

METHODS

All patients who underwent parathyroidectomy for PHPT between 2014 and 2019 at a single institution were reviewed. Patients who had a 4D CT were included. We compared outcomes of 4D CT as a second line imaging modality to those of USG and SES as first line modalities. An imaging algorithm was proposed based on these findings.

RESULTS

There were 84 patients identified who had a 4D CT after unsuccessful first line imaging. A 4D CT localized parathyroid adenoma to the correct quadrant in 64% of cases, and to the correct laterality in 75% of cases. Obese patients had significantly lower rates of adenoma localization with USG (33.4%), compared to non-obese patients (67.5%; P = .006). In determining multigland disease the sensitivity of 4D CT was 86%, while the specificity was 87%.

CONCLUSIONS

A 4D CT has impressive rates of accurate localization of parathyroid adenomas; however due to the radiation exposure involved, it should remain a second line imaging modality. PHPT patients should first be evaluated with USG, with 4D CT used if this is unsuccessful and patients are greater than 40 years old, have a high BMI, or are having revision surgery.

Accuracy of Four-Dimensional Computed Tomography and Different Imaging Modalities in Primary Hyperparathyroidism

Background This study aimed to compare the accuracy of different imaging modalities in the preoperative localization of parathyroid pathology in primary hyperparathyroidism. Methodology This prospective study enrolled 70 patients who were biochemically diagnosed with primary hyperparathyroidism between 2021 and 2022 at our center. Patients underwent scanning using three imaging modalities, namely, Tc99m sestamibi scan (sestamibi), parathyroid ultrasonography, and four-dimensional computed tomography (4DCT). A descriptive analysis was performed to determine and compare the respective localizing sensitivities. Results The most common site of parathyroid adenoma (PA) was the left inferior parathyroid gland, seen in 28 (40%) patients. Three patients had false-positive imaging studies with no parathyroid pathology identified surgically or on histological examination. The median levels of parathyroid hormone decreased significantly (p < 0.001) after the surgery, with a median of 24.3 (1.90-121). Furthermore, 4DCT accomplished a sensitivity of 97.14% for diagnosing the side and 94.03% for overall localization of PA. This sensitivity was superior to the sensitivity of ultrasonography and sestamibi scan to detect the side and quadrant of the adenoma. 4DCT was significantly higher in sensitivity when compared to the combination of ultrasound and sestamibi (p < 0.001). Conclusions 4DCT yielded the highest sensitivity in localizing parathyroid pathology from the imaging modalities studied with the lowest false-negative rate. Using ultrasound with 4DCT could be the most cost-effective combination for detecting primary hyperparathyroidism.

Dual-phase computed tomography for localization of parathyroid lesions in children and adolescents with primary hyperparathyroidism

BACKGROUND

Childhood and adolescent primary hyperparathyroidism (PHPT) is a rare disease caused by single adenomas in 65-94% of patients. In this patient group, there is no data on computed tomography (CT) for pre-operative parathyroid localization that may facilitate focused parathyroidectomy.

METHODS

Two radiologists reviewed dual-phase (nonenhanced and arterial) CT images of twenty-three operated children and adolescents [20:single-gland disease(SGD), 3:multi-glandular disease(MGD)] with proven histopathological PHPT. Percentage arterial enhancement (PAE) was calculated as [100*{arterial-phase Hounsfield unit (HU)-nonenhanced phase HU}/nonenhanced HU] of the parathyroid lesion(s), thyroid, and lymph node.

RESULTS

Dual-phase CT lateralized 100%, localized to the correct quadrant/site 85% SGD (including 3/3 ectopic), and identified 1/3 MGD. PAE (cutoff ≥ 112.3%) was sensitive (91.3%) and specific (99.5%) in distinguishing parathyroid lesions from local mimics (P<0.001). The average effective dose was 3.16±1.01mSv, comparable to the planar/single photon emission CT (SPECT) Technetium 99m(Tc)-sestamibi and choline positron emission tomography (PET)/CT scans. Solid-cystic morphology identified in 4 patients harboring pathogenic germline variants (3:CDC73, 1:CASR) may serve as a radiological clue to molecular diagnosis. Nineteen out of 20 (95%) patients with SGD who had undergone single gland resection based on pre-operative CT findings were in remission over a median follow-up of 18 months.

CONCLUSION

As most children/adolescents with PHPT have SGD, dual-phase CT protocols which reduce the effective radiation dose with high localization sensitivity for single parathyroid lesions may be a sustainable pre-operative imaging modality in this patient group.

Advances in Endocrine Surgery

Recent changes in the landscape of endocrine surgery include a shift from total thyroidectomy for almost all patients with papillary thyroid cancer to the incorporation of thyroid lobectomy for well-selected patients with low-risk disease; minimally invasive parathyroidectomy with, and potentially without, intraoperative parathyroid hormone monitoring for patients with well-localized primary hyperparathyroidism; improvement in the management of parathyroid cancer with the incorporation of immune checkpoint blockade and/or targeted therapies; and the incorporation of minimally invasive techniques in the management of patients with benign tumors and selected secondary malignancies of the adrenal gland.

An Ectopic Parathyroid Adenoma Mimicking Submandibular Gland on 99mTc-MIBI Parathyroid Scintigraphy

ABSTRACT

A 67-year-old woman complained of continuous low back pain for 4 months. She was referred for a 99mTc-MIBI parathyroid scintigraphy with neck SPECT/CT imaging. The planar images showed no abnormal uptake. However, on the SPECT/CT scan, a soft tissue nodule with high uptake was noted adjacent to the left submandibular gland, mimicking normal submandibular gland uptake. Pathological examination from surgical specimen showed that it was an ectopic parathyroid adenoma.

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.

A Prospective Comparative Study of Using Ultrasonography, 4D-CT and Parathyroid Dual-Phase Scintigraphy with SPECT in Patients with Primary Hyperparathyroidism

Thirty-one consecutive patients were included in this study who were planned for parathyroidectomy due to primary hyperparathyroidism. They were studied with US, 4D-CT and dual-phase scintigraphy including SPECT/CT, and possible adenomas were identified in each imaging modality. Imaging data were quantified with US, CT and SPECT. Parathyroidectomies were performed as minimally invasive according to preoperative imaging findings. A total of 16 adenomas were found in 15 patients, and the surgery was negative in four patients. The imaging results were compared with each other and correlated to histology findings and blood biochemistry (S-Ca and P-PTH). Quantitative SPECT found a strong correlation between the quantification methods—Conjugate Gradient with Attenuation and Scatter Correction with a zone map (CGZAS) and Conjugate Gradient with Attenuation and Scatter Correction (CGAS)—measured as SUVmax and kBq/mL. However, a statistically significant correlation between the quantitative parameters (CGZAS and CGAS) and serum biomarkers (S-PTH and S-Ca) was not observed. The sensitivities of the imaging methods were calculated using histopathology as a gold standard. SPECT/CT demonstrated 93% sensitivity, 4D-CT 93% sensitivity and ultrasonography 73% sensitivity. The imaging methods were compared with each other using parathyroid regions because findings and locations varied between the modalities. Our prospective study supports that quantitative SPECT/CT is useful for presurgical assessment of primary hyperparathyroidism.

Direct Comparison of Preoperative Imaging Modalities for Localization of Primary Hyperparathyroidism: A Systematic Review and Network Meta-analysis

Importance

Accurate preoperative localization of primary hyperparathyroidism (pHPT) is an important and challenging issue for a successful parathyroidectomy. Although new imaging modalities have been introduced during the past decade, direct comparative studies on advanced imaging techniques are limited.

Objective

To compare the performance of different preoperative imaging modalities for the localization of pHPT by performing a network meta-analysis (NMA).

Data Sources

PubMed, Embase, and the Cochrane Library were searched from the earliest available indexing date through September 28, 2020.

Study Selection

The inclusion criteria were diagnostic tests with sensitivities of 2 or more different preoperative imaging modalities for the same indivduals.

Data Extraction and Synthesis

Two researchers independently reviewed the literature according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses extension statement of health care intervention guidelines for network meta-analyses.

Main Outcomes and Measures

After classifying various imaging modalities into 8 representative imaging categories, the pooled estimation between the odds ratio and 95% credible intervals (CrIs) was calculated in the sensitivity for localization of pHPT. The surface under the cumulative ranking curve (SUCRA) values were obtained to calculate the probability of each imaging modality being the most effective diagnostic method.

Results

A total of 8495 patients from 119 direct comparative studies using 2 or more imaging modalities for localization of pHPT were included. The sensitivity of choline positron emission tomography and computed tomography (PET-CT) was significantly higher than that of technetium 99m sestamibi single-photon emission computed tomography (MIBI SPECT) in both patient-based and lesion-based analyses (patient-based analysis: odds ratio, 5.22; 95% CrI, 2.36-11.80; lesion-based analysis: odds ratio, 17.70; 95% CrI, 5.79-60.10). Among 8 representative imaging modality categories, choline PET-CT showed the highest SUCRA value in both patient-based and lesion-based analyses. In patient-based analysis after 2010, choline PET-CT showed the highest SUCRA value, followed by the CT category, although MIBI SPECT had the highest SUCRA value in analysis before 2009.

Conclusions and Relevance

The results from this network meta-analysis suggest that choline PET-CT showed the best performance in both patient-based and lesion-based analyses and that choline PET-CT would be the best preoperative imaging modality for localization of pHPT.

Recurrence after successful parathyroidectomy-Who should we worry about?

BACKGROUND

Preventing cervical reoperations is important-especially after parathyroidectomy. We sought to examine early predictors of recurrence of primary hyperparathyroidism after surgical cure.

METHODS

Adult patients with sporadic primary hyperparathyroidism treated with parathyroidectomy between September 1, 1997, and September 1, 2019, with confirmed eucalcemia at 6 months postoperatively were identified. Recurrence was defined as hypercalcemia (>10.2 mg/dL) with an elevated or nonsuppressed parathyroid hormone level on subsequent follow-up.

RESULTS

Parathyroidectomy was performed in 522 patients (median age, 62.1 years, 77% female) with the majority undergoing planned minimally invasive parathyroidectomy (85.4%, n = 446). After a median follow-up of 30.9 months, 13 patients (2.5%) recurred (median time to recurrence 50.2 months, interquartile range 27.9-66.5), all of whom underwent planned minimally invasive parathyroidectomy (n = 13/446, 2.9%). Recurrence was more common in those with higher (but still normal) 6-month calcium (10.1 vs 9.3 mg/dL, P < .001) or parathyroid hormone values (64 vs 46 pg/mL, P < .01). Multivariate analysis revealed that age >66.5 years, calcium ≥9.8mg/dL and parathyroid hormone ≥80 pg/mL at 6 months were associated with increased risk of recurrence. In addition, the presence of at least 1 preoperative imaging study that conflicted with intraoperative findings among minimally invasive parathyroidectomy patients (n = 446) was associated with increased risk of recurrence (hazard ratio 4.93, 95% confidence interval 1.25-16.53, P = .016).

CONCLUSION

Recurrence of sporadic primary hyperparathyroidism after initial surgical cure in the era of minimally invasive parathyroidectomy is 2.5%. Identification of those at risk for recurrence using 6-month serum calcium ≥9.8 mg/dL, parathyroid hormone ≥80 pg/mL, and/or potentially conflicting localization studies may inform surveillance strategies.

Personalized nuclear imaging protocol in cases with nodular goiter and parathyroid adenoma

A 62 years old woman was diagnosed with multinodular toxic goiter and primary hyperparathyroidism/left parathyroid adenoma by hormonal assessment, ultrasound and nuclear thyroid/parathyroid scans. Cervical ultrasound illustrated a multinodular aspect of the thyroid with solid nodules and cystic-component nodules; the larger one represented a multinodular complex with necrosis areas in the left thyroid lobe, ACR TI-RADS score 4 (moderately suspicious). Functional nuclear imaging was performed for accurate differential diagnosis between thyroid vs. parathyroid localization, between cold vs. hot nodules, and eventually, for guiding the choice of a subsequent Fine-Needle Aspiration Biopsy (FNAB). Scans described an early intense ^99mTc-sestaMIBI uptake with no ^99mTc-pertechnetate uptake in the left thyroid lobe larger nodule. Due to the suspicion of malignancy for this nodule, we performed an additional scan (1 hour before the classical 2 hours parathyroid delayed scan). The intense uptake persists in both delayed scans suggesting no malignant phenotype and which was confirmed after surgery by benign histology. In conclusion, using a ^99mTc-sestaMIBI personalized protocol, related to the radiotracer cellular uptake mechanisms: 1 hour scan (supplementary image, corresponding to the maximum uptake pattern of ^99mTc-sestaMIBI for cancer cells) and 2 hours scan (for parathyroid washout evaluation) may avoid unnecessary extensive thyroid surgery.

Improving the detectability of overactive glands in dual-phase parathyroid SPECT/CT: a Monte Carlo simulation study

Objective. SPECT-CT is a standard procedure conducted before minimally invasive surgery for the treatment of primary hyperthyroidism. In order to improve image quality, it is important to know how defect detectability is influenced by acquisition and processing parameters. The objective of this study is to continue prior physical phantom optimization studies by performing Monte Carlo simulations for the dual phase parathyroid SPECT-CT protocol using a digital anthropomorphic phantom.Methods. The dual phase parathyroid SPECT-CT imaging procedure with 99mTc-Sestamibi was simulated using the previously extensively validated SIMIND software for the first time. An anthropomorphic ZUBAL based phantom was built to represent an adenoma. Its diameter was set to 0.76 cm which corresponded to more than three times the pixel size and the target-to-background ratio was set to 16:1 based on previous studies. Four different collimators were tested. Contrast-to-noise (CNR) values were determined for different scatter correction options and processing parameter values. The OSEM algorithm was used for image reconstruction.Results. CNR values were improved from about zero (LEGP collimator, 16 iterations, attenuation correction: on, scatter correction: off) up to 3.7 (LEUHR collimator, 16 iterations, attenuation correction: on, scatter correction: off). The subjective visual assessment of detectability on simulated images agreed with the quantitative CNR values.Conclusion. Higher resolution collimators gave better CNR as confirmed by similar studies. The effect of scatter correction was found beneficial only if both the resolution and sensitivity of the collimator were relatively high. This is a significant finding since there is a shortage of definitive guideline on the use of scatter correction for parathyroid SPECT imaging.

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.

Comparing the diagnostic accuracy of 4D CT and 99mTc-MIBI SPECT/CT for localizing hyperfunctioning parathyroid glands: a systematic review and meta-analysis

PURPOSE

To compare the diagnostic accuracy of dual-phase 99mTc-MIBI single photon emission computed tomography/computed tomography (SPECT/CT) and 4D CT for the localization of hyperfunctioning parathyroid glands, a systematic review and meta-analysis was performed. Whether 4D CT combined to SPECT/CT [contrast-enhanced (CE)-SPECT/CT] had a better diagnostic performance than SPECT/CT alone in this scenario was also evaluated.

MATERIAL AND METHODS

PubMed and Embase databases were searched for eligible studies. To reduce interstudy heterogeneity, only studies with clear head-to-head comparison were included. Publication bias was assessed by the Deeks funnel plot. The pooled sensitivity, specificity and the area under the curve (AUC) for 4D CT, SPECT/CT and CE-SPECT/CT were determined by random-effect analysis, respectively.

RESULTS

Nine studies met the inclusion criteria, with a total of 911 participants. The sensitivity and specificity of 4D CT were 0.85 [95% confidence interval (CI), 0.69-0.94] and 0.93 (95% CI, 0.88-0.96), whereas the sensitivity and specificity for SPECT/CT were 0.68 (95% CI, 0.51-0.82; P = 0.048 compared with 4D CT) and 0.98 (95% CI, 0.95-0.99; P = 0.014 compared with 4D CT), respectively. CE-SPECT/CT is comparable to SPECT/CT in specificity and AUC, but it may improve the sensitivity (although there was a lack of statistical difference, 0.87 vs. 0.78; P = 0.125).

CONCLUSION

Although 4D CT shows comparable AUC and borderline better sensitivity than SPECT/CT, its clinical application is confined by relatively low specificity and high radiation exposure. CE-SPECT/CT may improve the sensitivity without compromising the specificity and AUC of SPECT/CT.