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

Clinical predictors of negative/equivocal SPECT imaging outcomes in primary hyperparathyroidism: Factors calling for 18F-choline-PET

PURPOSE

For minimally invasive surgery of parathyroid adenomas, exact localization diagnostics are essential. Main imaging modalities used for diagnostics are sonography, SPECT with/without CT (traditional imaging) and 18F-choline-PET. The aim of our study was to identify predictors for inconclusive SPECT imaging and subsequently determine in which cases 18F-choline-PET is needed.

METHODS

Retrospective analysis of 138 patients with histologically confirmed primary hyperparathyroidism (pHPT). After sonography, patients underwent SPECT or SPECT/CT imaging, with subsequent 18F-choline-PET in cases of disconcordant results. Logistic regression analysis was used to identify clinical and laboratory factors predictive for negative SPECT results.

RESULTS

Sensitivity rates for sonography, SPECT, SPECT/CT, and choline-PET were 47 %, 49 %, 71.7 %, and 97 %, respectively. Logistic regression revealed lower PTH levels (p < 0.001), presence of structural thyroid disease (p = 0.018), and negative sonography (p < 0.001) as predictive of negative/equivocal SPECT outcome. An additional traditional imaging CT scan to a SPECT enhanced detection odds, as did greater adenoma weight. Urolithiasis, osteoporosis, and calcium values as measurement of activity and duration of disease showed no significant association with the detection rate. Furthermore, our study demonstrated that 18F-choline-PET exhibited remarkable sensitivity in detecting adenomas among patients with negative/equivocal SPECT results.

CONCLUSION

Our study reveals potential predictive factors for a negative/equivocal SPECT outcome in pHPT. Identifying these factors might allow minimizing futile SPECT examinations and perhaps encourage timely utilization of 18F-choline-PET imaging. Our study reinforces the clinical significance of 18F-choline-PET, especially in complex cases with disconcordant results by conventional parathyroid imaging methods.

[11C]Choline PET/CT in a Patient with Prostate Cancer Biochemical Recurrence Showing Two Suspicious Findings in the Breast and Liver

A 79-year-old man with prostate cancer (PCa) was referred to our center to perform a [11C]Choline PET/CT for biochemical recurrence. Positron emission tomography/computed tomography (PET/CT) scan detected PCa recurrence in the prostate gland and several pelvic and abdominal lymph nodes. Two abnormal uptakes were also identified in the right breast and in the liver, respectively. Breast histological findings turned out to be gynecomastia, while the liver lesion resulted in a benign perfusion anomaly at follow-up magnetic resonance imaging (MRI). Although incidental findings were benign in this case, it is important to always investigate abnormal uptakes of [11C]Choline, as it could be an expression of further metastases or synchronous malignancies such as breast cancer and hepatocellular carcinoma.

Localization of Brown Tumors With 18F-Fluorocholine PET/CT Imaging in Severe Primary Hyperparathyroidism

ABSTRACT

We present the case of a 68-year-old woman with a painful tibial tumor and fatigue. Histology and laboratory studies were consistent with a brown tumor secondary to initially unrecognized, severe primary hyperparathyroidism. 18F-fluorocholine PET/CT revealed a large hypermetabolic parathyroid mass and multiple bone foci considered as brown tumors. Unilateral neck exploration confirmed a large parathyroid adenoma. Serum calcium and parathyroid hormone levels normalized quickly, and symptoms subsided gradually after parathyroidectomy. Brown tumors are a rare complication of severe hyperparathyroidism. 18F-fluorocholine PET/CT allows the localization of parathyroid adenomas and brown tumors, and can be used as a single imaging modality.

18F-fluorocholine PET/MRI versus ultrasound and sestamibi for the localization of parathyroid adenomas

PURPOSE

Accurate preoperative localization is imperative to facilitate a minimally invasive parathyroidectomy (MIP) in primary hyperparathyroidism (pHPT). This study aims to compare the diagnostic value of standard-of-care localization techniques (ultrasound [US] and 99mTechnetium (99mTc) -sestamibi scintigraphy) to [F-18]-fluorocholine positron emission tomography/magnetic resonance imaging (FCH-PET/MRI) to determine the additional clinical usefulness of PET/MRI in a Canadian cohort.

METHODS

We conducted a prospective, appropriately powered, study to compare the diagnostic value of -FCH PET/MRI to that of the US and 99mTc-sestamibi scintigraphy for localization of parathyroid adenomas in a patient with pHPT. The primary outcome was the per-lesion sensitivity and positive predictive value (PPV) of FCH-PET/MRI, US, and 99mTc-sestamibi scintigraphy. Intraoperative surgeon localization, parathormone levels, and histopathological findings were used as reference standards.

RESULTS

Forty-one patients underwent FCH-PET/MRI of which 36 patients had parathyroidectomy. In these 36 patients, 41 parathyroid lesions were histologically confirmed as adenomas or hyperplastic glands. Per-lesion sensitivity of FCH-PET/MRI was 82.9% and of US and 99mTc-sestamibi scintigraphy combined at 50.0%, respectively. The sensitivity of FCH-PET/MRI was superior to that of US and 99mTc-sestamibi scintigraphy (p = 0.002). In the 19 patients in whom both US and 99mTc-sestamibi scintigraphy were negative, PET/MRI correctly identified the parathyroid adenoma in 13 patients (68%).

CONCLUSIONS

FCH-PET/MRI is a highly accurate imaging modality for localization of parathyroid adenomas in a tertiary center in North America. It is a superior functional imaging modality to 99mTc-sestamibi scintigraphy alone and more sensitive for localization of parathyroid lesions than US and 99mTc-sestamibi scintigraphy combined. This imaging modality could become the most valuable preoperative localization study given its superior performance in localizing parathyroid adenomas.

The relationship between 18F-FCH uptake intensity and cell content in parathyroid lesions

PURPOSE

To investigate the relationship between cell content and histopathological features of parathyroid lesions and 18F-FCH uptake intensity on PET/CT images.

METHODS

Patients with primary hyperparathyroidism (age > 18) who were referred to 18F-FCH PET/CT were involved. All patients underwent parathyroidectomy. Correlation of SUVmax with following factors were statistically analysed: serum PTH, Ca, P levels and histopathological parameters, total absolute amounts of chief cell, oxyphyllic cell and clear cell components calculated by the multiplication of the volume of the parathyroid lesion and the percentage of each type of cell content (called as Absolute_chief, Absolute_oxyphyllic and Absolute_clear reflecting the total amount of each cell group).

RESULTS

A total of 34 samples from 34 patients (6M, 28F, mean age: 53.32 ± 15.15, min: 14, max: 84) who had a positive 18F-FCH PET/CT localizing at least one parathyroid lesion were involved. In the whole study group, SUVmax was found to be correlated with the greatest diameter and volume of the lesion and Absolute_chief (p = 0.004, p = 0.002 and p = 0.035, respectively). In the subgroup analysis of 28 samples with longest diameter > 1 cm, the correlation between SUVmax and Absolute_chief remained significant (p = 0.036) and correlation between SUVmax and volume and longest diameter became stronger (p = 0.011 and p > 0.001, respectively). No correlation was found between SUVmax and Absolute_oxyphyllic or Absolute_clear.

CONCLUSIONS

There might be a relationship between 18F-FCH uptake intensity and chief cell content in patients with parathyroid adenoma. Further studies with larger patient groups would be beneficial to support the data.

18F-fluorocholine PET/CT semi-quantitative analysis in patients affected by primary hyperparathyroidism: a comparison between laboratory and functional data

INTRODUCTION

This retrospective study aims to establish ¹⁸F-fluorocholine (FCH) positron emission tomography/computed tomography (PET/CT) performance in finding hyperfunctioning parathyroid glands, analyze a potential role for semi-quantitative PET parameters and assess factors that may influence PET/CT outcome.

METHODS

Forty patients with suspect primary hyperparathyroidism (pHPT) and negative/equivocal conventional imaging underwent FCH-PET/CT in our Institution. For every lesion, visual and semi-quantitative analyses were performed on PET/CT images. In qualitative analysis, a lesion was considered positive if a clear focus of uptake, significantly higher than normal thyroid tissue, was identifiable. Ectopic focal uptake was also regarded as positive PET result. Lesion SUV_Max was measured by assigning a spheric VOI to the suspect area of uptake. Thyroid SUV_Mean was assessed by placing a spheric VOI inside the contralateral thyroid lobe, and SUV_ratio was calculated using this background region. All patients were subsequently submitted to surgery and histopathologic workup. Sensitivity, positive predictive value (PPV) and accuracy were calculated based on histopathologic reports for every lesion. Pearson's test was used to assess a correlation between laboratory and histopathologic features with SUVr.

RESULTS

Four out of the 40 patients who underwent surgery for pHPT had more than one histologic proven unhealthy parathyroid and three had papillary thyroid cancer (PTC). A total of 48 lesions were analyzed. We found 42/48 lesions (87.5%) to have true-positive uptake, whereas three lesions (6.7%) had false-positive uptake (PTC). Three histologic proven parathyroid adenomas showed no uptake (6.7%); the sensitivity/PPV were 93.3% and accuracy was 87,8%. Pearson's test showed a significant correlation between PTH values and parathyroid size with SUVr values (r = 0.56 and 0.55, respectively, p < 0.01 for both features).

DISCUSSION

As stated in recent literature, we observed excellent diagnostic sensitivity of FCH-PET/CT in patients with pHPT, providing surgeons a fine tool to optimize treatment. More studies are needed to improve the evaluability of semi-quantitative parameters towards a further improvement of diagnostic accuracy.

Performance of quantitative measurements in [18F]fluorocholine positron emission tomography/computed tomography for parathyroid imaging (P2TH study)

Objective

[¹⁸F]Fluorocholine positron emission tomography/computed tomography (PET/CT) is used frequently in addition to [^99mTc]Tc-Sestamibi scintigraphy and ultrasonography for the location of hyperfunctioning parathyroid glands. The aim of this study is to evaluate the performance of quantitative criteria in [¹⁸F]fluorocholine PET/CT for localization of hyperfunctioning parathyroid glands. The secondary objective is to highlight a correlation between the detection rate of [¹⁸F]fluorocholine PET/CT and serum parathyroid hormone (PTH) level.

Materials and methods

In two academic centers, we retrospectively included patients with biological hyperparathyroidism (HPT) and who had [¹⁸F]fluorocholine PET/CT. After a visual analysis, to measure the overall performance of [¹⁸F]fluorocholine PET/CT, a blind reading was carried out with standardized measurements of maximum standardized uptake value (SUV_max), liver ratio, thyroid ratio, and size ratio. We analyzed the quantitative criteria of [¹⁸F]fluorocholine PET/CT compared to the histological results, in particular to identify differences between adenomas and hyperplasias. We compared the performance of each quantitative criterion to the overall sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of [¹⁸F]fluorocholine PET/CT. The detection rate of hyperfunctioning parathyroid glands was calculated in subgroups of serum PTH level.

Results

The quantitative criteria in [¹⁸F]fluorocholine PET/CT were measured for 120 patients (135 lesions). The areas under the receiver operating characteristic (ROC) curve representing SUV_max and liver ratio were significantly increased. The optimal cut-off values represented by the maximum Youden index was >4.12 for SUV_max and >27.4 for liver ratio. Beyond certain threshold values of SUV_max (>4.12) or liver ratio (>38.1), all the lesions were histologically proven adenomas. SUV_max and liver ratio were significantly higher for adenomas than for hyperplasias and differential diagnosis (p = 0.0085 and p = 0.0002). The positivity of [¹⁸F]fluorocholine PET/CT was correlated with PTH level. Detection rates were 55.56, 75.56, and 87.5%, respectively, for serum PTH < 70, 70 to 120, and >120 ng/ml.

Conclusion

Semi-quantitative measurements (SUV_max and liver ratio) should be considered as additional tools in interpretation of [¹⁸F]fluorocholine PET/CT. These quantitative parameters have lower overall performance but higher specificity than overall visual analysis in identifying an adenoma. Above certain threshold values, all lesions are adenomas. [¹⁸F]fluorocholine PET/CT confirms excellent performance for the detection of hyperfunctional parathyroids. For serum PTH levels < 70 ng/ml, the detection rate of [¹⁸F]fluorocholine PET/CT is strongly decreased.

Non-conventional and Investigational PET Radiotracers for Breast Cancer: A Systematic Review

Breast cancer is one of the most common malignancies in women, with high morbidity and mortality rates. In breast cancer, the use of novel radiopharmaceuticals in nuclear medicine can improve the accuracy of diagnosis and staging, refine surveillance strategies and accuracy in choosing personalized treatment approaches, including radioligand therapy. Nuclear medicine thus shows great promise for improving the quality of life of breast cancer patients by allowing non-invasive assessment of the diverse and complex biological processes underlying the development of breast cancer and its evolution under therapy. This review aims to describe molecular probes currently in clinical use as well as those under investigation holding great promise for personalized medicine and precision oncology in breast cancer.