Diagnostic Rechallenge with 18F-FCH PET/CT Often Allows Minimally Invasive Parathyroidectomy While Maintaining Exceptional Cure Rates.

BACKGROUND: Minimally invasive parathyroidectomy (MIP) has gained acceptance as the preferred surgical procedure for management of primary hyperparathyroidism (pHPT). Appropriate selection of patients for a MIP is a crucial step in its utilization. The aim of the study was to evaluate the role of 18F-FCH PET/CT as second-line imaging for accurately directing MIP. METHODS: This is a retrospective single-center study. Seventy-two patients with biochemical evidence of pHPT and a non-conclusive or negative first-line imaging (ultrasound and dual isotope subtraction scintigraphy) received 18F-FCH PET/CT between January 2018 and February 2020. All imaging studies were performed at our institution. Assessment of therapeutic changes and outcomes was performed. RESULTS: of the 72 patients imaged with 18F-FCH PET/CT, 54 subsequently underwent parathyroidectomy. When considering the ability of 18F-FCH PET/CT alone to predict a uniglandular disease, the sensitivity, specificity, PPV and NPV were 92.7% (95%CI: 80.1-98.5), 46.2% (19.2-74.9), PPV 87.3% (80.5-92) and NPV 61.2% (31.4-84.5), respectively. When we combined the data provided by 18F-FCH PET/CT with the data already collected from 1st line imaging we were able to complete a minimally invasive surgery in 38 of the 41 (92%) patients with a uniglandular disease. Thirteen patients (24%) had a multiglandular disease, all of them except one underwent bilateral neck exploration based on the data collected by all imaging modalities combined. Overall, cure was achieved in 53 (98%) patients. CONCLUSION: 18F-FCH PET/CT, interpreted along with first-line imaging results in selected patients, can better facilitate utilization of MIS while maintaining exceptional cure rates.

Value of 123I/99mTc-sestamibi parathyroid scintigraphy with subtraction SPECT/CT in primary hyperparathyroidism for directing minimally invasive parathyroidectomy.

BACKGROUND: Primary hyperparathyroidism/(PHPT) is one of the most common endocrinological conditions. Surgery remains the only curative option. We have evaluated the performance of double isotope 123I/99mTc-sestamibi parathyroid scintigraphy/(PS) with subtraction SPECT/CT in PHP for identifying uniglandular disease. METHODS: Ninety PHPT patients undergoing parathyroidectomy (December 2015-August 2016) were included. All patients were evaluated with neck ultrasound/(US), PS and SPECT/CT with a new protocol. Outcomes from imaging modalities were reported as: uniglandular disease/(UGD), multiglandular disease/(MGD), or negative, and were compared to post-operative diagnoses. RESULTS: Post-operatively, 72 and 18 patients had true UGD and MGD, respectively. Sensitivities and specificities of US, pinhole scintigraphy with subtraction, pinhole and SPECT/CT with subtraction, and all modalities combined were 91.7%/38.9%, 88.9%/72.2%, 93%/66.7% and 84.72%/77.78%, respectively: specificity of US + PS superior to US alone, p = 0.074. SPECT/CT enables reclassification of doubtful uptake foci. CONCLUSIONS: Combination of neck US and PS with subtraction SPECT/CT offers a higher specificity for guiding towards minimally invasive parathyroidectomy.

Preoperative imaging for focused parathyroidectomy: making a good strategy even better.

OBJECTIVE: Surgical treatment for primary hyperparathyroidism (pHPT) has undergone a major paradigm shift during the last decades from bilateral cervicotomy with four-gland neck exploration to image-guided focused approaches. The primary objective of the present study was to compare the performances of parathyroid scintigraphy (PS), parathyroid ultrasonography (US), and the combination of both procedures for guiding a focused approach on the basis of modified interpretation criteria. METHODS: Data from 199 patients operated for apparent sporadic pHPT and evaluated with US and PS using dual-isotope (123)I/(99m)Tc-sestamibi planar pinhole and single-photon emission computed tomography (SPECT) acqusitions were evaluated. RESULTS: A total of 127 patients underwent a focused approach and the remainder had bilateral cervicotomy. In 42 cases, a focused approach was not performed due to the absence of concordant results between US and PS for a single-gland abnormality. Four patients had persistent disease and three had recurrent disease. A localizing preoperative PS had a sensitivity of 93.3%, positive predictive value of 85.8%, negative predictive value of 73.0%, and accuracy of 83.4% for predicting uniglandular disease. Additional SPECT images accurately localize posterior adenomas that are often missed by US. Compared with PS, US had a lower sensitivity (P<0.01). Our imaging protocol also enabled diagnosis of multiglandular disease in 60.6%. CONCLUSIONS: PS using a highly sensitive dual-tracer subtraction method is the most accurate technique for directing a focused approach. PS could be sufficient for directing a focused approach in the presence of a negative US in two major circumstances: posterior locations due to acquired ectopia that could be missed by US, and previous history of thyroidectomy due to interpretation difficulties.