Enabling minimal invasive parathyroidectomy for patients with primary hyperparathyroidism using Tc-99m-sestamibi SPECT–CT, ultrasound and first results of ¹⁸F-fluorocholine PET–CT

Highlights

• We examined an optimal pre-operative imaging strategy.

• Goal was to perform minimal invasive parathyroidectomy.

• Ultrasound significantly decreased the PPV when added to SPECT–CT.

• ¹⁸F-fluorocholine was positive in 4/5 cases with negative conventional imaging.

Abstract

Objective

Assessment of the diagnostic value of ultrasound (US), single photon-emission computed tomography–computed tomography (SPECT–CT) and ¹⁸F-fluorocholine (FCH) PET–CT for preoperative localization of hyper-functioning parathyroid(s) in order to create a more efficient diagnostic pathway and enable minimal invasive parathyroidectomy (MIP) in patients with biochemical proven non-familial primary hyperparathyroidism (pHPT).

Methods

A single-institution retrospective study of 63 consecutive patients with a biochemical diagnosis of non-familial pHPT who received a Tc-99m-sestamibi SPECT–CT and neck ultrasound. Surgical findings were used in calculating the sensitivity and the positive predictive value (PPV) of both imaging modalities. Furthermore we present 5 cases who received additional FCH PET–CT.

Results

A total of 42 (66.7%) patients underwent MIP. The PPV and sensitivity of SPECT–CT, 93.0% and 80.3%, were significantly higher than those of US with 78.3% and 63.2%, respectively. Adding US to SPECT–CT for initial pre-operative localization did not significantly increase sensitivity but did significantly decrease PPV. Performance of US was significantly better when performed after SPECT–CT. ¹⁸F-fluorocholine PET–CT localized the hyper-functioning parathyroid gland in 4/5 cases with discordant conventional imaging, enabling MIP.

Conclusion

SPECT–CT is the imaging modality of choice for initial pre-operative localization of hyper-functioning parathyroid gland(s) in patients with biochemical pHPT. Ultrasound should be performed after SPECT–CT for confirmation of positive SPECT–CT findings and for pre-operative marking allowing MIP. In cases with negative or discordant imaging additional FCH PET–CT should be considered since this might enable the surgeon to perform MIP.

Introduction

Primary hyperparathyroidism (pHPT) is a common endocrine disorder. It is characterized by autonomous hyper-secretion of parathyroid hormone (PTH) by the parathyroid gland(s), leading to an elevated serum calcium concentration. Diagnosis is based upon these biochemical abnormalities, which are often discovered during routine screening [1]. In about 84% of cases, pHPT is caused by a single adenoma. Less frequent causes are multi glandular disease (MGD), hyperplastic disease and, very rarely, a carcinoma. Multi glandular disease is associated with several familiar syndromes, of which familial isolated primary hyperparathyroidism, multiple endocrine neoplasia (MEN) 1 and MEN2A are the most common [2].

Patients can be treated with either medication or surgery. When patients are symptomatic or aged younger than fifty, surgery is performed. If patients are asymptomatic, refuse surgery or are considered to have high operative risks, medication is given [3]. In the non-familial cases, surgical intervention has shifted the past decade, from extensive bilateral neck exploration (BNE) to minimal invasive parathyroidectomy (MIP) [4]. Minimal invasive surgery is favorable due to shorter operative time, lower complication rate, and smaller incision length [5]. For MIP to be successful, adequate pre-operative imaging is needed.

Conventional imaging for patients without history of neck surgery includes ultrasound (US) and different kinds of Tc-99m-sestamibi scintigraphy. The diagnostic value of single photon emission computed tomography (SPECT–CT) in predicting the localization of the adenoma has been proven to be the best imaging modality in comparison to normal SPECT, dual-phase planar scintigraphy and subtraction scintigraphy [6], [7], [8]. However, even SPECT–CT fails to identify the gland in up to 30% of the cases [9]. For these cases several second-line imaging modalities are described such as magnetic resonance imaging and four dimensional computed tomography (4D-CT). Also, recently 2 studies with preliminary results regarding 18F-fluorocholine (FCH) PET–CT were published showing superior performance [10], [11]. Though, total body of evidence is still very scarce and little is known about its applicability in the case of negative SPECT–CT. We present here our single-institution experience regarding the use of US, SPECT–CT and FCH PET–CT for the pre-operative work-up of patients with non-familial pHPT.