Enabling minimal invasive parathyroidectomy for patients with primary hyperparathyroidism using Tc-99m-sestamibi SPECT–CT, ultrasound and first results of 18F-fluorocholine PET–CT
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.
Section snippets
Patients
The group that is subject to this study consists of 63 consecutive patients with a biochemical diagnosis of non-familial pHPT, including five patients with recurrent disease and six patients with persistent pHPT. All patients were operated in the University Medical Center of Utrecht between March 2011 and January 2015. Of these, 54 patients were referred for pre-operative SPECT–CT combined with US, nine patients for SPECT–CT only and five patients underwent additional FCH PET–CT for precise
Results
Our study group consisted of 47 (74.6%) females and 16 (25.4%) males with a mean age of 58 years (SD 12; range 18–79 years). Pre-operative mean PTH level was 20.0 pmol/L (SD 13.0; range 7.2–57.0 pmol/L, reference value 1.0–7.0 pmol/L) and pre-operative mean iCa level was 1.49 mmol/L (SD 0.22; range 1.24–2.89 mmol/L, reference value 1.15–1.32 mmol/L).
In 42 patients (66.7%) pre-operative imaging allowed MIP, whereas the other patients underwent UNE (n = 14), BNE (n = 6) or thoracotomy (n = 1). In 7 patients
Discussion
This is one of the first studies to present the clear added value of FCH PET–CT imaging in a patient series in localizing the pathological parathyroid gland and enabling MIP when conventional imaging fails to do so. In our series, 39 patients (61.9%) underwent MIP using conventional imaging and an additional 4 were eligible for focused surgery after FCH PET–CT. Furthermore we investigated the performance of the most commonly used imaging modalities, US and SPECT–CT, and showed that performing
Conclusion
In summary, we advise to use SPECT–CT for initial pre-operative localization of the abnormal parathyroid gland(s) in the case of biochemical pHPT. Ultrasound could be preserved for cases with negative SPECT–CT since it might increase sensitivity but can also lead to unnecessary neck explorations. 18F-fluorocholine PET–CT seems a promising new tool for the detection of parathyroid adenomas, due to its superior spatial resolution, low radiation burden, short scanning time and wide tracer
Conflict of interest statement
The authors declare that there are no conflicts of interest.
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