Adrenal gland scanning using PET/CT with a specific tracer (11C-metomidate) in patients with hypertension due to overproduction of aldosterone.

Rationale:

Primary aldosteronism (PA) is a relatively common secondary cause of hypertension. PA is usually due to either bilateral adrenal hyperplasia (BAH) or an aldosterone producing adrenal adenoma (APA). Less frequently, PA is caused by primary unilateral adrenal hyperplasia (PAH). Clinically, PAH behaves like APA and the distinction between these two subtypes can only be made by pathologic examination of the removed adrenal gland, demonstrating either hyperplasia or adenoma, respectively. The recommended treatment for BAH is medical treatment with antihypertensive drugs (aldosterone antagonist), whereas APA and PAH can be cured in many cases by unilateral adrenalectomy. Thus, it is of clinical importance to differentiate correctly between BAH and APA/PAH. Current guidelines recommend adrenal venous sampling (AVS) as the gold standard for the differentiation between BAH and APA/PAH in every patient with PA who is a candidate for surgery. However, AVS is an invasive diagnostic test and is therefore not without risks. Moreover, AVS requires an experienced radiologist, and is time-consuming and expensive. Therefore, there is an urgent need for a non-invasive, faster and less expensive diagnostic test which can correctly distinguish between the two main subtypes of PA. PET/CT with 11C-metomidate has successfully been used as a functional imaging technique for several adrenal gland diseases. Until now, its value in the differential diagnosis in PA has not been well investigated. Our hypothesis is that 11C-metomidate PET/CT is selectively taken up by aldosterone producing adrenal cortical tissue, resulting in a symmetrical tracer uptake in case of BAH and in a unilateral tracer uptake in a patient with an APA or PAH.



Objective:

Main objective is to determine whether 11C-metomidate PET/CT can differentiate between BAH and APA/PAH.



Study design:

Comparative diagnostic study.



Study population:

Adult patients (=/> 18yrs) with PA after a successful AVS (n=10).



Intervention:

Patients will undergo a whole-body 11C-metomidate PET/CT scan.



Main study parameters/endpoints:

Main study parameter is the concordance between the results of AVS (=gold standard) and 11C-metomidate PET/CT.

Our hypothesis is that 11C-metomidate is selectively taken up by aldosterone producing adrenal cortical tissue, resulting in a symmetrical tracer uptake in case of bilateral adrenal hyperplasia (BAH) and in a unilateral tracer uptake in a patient with an aldosterone producing adenoma (APA)or primary adrenal hyperplasia (PAH).

N/A

Study subjects are pretreated with a 5-day course of 3 mg dexamethasone qd directly before scanning. The scanning procedure itself will take approximately 1.5 hours. Before arriving at the department, patients should have fasted for 4 hours. In the first part of the investigation, patients will receive an intravenously injection with 400 MBq 11C-metomidate. In the second part of the investigation, 20 minutes after tracer injection, patients will be placed for approximately 45 minutes in the PET/CT camera to acquire whole-body images (head to pelvis).