Role and Cost-effectiveness of Adrenal Imaging and Image-guided FNA Cytology in the Management of Incidentally Discovered Adrenal Tumours

Abstract

Incidentally discovered adrenal masses (incidentalomas) are relatively frequent and unsuspected incidentalomas (AI) of more than 1 cm in size may be found in 1-5% of patients who have undergone abdominal or chest computed tomography (CT)-scan for unrelated reasons. Once an AI is detected, the two major questions are whether the patient has biochemical evidence of adrenal hyperfunction, and whether the mass is an adrenal metastasis or a malignant adrenal tumour. In most cases (>90%) AI are non-functioning, with a low (<10%) risk of being malignant, and an estimated cumulative risk of malignant transformation of less than 1:1000. However, all patients with non-functioning AI usually undergo several imaging studies, but the impact of imaging techniques and image-guided fine-needle aspiration cytology (FNAC) on the cost-effectiveness in the management of patients is not well established. A single test for disease probabilities is not always more cost-effective than two-test approaches and it has been shown that the cumulative sensitivity and accuracy of both FNAC + magnetic resonance imaging (MRI) and FNAC + norcholesterol adrenal scintigraphy reach 100%, at a similar cost-to-accuracy ratio (7.5 vs. 7.0), whilst the strategy CT-scan + MRI together is less sensitive at a lower cost-to-accuracy ratio. In conclusion, the significance of AI, as well as the optimal management approach to treatment, is still under discussion. However, image-guided FNAC in conjunction with MRI as the exclusive imaging test has the major role and cost-effectiveness in the management of patients with AI, and should be considered the strategy of choice in distinguishing between benign and malignant non-functioning adrenal masses of more than 2 cm in diameter.