The 10 Hounsfield units unenhanced computed tomography attenuation threshold does not apply to cortisol secreting adrenocortical adenomas

Abstract

ContextComputed tomography (CT) unenhanced attenuation value of <10 Hounsfield units (HU) has an excellent specificity (98%) to diagnose lipid-rich adrenocortical adenomas (ACAs) with a weaker sensitivity (71%).ObjectiveTo determine from a routine clinical perspective if unenhanced attenuation value is influenced by cortisol secretion in ACAs.DesignThis was a retrospective study of cases collected between 2009 and 2012.SettingThis study was conducted in a tertiary-care university hospital.PatientsSeventy-two patients operated on for an ACA (Weiss score ≤2) were analysed. Thirty-four patients had an ACA oversecreting cortisol (Cush-ACA). Thirty-eight patients had an ACA without cortisol oversecretion (Non Hyper-ACA).Main outcome measureCT unenhanced attenuation value was correlated with the functional status. The Weiss score items were analysed.ResultsAmong the 34 patients with a Cush-ACA a minority (n=7) had an unenhanced attenuation value under 10 HU. Among the high precontrast density (>10 HU) Cush-ACAs, washout analysis after contrast administration was consistent with the benign nature of the tumor in ∼60% of the cases. Less than 25% clear cells (lipid-rich cells), a Weiss score item, was present in 50% of the Cush-ACAs in favour of a lipid-poor content.ConclusionsUnenhanced attenuation value has a poor sensitivity to diagnose an ACA in case of cortisol oversecretion due to poor lipid content. Nevertheless, the accuracy of washout analysis was preserved in the group of Cush-ACAs.