FROM NEEDLES TO NUMBERS - CAN NONINVASIVE IMAGING DISTINGUISH BENIGN AND MALIGNANT ADRENAL LESIONS

Adrenal masses are a relatively common finding on computed tomography (CT) and magnetic resonance imaging (MRI). Until recently, adrenal bio psy, resection, or clinical follow-up were the only methods of disting uishing benign adenomas from malignancies. On the basis of their highe r lipid content, adenomas have characteristic appearances on CT and MR I that can be used to separate them from non-lipid-containing lesions such as metastases. CT densitometry with or without contrast media and chemical shift MRI (CSI) are two examples of techniques with adequate sensitivity (50-90%) and excellent specificity (> 95%) for adrenal ad enomas. While the need for invasive tissue sampling is reduced because of these techniques, it is eliminated because lesions not meeting the criteria for adenomas are not always malignant. However, CT densitome try and CSI are likely to reduce significantly the need for histology sampling of incidentally discovered adrenal masses due to the high spe cificity of these new techniques.