If adrenal-specific imaging is nondiagnostic, a 6- to 12-month follow-up examination can be performed to document stability [12]. One study by Herrera et al [5] examined 342 patients without a history of malignancy and found that the rate of malignancy in adrenal nodules was only 1.5% and that all malignant lesions were >5 cm. In another series of 887 patients who had adrenal incidentalomas, a diameter >4 cm was shown to have 90% sensitivity for the detection of adrenocortical carcinoma but low specificity; only 24% of lesions >4 cm in diameter were malignant [27]. Although many guidelines exist regarding the appropriate time interval for follow-up, no true agreement has been achieved. Stability of a lesion should be assessed by repeat imaging, if possible in the same modality as initial imaging to allow for accurate comparison. If prior imaging is or becomes available or a lesion has been stable for 1 year or more, it can generally be considered benign, and no additional imaging follow-up is required [12,13]; however, it may be performed per clinical discretion. Although both benign and malignant adrenal masses can enlarge over time, interval growth of adrenal masses has been advocated as a potential indicator of malignancy. However, there is scant information on what size change over what time interval requires further investigation. A study has shown that a growth of 0.8 cm on follow-up CT had the highest combination of sensitivity (72%) and specificity (81%) when evaluating absolute size change, growth rate, and growth percent in 111 benign and 25 malignant pathologically proven adrenal lesions. Although the unadjusted odds ratio for this threshold was 11.02, no threshold was found with 100% sensitivity or specificity [32]. Adrenal Mass Evaluation CT Abdomen Evaluation of an adrenal mass indeterminate on initial imaging consists of an adrenal CT protocol.
Adrenal Mass Evaluation. If adrenal-specific imaging is nondiagnostic, a 6- to 12-month follow-up examination can be performed to document stability [12]. One study by Herrera et al [5] examined 342 patients without a history of malignancy and found that the rate of malignancy in adrenal nodules was only 1.5% and that all malignant lesions were >5 cm. In another series of 887 patients who had adrenal incidentalomas, a diameter >4 cm was shown to have 90% sensitivity for the detection of adrenocortical carcinoma but low specificity; only 24% of lesions >4 cm in diameter were malignant [27]. Although many guidelines exist regarding the appropriate time interval for follow-up, no true agreement has been achieved. Stability of a lesion should be assessed by repeat imaging, if possible in the same modality as initial imaging to allow for accurate comparison. If prior imaging is or becomes available or a lesion has been stable for 1 year or more, it can generally be considered benign, and no additional imaging follow-up is required [12,13]; however, it may be performed per clinical discretion. Although both benign and malignant adrenal masses can enlarge over time, interval growth of adrenal masses has been advocated as a potential indicator of malignancy. However, there is scant information on what size change over what time interval requires further investigation. A study has shown that a growth of 0.8 cm on follow-up CT had the highest combination of sensitivity (72%) and specificity (81%) when evaluating absolute size change, growth rate, and growth percent in 111 benign and 25 malignant pathologically proven adrenal lesions. Although the unadjusted odds ratio for this threshold was 11.02, no threshold was found with 100% sensitivity or specificity [32]. Adrenal Mass Evaluation CT Abdomen Evaluation of an adrenal mass indeterminate on initial imaging consists of an adrenal CT protocol.