Contrast CT distinguishes benign from malignant adrenal masses

Adrenal masses are commonly seen at contrast-enhanced CT and most are benign, but when confirmation is critical, additional exams such as unenhanced CT, MR, washout CT, and PET are often ordered to make the call. But can contrast-enhanced CT do the job reliably without more tests?

A research team led by Dr. Julie Song from Rhode Island Medical Imaging looked at 211 adrenal masses (1-4 cm) for which the final diagnosis had been established. Three readers blinded to the final diagnosis looked at the contrast-enhanced CT cases, paying particular attention to morphology.

Irregular margins and low central attenuation were associated with malignancy, they found. No imaging features were reliable in establishing benignity, but CT was 54% to 74% sensitive and 96% to 97% specific for detecting malignancy in suspicious masses.

"When an adrenal mass has malignant morphologic features (irregular margins and heterogeneous density with thick enhancing rim) at presenting contrast-enhanced CT, it likely represents a malignant lesion," Song wrote in an email to AuntMinnie.com. "The remaining features (including smooth margins and homogeneous density) can be seen in both benign and malignant disease, and further workup should be pursued in patients with history of malignancy."