Adrenal masses: characterization with T1-weighted MR imaging.

The ability of a T1-weighted spin-echo magnetic resonance (MR) sequence to allow differentiation of benign from malignant adrenal masses at 0.5 T was investigated in 28 patients with 35 adrenal masses. All nine lesions with an adrenal mass-liver signal intensity ratio of 0.71 or less were metastases, and all 15 with a ratio of 0.78 or more were adenomas. Eleven masses (31%)--including six adenomas, three metastases, a pheochromocytoma, and a neuroblastoma--had ratios between these values. Nine of ten masses with adrenal mass-fat intensity ratios of 0.35 or less were metastases, and all 12 with ratios of 0.42 or more were benign. Eleven masses (31%), four malignant and one benign, had ratios between these values. The ratios for two masses could not be calculated due to lack of fat. The specificity of T1-weighted MR imaging in differentiating benign from malignant adrenal masses appears similar to that reported for T2-weighted imaging. However, significant overlap occurred, as has also been reported for T2-weighted imaging. While both imaging sequences may help distinguish benign from malignant adrenal masses in some cases, biopsy is still necessary when an accurate histologic diagnosis is essential.

Duke Scholars

Author Rendon C. Nelson Radiology