CT AND MR DISTINCTION OF ADENOMAS AND NONADENOMAS OF THE ADRENAL-GLAND

Objective: Because the distinction between adenomas and nonadenomas of the adrenal gland is essential, we investigated which of the following parameters-size, CT attenuation values, MRI signal intensity ratios on T1- and T2-weighted sequences, calculated T2 relaxation times, or T2 relaxation time ratios-provides better discrimination. Materials and Methods: We compared these parameters in 44 adrenal masses of 37 patients by means of the Student t test and receiver operating characteristics (ROC) analyses. Results: Only size, CT attenuation values, and signal intensity ratios on TZ-weighted MR images of adenomas showed a significant difference from those of nonadenomas. With use of ROC analysis, CT demonstrated a significantly larger area under the curve compared to size and T2 signal intensity ratios, indicating superior performance. Conclusion: We found attenuation values on non-contrast-enhanced CT to be the best method in discriminating adrenal adenomas from nonadenomas. Adrenal masses with CT attenuation values below 15 HU warrant no further investigations.