Diffusion weighted MRI findings in adrenal lesions?

The aim of our study was to determine usefullness of apparent diffusion coefficient (ADC) measurement in differentiation of normal adrenal tissue and adrenal lesions with subtyping adrenal lesions through ADC values.Diffusion-weighted magnetic resonance imaging (DWMRI) using b100, b 600, and b 1000 diffusion gradients were performed on 39 cases (11 men, 28 women ) who had 43 adrenal lesions. At least three ADC measurements of all lesions and normal adrenal tissues were performed and their mean values were calculated and recorded.Mean ADC values at b100, b600 and b1000 gradients were 3.12±0.75, 2.47±0.63 and 1.67±0.35 in normal adrenal tissues; 2.81±0.96, 2.25±0.79, and 1.68±0.37 in adrenal lesions; 2.71±0.96, 2.15±0.79 and 1.56±0.37 in adenomas; 2.98±0.92, 2.48±0.73, and 1.91±0.75 in non-adenoma lesions; 2.71±0.18, 2.32±0.15, 1.83±0.11 in benign lesions, and 3.28±0.16, 2.29±0.18, 1.47±0.08 mm²/s in malignant lesions, respectively. Mean ADC values of normal adrenal tissue and adrenal lesions; adenomas and nonadenoma lesions, and benign and malignant adrenal lesions were not statistically significant (p>0.05). When lesions were compared among themselves, statistically significant different ADC values were found as between adenoma and hematoma, cyst and tuberculosis. Also metastasis significantly differentiated from hematoma, cyst, myelolipoma and tuberculosis. Hematoma and cysts showed statistically significant different mean ADC values from myelolipoma and phechromocytoma at b1000 gradient (p<0.05).The most significant value for evaluation of adrenal lesions with DAMRG is b1000 gradient. This study yielded that ADC measurements in normal and pathological adrenal tissues are possible. Diffusion-weighted imaging as a noninvasive, fast and effective imaging method may be an alternative to current diagnostic methods for differentiation of some adrenal lesions from each other without contrast agent usage at b1000 gradient value.Key Words: Diffusion-weighted magnetic resonance imaging (DWMRI), adrenal lesion, apparent diffusion coefficient (ADC),