Valueof DTI in differentation ofadrenal gland lesions

Objective:Magnetic Resonance Imaging (MRI) is a valuable modality in the evaluation of mass lesionsof adrenal glands because of its multiplanar imaging, tissue characterization, and high tissuecontrast capabilities. Differential diagnosis can be performed with MRI since it can show thecontents of lesions in the adrenal glands.Recently, Diffusion Weighted Imaging (DWI) and Diffusion Tensor Imaging (DTI) whichwere developed in addition to conventional MRI, have become the most commonly studiedsubjects with regard to differential diagnosis of brain tumors. There are studies suggestingthat DTI could be used as a diagnostical method for the evaluation of various addominallesions. In this method, local water diffusion in each voxel is described by the designatedtensor. Geometric structure of the diffusion tensor enables quantitative calculation of differenttissue structures such as bone, muscle, white matter. Some published studies indicate that thevalue of Apparent Diffusion Coefficient (ADC) can be of significant help in differentiation ofbenign and malignant lesions. However, in the literature, there is no study focusing on thevalue of DTI in differentiation of adrenal gland lesions. Therefore, in this study, we aim toinvestigate the efficiency of this method in differential diagnosis.Materials and Methods:In this study, cases believed to have a lesion of the adrenal glands and referred to the MRI,were included. Thirty-three adrenal mass in 33 patients (27 male and 6 female) aged between18-80 years (mean age: 59) were evaluated by MRI and DTI. Study group was consisted of 19adenoma and 14 metastasis patients with definitive diagnoses. In addition to abdominal MRIby 3 Tesla MRI devices, Diffusion Tensor Imaging (DTI) sequence was performed for 6minutes. This procedure was carried out in our Radiology Department by 3 Tesla MRI systemwith the help of a whole-body surface coil. Total length of imaging was about 25-30 minutes.Each case was given a numerical code representing clinical data known only by us. FA(Fractional Anisotropy) and ADC (Apparent Diffusion Coefficient) maps were generated byanalyzing the acquired data with a specific software. Statistical FA and ADC values werecalculated with the help of those maps, and the contribution of those values to the differentialdiagnosis was evaluated.Y. IŞIK, 2010 67Results:Median ADC value for adenomas was 1.44, whereas it was 1.29 for metastases. Thedifference between was not found to be statistically significant (p>0.008).Median FA value for adenomas located over the adrenal glands was 0.52, while it was 0.35for metastases. FA values for metastases were observed to be statistically significantly lowerthan those for adenomas.Conclusion:In this study, we showed that DTI for adrenal gland can be performed with a 3T MRI system.While ADC measurements were not found to be statistically significant in differentiation ofmetastases from adrenal adenomas, FA values were observed to be statistically significantlylower for adrenal metastases than for adenomas.