Fat has been used in many studies on magnetic resonance (MR) imaging as the tissue of reference in comparing regional signal intensities from various tissues using different imaging parameters. This is a retrospective study of 78 patients selected to assess the influence of different factors such as age, gender, obesity, and weight loss on the T1 and T2 relaxation parameters of fat in different areas of the body. The T1 values of fat were not influenced by the factors studied or by anatomic location of the fat. The T2 values were significantly lower in patients older than 65 years and in patients with significant weight loss caused by carcinoma or chronic disease. Nevertheless, these variations were small, with considerable overlap of the mean and rather large standard deviation values. In conclusion, fat is a valuable reference tissue for MR studies and is relatively uninfluenced by the factors studied.
