Quantitative magnetic resonance imaging of subcutaneous adipose tissue

Abstract

Quantitative transverse relaxation time (T(2)) magnetic resonance (MR) imaging has been used with the aim to characterize subcutaneous adipose tissue. Protons in adipose tissue have a fast exchange behavior giving bi-component transverse relaxation processes with short and long relaxation time values depending on the tissue properties. MR images were acquired on a 1 T Siemens MR scan using a multi-spin-echo sequence. A high sensitive surface coil, enabling low noise MR images with voxel size of 10 mm(3), was used for performing accurate quantitative T(2) imaging. These acquisition parameters were determined by a preliminary study performed on an oil phantom known to be a valuable model for mimicking in vivo adipose tissue. In vivo study of the thigh adipose tissue was carried out on 30 volunteers. 20 women with various clinically diagnosed cellulite grades and 10 males, among them five showed overweight. Tissue characterization was finally performed through the analysis of the T(2) distributions. Phantom study showed that improvements in the precision in T(2) measurement are obtained at the expense of the spatial resolution. Uncertainties in T(2) measurements are three times lower by considering a region of interest of 3 x 3 pixels compared with a pixel by pixel analysis. The in vivo study showed that women groups present higher mean short T(2S) component values than men. Histogram of T(2) distribution showed that the maximum amplitude is observed at a lower value for the overweight men group. In addition, larger values around the septae were visualized on the long relaxation time images. This study shows that precise T(2) map of adipose tissue can be computed. The balance between precision and spatial resolution is examined. Preliminary results relative to tissue organization and to difference between clinical groups proves the potential of the quantitative MRI.