In vivo quantitative lipidic map of brown adipose tissue by chemical shiftimaging at 4.7 tesla

In the present paper, chemical shift imaging techniques are applied to quan titative in vivo evaluation of fat and water content in interscapular brown adipose: tissue (BAT), The experiments have been carried out on five femal e Sprague-Dawley rats after calibration and testing with suitable phantoms containing known amounts of water and oil. We found that, in the interscapu lar BAT, the fat is about 50% at the surface (mainly unilocular) region, bu t its percentage drops to 20-30% in the deepest (mainly multilocular) porti on, The perirenal deposits of white adipose tissue (WAT) contained signific antly higher amount of fat with large areas ranging from 70 to 90%, Later t he rats were killed and the same procedure was repeated with dead animals. Experiments performed in dead rats show a modification of the hydro-lipidic ratio more evident in the multilocular portions of the deposit. The presen t work demonstrates that MRI-based methods allow a non-invasive, in vivo qu antitative mapping of the lipid content which can be applied to investigati on of brown adipose tissue deposits in small experiment animals.