[Animal experiment studies on the influence of fatty infiltration of liver cells on tissue relaxation times and signal changes in magnetic resonance tomography].

Using a spectrometer (n = 60) in vitro and MRT imaging (n = 8) in vivo, we studied the influence of fatty changes of liver cells on the relaxation times of the liver (two animal models of fatty liver disease/orotic acid, L-ethionine). Induction of fatty degeneration of the liver by means of an orotic acid diet resulted in pure deposition of fat in the liver without any histological or serological proof of inflammatory changes. Although accumulation of triglyceride in the liver reduced the T1 relaxation time only relatively slightly (-15%), there was good correlation (r = 0.88) between fat content and T1. There was also good correlation (r = 0.92) between T2 and histological fat content. Inflammatory changes besides fatty deposition were seen both serologically and histologically in the L-ethionine model, so that the fatty content did not correlate with T1. In-vivo MRT imaging showed that spin-echo sequences are inappropriate for diagnosing fatty infiltration of the liver despite the relaxation time changes produced by the fatty deposition. On the other hand, chemical-shift imaging sequences are very sensitive to identify fatty deposits, and are also independent of any additionally existing inflammatory changes.