Proton nuclear magnetic resonance of regenerating rat liver after partial hepatectomy

Spin-lattice (T 1) and spin-spin (T 2) proton nuclear magnetic resonance relaxation times were measured over a 48-hours period of experimental liver regeneration in Wistar rats. T 2 showed an early significant increase reaching a plateau 30 % above baseline from the 10th hrs onwards. Laparotomized control animals showed no change in T 2 values. The increase in T 1 occured at a later stage but was no different from that in laparotomized controls. T 1 reached a peak, 20 % above baseline, around the 30th hr. The changes observed were far less marked than those previously described for cancer tissue, which showed about a 60 % increase in T 1. Liver T 1 fluctuations followed a circadian pattern, with a minimum at night's end and a maximum around mid-day. No circadian rhythm was seen for T 2. The observed T 1 and T 2 changes are discussed with respect to mitotic and metabolic events known to occur during regeneration of the liver.