[Detection of cardiac graft rejection using proton nuclear magnetic resonance]

Rejection of cardiac transplants can be detected by NMR imaging if it is associated with a change in myocardial T1 and/or T2 proton relaxation time. T1 and T2 were studied in 14 Lewis rats that underwent heterotopic cardiac transplantation. T1 and T2 were measured in vitro immediately after sacrifice 3, 4, 7 or 11 days after the graft using a Minispec BRUKER PC20. The myocardial water content was measured by dehydration in a vacuum for 24 hours. Histological analysis of sections classified the rejection process in 4 stages according to the degree of lymphocyte infiltration and percentage of myolysis. There was a significant difference between the ortho and heterotopic hearts: (Formula: see text). In particular, there was highly significant relationship between T2 and the stage of rejection (r = 0.90, p less than 0.005), and between T2 and % myolysis (r = 0.84, p less than 0.005). In addition, there was a close relationship between the T2 of the ortho and heterotopic hearts and their water content (r = 0.95, p less than 0.001). If these results are confirmed in man, is should be possible to detect rejection by NMR imaging using sequences of activation concentrating on changes of T2.