In vitro proton T1 and T2 studies on rat liver: Analysis of multiexponential relaxation processes

Abstract

AbstractAt 37°C and 20 MHz, the T1 and T2 proton relaxation processes in intact rat liver tissue are multiexponential functions which in the majority of cases were decomposed into a major (α* ≈ 90%, T = 374 ms, T = 58 ms) and a minor (α** ≈ 10%, T = 130 ms, T = 181 ms) component. Both, T1 and T2, are temperature‐dependent with a temperature shift of ΔT1 = 1.5 ms/°C and ΔT2 = 0.5 ms/°C, respectively. Storage of liver tissue at 4°C and 37°C led to remarkable changes of the T1 and T2 values. For T2 these changes occurred after a shorter storage time than for T1, but they are more pronounced for T1, To avoid such influences the relaxation measurements were performed within one hour after excision of the tissue. Even at 4°C, long‐term storage (>3h) must be avoided. A method for the quantitative determination of the fat content in liver based on multiexponential analysis of the T1 relaxation process was evaluated employing mixtures of triolein with liver homogenate. Triolein is a two‐component system with T = 144 ms (α* = 62%) and T = 355 ms (α** = 38%). Finally, liver‐specific protocol conditions were defined for in vitro relaxation studies. © 1986 Academic Press, Inc.