In vitroprotonT1andT2studies on rat liver: Analysis of multiexponential relaxation processes

Abstract

At 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.