T1 and T2 frequency dependency of adult, neonatal and gadolinium-doped rat tissues

NMR (nuclear magnetic resonance) T1 and T2 relaxation times were measured of excised tissues from normal adults and juvenile rats and those receiving intraperitoneal gadolinium-DPTA. Measurements were made at frequencies between 2.5 and 87 MHz. T1 showed greater frequency dependence that T2 but T1 frequency dependence varied between tissues. The effect of Gd-DTPA depended on tissue uptake. When uptake was sufficient to reduce tissue T1 it was found that the frequency dispersion curve was shifted to lower T1 values and the frequency dependence of T1 was reduced. Physical and biochemical changes occurring during early development in certain tissues lead to increased frequency dependence of T1 but not of T2.<>