DETERMINATION OF T(1)P VALUES FOR HEAD AND NECK TISSUES AT 0.1T - A COMPARISON TO T-1 AND T-2 RELAXATION-TIMES

In order to optimize head and neck magnetic resonance (MR) imaging wit h the spin-lock (SL) technique, the T(1)rho relaxation times for norma l tissues were determined. Furthermore, T(1)rho was compared to T-1 an d T-2 relaxation times, Ten healthy volunteers were studied with a 0.1 T clinical MR imager, T(1)rho values were determined by first measuri ng the tissue signal intensities with different locking pulse duration s (TL), and then by fitting the signal intensity values to the equatio n with the least-squares method, The T(1)rho relaxation times were sho rtest for the muscle and tongue, intermediate for lymphatic and paroti d gland tissue and longest for fat. T(1)rho demonstrated statistically significant differences (p < 0.05) between all tissues, except betwee n muscle and tongue. T(1)rho values measured at locking held strength (B1L) of 35 mu T were close to T-2 values, the only exception being fa t tissue, which showed T(1)rho values much longer than T-2 values, Det ermination of tissue relaxation times may be utilized to optimize imag e contrast, and also to achieve better tissue discrimination potential , by choosing appropriate imaging parameters for the head and neck spi n-lock sequences. (C) 1998 Elsevier Science Inc.