Bayesian estimation of relaxation times T-1 in MR images of irradiated Fricke-agarose gels

The authors present a novel method for processing T-1-weighted images acqui red with Inversion-Recovery (LR) sequence. The method, developed within the Bayesian framework, takes into account a priori knowledge about the spatia l regularity of the parameters to be estimated. Inference is drawn by means of Markov Chains Monte Carlo algorithms. The method has been applied to th e processing of IR images from irradiated Fricke-agarose gels, proposed in the past as relative dosimeter to verify radiotherapeutic treatment plannin g systems. Comparison with results obtained from a standard approach shows that signal-to noise ratio (SNR) is strongly enhanced when the estimation o f the longitudinal relaxation rate (R1) is performed with the newly propose d statistical approach. Furthermore, the method allows the use of more comp lex models of the signal. Finally, an appreciable reduction of total acquis ition time can be obtained due to the possibility of using a reduced number of images. The method can also be applied to T-1 mapping of other systems. (C) 2000 Elsevier Science Inc. All rights reserved.