1 PERFIDI filters to suppress and/or quantify relaxation time components in multicomponent systems: An example for fat-water systems Villiam Bortolotti a , Paola Fantazzini b,* , Mirko Gombia b , Danilo Greco c , Giuseppe Rinaldin b , and Stanislav Sykora d a Department DICAM, University of Bologna, Viale Risorgimento 2, 40136 Bologna, Italy b Department of Physics, University of Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy c ESAOTE S.p.A. Via A. Siffredi 58, 16153 Genova, Italy d Extra Byte, Via Raffaello Sanzio 22/c, 20022 Castano Primo (MI), Italy; http://www.ebyte.it/ * Corresponding Authors: Paola Fantazzini (paola.fantazzini@unibo.it ), Stan Sykora (mailto:sykora@ebyte.it ). Abstract Parametrically Enabled Relaxation FIlters with Double and multiple Inversion (PERFIDI) is an experimental NMR/MRI technique devised to analyze samples/voxels characterized by multi- exponential longitudinal relaxation. It is based on a linear combination of NMR sequences with suitable preambles composed of inversion pulses. Given any standard NMR/MRI sequence, it permits one to modify it in a way which will attenuate, in a predictable manner and before data acquisition, signals arising from components with different r rates (r = 1/T1). Consequently, it is possible to define relatively simple protocols to suppress and/or to quantify signals of different components. This article describes a simple way to construct low-pass, high-pass and band-pass PERFIDI filters. Experimental data are presented in which the method has been used to separate fat and water proton signals. We also present a novel protocol for very fast determination of the ratio between the fat signal and the total signal which avoids any time-consuming magnetization recovery multi-array data acquisition. The method has been validated also for MRI, producing well T1-contrasted images. Keywords: NMR, MRI, PERFIDI, relaxation filters, inversion pulse, spectroscopy, imaging, relaxometry, T 1 , Inverse Laplace Transform, fat suppression. Copyright notice This is a preliminary draft of the article which appeared on Journal of Magnetic Resonance, 206 (2010) 219 – 226; doi: 10.1016/j.jmr.2010.07.010 As such, though most editing changes were respected, it is not necessarily identical to the definitive version published by Journal of Magnetic Resonance. In case of doubt or controversy, consult the actually published text which is the only binding reference. This document is fully compliant with the copyright instructions as signed by the Authors and published on the Elsevier website http://www.elsevier.com/copyright . Its use is allowed only for strictly personal, non-commercial uses. ---------------------------------------------------------------------------------------------------- This document’s URL is http://www.ebyte.it/perfidi/Perfidi_Jmr2010_Draft.pdf .