Quantitative determination of longitudinal and transverse cross-relaxationrates

We describe a quantitative processing method which gives access to the long itudinal and transverse cross-relaxation rates from off-resonance ROESY int ensities, This method takes profit of the dependence of the off-resonance R OESY experiments at any mixing time and any spin-lock angle theta on two re laxation matrices, the longitudinal and the transverse ones, This allows on e to take into account multi-step magnetization transfers and to determine the longitudinal and transverse cross-relaxation rates without assuming a s tructure or a model of motion.