In vivo and simulation approaches diagrams representation.

<p>The IN VIVO approach uses a long series of imaging experiments to investigate how the change in MRI scanning parameter affects the SNR of tissues. Once completed, the CNR between selected tissues is analyzed (CNR data analysis) and “<i>optimal in vivo scanning parameters</i>” are identified. Conversely, the SIMULATION approach uses a numerical calculation to estimate the magnetization effects on tissues. The simulation uses T1, T2 and T2* values of such tissues, and, in addition, dynamically varies the scanning parameters as input variables. The CNR between selected tissues are then computed and analyzed by the simulation program. “<i>Optimal computed scanning parameters</i>” are therefore provided to the user. A verification of the computed scanning parameters versus the in vivo scanning parameters is necessary at this stage (scanning parameter compared analysis). If the outcome is positive (YES), computed and in vivo scanning parameters are similar and the parameter will therefore be considered as an “<i>optimal in vivo scanning parameter</i>”. In a negative case (NO), those parameters that differ from the in vivo case, will be reinserted in the simulation emulating the in vivo value and the simulation rerun. Such diagrams are valid in both pre- and post-contrast conditions. Note that the in vivo method is much more time consuming than the simulated approach due to the lengthy parameters’ acquisition experiments that will be mostly replaced by a numerical calculation when using the simulation.