Monte Carlo Bloch Simulation of T1, T2 uncertainties in NMR and MRI pulse sequences

Bloch simulators have been used extensively in NMR and MRI to develop and understand new pulse sequences, investigate artifacts, and more recently for advanced imaging techniques that depend on dictionary lookup tables. Here, we present a new class of Bloch solvers designed to investigate uncertainties in quantitative MRI techniques. Our system couples a Bloch simulator to a Monte Carlo based sampling of a large number of uncertainties and non-idealities that are inherent in NMR and MRI. These include B0 and B1 inhomogeneities, time base jitter and imperfections, transmit and receive phase jitter, temperature variations, coil and electronic noise, variations in initial conditions, nonlinear gradients, jitter in gradient and RF waveforms, errors in fitting due to noise and imperfect data. The Monte Carlo Bloch solver was used to establish uncertainties in primary calibrations of SI-traceable phantom solutions where absolute accuracies are on the order of 1%. After validation of the solver using precision NMR techniques, the system is then applied to MRI systems in which the pulse sequences are less ideal due to the need to minimize imaging time and RF dose. Output simulations are then compared with international MRI T1, T2 round robin studies using the NIST MRI system phantom.