A general quantitative diffusion MRI model of water exchange, confinement, and hindrance with arbitrary gradient waveform encoding

This study proposed and validated a general diffusion MRI biophysical model enabling simultaneous estimation of cell size, intracellular volume fraction, and transcytolemmal water exchange. The model introduces two-mode intracellular diffusion, corrects for restriction-induced “edge-enhancement” effect, and handles arbitrary diffusion gradient waveforms. The results of both in silico and in vitro experiments suggest this model not only improves the accuracy of estimated microstructural parameters such as cell size but also provides reasonable estimates of water exchange rate constant that is usually ignored previously. Such a comprehensive model may have potential to probe tumor status more precisely which is feasible in clinics.