Effect of diffusion-sensitizing gradient timings on the exponential, biexponential and diffusional kurtosis model parameters: in-vivo measurements in the rat thalamus

Abstract

The parameters of the biexponential and diffusional kurtosis models are more sensitive than the exponential model to Delta and delta; however, observed effects are too small to account for the discrepancies found in literature.

Effect of gradient pulse duration on MRI estimation of the diffusional kurtosis for a two-compartment exchange model

“…Although not definitive, our results do suggest that the water ADK in brain is insensitive to changes in the pulse duration, supporting the robustness of ADK estimates based on clinical DW-MRI. The previously mentioned rat thalamus experimental study also observed the water ADK to change very little with pulse duration [17], in consistency with our findings.…”

“…One special property of the KM is that the ADC is independent of the pulse duration, but this is largely consistent with empirical observations for water diffusion in brain [17]. The ADK for the KM does, in contrast, depend on the pulse duration, as we shall show explicitly for the case of two compartments.…”

“…However, a prior theoretical study of diffusion in open geometries [3] and an experimental study of water diffusion in rat thalamus [17] have both found the effect of pulse duration on the ADC to be relatively small. These results therefore help to justify use of the ADC for clinical applications.…”

“…Just as for the ADC, the apparent diffusional kurtosis (ADK) obtained with DW-MRI can potentially depend on the gradient pulse duration. Although one experiment has found the ADK in rat thalamus to be robust with respect to pulse duration changes [17], the pulse duration sensitivity of the ADK has not been previously addressed theoretically. In this article, we investigate the effect of pulse duration for a specific diffusion model that permits analytic solution.…”