New insight into the contrast in diffusional kurtosis images: Does it depend on magnetic susceptibility?

Abstract

Our results suggests a concomitant and complementary existence of multi-compartmentalized diffusion process and Δχ (H2O-TISSUE) in DKI contrast that might explain why kurtosis contrast is more sensitive than DTI in discriminating between different tissues. However, more realistic numerical simulations are needed to confirm this statement.

Concerning the matching of magnetic susceptibility differences for the compensation of background gradients in anisotropic diffusion fibre phantoms

“…These distortions, i.e., magnetic field gradients, depend on the difference in magnetic susceptibility, Δ χ = χ 2 - χ 1 , as well as on the geometric configuration of the media (curvature radii, interface orientation relative to the magnetic field, etc.). Thus, microscopic, susceptibility-induced magnetic field gradients (further on referred to as background gradients) are ubiquitous in NMR and MRI experiments involving magnetically heterogeneous media such as, among others, porous materials [23–25] and biological tissues [26–29]. In particular, background gradients appear as a common feature in anisotropic diffusion phantoms where the magnetic susceptibility of the diffusing liquid is a priori different from that of the diffusion-restricting material [4,20,21,30].…”

Detection of smoke‐induced pulmonary lesions by hyperpolarized 129Xe diffusion kurtosis imaging in rat models

“…Therefore, there was no comparability of the D app values obtained by the two different HP gases. In contrast, the K app was regarded as a measurement of the variability and intricacy of the tissue structure , and it probably had little relation to the magnitude of the intrinsic HP gas diffusivity. Therefore, due to the more limited pulmonary airspace in rats than in humans, the K app values in the control rats in our study with HP xenon (1.1823 ± 0.0603) were much larger than those in the healthy subjects (0.3430 ± 0.0290) in a previous study of helium pulmonary DKI .…”

“…The corresponding imaging parameters were as follows: field of view ¼ 5 Â 5 cm; matrix size ¼ 96 Â 96; echo time ¼ 3.842 ms; pulse repetition time ¼ 9.904 ms; bandwidth ¼ 50 kHz; and a flip angle of 9.5 . The second part, the experiment used DKI with 14 b values (4,8,12,16,20,24,28,32,40,48,56,64, 72, and 80 s/cm 2 ) to study the critical b values in two healthy rats. Due to the limitations of the maximum gradient strength, the diffusion time D increased to 2.5 ms to achieve the maximum b value of 80 s/cm 2 , whereas to ensure the images' signal-to-noise ratio (SNR), the matrix was decreased to 48 Â 48.…”

Recent Developments in Fast Kurtosis Imaging

“…Such studies have been carried out for experimental stroke [5,90], stress and depression [60,91], and kidney fibrosis [62] to name a few. Furthermore, studies have been performed to elucidate the relation between DKI metrics and tissue magnetic susceptibility [92,93] with results suggesting a susceptibility contribution in DKI metrics warranting further investigation. Similarly, studies have been performed to optimize diffusion sampling schemes for DKI [3] and to assess the DKI metric reproducibility across field strengths [94].…”