Time-dependent diffusivity and kurtosis in phantoms and head and neck cancer patients

Published

October 11, 2022

Author(s)

Eddy Soloman, Stephen Russek, Sungheon Gene Kim

Abstract

Purpose: To assess the reliability of measuring diffusivity, diffusional kurtosis and cellular-interstitial water exchange time with long diffusion times (100-800 ms) using stimulated-echo diffusion-weighted imaging. Methods: Time-dependent diffusion MRI (dMRI) was tested on two well-established diffusion phantoms and in five patients with head and neck cancer. Measurements were conducted using an in-house diffusion-weighted STEAM-EPI pulse sequence with multiple diffusion times at a fixed echo time on three scanners. We used the weighted linear least-squares fit method to estimate time-dependent diffusivity, () and diffusional kurtosis,(). Additionally, the Kärger model (KM) was used to estimate cellular-interstitial water exchange time (). Results: Diffusivity measured by time-dependent STEAM-EPI measurements and commercial SE-EPI showed comparable results with R2 of above 0.98 and overall 5.4±3.0% deviation across diffusion times without noticeable trends. Diffusional kurtosis phantom data showed expected patterns: constant and = 0 for negative controls and slow varying and for samples made of nanoscopic vesicles. Time-dependent dMRI in head and neck cancer patients found that KM could be considered valid in about 72% of the voxels in the metastatic lymph nodes. The median cellular-interstitial water exchange time estimated for lesions was between 58.5 and 70.6 ms. Conclusion: Based on two well-established diffusion phantoms, we found that timedependent dMRI measurements can provide stable diffusion and kurtosis values over a wide range of diffusion times and across multiple MRI systems. Moreover, estimation of cellular-interstitial water exchange time can be achieved using KM for the metastatic lymph nodes in head and neck cancer patients.

Citation

Magnetic Resonance in Medicine

Pub Type

Journals

Citation

Soloman, E. , Russek, S. and Kim, S. (2022), Time-dependent diffusivity and kurtosis in phantoms and head and neck cancer patients, Magnetic Resonance in Medicine (Accessed July 5, 2025)