Joint estimation of compartment-specific T2 relaxation and tumor microstructure using multi-echo-time IMPULSED MRI

Motivation: The heterogeneity of T2 in tumors and its influences on estimates of tissue microstructure using diffusion MRI are poorly understood. Goal(s): Assessing how T2 heterogeneity biases IMPULSED-derived metrics of tumor microstructure and evaluating the potential of estimating multi-compartmental T2 and microstructural parameters simultaneously. Approach: This study quantifies the impact of T2 relaxation on IMPULSED-derived microstructural parameters using simulations and in vivo animal MRI in five tumor models, including brain, breast, prostate, melanoma, and colon cancer. Results: TE has a negligible impact on IMPULSED-derived cell sizes, and the TE-dependence of IMPULSED-derived intracellular volume fractions can be used to estimate the compartmental T2 values. Impact: Findings in this study contribute to the ongoing development and refinement of practical, non-invasive MRI techniques for characterizing tissue microstructure.