Microstructural mapping based on time-dependent diffusion MRI for differentiating rectal neuroendocrine tumor and rectal adenocarcinoma

Motivation: Rectal neuroendocrine tumors, commonly mistaken for adenocarcinoma, are usually diagnosed invasively due to conventional MRI's limited microscopic detail. Advanced MRI techniques offer a non-invasive solution. Goal(s): This study aims to investigate the feasibility of time-dependent diffusion MRI (td-dMRI) in differentiating between rectal neuroendocrine tumors and rectal adenocarcinoma. Approach: The td-dMRI was used to analyze extracellular diffusivity (Dex), cell diameter (d), volume fraction (Vin), and cellularity to distinguish between rectal neuroendocrine tumors and rectal adenocarcinoma. Results: The td-dMRI-derived parameters, particularly d and cellularity, effectively distinguished neuroendocrine tumors from adenocarcinoma, highlighting its potential for non-invasive histopathology. Impact: Microstructural parameters derived from td-dMRI have the potential to serve as imaging biomarkers for the non-invasive differentiation of rectal neuroendocrine tumors, thus aiding in the prediction of histopathological types of rectal cancer.