Diffusion time effects over the adult lifespan indicates persistent zone-specific microstructural alterations in the human prostate with aging

PurposeThe purpose of this study was to investigate microstructural changes in the aging adult prostate by comparing the effects of varying diffusion times using diffusion MRI, and to provide an age-related benchmark for future prostate cancer studies.MethodsThe prostates of normal male volunteers (n = 70, 19-69 years) were scanned at 3 T with an oscillating gradient spin echo (OGSE: 6 ms), pulsed gradient spin echo (PGSE: 40 ms) and pulsed gradient stimulated echo (PGSTE: 100 ms), and anatomical T2-weighted image. Volume and mean diffusivity (MD) were measured in the peripheral (PZ) and transition zones (TZ), which were assessed versus age.ResultsPZ and TZ showed quadratic age trajectories for all diffusion scans, with MD decreasing from 19 years to a minimum 30-40 years followed by a greater increase at older ages. Short (OGSE) and medium (PGSE) diffusion time MD had similar age trajectories, whereas long diffusion time (PGSTE) MD was significantly lower, particularly in PZ (22%). MD difference (triangle MD) of OGSE-PGSTE and PGSE-PGSTE showed significant positive linear correlations with age for both PZ (larger slope) and TZ, resulting in 3.3x (PZ) and 1.8x (TZ) greater triangle MD from 19 to 69 years. MD and triangle MD versus age relationships differed from volume, which conversely had greater proportional growth in TZ than PZ.ConclusionThe diffusion time effects suggest age-related microstructural changes consistent with development of persistently larger cell dimensions mainly in the prostate peripheral zone over the adult lifespan. This normative data can be used for comparison to prostate cancer factoring in age.