A 3-D neuroimager was a highly advanced medical system used to scan a body's nervous system that was used in hospitals throughout the Central Planets.
In 2517, Doctor Simon Tam organized an infiltration and robbery of Saint Lucy's hospital on Ariel to use one on his sister, River Tam. Simon knew that the system would help him determine what Dr. Mathias and his associates had done to River's brain. While the rest of the crew robbed the hospital of piles of expensive medicine, Simon successfully used the system to learn that River had been operated on repeatedly, and that her amygdala had been stripped. Jayne Cobb, regretting his traitorous decision to turn them in and collect a reward from federal marshal McGinnis, rushed them out early. Simon wished to stay longer, but was satisfy to flee with the downloaded content from the 3-D neuroimager.