From medicine to geology, MRI noninvasively provides detailed information from samples as diverse as human tissues or porous rocks. However, the use of the imaging technique is limited by the complexity and cost of the superconducting magnets needed to generate high magnetic fields, the low sensitivity of traditional detection systems, and the need for cryogenic cooling of sensitive superconducting quantum magnetometers to record measurements. Shoujun Xu et al. attempted to overcome these hurdles by developing a low-field MRI system by using optical atomic magnetometry. Optical magnetometers can detect weak magnetic fields, which eliminates the need for both superconducting magnets and cryogenics and reduces the overall cost and size of the device. Using this MRI technique, Xu et al. obtained two-dimensional images of water flow with enhanced sensitivity and time resolution compared with traditional MRI. According to the authors, this low-field MRI method paves the way for portable, battery-powered devices, which will expand the already diverse uses of MRI. — F.A.