MRI Sensor Reveals Molecular Changes in Cells for Disease Insights

Researchers at the University of California, Santa Barbara have developed a new genetic sensor that allows MRI machines to visualize molecular activity inside cells. This breakthrough, published in Science Advances on March 5, 2026, could transform how scientists study diseases like cancer, neurodegeneration, and inflammation by enabling them to observe changes at the molecular level—something previously beyond the reach of traditional MRI technology.

Since the 1970s, magnetic resonance imaging (MRI) has been a crucial diagnostic tool, providing detailed images of the body’s internal structures using magnetic fields and radio waves. However, MRIs have historically been limited to detecting changes in anatomy. Detecting molecular-level changes, which often precede structural alterations, has remained a significant challenge.

Seeing the Unseen: Molecular-Level Imaging

“You can see the structures of your tissues—whether it’s the brain, the heart, the kidneys, or the stomach—but you don’t get molecular information,” explained Arnab Mukherjee, an associate professor of chemical engineering at UC Santa Barbara’s Robert Mehrabian College of Engineering. “So, the only time you can know that something is going wrong or something has changed is if you take another MRI, and the structure and morphology of the tissue changes.”

Mukherjee added that by the time structural changes are visible on an MRI, the disease has often already progressed. The new sensor aims to address this limitation by providing a way to detect these earlier, molecular-level changes.

The sensor is described as modular, genetically encoded, and protein-based. This means it can be genetically engineered into cells, allowing researchers to visualize molecular processes using MRI technology. The modular design allows for customization, enabling researchers to target different processes within cells by attaching or substituting specific proteins.

How the Sensor Works

The key to the sensor’s functionality lies in its ability to interact with water molecules, which are naturally tiny magnets. By controlling the movement of water molecules across the cell membrane, the sensor can create a detectable signal within the MRI’s magnetic field. This signal is specific to certain types of cells or biological processes, allowing the MRI to report on these processes at the molecular level.

The sensor utilizes a protein called aquaporin, which forms a channel in the cell membrane that allows water to move in and out of the cell. “Our water molecules are tiny, tiny magnets,” Mukherjee said. “If you can control or affect the rate at which water molecules move back and forth across the cell, you can make that magnetic signal specific to certain types of cells or biological processes, which would allow the MRI to report on this process at the molecular level, thus providing much more detailed information than are currently possible.”

MAPPER: A Versatile System

The researchers developed a system called MAPPER (modular aquaporin-based protease-activatable probes for enhanced reporting). MAPPER allows them to combine aquaporin with different proteins to create genetic “circuits” tailored to specific research needs. Asish Ninan Chacko, a former chemistry and biochemistry PhD student in Mukherjee’s lab, emphasized the system’s versatility.

According to Chacko, MAPPER can currently detect close to ten different systems, whereas previously, only four or five genetic sensors were available, each designed to detect a single analyte—the chemical or compound being measured.

Potential Applications and Future Directions

The researchers believe their tool has the potential to improve the reliability of animal studies in disease progression and reduce the number of animals needed for research. Currently, studying internal organs often requires sacrificing the animal, providing only a single snapshot in time. MAPPER allows for continuous imaging of the same animal over the course of a study, offering a more accurate picture of disease and biological processes.

The modular nature of MAPPER means researchers won’t need to design a new MRI sensor from scratch each time they want to monitor a new chemical or process. Instead, they can add different components to the existing system, potentially developing a new sensor within a few months. Mukherjee envisions creating a training program for undergraduates to learn how to utilize the technology.

“We want to take these sensors and put them in the hands of people who will actually use them,” Mukherjee said, “whether that’s neuroscientists, who would be able to use MAPPER to look at calcium changes in the brain, or developmental biologists, who could use the tools to track mouse development from embryo to adult.”

Source: UC Santa Barbara