Madison, Wis. — Diego Hernando lays prone within the narrow chamber of one of the MRI machines at UW Health. As he quietly waits for the loud drone of the MRI machine to end, a silent and vibrant conversation resonates within the bulky machine’s inner chamber. The conversation is not one of human language, but a molecular one, a tête-à-tête between the water molecules swirling throughout Hernando’s body and the MRI machine itself.
Hernando is not undergoing this MRI scan as a patient, but as a researcher. As an assistant professor of radiology and medical physics at UW-Madison, Hernando and his team in the Quantitative Imaging Methods Lab seek to transform the ways MRI can be used to care for patients, particularly those with liver cancer and other liver diseases.
MRI, or magnetic resonance imaging, is a workhorse tool in the medical field, allowing clinicians to create images of their patients’ internal organs to look for abnormalities, like tumors.
Perhaps most importantly, MRI, which is based on the application of magnetic fields, is a very safe imaging tool. “I’ve had my liver scanned countless times,” said Hernando, who’s also a new UW Carbone Cancer Center member.
When an individual undergoes a MRI scan, the water molecules in their body briefly respond to this strong magnetic field in a similar way to how a compass needle will always swing north. As the water molecules reorient, they also release radio signals that the MRI machine can tune in to and translate into vivid images of brains and livers. How the water molecules respond to the MRI machine will depend on what type of tissue or organ the water is in, allowing physicians to detect changes in that tissue, such as development of a tumor.
But getting detailed images of those organs and abnormalities using traditional MRI techniques is a challenge, particularly for abdominal organs like the liver. The typical resolution of an MRI image cannot capture the microscopic details of lesions and tumors. Unique techniques such as diffusion MRI, where the image is sensitive to the microscopic motion of water molecules, can overcome these limits.
“Diffusion MRI is an outstanding tool for detecting and characterizing cancers,” Hernando said. “It can help decide if a lesion is benign or malignant and monitor how a patient’s tumor is responding to treatment.”
Diffusion MRI, however, is limited by technical challenges, particularly when trying to image organs like the heart or liver. “It’s like trying to operate an apparatus to make very careful measurements, but you’re on a ship in the middle of a storm,” Hernando said. “You have all these macroscopic motions, like breathing and cardiac-related motion, that simply overwhelm the microscopic molecular motion you’d like to probe.”
In response to these limitations, Hernando and his group are working to develop new diffusion MRI techniques. By modifying how the MRI machine speaks to the water molecules in a patient’s body and interprets the responses, they can amplify the response from water molecules that arises from microscopic differences in tissues.
Hernando was trained as an engineer, and most of the work to optimize diffusion MRI involves designing different ways for the MRI machine’s magnetic field to better probe the desired tissue properties. Collaborations with other UW Carbone members, including Ali Pirasteh, MD, and Nataliya Uboha, MD, PhD, as well as with other research institutions, are helping bring his team’s studies into the clinic.
“We have an ongoing pilot study in patients with liver metastases, and are very excited about our preliminary results,” he said. “The outstanding collaborative environment and colleagues at UW empowers technically focused researchers to partner with clinician scientists. This is a powerful formula to maximize the impact of our work.”