News | Magnetic Resonance Imaging (MRI) | March 14, 2016

Advanced MRI Technology Tracks Cells in the Body

New fluorine-based tracer, enhanced by iron, has potential to clearly, quickly track cells and molecules

MRI, fluorine tracer agent, UC San Diego, Eric Aherns

March 14, 2016 — Writing in the March 14 online issue of Nature Materials, researchers at University of California, San Diego School of Medicine describe a new, highly sensitive chemical probe that tags cells for detection by magnetic resonance imaging (MRI).

The need to non-invasively “see” and track cells in living persons is indisputable – a boon to both research and development of future therapies. Emerging treatments using stem cells and immune cells are poised to most benefit from cell tracking, which would visualize their behavior in the body after delivery. Clinicians require such data to speed these cell treatments to patients.

A research team led by senior author Eric T. Ahrens, Ph.D., professor of radiology, and Roger Tsien, Ph.D., professor of pharmacology, chemistry and biochemistry (whose work with fluorescent proteins earned him a share of the 2008 Nobel Prize in chemistry) have synthesized a new cell labeling probe using fluorine-19, the stable isotope of the element fluorine. Agents are formulated as a “nanoemulsion” that contains microscopic droplets of an inert fluorine-based agent that is taken up by cells of interest. The fluorine agent in cells is directly detected by MRI, enabling one to observe movement of cell populations.

“Fluorine-19 tracer agents are an emerging approach that produces positive signal hot-spot images with no background signal because there’s virtually no fluorine concentration in tissues,” said Ahrens. “We have made a major leap in sensitivity. We have figured out how to dissolve and encapsulate metals inside the fluorine-based droplets. The net effect is to greatly amp up the MRI signal.”

Ahrens, Tsien and Alex Kislukhin, a postdoctoral scholar in their labs, increased the sensitivity of the fluorine MRI agent by creating a new imaging medium that combines highly fluorinated nanoemulsions with the magnetic properties of metals – a technique that increases the visibility of fluorine by MRI. Unexpectedly and serendipitously, they also discovered that iron is particularly effective at enhancing the fluorine MRI signal.

“The chemist’s iron hand has moved the field of biomedical imaging forward,” said Ahrens. “To the best of our knowledge, iron has never been considered as an enhancer of 19F MRI signals, yet our analysis shows that iron is fundamentally magnetically superior to all other metal ions for enhancing fluorine MRI.”

Added Tsien: “It’s a wonderful coincidence that fluorine MRI benefits most from iron, which is biologically friendlier and cheaper than gadolinium, still the favorite for proton MRI.”

While more research remains to be done, Ahrens said 19F MRI aided by iron represents a significant advance in tracking cells in many emerging therapeutic areas, such as immunotherapy, stem cells and treating inflammation.

Co-authors include Hongyan Xu, Stephen R. Adams and Kazim H. Narsinh, all at UC San Diego. Tsien is also a member of the Howard Hughes Medical Institute at UC San Diego.

Funding for this research came, in part, from the National Institutes of Health (grants T32-CA121938, R01-EB017271), Radiological Society of North America and the California Institute for Regenerative Medicine.

For more information: www.nature.com/nmat

Related Content

IBM collected a dataset of 52,936 images from 13,234 women who underwent at least one mammogram between 2013 and 2017.

IBM collected a dataset of 52,936 images from 13,234 women who underwent at least one mammogram between 2013 and 2017, and who had health records for at least one year prior to the mammogram. The algorithm was trained on 9,611 mammograms. Image courtesy of Radiology.

Feature | Artificial Intelligence | July 19, 2019 | Michal Chorev
Breast cancer is the global leading cause of cancer-related deaths in women, and the most commonly diagnosed cancer...
Two brain metastases from primary lung cancer are contrast enhanced in the brain of a 61-year-old male. Speakers at AHRA 2019 will state that ProHance and other macrocyclic MR agents present a very low risk to patients. Images courtesy of Bracco

Two brain metastases from primary lung cancer are contrast enhanced in the brain of a 61-year-old male. Speakers at AHRA 2019 will state that ProHance and other macrocyclic MR agents present a very low risk to patients. Images courtesy of Bracco

Feature | Contrast Media | July 18, 2019 | By Greg Freiherr
Macrocyclic contrast agents have the best safety profile of all the magnetic resonance (MR) contrast media that are n
AAPM 2019 Features More Than 40 Presentations on ViewRay's MRIdian MRI-guided Radiotherapy
News | Image Guided Radiation Therapy (IGRT) | July 16, 2019
ViewRay Inc. announced that the company's MRIdian System is the focus of more than 40 abstracts selected by the...
NorthStar Medical Radioisotopes Completes Construction on Beloit, Wis. Molybdenum-99 Processing Facility
News | Radiopharmaceuticals and Tracers | July 16, 2019
NorthStar Medical Radioisotopes LLC  announced completion of construction on its 20,000-square-foot molybdenum-99 (Mo-...
FDA Approves Bayer's Gadavist Contrast for Cardiac MRI in Adult Coronary Artery Disease Patients
Technology | Contrast Media | July 15, 2019
The U.S. Food and Drug Administration (FDA) has approved Gadavist injection for use in cardiac magnetic resonance...
Insightec's Exablate Neuro Approved With GE Signa Premier MRI in U.S. and Europe
News | Focused Ultrasound Therapy | July 10, 2019
GE Healthcare and Insightec announced U.S. Food and Drug Administration (FDA) approval and CE mark for Insightec’s...
Delta T1 Maps Provide Quantitative, Automated Solution to Assess Brain Tumor Burden
News | Neuro Imaging | July 05, 2019
Imaging Biometrics LLC (IB) a subsidiary of IQ-AI Ltd., is highlighting a recently published study in the American...
Medic Vision Wins Japanese PMDA Clearance for iQMR Image Reconstruction Solution
News | Magnetic Resonance Imaging (MRI) | July 05, 2019
Medic Vision Imaging Solutions announced that its 3-D iterative image reconstruction technology for shortening magnetic...
Bracco Imaging Acquires Blue Earth Diagnostics
News | Radiopharmaceuticals and Tracers | July 01, 2019
Bracco Imaging S.p.A. has signed a definitive agreement to acquire Blue Earth Diagnostics, a molecular imaging company...