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Imaging pH Levels With a Cobalt MRI Probe

Published July 10, 2018

Left: pH-sensitive ratiometric response. Right: A pH map.
Left: pH-sensitive ratiometric response. Right: A pH map.

A new pH sensitive contrast agent for MR imaging has been developed that produces image contrast based on the local pH and that has great potential for use in living animals and medical diagnostics.

What did the scientists discover?

MagLab users demonstrated the use of molecular cobalt complexes as ratiometric magnetic resonance imaging (MRI) pH sensors. These complexes feature two responsive functional groups that influence the surrounding bulk water molecules with opposing pH dependence. This provides a highly pH-sensitive ratiometric response that can be used to generate a pH map.

Why is this important?

Reduced tissue pH is closely associated with a number of pathological conditions, including tissue inflammation, cancer, and ischemia (inadequate blood supply to an organ). As such, the ability to accurately map tissue pH in a noninvasive manner would be of great importance for the early detection and treatment of many diseases. This approach exhibits the potential for visualizing pH changes with unprecedented sensitivity using MRI.

Who did the research?

Agnes E. Thorarinsdottir1, Kang Du1, James H. P. Collins2, T. David Harris1

1Northwestern University; 2National MagLab

Why did they need the MagLab?

The high probe sensitivities of the unique instruments at the MagLab’s AMRIS Facility, in conjunction with the strong MRI technique experience of the AMRIS staff, enabled the acquisition of high-resolution phantom images of our pH-sensing compound even at low concentrations.

Details for scientists


This research was funded by the following grants: G.S. Boebinger (NSF DMR-1157490, NSF DMR-1644779); T.D. Harris (FA8650-15-5518, NSF NNCI-154220)

For more information, contact Joanna Long.

Tools They Used

This research was conducted in the 750 MHz MRI system at the MagLab's AMRIS Facility located at the University of Florida.

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Last modified on 28 December 2022