Seeking Alternatives to Chemotherapy

MagLab biophysicist Victor Schepkin uses the 900 MHz NMR magnet to study brain tumors. In research funded by the National Institutes of Health, Schepkin is doing two kinds of MRI: diffusion MRI and sodium MRI.

In general, MRI machines take pictures of water. The magnet is tuned to find the hydrogen protons, so it can make a map of all the H₂O in your body; that's why it's so good at taking pictures of soft tissue, which is full of water, rather than your skeleton, which is (forgive the pun) bone dry.

By contrast, diffusion MRI tracks not just the location of water in the body, but the movement of that water. Schepkin uses this technique to study the effects of chemotherapy in rats with brain tumors. The images below depict water diffusion in the brain of one such rodent. The scan on the left shows the brain prior to chemotherapy; the lighter region is the tumor. The image on the right shows the same part of the brain four days after chemotherapy. The lighter shading in the tumor on the right indicates more water is flowing around those tumor cells, a sign they are breaking down and that the treatment is working.

"This is the very first sign that the treatment is working and that the tumor will shrink in the near future," says Schepkin.

Hydrogen protons aren't the only things MRIs can identify. Among a few other elements, they can also pinpoint sodium, essential to a number of biological functions. In fact, Schepkin has made some exciting images doing sodium MRI on rats with brain tumors.

Diffusion MRI is currently in clinical trial and will soon be used widely in hospitals, but the power of sodium MRI remains unknown for now, Schepkin says.

Images of a rat brain made with the 900 MHz NMR magnet. The image on the left shows the brain prior to chemotherapy; the lighter region is the tumor. The image on the right shows the area four days after chemotherapy; the lighter shading indicates more water is flowing in those tumor cells, a sign they are breaking down and that the treatment is working.

Chemotherapy, of course, triggers death in cancer cells. Unfortunately, it also destroys some perfectly good tissue. But Schepkin's research suggests there may be a better way of killing cancer cells. His scans indicate that after chemotherapy takes place, but before the cells break down, the sodium balance in those cells is destroyed. Only afterwards do the cancer cells begin to die.

"This is a very exciting finding because of the consequences it could bring," says Schepkin. "It suggests that our goal in cancer therapy should be different."

In other words, there may be an alternative to chemotherapy, which essentially requires injecting poison into the body. A more targeted approach might be to somehow induce a sodium imbalance in those cells instead, precisely targeting the cancer while sparing healthy cells from the blunt instrument of chemotherapy.

"It means we can destroy cancer cells by a different way than we did before," said Schepkin. "We're learning some clues about a new mechanism."

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