Thanks, in part, to an initiative launched by President Obama in his State of the Union Address in January, precision medicine is emerging as a central topic in U.S. health care. At this year’s American College of Radiology conference in Washington, D.C., Dr. James Thrall of Massachusetts General Hospital gave an insightful lecture on how precision medicine will shape the role of imaging.

“Imaging may often be the earliest and more efficient way to assess response to therapy,” said Thrall. “We have information that is unique, that no other laboratory, pathological or genetic testing method can duplicate.”

The National Research Council published a white paper in 2011 that defined precision medicine as the tailoring of treatment to the individual characteristic of each patient. The council stated that patients need to be separated into small sub-populations, and the way to do that is through understanding phenotype and genotype.
Thrall described four subphenotypes — no response, partial response, complete response and disease progression — and provided the audience with examples. He showed a PET image of a patient with lymphoma who had a partial response to chemotherapy but then exhibited disease progression two months later and then showed another PET image of a patient who underwent chemotherapy and had a complete metabolic response.

Historically, the international scoring system was used as a prognostic indicator for patients with lymphoma, but now FDG PET scans may be a more accurate option. Thrall said regardless of an international prognostic score, if a patient's follow-up scan is negative, their likelihood of progression-free survival is extremely good, and vice versa.

“There is no other method in medicine to provide this kind of information,” said Thrall. “The pathologist cannot make this prediction, the geneticist cannot make this prediction — we make this prediction by imaging.”

For Alzheimer’s disease, imaging can help determine if treatments aimed at halting or decreasing the accumulation of amyloid plaque are effective. There are about a half dozen drugs involved in clinical trials right now, and imaging in conjunction with clinical psychometric testing can determine if they are working, said Thrall.

Imaging also plays a role in oncogenes. After Angelina Jolie found out that she inherited a BRCA1 mutation from her mother and had an 87 percent risk of breast cancer and 50 percent risk of ovarian cancer, she decided to have bilateral mastectomies.

But what about a woman who has the mutation, but a much lower risk than Jolie, and wants to breastfeed her children? Thrall said that’s where imaging comes into play by providing surveillance for the occurrence, location, extent and severity of a disease.

Thrall ended the lecture by telling the room full of radiologists that they are already doing more than they may realize. “We are already one of the supreme methods for phenotyping and we are learning more and more about the relationship between imaging phenotype and genotype,” he said.

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