If you ask NIST physicist Cassie Stoffer what she finds most exciting about science, it’s seeing what she learned in a textbook have real-world applications.

Cassie helps run calibration and measurement services related to magnetic resonance imaging (MRI) at NIST. Part of her work relates to phantoms — but not the ghost kind. These are standard reference objects used by the biomedical research community to make sure their systems and methods for imaging the human body are operating correctly.

These objects are scientific devices that serve as stand-ins for human tissue. They contain materials like salt solutions or gels that mimic the responses of human tissue under specific conditions. Cassie characterizes these materials by measuring certain parameters with a well-defined, low uncertainty.  

The parameters she measures are used in MRI as biomarkers, or numerical values that indicate biological processes in the human body. These biomarkers can tell a doctor what type of tumor a patient has or evaluate the body’s response to a specific treatment, for example.  

Cassie’s measurements provide reference values that are used to ensure that an MRI system accurately measures biomarkers.

MRI is conventionally a qualitative and nonnumerical tool; it produces images that radiologists study to make a diagnosis. Cassie and her group work in the field of quantitative MRI, where images contain numerical information that offer more precise details on what the images show.  

Cassie’s work aims to bring lower uncertainties to quantitative MRI measurements in phantoms and ultimately the human body.  

As an early career professional in this field, Cassie enjoys working with experts in this area and seeing how the work she does at NIST, a small piece of the bigger picture, has implications in the real world.