PET/MR Imaging: New Possibilities for Breast Cancer Management

Posted on February 2023

A clinical trial led by Amy Fowler, MD, PhD, alongside other members of the Breast Imaging and Nuclear Medicine Sections, aims to assess the use of PET/MR imaging in the staging and treatment of breast cancer. 

Imaging is a critical part of the detection and diagnosis of breast cancer, and also plays a role in informing management and treatment decisions. In current clinical practice, MR and PET imaging are used separately to gain information about a tumor. An MRI scan reveals the structure and anatomy of a tumor, and PET imaging – with a tracer for glucose – quantifies the tumor’s metabolic activity.  

PET–MRI is a quantitative hybrid imaging technology that pairs functional PET data with anatomical information from MRI. The combination has powerful implications. Simultaneous PET/MR imaging of invasive breast cancer may improve diagnostic accuracy and better inform surgical and medical treatment decisions. 

By reducing false-positive findings, this hybrid imaging technology could potentially avoid additional biopsies, decrease patient anxiety, reduce costs, and minimize time to surgery, as discussed in Dr. Fowler’s review article in The Lancet Oncology. Her co-author and collaborator, Roberta Strigel, MD, provides her crucial expertise in MRI to the project. 

In addition to assessing this emerging technology, Dr. Fowler is also pioneering novel tracers for PET imaging. Instead of glucose tracers, her research uses tracers specific to estrogen and progesterone receptors. 

“While conventional PET imaging gives you information about the tumor’s glucose metabolic activity, it doesn’t tell you about the receptors that will be targeted during treatment,” explains Dr. Fowler.  

In hormone positive (HR+) breast cancer, the most common subtype, tumor cells have receptors for estrogen and/or progesterone. Therefore, therapeutic strategies often target these same hormones. By using PET tracers specific to estrogen and progesterone receptors, Dr. Fowler hopes to pinpoint the kind of therapy that will be most effective for treating each patient’s breast cancer. 

In October of 2022, Dr. Fowler was awarded an R01 grant from the National Institutes of Health (NIH) for her project, “Precision Imaging of Breast Cancer for Guiding Neoadjuvant Endocrine Therapy.” 

In this project, patients with HR+ primary breast cancer will undergo standard anti-estrogen treatment. PET/MR imaging will be utilized both before, and during a follow-up exam, to assess their response. This five-year study will continue to test the clinical applicability of PET/MRI in breast cancer imaging. 

“Overall, we hope to use imaging to understand breast cancer biology better and to predict what kind of treatment will be best,” says Dr. Fowler.  

By using MRI and PET together, and implementing new tracers, Dr. Fowler and her colleagues hope to both improve diagnostic accuracy and tailor treatment with greater specificity, with the ultimate goals of advancing precision medicine and reducing the morbidity and mortality of breast cancer.