Clinical Research Projects

Amino acid PET/MRI takes advantage of the fact that brain tumors require amino acids as nutrients more than normal brain tissue. A radiolabel attached to the amino acid can be visualized as it is being taken into the brain tissue on PET imaging. As shown below, the brain tumor has much darker signal compared to normal brain which occurs over a larger area than that seen on contrasted MRI. This signal can be compared with the normal brain signal to generate a number value that physicians can use to determine the next step in treatment for each individual patient. This is known as personalized medicine. Dr. Veronesi and his collaborators are actively studying which of static and dynamic PET imaging parameters can provide the highest amount of accuracy. An example of an amino acid PET agent is 18F-Fluorethyltyrosine. 

Measuring the activity on amino acid PET/MR imaging can be recorded either as maximum activity or mean activity among others. An additional value of interest includes the volume of the activity that exceeds a certain threshold. These are called volumetric tumor to brain ratio maximum maps (TBRmax volume maps). A higher volume may be associated with worse prognosis although this needs to be further studied. An example image is shown below where the volume of the activity greater than 2.5 TBR ratio is in lime green.

The other part of a PET/MRI is the MRI exam which until recently was used primarily for anatomic characterization. However, over the past decade, important progress has been made with what is known as advanced MRI imaging. Examples include MR perfusion, MR diffusion, MR susceptibility mapping, MR spectroscopy, and MR chemical exchange saturation transfer or MR-CEST. MR-CEST can be performed in brain tumors by detecting the amide group as a part of amino acids and proteins inside the cell. Tumor cells have higher amounts of amino acids such as glutamate and glutamine, which can be detected with what is known as Amide-CEST. Dr. Veronesi and his team received approval from the institution to perform Amide-CEST in patients with brain tumors on a research basis to try to improve the detection of tumor tissue against a noisy background of treatment change of non-tumoral tissue often visualized on MRI.