RSNA: PET/MR scanners bring benefits, challenges to practice

CHICAGO—PET/MR hybrid scanners represent a leap forward for cardiac imaging, but technical challenges and reimbursement hurdles still limit widespread clinical use, according to a presentation at the annual meeting of the Radiological Society of North America (RSNA). PET/MR scanners offer a two-for-one for both patients and radiologists, performing each modality’s scan simultaneously. In clinical practice, PET/MR scanners can perform myocardial perfusion imaging as well as assess myocardial viability, which will hopefully become the standard of care, said presenter Pamela Woodard, MD, of the Washington University School of Medicine in St. Louis. Using a hybrid scanner for myocardial perfusion imaging reveals a simultaneous response to one physiological stimulus, while evaluating the myocardial viability through direct comparison of scar tissue with the MR component and metabolic function with the PET element. These scanners are particularly useful for patients who could have attenuation correction or small infarction as they better depict complex myocardial perfusion. “From the PET perspective, MR reduces radiation dose and shortens exam time by approximately 50 percent,” said Woodard. “From the MR point of view, PET may improve scan accuracy by providing better volume coverage.” While the hybrid scanners offer many benefits, challenges accompany their advent as well. These obstacles include validating the system, respiratory gating and motion correction, simultaneous and synchronous gating, radiopharmaceutical limitations, myocardial blood flow validation, and reimbursement. “There is certainly some clinical utility of PET/MR scanners, but the system is still in its infancy and the techniques are growing. There are certainly some challenges ahead—some practical, and some very technical,” concluded Woodard.