Strategists focus attention on body applications at 3T to encourage widespread adoption in clinical practice
Much of the potential for 3T MR has been proved in brain and musculoskeletal imaging. Lagging far behind, however, are body applications. GE and the Mayo Clinic plan to change that. The two are working together to develop imaging and spectroscopy protocols for the heart and coronaries, breast, liver, and prostate. The goal is to make sure 3T permeates clinical practice.
"We really believe 3T will make an improvement in clinical care," said Dr. Kimberly K. Amrami, chair of the division of body MRI in the department of radiology at the Mayo Clinic in Rochester, MN. "Our work will help us find out what we need to do in order for that to happen."
Amrami is the point person for the new project and is a natural to lead the research. She has one of the largest body MRI practices in the world and has been a strong advocate of body MRI at 3T for the past halfdozen years.
GE will provide engineering and medical physics support in addition to resources already deployed in conjunction with an existing MR collaboration with Mayo, a luminary site for MR development for the past 20 years. For example, a similar collaboration between the two resulted in GE's Vibrant breast protocol for use at 1.5T. Mayo patients were the first to gain from the team effort, but the work cleared the way for Vibrant's use in other facilities. Now Amrami hopes to do the same at 3T.
In the breast, GE and Mayo scientists are exploring ways to improve resolution so as to identify smaller lesions, accelerate exams, and tap into the spectroscopic signature of cancer, leveraging 3T's much stronger signal compared with that of 1.5T. Parallel imaging techniques are expected to do the heavy lifting for cardiac 3T. In the liver and prostate, Amrami plans to leverage both imaging and spectroscopy at 3T. Engineering fixes will be directed at clinical problems.
"We're not looking to turn this into a science fair project," Amrami said. "We want to develop meaningful clinical improvements."
Breast MR currently takes way too long to be practical. Single-phase acquisitions take as long as a minute for each breast-with multiple phases needed to produce a diagnostic image. Increased speed is a must, she said, but not at the cost of spatial resolution. Coil technology now being developed by GE, which the company plans to refine in tandem with Mayo, may solve the problem in part.
In the heart, Amrami and colleagues will be working with delayed perfusion to capture evidence of myocardial infarcts, leveraging the improved signal-to-noise ratio possible at 3T and parallel imaging to acquire data faster and eliminate motion artifact.
In the liver, she hopes to use 3T to construct a comprehensive MR exam, one whose improved spatial resolution will visualize smaller tumors than can be seen at 1.5T, while acquiring functional data using perfusion- and diffusion-weighted imaging.
The Mayo Clinic has already shown that 3T of the prostate can change clinical practice. At this field strength, Amrami and colleagues have visualized an accessory blood vessel serving the penis, a vessel present in up to 20% of patients undergoing prostate interventions but not easily seen on 1.5T. This vessel, she said, must remain intact to protect sexual function. Providing images that allow detailed preoperative planning has already changed the way these cases are being managed at Mayo.
"The clinicians love it and want us to do all preop prostates on 3T," she said.
Research may further refine the patient protocol thanks to the increased spatial resolution possible at 3T. Future protocols may involve spectroscopy as well, to help identify small malignant lesions in the prostate, a capability that will become more important with the development of minimally invasive techniques using ablative technologies.