New chemistry techniques improve hybrid scanner performance

TORONTO — A new PET/MR imaging system has been developed that can successfully provide whole-body images of rats and other small animals, according to researchers at SNM’s 56th Annual Meeting in Toronto. The new system could greatly improve imaging capabilities and advance research in many areas.

“Our system shows great promise because it is able to simultaneously provide the complementary strengths of PET and MRI in imaging rats and small animals,” said Mitsuaki Tatsumi, associate professor of radiology at Osaka University Graduate School of Medicine and Medical Hospital, Osaka, Japan. “This ability opens up exciting new opportunities in research in terms of increased understanding of kinetics, biodistribution of radiopharmaceuticals and, eventually, disease characteristics and physiological processes. Next steps include imaging body tumors in rats or mice and developing PET/MRI systems that can image people.”

A combined PET/MRI system delivers specific molecular information related to cell surface reactors, enzymes and gene expression that PET provides as well as important anatomical data, soft-tissue contrast and information about perfusion and permeability shown in MRI — at the same time.

The new combined PET/MRI system is a step forward from previous combined systems because it can image the bodies of rats and mice rather than just the brains. The system consists of depth-of-interaction block detectors and a permanent magnet for MRI.

In the study, researchers injected rats with the radionuclide C-11 methionine for PET imaging and with Gadoxetate for contrast MRI imaging. Simultaneous PET and MR imaging was performed from head to abdomen. PET, MR and co-registered fusion images were then evaluated for image quality.

The simultaneous PET/MRI system provided quality images in spite of the short half-life of C-11. The images showed excellent mapping of the liver and kidneys. C-11 methionine is known to accumulate in the pancreas, but it would have been difficult to image without clear mapping MR images. The use of Gadoextate as a contrast agent enhanced the power of the integrated PET/MRI system.

Scientific Paper 7: M. Tatsumi, Department of Radiology, Osaka University Graduate School of Medicine and Medical Hospital, Osaka, Japan, “Simultaneous C-11 Methionine (MET) PET and contrast-enhanced (CE) MRI rat imaging with an integrated PET/MRI system,” SNM’s 56th Annual Meeting, June 13-17, 2009.

About SNM — Advancing Molecular Imaging and Therapy

SNM is an international scientific and medical organization dedicated to raising public awareness about what molecular imaging is and how it can help provide patients with the best health care possible. SNM members specialize in molecular imaging, a vital element of today’s medical practice that adds an additional dimension to diagnosis, changing the way common and devastating diseases are understood and treated.

SNM’s more than 17,000 members set the standard for molecular imaging and nuclear medicine practice by creating guidelines, sharing information through journals and meetings and leading advocacy on key issues that affect molecular imaging and therapy research and practice. For more information, visit www.snm.org.

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