Recovery and Recycle of Xenon Isotopes for High Resolution MRI and SPECT

50348-98-I Recovery and Recycle of Xenon Isotopes for High Resolution MRI and SPECT--Creare, Inc., Etna Road, P.O. Box 71, Hanover, NH 03755-0071; (603) 643-3800 Mr. Michael G. Izenson, Principal Investigator Dr. W. Dodd Stacy, Business Official DOE Grant No. DE-FG02-98ER82558 Amount: $50,348 Xenon gas that is isotopically enriched with a variety of xenon isotopes can be used as an inhaled or injected imaging agent to produce very clear images of specific organs and blood flow by magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT). These images are vital for accurate diagnosis and treatment of brain and lung disorders. However, the enriched xenon are extremely expensive, and relatively large amounts are required for each clinical study. Current xenon dispenser and recovery systems trap the gas in a charcoal activated filter which is later disposed of, wasting the xenon isotope, greatly increasing the cost of each procedure, and adding to the radioactive waste stream. This project deals with a method to enable widespread use of expensive xenon isotopes in MRI and SPECT imaging. The innovation is a cryogenic gas trap that separates the xenon from the patient¿s exhaled breath and stores it for re-use. Phase I will prove the feasibility by demonstrating the operation of a compact xenon separation system. Efficient xenon recovery will be demonstrated in a cryogenic gas trap, an optimal cryocooler will be selected, and a system that can be integrated with existing xenon dispenser systems will be designed. Phase II will complete the development of a prototype and operation will be proved in clinical trials. Commercial Applications and Other Benefits as described by the awardee: The xenon recovery and recycle system will be a key component in xenon dispensers for low-cost, high-resolution magnetic resonance imaging (MRI) of blood flow and organs. The system can also be used to reduce the cost of high-resolution images made by single photon emission computed tomography (SPECT) using trace amounts of extremely expensive radioactive xenon isotopes._