Hyperpolarized Xenon MRI Biosensors Development Program

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Hyperpolarized (HP) Xenon magnetic resonance (MR) imaging biosensors have the potential to revolutionize the detection and characterization of disease and may perhaps one day provide a lower cost complement to positron emission tomography (PET) as a preferred method of molecular imaging. MR imaging biosensors have high spatial resolution (similar to MRI) with high sensitivity (similar to PET) without any of the ionizing radiation associated with PET. Additionally, xenon imaging biosensors are of significantly lower cost than PET. This lower cost and lack of ionizing radiation make these imaging biosensors more conducive to more frequent imaging studies.***Molecular imaging is inherently non-invasive and therefore may have considerably lower risk to a patient than current histological or pathological studies (surgical biopsies). Imaging biosensors are designed to have a high affinity to a particular pathological molecule or cell within the body. These pathological areas of interest can be detected by applying one of many imaging modalities. Furthermore, molecular imaging may even differentiate between different forms of a particular disease. For example, molecular imaging has the potential to differentiate between two similar cancerous tumours: one which warrants aggressive treatment and another subtype which is better treated in a more conservative way. ***HP Xe MR imaging biosensors use a cage molecule that encapsulates a xenon atom. The applicants recently obtained the first ever in vivo images of a xenon biosensor contrast agent, paving the way for the creation of xenon gas imaging biosensors. In this project, we propose to develop, characterize and test, first in vitro and then in vivo, Xe imaging biosensors that will extend HP imaging with sensitive biosensors. In this research program, by combining a xenon cage molecule with a variety of affinity tags, we will develop biosensors and perform the basic research and engineering that will make HP Xe imaging a practical and affordable alternative to conventional PET imaging techniques. We intend to use our resources and expertise in HP gas MRI to address engineering challenges in fundamental chemistry and MRI engineering that will make HP gas imaging possible in vivo on the molecular level. This technique would have PET-like sensitivity with MRI-like resolution, without the use of ionizing radiation, all at a lower cost than existing PET studies. The fulfillment of our program goals have the potential to eventually render invasive biopsies a thing of the past.