Magnetic Resonance Water Tracer Imaging Using 17O-Labeled Water

Abstract

Magnetic resonance imaging (MRI) is a crucial imaging technique for visualizing water in living organisms. Besides proton MRI, which is widely available and enables direct visualization of intrinsic water distribution and dynamics in various environments, MR-WTI (MR water tracer imaging) using 17O-labeled water has been developed, benefiting from the many advancements in MRI software and hardware that have substantially improved the signal-to-noise ratio and made possible faster imaging. This cutting-edge technique allows the generation of novel and valuable images for clinical use. This review elucidates the studies related to MRI water tracer techniques centered around 17O-labeled water, explaining the fundamental principles of imaging and providing clinical application examples. Anticipating continued progress in studies involving isotope-labeled water, this review is expected to contribute to elucidating the pathophysiology of various diseases related to water dynamics abnormalities and establishing novel imaging diagnostic methods for associated diseases.

Human brain clearance imaging: Pathways taken by magnetic resonance imaging contrast agents after administration in cerebrospinal fluid and blood

“…It should be noted that these mainly monitor water transport across the BBB or from blood‐to‐CSF, and therefore only provide information on a small, although potentially important, part of the brain clearance system. Interestingly, these phenomena can also be studied with O17‐H2O MRI, which provides a completely complementary viewpoint to the Gd‐based contrast agent for probing the brain clearance system and has the advantage over ASL that it does not suffer from fast decay times 144,145 . The diffuse, and not centripetal, enhancement of intrathecally injected O17‐H2O in one study may suggest that water is quickly resorbed by blood vessels and recirculated into brain, 146 which may be corroborated by the observations of large, continuous water fluxes over the vessels wall by ASL 26 .…”

Imaging of ¹⁷O-labeled Water Using Fast T2 Mapping with T2-preparation: A Phantom Study

“…9 Recently, attempts have been made to visualize CSF dynamics in vivo through intrathecal administration of 17 O-labeled water. 6,10,11 These reports did not use a direct method ( 17 O-nuclear MR), which requires specialized hardware and sequences. Instead, an indirect method using scalar coupling with protons (J = 92.5 Hz) was employed, allowing 17 O-labeled water to be used as a T2-shortening contrast agent in proton MRI.…”