Mixing oxygen with hyperpolarized (3)He for small-animal lung studies.

Published

Journal Article

Hyperpolarized helium (HP (3)He) is useful for direct MR imaging of the gas spaces of small animal lungs. Previously, breaths of 100% HP (3)He were alternated with breaths of air to maximize helium signal in the lungs and to minimize the depolarizing effects of O(2). However, for high-resolution imaging requiring many HP (3)He breaths (hundreds) and for pulmonary disease studies, a method was needed to simultaneously deliver O(2) and HP (3)He with each breath without significant loss of polarization. We modified our existing computer-controlled ventilator by adding a plastic valve, additional relays and a controller. O(2) and HP (3)He are mixed at the beginning of each breath within the body of a breathing valve, which is attached directly to the endotracheal tube. With this mixing method, we found that T(1) relaxation of HP (3)He in the guinea pig lung was about 20 s compared to 30 s with alternate air/HP (3)He breathing. Because imaging times during each breath are short (about 500 ms), the HP (3)He signal loss from O(2) contact is calculated to be less than 5%. We concluded that the advantages of mixing HP (3)He with O(2), such as shorter imaging times (reduced T(1) losses in reservoir) and improved physiologic stability, outweigh the small signal loss from the depolarizing effects of oxygen on HP (3)He.

Full Text

Duke Authors

Cited Authors

  • Hedlund, LW; Möller, HE; Chen, XJ; Chawla, MS; Cofer, GP; Johnson, GA

Published Date

  • June 2000

Published In

Volume / Issue

  • 13 / 4

Start / End Page

  • 202 - 206

PubMed ID

  • 10867697

Pubmed Central ID

  • 10867697

International Standard Serial Number (ISSN)

  • 0952-3480

Language

  • eng

Conference Location

  • England