title: 1991 I.I. Rabi Award. Estimating oxygen saturation of blood in vivo with MR imaging at 1.5 T.
abstract: The use of magnetic resonance (MR) imaging is investigated for noninvasively estimating the oxygen saturation of human blood (%HbO2) in vivo by means of relaxation characteristics identified in earlier MR spectrometry studies. To this end, a sequence is presented for determining the T2 of vascular blood in regions in which motions of the body and of the blood itself present a major challenge. With use of this sequence on a commercial 1.5-T whole-body imager, the relationship between the T2 and %HbO2 of blood is calibrated in vitro for the conditions expected in vivo. T2 varies predictably from about 30 to 250 msec as %HbO2 varies from 30% to 96%. T2 values measured in situ for vascular blood in the mediastinum of several healthy subjects qualitatively reflected the behavior observed in vitro. Estimates of %HbO2 for these vessels obtained with the in vitro calibration appear reasonable, particularly for venous blood, although difficulties arise in selecting the appropriate calibration factors. These encouraging initial results support a more systematic study of potential sources of error and an examination of the accuracy of in vivo measurements by comparison with direct measurements of %HbO2 in vessels.
authors.affiliation: Magnetic Resonance Systems Research Laboratory, Stanford University, CA 94305.
authors.forename: G A
authors.initials: GA
authors.lastname: Wright
authors.forename: B S
authors.initials: BS
authors.lastname: Hu
authors.forename: A
authors.initials: A
authors.lastname: Macovski
mesh_terms: D001363:Awards and Prizes; D002138:Calibration; D006801:Humans; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008961:Models, Structural; D010100:Oxygen / Q000097:blood*; D011871:Radiology; D012955:Societies, Medical; D014481:United States
chemical_list: D010100:Oxygen