In vitro and in vivo studies of H-1 NMR visibility to detect deoxyhemoglobin and deoxymyoglobin signals in myocardium

H-1 nuclear magnetic resonance (NMR) spectroscopy can be used noninvasively to detect the proximal histidyl NK proton signals of deoxymyoglobin in the myocardium. However, the quantification of deoxymyoglobin is based on the assumption that the deoxymyoglobin signal detected is not contaminated by t he deoxyhemoglobin signals contributed from the blood. The purpose of this study was to conduct in vitro and in vivo H-1 NMR studies to examine the in vivo NMR visibility of deoxyhemoglobin in the myocardium, The results demo nstrate that the NMR visibility of alpha and beta subunits of deoxyhemoglob in is sensitive to the pulse width for spin excitation because of short T-2 relaxation times, and they are not NMR visible in the canine myocardium in vivo at 4.7 T when a 0.5-1.0 msec long Gaussian excitation pulse is used. Therefore, the resonance peak detected at similar to 72 ppm (relative to th e water resonance) in the ischemic canine myocardium in vivo is dominated b y deoxymyoglobin. Magn Reson Med 42:1-5, 1999. (C) 1999 Wiley-Liss, Inc.