WATER-MACROMOLECULAR PROTON MAGNETIZATION-TRANSFER IN INFARCTED MYOCARDIUM - A METHOD TO ENHANCE MAGNETIC-RESONANCE IMAGE-CONTRAST

Water proton nuclear magnetic resonance relaxation times and magnetiza tion transfer (MT)-parameters of rat hearts were studied 24 h or 4 wee ks after ligation of the left coronary artery or sham operation. Compa red with sham-operated controls, measured relaxation times (T-1sat, an d T-2) of both acute and chronic myocardial infarction increased. The MT effect significantly decreased in the infarcted myocardium. The cha nges in relaxation times and MT effect were significantly greater in c hronic infarcts compared with acute infarcts. Improvements in calculat ed image contrast between normal and infarcted tissue were supported b y images of ex vivo hearts with chronic infarction. Image contrast was increased at short echo times in the presence of macromolecular proto n pool irradiation. Exploiting changes in tissue MT following myocardi al infarction to enhance contrast between normal and infarcted tissue should allow improved identification and characterization of infarcted myocardium.