| Objective：The purpose was to study the feasibility of measuring blood oxygen saturationusing MRI and discuss its application in non-invasive coronary sinus blood oxygensaturation measurement., Furthermore it describes the application of this method indetecting the myocardial oxygen consumption according to Fick’s law. At last, studythe application of noninvasive MRI of myocardial oxygen consumption in healthypeople and the patients with Heart Failure With Normal Left Ventricular EjectionFraction.Materials and methods：1.In the study of blood oxygen saturation using MRI, in vitro preparation of8groups of venous blood samples, and blood oxygen saturation was between30%to94%.Five groups were succeeded prepared.The five groups of samples undergoecho spin echo sequence scaning, measuring T2values in each samplegroup.According to the chemical model of Luz-Meiboom1/T2=1/T2O+K(1-100%%HbO2/)2, the use of Matlab software for the least squares curve fitting,getting the curving of blood oxygen saturation-T2, and ultimately determine the Kvalue and T2O;2. In the study of noninvasive coronary sinus oxygen saturation usingMRI, recruited6healthy people for the research.The sepuence of MRI was multipleecho spin echo sequence, and the location was coronary sinus respectively0mm,10mm,20mm,30mm,40mm,50mm distance to the coronary sinus ostium. Andaccording to the first part of the%HbO2-T2curving, calculate the correspondingblood oxygen saturation, and determine the accurate positioning standards;3. MRI ofcoronary sinus blood oxygen in the quantitative method in the application ofmyocardial oxygen consumption measurement, according to Fick’s law, namely themyocardial oxygen consumption MVO2={(%aO2%csO2)×CBF×[Hb]×1.36per 100g1.36per100g left ventricular mass}.If we can get coronary blood flow,coronary sinus blood oxygen saturation and the myocardial mass, we can caculateMVO2.30healthy people as the research object, male15cases and female15cases.Then all research objects undergo MRI scaning, including FIESTA, film phasecontrast sequences and multiple echo spin echo sequence scan. The imagings of theFIESTA and film phase contrast image sequences diliver to GE AW ReportCARDsoftware, and obtain the blood flow of left anterior descending coronary artery andleft ventricular mass.And left ventricular mass is left ventricular volume multipliedby the myocardial density (1.05g/l).Coronary arterial blood oxygen saturationobtained from peripheral arterial blood gas analysis, hemoglobin concentrations wasobtained from a hematology test, integrated the above data, according to Fick’s lawof computing MVO2;4. In clinical application,25patients with normal ejectionfraction of heart failure as case group,30cases of healthy volunteers as controlgroup, all samples undergo MRI examination,and7cases of patients with cardiaccatheterization examing, extract the coronary vein blood samples for laboratorymeasurement of blood oxygen saturation, case group and control group’ results wereapplied comparative t test to perform statistical analysis, while coronary venousblood oxygen saturation values in MRI quantitative method and cardiaccatheterization method made a correlation analysis, to evaluate the feasibility andaccuracy of MRI noninvasive myocardial oxygen consumption method.Result:1.As the blood samples of blood oxygen saturation increases, the T2values alsoshowed a trend of increasing, and the K and T2O value were14.036s-1、229.5157msec.2. In MRI of noninvasive coronary sinus blood oxygen saturation measurement,the closer to the coronary sinus ostium, the higher coronary venous blood oxygensaturation was. Within the30mm to the coronary sinus ostium, the coronary venousblood oxygen saturation changed significant (（Δ%csO2）0-30mm=20.500±2.074%）),and coronary venous blood oxygen saturation almost no significant change at greater than30mm away to the coronary sinus ostium (（Δ%csO2）30-50mm=4.833±1.329%).3. The application of MRI in myocardial oxygen consumption measurement inhealthy cases shows, males and females’ left anterior descending coronary arteryblood flow,%csO2, left ventricular mass and myocardial oxygen consumptionrespectively were111.32±16.57ml/min,50.80±4.36%,124.56±12.36g,10.56±2.10ml（/min·100g）and110.18±14.92ml/min,49.20±5.17%,86.80±9.38g,7.80±1.82ml/（min·100g）.The left ventricular mass and myocardial oxygen consumptionstatistical differences between males and females (P <0.05), the average leftanterior descending coronary artery blood flow,%csO2has no statistical differencebetween males and females (P>0.05).4. In the study of MRI noninvasive myocardial oxygen consumptionmeasurement method in normal ejection fraction of heart failure, case group’s andcontrol group’s left anterior descending coronary artery blood flow、%csO2、leftventricular mass and myocardial oxygen consumption respectively were165.69±13.42ml/min、30.77±4.71%、115.75±17.25g、16.631±3.33ml/（min·100g）and110.75±15.50ml/min、50.00±4.77%、105.68±22.01g、9.18±2.39ml/（min·100g）.The left anterior descending coronary artery blood flow,%csO2andmyocardial oxygen consumption statistical differences between the case group andcontrol group (P <0.05), the quality of myocardial no statistical difference betweencase group and control group (P>0.05).In addition, magnetic resonance imaging(MRI) and cardiac catheterization method measuring coronary venous blood oxygensaturation in the comparative study shows, there is no statistical difference betweengroups (P=3.867, P>0.05), correlation analysis showed that significant linearcorrelation between (R=0.812, P=0.812).Conclusion1. The MRI T2value can reflect the blood oxygen saturation, and T2values andthe blood oxygen saturation.have the inherent relationship.2. MRI echo more spin echo sequence can quantitatively measure the coronaryvenous blood oxygen saturation, and the blood oxygen saturation is closer to the real value in the distance of coronary sinus ostium30mm.3. The MRI can quantitatively measure the myocardial oxygen consumption,provide a non-invasive method to detect myocardial oxygen consumption forclinical. |
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