RESUMEN
We describe the technique and the measure of the relaxation time T2 for the free precession of protons in the earth field. In vitro and in vivo experiments on human physiological fluids, including blood coagulation, are reported. We put forward the evident interest of this technique to study the meconium in the amniotic liquid and small quantities of oscite observed in situ.
Asunto(s)
Líquidos Corporales , Espectroscopía de Resonancia Magnética , Líquido Amniótico , Líquido Ascítico , Coagulación Sanguínea , Femenino , Humanos , Espectroscopía de Resonancia Magnética/instrumentación , Meconio , EmbarazoRESUMEN
Dispersion curves of the longitudinal relaxation T1 of protons in healthy amniotic fluid in a meconium solution are distinct at low Larmor frequencies (V0 less than 100 kHz). We are thus able to distinguish these fluids by T1 measurements in this range.
Asunto(s)
Líquido Amniótico/análisis , Enfermedades Fetales/diagnóstico , Meconio/análisis , Femenino , Humanos , Espectroscopía de Resonancia Magnética/métodos , Embarazo , Diagnóstico PrenatalRESUMEN
In order to show that for a possible application in medical diagnosis NMR-relaxation experiments at low Larmor frequencies (v0 less than or equal to 20 kHz) are more sensitive than the up to now done high field measurements in the MHz-range, we present dispersion curves (v0 = 50 Hz to 50 MHz) of the proton longitudinal relaxation time T1 and values of the transversal relaxation time T2 for the example of amniotic fluids. Only for Larmor frequencies below congruent to 100 kHz the relaxation times for healthy amniotic fluid and pathological meconium solutions are significantly different, whereas at high Larmor frequencies, i.e. in the conventional MHz-range, the observed changes are rather small.
Asunto(s)
Líquido Amniótico/análisis , Meconio/análisis , Técnicas de Laboratorio Clínico , Femenino , Humanos , Espectroscopía de Resonancia Magnética/métodos , Embarazo , Diagnóstico Prenatal/métodosRESUMEN
Measurements are reported of NMR relaxation times (T2) on hydrogen in water of isotonic NaCl solutions and of normal human amniotic fluid in which known concentrations of meconium (fetal feces) were dissolved. Magnetic fields for resonance of 23.5 X 10(3) and 0.6 oersteds were used. From the measured T2 values, reliable estimates of meconium concentrations could be obtained that might be considered estimates of fetal distress. Observed minor variation of T2 values was probably due to the mucopolysaccharides comprising 80% of the meconium weight. Advantages of this technique for possible clinical use in obstetrics include small volume of sample required (0.1 ml), lack of necessity for sample filtration or centrifugation, and shortness of time required for analysis (less than 30 min).