Feasibility of NMR Detection of Decompression Bubbles

The reported program had four tasks 1 construct the bubble generator and modify the NMR equipment to contain it 2 make the NMR measurements and determine T11, T12, and T2 in blood samples both with and without bubbles of oxygen, air, and nitrogen and 3 obtain a magnetic resonance image MRI of the knee and calculate the values of T1 and T2 in the synovial fluid in the knee and 4 final report. All of these tasks were completed. The bubble generator and the equipment modifications were made, tested successfully, and used to make two sets of NMR measurements on 25 samples of blood, in one sample of plasma and in two samples of water. Each sample had one of the following conditions oxygen tonometer, oxygen bubbles, air tonometer, air bubbles, nitrogen tonometer, or nitrogen bubbles. In addition, some NMR measurements were made with flowing bubbles. From the NMR data, the relaxation times T2, T11, and T12 were calculated. Two references were found which reported data that showed that the value of T2 varied directly with the percent oxyhemoglobin and this condition was verified by the NMR measurements. From the data, it was concluded that it was feasible to use NMR measurements in blood to indicate the difference between fixed oxygen bubbles, fixed air bubbles, and fixed or flowing nitrogen bubbles in blood. jhd