Introduction: T1 mapping is a very effective quantitative MRI method. By changing the T1 relaxation time, we can ascertain the level of tissue damage. Variable flip angle pulse sequence is based on T1-weighted gradient echo pulse sequence, and is a very useful method of imaging abdominal organs. In doing so, we employ two or more different flip angles, for non-linear T1 curve fitting to calculate the T1 map. Dissolved oxygen has paramagnetic properties. As the level of oxygen dissolved in blood increases, partial arterial pressure increases as well, which is reflected in altered T1 relaxation time. Purpose: The fact that dissolved oxygen shortens T1 relaxation time is known; however, that researches have limitations. The purpose of the following master’s thesis is to reaffirm the technique of T1 mapping by using the method of variable flip angle and inhalation of 100% oxygen to assess liver damage in mice. Method: We have included 16 mice in the research, and divided them in groups of eight. The first group was injected with a toxin during the imaging, whereas the second group was injected with a solvent. Magnetic-resonance protocol consisted of pulse sequence with spin echo for orientation, pulse sequence with the variable flip angle method, and pulse sequence with the method of actual flip angle. Firstly, the mice were breathing air during imaging, which was followed by 100% oxygen. After that we have intraperitoneally injected either the toxin or the solvent, and repeated the imaging both while breathing air and 100% oxygen. We analyzed and statistically examined the images by using MatLab. Results: T1 relaxation time while breathing air before the application was 936.1 ± 240.4ms. After breathing 100% oxygen, T1 relaxation time was shortened by 261.4ms (674.7 ± 230ms). The results included all the healthy mice. After the application of the toxin while breathing air in the first group (n = 8), T1 was 639.6 ± 216.1ms. While breathing 100% oxygen, T1 relaxation time differed by 70.8ms. After the application of the solvent in the second group, T1 relaxation time during breathing of air was 1403.88 ± 327ms. While breathing 100% oxygen, the T1 relaxation time was shortened by 377,6ms (1026,2 ± 245,8ms). Discussion and conclusion: The research shows that there is a significant shortening of T1 relaxation time occurring when breathing 100% oxygen in comparison to breathing air at normal liver functioning. After the application of the toxin this effect was not detected. The toxin influences liver functioning. We assume that livers no longer absorbed oxygen. This is the reason why T1 relaxation time did not shorten further after breathing 100% oxygen. The typical effect of shortening T1 relaxation time was measured in the second group after the application of the solvent while breathing oxygen in comparison to breathing air. However, T1 relaxation time was lengthened while breathing air in contrast to the base state before the application. Other than alcohol, the solvent also consisted physiological solution, as water may increase the T1 relaxation time. We believe that T1 mapping with pulse sequencing of variable flip angle and the usage of 100% oxygen is a good method for assessing liver function.
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