Quantitative MRI Research On Transportation Of Magnetic Nanoparticles In Body

A large number of studies have shown that small amount of magnetic nanoparticles (MNPs) can cause obvious magnetic resonance signal enhancement of tissues, which can be displayed by traditional weighted imaging. Based on quantitative magnetic resonance imaging (MRI) technique, this paper quantifies the transportation and distribution of MNPs in body from a macro level, increasing the effectiveness of magnetic targeted tumor therapy.T2-mapping imaging is a kind of quantitative MRI whose basis is T2weighted (T2-W) imaging. This paper improves its stability and clinical feasibility by reducing noises and optimizing acquisition parameters including initial echo, echo number, TR and echo interval. In addition, this study introduces T2-mapping correction, in order to reduce errors brought by flexible and variable choices of sequences and parameters.The biggest shortage of T2-mapping imaging is that it cannot show pathological specificity of tissues, however, multi-component T2analysis can compensate for this shortcoming. One important application of multi-component T2analysis is myelin water imaging. This study introduces two corresponding algorithms, and compares them from various angles, verifying the feasibility of using6T2-W echoes, and reducing scanning time by72%under the guarantee of ensuring image quality.According to a great quantity of comparisons between T2-W and T2-mapping images, it is shown that T2-mapping imaging has more advantages on early diagnoses of diseases related to brain and cartilage tissues. Through comparisons among T2-W, T2-mapping and myelin water imaging, it is shown that myelin water imaging owns superiority over T2-W and T2-mapping imaging in change detection of multi-component T2within brain tissues.Based on T2-mapping imaging, this paper studies the transportation principle of MNPs in body, discovering that the metabolism of MNPs in liver is the fastest. MNPs via intravenous injection reduce T2of liver by22.6%within15mins during its passive targeted transportation with blood circulation, while external gradient magnetic field cannot make MNPs enter into targeted tissues through directed attraction within a certain time.