Dual current injection-magnetic resonance electrical impedance tomography using spatial modulation of magnetization

Naji, Nashwan
Electrical conductivity of biological tissues provides valuable information on physiological and pathological state of tissues. This may provide conductivity imaging a great potential to have diagnostic applications in clinical field. Developing a method that is able to recognize conductivity variations inside human body has received a great attention over the last decades. Magnetic Resonance Electrical Impedance Tomography (MREIT) is an imaging modality that utilizes current injection during magnetic resonance imaging to visualize conductivity distributions. In conventional MREIT pulse sequence, current is injected once in each repetition time (TR), which makes scan time quite long. Reducing imaging time helps in avoiding motion artifacts and reducing patient discomfort. In addition, a shorter scan time facilitates improving Signal-to-Noise Ratio (SNR) by averaging, and obtaining 3D images. In this thesis, a novel MREIT pulse sequence is proposed to reduce scan time by injecting two current profiles in each TR. This pulse sequence utilizes Spatial Modulation of Magnetization (SPAMM) technique to make recovering magnetic flux information due to each injected current profile achievable. This concept is implemented in two different pulse sequences, Spin-Echo (SE) and Gradient-Echo (GE), and evaluated using simulation models and phantom experiments. The performance of the proposed method is investigated in SNR, minimum measurable current and T 2* relaxation effect. Obtained results demonstrated that the proposed method is able to collect data twice faster with retained resolution, in comparison with the conventional MREIT.