Purpose: In performing human MREIT imaging experiments, we addressed two technical issues of the chemical shift artifact and measurement noise. In this study, we present improved conductivity images of in vivo human lower extremity using the chemical shift artifact correction and multi-echo methods. Methods: To remove the chemical shift artifact in both MR magnitude and phase images, the three-point Dixon's waterfat separation technique was modified for MREIT. Since the knee is more sensitive to injection currents, we limited the current amplitude in knee experiments to 3 mA to avoid painful sensation. We implemented this technique by incorporating a lately developed multi-echo based MREIT pulse sequence to enhance MR signals themselves and also by prolonging the total current injection time. Results: Experimental results clearly show that the correction method effectively eliminates artifacts related with the chemical shift phenomenon in reconstructed conductivity images. The multi-echo method is advantageous in terms of SNR of MR magnitude, noise level of Bz compared with single-echo. The chemical shift artifact correction using multi-echo method allowed conductivity image reconstruction of the knee with 3 mA injection currents. Conclusions: We expect that MREIT conductivity imaging incorporating both the chemical shift artifact correction and multi-echo pulse sequence would accelerate further experimental MREIT studies.
- Chemical shift artifact correction
- Conductivity image
- Human lower extremity
- Magnetic resonance electrical impedance tomography
ASJC Scopus subject areas
- Biomedical Engineering