High-temperature superconducting (HTS) coil is one of the best ways to increase the signal-to-noise ratio (SNR). Bi2Sr2Ca2Cu3Ox (Bi-2223) tapes were suitable to use because of the easier fabrications and lower cost. In this study, we built HTS Bi-2223 tape coils and demonstrated that the SNR of using the HTS tape coil was 3 or 4 folds higher than that of the traditional copper coil for a rat brain MR study. Acquisition time of MR diffusion tensor imaging (DTI) can be reduced by factor of 9 for the same signal-to-noise. Accuracy of fiber tracking using DTI is also significantly improved by a factor of 2.5 or so using HTS coil. In summary, with this HTSC system, a 3T MR system could reach the high signal-to-noise of 12 T MR system with the advantage of less T2 shortening effects at high field. Currents researches are focused on brain connectivity and fMRI studies.