ИСТИНА

The problem which is being considered by our group now is to make an optimal protocol of 23Na MR study for small animals (rat, mouse) on 7T MR scanner Bruker Biospec 70/30 USR. We made 14 phantoms with different concentrations of NaCl (0.05, 0.1, 0.14 and 5.3 M) and gelatine (0, 1, 2 and 4%). Distillated water was used as a solvent in all cases. Each phantom was enclosed in a plastic vial with the volume 14 ml. The protocol of study comprises two parts: proton and sodium. The first one consists of shimming and localizing. The 23Na part includes obtaining of 23Na MR spectrum and image. The FID signal for 23Na MRS was acquired with a 90° single pulse of duration 90 μs. The linewidth of 23Na peaks is in the range from 35 to 45 Hz. 3D FLASH method is applied for 23Na MRI with the following parameters: TR/TE = 10/3.8 ms, FA = 30°, FOV = 6×4×4 cm, MTX = 64×64×8. We used RARE-VTR and MSME pulse sequences to measure T1 and T2 values. Sodium nuclei excitation and signal reception were implemented by means of a radiofrequency surface coil with 2 cm internal diameter. The 23Na coil is a modified proprietary transceiver coil T6614 originally tuned to the 13C frequency.