Multichannel transceiver dual-tuned RF coil for proton/sodium MR imaging of knee cartilage at 3 T

In vivo sodium MR imaging of the abdomen at 3T

“…The SNR reported in this work for abdominal imaging is slightly lower than the literature reported SNR of ~36 for volume type bird cage sodium coils developed for knee and brain imaging applications but considering that the coil presented in this work is a surface-type phased-array coil, the SNR is optimal and adequate for abdominal sodium imaging and has SNR comparable to abdominal sodium work presented by Steidle et al [26]. The in-plane resolution achieved with this coil (0.3 × 0.3 cm 2 ) is also comparable to the reported values [27, 28]…”

Quantitative 23Na MRI of human knee cartilage using dual‐tuned 1H/23Na transceiver array radiofrequency coil at 7 tesla

“…High‐resolution 1 H knee images were obtained using a three‐dimensional (3D) fast double echo and steady state (DESS) sequence (flip angle = 25°, repetition time/echo time [TR/TE] = 15/5 ms, slice thickness = 1.5 mm, in‐plane resolution = 0.57 mm 2 ). Without repositioning the subject, 23 Na MRI was performed using 3D ultra‐short‐echo‐time (UTE) spiral sequence (TR/TE = 100/0.27 ms, flip angle = 90°, isotropic resolution = 1.7–5 mm 3 , and total acquisition time = ∼15 min) . The spiral trajectory was designed with maximal gradient amplitude of 34 mT/m and maximal slew rate of 150 T/m/s.…”

Unshielded asymmetric transmit-only and endorectal receive-only radiofrequency coil for23Na MRI of the prostate at 3 tesla

“…15 Unfortunately, this method has a high specific absorption rate, low signal-to-noise ratios, and requires specific corrections for the inhomogeneities caused by the sensitivity to the B 1 and B 0 fields 16,17 and its in vivo application remains challenging. Most recently, 3T human 23 Na MRI has been applied to knee, 18 brain 19 and prostate of healthy volunteers in which external 12 or internal (invasive) 20,21 RF resonators were used. While 23 Na resonators such as endorectal (ER) RF coils (invasive) may seem less desirable due to the nature of the procedure or where distortion of the gland is not acceptable, e.g., for biopsy or radiation treatment planning, a significantly higher SNR can be achieved due to the proximity of the coil to the prostate compared with external resonators.…”