A Multitransmit External Body Array Combined With A H-1 And P-31 Endorectal Coil To Enable A Multiparametric And Multimetabolic Mri Examination Of The Prostate At 7t

Purpose In vivo H-1 and P-31 magnetic resonance spectroscopic imaging (MRSI) provide complementary information on the biology of prostate cancer. In this work we demonstrate the feasibility of performing multiparametric imaging (mpMRI) and H-1 and P-31 spectroscopic imaging of the prostate using a P-31 and H-1 endorectal radiofrequency coil (ERC) in combination with a multitransmit body array at 7 Tesla (T). Methods An ERC with a P-31 transceiver loop coil and H-1 receive (Rx) asymmetric microstrip (P-31/H-1 ERC) was designed, constructed and tested in combination with an external 8-channel H-1 transceiver body array coil (8CH). Electromagnetic field simulations and measurements and in vivo temperature measurements of the ERC were performed for safety validation. In addition, the signal-to-noise (SNR) benefit of the H-1 microstrip with respect to the 8CH was evaluated. Finally, the feasibility of the setup was tested in one volunteer and three patients with prostate cancer by performing T-2-weighted and diffusion-weighted imaging in combination with H-1 and P-31 spectroscopic imaging. Results Electromagnetic field simulations of the P-31 loop coil showed no differences in the E- and B-fields of the P-31/H-1 ERC compared with a previously safety validated ERC without H-1 microstrip. The hotspot of the specific absorption rate (SAR) at the feed point of the P-31/H-1 ERC loop coil was 9.42 W/kg when transmitting on P-31 at 1 W. Additional in vivo measurements showed a maximum temperature increase at the SAR hotspot of 0.7 degrees C over 6 min on P-31 at 1.9 W transmit (Tx) power, indicating safe maximum power levels. When transmitting with the external H-1 body array at 40W for 2:30 min, the temperature increase around the ERC was We developed a setup with a P-31 transceiver and H-1 Rx endorectal coil in combination with an 8-channel transceiver external body array coil and demonstrated its safety and feasibility for obtaining multiparametric imaging and H-1 and P-31 MRSI at 7T in patients with prostate cancer within one MR examination.